Enhance Monitoring

Enhancing Campervan Safety and Efficiency with Battery Monitoring Systems

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Monitoring a battery isn’t just about reading its voltage. Something to remember is that battery voltage isn’t equivalent to state of charge, this is a common misconception that’s made. For a more detailed idea of battery and system health, we need to employ a battery monitoring system.

Incorporating a battery monitoring system into a campervan offers numerous benefits, including efficient power management, enhanced safety, and optimised battery maintenance. With real-time data and alerts, you can make informed decisions, avoid battery-related issues, and extend the lifespan of their battery system. As technology continues to advance, battery monitoring systems will undoubtedly play a vital role in ensuring a reliable and enjoyable experience in your campervan, ensuring peace of mind.

One of the primary advantages of a battery monitoring system is its ability to optimise power management in a campervan. By monitoring the battery’s state of charge and voltage, users can accurately gauge the remaining capacity and plan their energy consumption accordingly. This prevents over-discharging the batteries, which can lead to irreversible damage and decreased lifespan.

Safety

Battery monitoring systems play a vital role in the safety of your campervan. By monitoring battery parameters, these systems can detect anomalies and provide early warnings about potential issues such as overcharging, overheating, or voltage fluctuations. This enables you to take prompt action to prevent accidents, electrical failures, or even fires.

Additionally, a battery monitor can safeguard against dangerous situations like overloading. By monitoring the current flow, the system can prevent excessive strain on the battery, minimising the risk of overheating, electrical fires, or damage to sensitive electronic equipment.

Think of your battery monitoring system as your first line of defence against faults. It’s likely that it’ll detect minor issues and notify you via your smartphone or controller. This is a very handy and useful safety tool to have installed within your system.

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Maintenance & longevity of your battery system

Maintaining the batteries in a campervan is crucial for their longevity and overall performance.

Battery monitoring systems simplify this process by providing insights into battery health, allowing users to detect early signs of degradation or malfunction. This proactive approach enables campervan owners to take timely action, such as replacing aging batteries or adjusting charging patterns, before a complete failure occurs.

Additionally, some battery monitoring systems offer historical data analysis, providing trends and patterns related to battery usage. This information can help optimise battery maintenance schedules and ensure the batteries maximum lifespan.

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Real time data and remote monitoring

Battery monitoring systems offer real-time data visualisation, allowing you to monitor battery performance at a glance. Additionally, with wireless connectivity and smartphone applications, many systems enable remote monitoring and control. This enables you to keep track of your battery’s status even when you are away from your campervan, ensuring peace of mind and allowing for efficient planning of power usage.

A service that we at Tiny Build Electrics offer is remote monitoring and adjustment of your system. With the correct components and setup we can remotely access your system to commission, fault find or adjust the system parameters. This service enables you to get the most from your investment.

If this is something you may be interested in, be sure to drop us a message and we’ll be happy to help.

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Why Victron?

We at Tiny Build Electrics recommend using Victron Energy battery monitoring systems, as they can provide several benefits, including accurate monitoring of your battery’s status, improved battery performance, and increased awareness of your power consumption.

Here are some steps to help you set up and utilise a Victron Energy battery monitoring system in your campervan:

1 – Contact Tiny Build Electrics for a 30 minute consultation: to help you choose the appropriate Victron Energy battery monitoring system. Victron offers various monitoring systems suitable for different applications. The system needs to match your campervan’s battery setup and your monitoring requirements. Popular options include the Smartshunt, BMV-700 or BMV-712 Smart Battery Monitors.

2 – Install the battery monitor: Follow the manufacturer’s instructions to install the battery monitor in your campervan. Typically, this involves connecting the monitor to the battery bank and configuring the appropriate settings.

3 – Connect the shunt: The battery monitor requires a shunt, which is a precision resistor that measures the current flowing in and out of the battery bank. Connect the shunt to the negative battery terminal, following the installation instructions provided. Nothing must bypass the shunt, this is critical in order to receive the most accurate data.

4 – Configure the settings: Once the battery monitor is installed, configure its settings according to your specific battery bank and preferences. This may involve specifying battery type (e.g., lead-acid, lithium), capacity, and other parameters. Tiny Build Electrics can help you configure your settings if you require.

Remember to consult the user manual and resources provided by Victron Energy for detailed instructions specific to your chosen monitoring system. It’s also advisable to ensure your campervan’s electrical system is properly installed and conforms to relevant safety standards to ensure reliable and safe operation.

Confused about which monitoring system you require?

Contact us to book a 30 minute consultation.

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Extending Your Battery’s Lifespan

The batteries in your tiny build are a significant investment and their lifespan directly impacts the overall cost of ownership. A battery monitoring system plays a vital role in extending battery life by providing crucial information on the batteries overall health. It closely monitors the battery’s parameters, it can detect anomalies or irregularities, allowing for timely maintenance or replacement, thereby avoiding unexpected breakdowns and costly repairs.

Understanding and knowing the cycle life of your battery setup is a really handy tool if you’re living on the road and wanting to ensure your campervan is working efficiently. The number of cycles indicates how many times the battery has gone through a complete discharge and recharge cycle. As a battery goes through more cycles, its performance tends to degrade. Knowing the cycle count helps assess how much life the battery has left before it becomes less effective in storing and delivering electrical energy.

Many leisure battery manufacturers provide warranties that cover a certain number of cycles or a specific time period. Keeping track of the cycle count is essential for validating warranty claims. If a battery fails prematurely within the warranty period, the manufacturer may require information about the cycle count to assess whether the failure is covered under warranty.

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Battery Management Systems (BMS)

A Battery Management System (BMS) is an electronic system designed to monitor, control, and safeguard the operation of rechargeable, lithium batteries. It serves as the brain of the battery, continuously monitoring its vital parameters, such as voltage, current, temperature, and state of charge (SOC). The BMS utilises this information to make intelligent decisions and optimise battery performance while ensuring its safe and efficient operation.

Battery Safety

Overvoltage and Undervoltage Protection: The BMS prevents the battery from operating outside safe voltage limits. If the voltage exceeds the upper threshold or drops below the lower threshold, the BMS activates protection mechanisms, such as disconnecting the load or activating safety relays to prevent further damage.

Overcurrent Protection: The BMS monitors the current flowing in and out of the battery. In the event of an excessive current draw or a short circuit, the BMS will intervene to protect the battery from potential damage by disconnecting the circuit or limiting the current flow.

Overtemperature Protection: Batteries are sensitive to temperature extremes. The BMS continuously monitors the battery’s temperature and activates cooling systems or triggers alarms if the temperature exceeds safe limits. It ensures that the battery operates within the recommended temperature range, preventing thermal runaway or premature degradation.

Cell Balancing: In multi-cell battery packs, the BMS ensures that each individual cell is balanced in terms of voltage and capacity. It redistributes charge among cells to equalise their levels, maximising the overall battery performance and longevity.

Battery Performance

State of Charge (SoC) Estimation: The BMS provides accurate SoC information by analysing battery voltage, current flow, and other parameters. This information allows users to estimate the remaining battery capacity and plan their power usage accordingly, preventing over-discharge or overcharge scenarios.

Charging Control: The BMS manages the charging process by regulating the charging voltage and current. It ensures that the battery is charged within the manufacturer’s recommended limits, preventing overcharging and optimising charging efficiency.

Discharge Control: The BMS prevents the battery from discharging beyond safe levels, protecting it from damage. It can disconnect the load or activate warning alarms to alert users when the battery reaches a critical discharge level.

Data Logging and Diagnostics: BMS collects and stores data regarding battery performance and events, allowing users to analyse battery behaviour and identify potential issues. It enables informed decision-making and facilitates troubleshooting if any problems arise.

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Shunts And The Role They Play In Monitoring

A shunt is an essential component that plays a crucial role in monitoring and protecting an electrical system, including the batteries. Let’s dive into how a shunt works and why it is important.

A shunt is typically a precision resistor that allows a small and known fraction of the total current to pass through it. By measuring the voltage drop across the shunt, the current flowing through the circuit can be determined using Ohm’s law (V = I x R), where V is the voltage, I is the current, and R is the resistance (the shunt).

In a battery monitoring system, the shunt acts as a current sensor. It provides an accurate measurement of the current flowing in and out of the battery bank. This information is crucial for monitoring the state of charge, evaluating the efficiency of the charging system, and detecting any abnormalities or faults.

The shunt also serves as a protective measure for the electrical system. By monitoring the current, it can help prevent overcharging or excessive discharge of the batteries. It allows the battery monitoring system to trigger alarms or take corrective actions when the current exceeds safe limits, protecting the batteries from potential damage due to overloading or short circuits.

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Victron Energy Monitoring Systems

Victron Energy offers various battery monitoring systems that allow users to view the data and information displayed by their battery monitor.

Victron BMV-700/702/712: These battery monitoring systems are part of the Victron BMV series. They provide real-time information about battery voltage, current, state of charge (SOC), and time remaining. They have a built-in battery monitor and can be connected to various types of batteries, including lead-acid, lithium-ion, and more.

Victron Lynx Shunt: The Lynx Shunt is a shunt that can be used in larger battery systems or installations with multiple battery banks. It connects to the Victron Lynx Distributor and provides detailed information on current, voltage, SOC, and other parameters for each individual battery bank.

Victron SmartShunt: The SmartShunt is a compact battery monitoring device that connects to a smartphone or tablet via Bluetooth. It provides real-time information on battery voltage, current, SOC, and power consumption. The data can be accessed through the VictronConnect app, making it convenient for monitoring battery status remotely.

Victron Cerbo GX: The Cerbo GX acts as a central hub for monitoring and controlling different aspects of an energy system. It features a touch-screen display and an intuitive user interface that allows you to access and configure various system parameters. It also provides real-time monitoring of energy production, consumption, battery status, and other relevant data.

Conclusion

A battery monitoring system is a valuable addition to any campervan, providing enhanced safety, optimised power usage, and peace of mind.

By monitoring critical battery parameters, campers can avoid potential issues, maximise battery life, and reduce the risk of accidents. Additionally, the ability to remotely monitor and control the battery system offers convenience and flexibility during camping trips. With the advancements in battery monitoring technology, campervan owners can now enjoy their adventures with improved reliability and confidence in their system, making every journey a worry-free experience.

If a monitoring system would suit your electrical system then book in for a 30 minute consultation. Book Now and let us configure an appropriate system for you.

Tom Alderdice

Hey, I’m Tom – founder of Tiny Build Electrics

My mission is to help sustainable-minded folks develop their electrical knowledge, giving them the confidence to do their own tiny build electrics.

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Beach Van

A Comprehensive Guide to Battery to Battery Chargers: Everything You Need to Know

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Battery to battery chargers, also commonly known as DC to DC chargers, are fitted between your engine battery and leisure battery system. They take the voltage produced by the alternator of the vehicle and turn this voltage into a preferred charge voltage and current better suited to your leisure batteries. These devices are critical to the longevity of a system. Batteries with a more complex make up cannot just be blasted with 14.4V straight from a alternator, they require a delicate three stage charge process.

Understanding battery to battery chargers:

Battery to battery chargers are electrical devices designed to convert the direct current (DC) power from a vehicle’s starting battery into a suitable charging voltage for auxiliary batteries. Unlike conventional battery chargers, which typically rely on alternating current (AC) sources, DC to DC chargers are specifically designed for mobile applications and can efficiently charge the auxiliary battery system while the vehicle is running.

1. Voltage Conversion: The charger steps down the higher voltage output from the alternator to a suitable charging voltage for the auxiliary battery system. This voltage conversion ensures that the battery receives the optimal charging voltage without overcharging or damaging the cells.

2. Multi-Stage Charging: Battery to battery chargers often incorporate multi-stage charging algorithms. These algorithms monitor the auxiliary battery’s state of charge (SOC) and adjust the charging voltage and current accordingly. The charger begins with a bulk charging stage, delivering a higher current to rapidly recharge the battery. Then, it switches to a absorption and float stage to maintain the battery at full capacity without overcharging.

3. Charge Isolation: Battery to battery chargers provide charge isolation between the vehicle’s starting battery and the auxiliary battery system. This ensures that the auxiliary battery is charged independently and prevents any power drain from the auxiliary battery to the starting battery, which could potentially leave the vehicle stranded.


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How They Work

As mentioned above in the multi-stage charging section, battery-to-battery chargers utilise a three-stage charging process. The three stages are:

1. Bulk Stage: During this initial stage, the charger delivers a constant current to the leisure batteries. It charges the batteries rapidly until they reach a predetermined voltage, typically around 80%.

2. Absorption Stage: Once the leisure batteries reach the predetermined voltage, the charger switches to the absorption stage. Here, the charger supplies a constant voltage, allowing the batteries to absorb the remaining charge gradually. This stage prevents overcharging and maintains a healthy lifespan for the batteries.

3. Float Stage: After the absorption stage, the charger enters the float stage. The charger continuously monitors the leisure batteries voltage and maintains it at a safe level, preventing overcharging. This stage is essential for long-term battery health, as it keeps the batteries ready for use without any risk of damage.

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The Big Question: Isolated or Non-Isolated?

An isolated battery to battery charger and a non-isolated battery to battery charger differ in terms of their electrical isolation and how they handle the transfer of power between batteries.

Here’s a breakdown of each type:

Isolated Battery to Battery Charger:

Electrical Isolation: An isolated charger physically separates the input and output circuits using a transformer. This isolation provides a complete separation between the input and output voltages, ensuring there is no direct electrical connection between the two batteries.

Separation: Isolated chargers are incredibly useful for breaking up ground loops, thus separating parts of a circuit that are sensitive to noise. Electrical noise occurs when electrical signals produce undesirable effects in the electronic circuits of the control system. These electrical signals can affect sensitive equipment such as can-bus systems.

Safety: As touched on above, isolated chargers offer the safety of the the vehicle electrical system and the leisure system being isolated away from each other. Reducing the risk of interference or even damage to sensitive equipment in your vehicle.

Non-Isolated Battery to Battery Charger:

Electrical Connection: A non-isolated charger does not have physical separation between the input and output circuits. The input and output batteries are connected directly through the unit.

Benefits: Non-isolated chargers are typically simpler, smaller, and less expensive compared to isolated chargers. They are suitable for applications where the input and output batteries have the same voltage.

Note: These should only be installed if you can confirm there is a common ‘ground’ between your two battery systems. For example, the metal work of the vehicle could be sufficient to be a common ground between the batteries and therefore the charger can work efficiently. If your campervan or motorhome does not have a metallic body, you should opt for an isolated model. That way, each side of the charger has its own respective ground from each respective battery.

The choice between isolated and non-isolated chargers depends on many factors. Some applications require isolation for safety reasons, and others may benefit from a floating output by breaking up ground loops or shifting of reference voltages. However, where isolation is not required, a non-isolated converter may provide a decrease in cost, size, and/or an increase in efficiency.

What if my engine and leisure batteries voltage differ?

Certain battery to battery chargers on the market are designed to charge one battery from another battery with different voltages. These chargers typically convert the voltage from the engine battery to match the voltage requirements of the leisure batteries. This allows you to charge a battery with a higher or lower voltage from another battery without the need for a direct connection or voltage conversion from an external power source.

Batteries

When using a battery to battery charger, it is essential to ensure that the charger is compatible with the specific voltage requirements of the batteries you want to charge. Additionally, make sure to follow the manufacturer’s instructions and guidelines for safe and proper usage.

Temperature Regulating Your Battery to Battery Charger

1. Temperature Regulation: Battery to battery chargers, like any electronic device, generate heat during operation. Excessive heat can not only damage the charger but also reduce the charging capabilities of the charger itself. With heat comes resistance and with resistance comes a lower charging current as the charger is having to work harder.

2. Preventing Overheating: In a campervan, the charger may be located in a confined space or near other heat-generating components like batteries or inverters. In such conditions, the charger may be prone to overheating, which can lead to reduced performance or even premature failure. Cooling mechanisms such as fans or heat sinks help dissipate the heat and keep the charger operating within its optimal temperature range. The surface in which you mount your battery to battery charger plays a huge part in how heat is dissipated away from the charger, therefore think about mounting the charger on a non combustible material such as an aluminium sheet.

3. Efficiency Optimisation: Battery to battery chargers are designed to convert power from one voltage level to another, typically from the campervan’s engine battery to auxiliary batteries. Cooling the charger can help maintain its efficiency by preventing heat buildup, which can cause energy losses. When the charger operates at a lower temperature, it can deliver power more effectively and maximise the charging efficiency.

4. Safety Considerations: Overheating can pose safety risks in a campervan. High temperatures can increase the likelihood of electrical malfunctions, short circuits, or even fires. By cooling the battery to battery charger, you mitigate these risks and promote a safer environment within the campervan. By installing the charger on a non-combustible surface you will help to dissipate the heat and mitigate any potential hazards.

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Sizing your battery to battery charger

To size a battery charger for your campervan, you’ll need to consider a few key factors. Here are the steps to help you determine the appropriate battery charger size:

1. Determine your battery type and capacity: Identify the type of battery used in your campervan (lead-acid, AGM, lithium-ion etc) and find out its capacity, usually measured in amp hours (Ah). The battery capacity is an important consideration when sizing the charger.

2. Calculate the charging current: Determine the desired charging current for your battery. Here you must consult the battery’s datasheet. Within the data sheet you will be given the parameters in which the battery can be charged at. This is a vital bit of information when selecting your battery to battery charger.

3. Consider charging efficiency: Take into account the charging efficiency of the battery charger. Not all energy drawn from the charger is converted into stored energy in the battery due to losses in the charging process. Typically, a charging efficiency of around 80-90% is considered reasonable.

4. Account for the size of the vehicles alternator: Here you must determine the size of the vehicles alternator. This can be found on the data sheet of the vehicle. Although this will give you the output of the alternator this is by no means the full amount of current you have to play with. You must take into account other loads that are put onto the alternator, such as powered air conditioning, heated seats, lights, heaters and entertainment systems. We at TBE use equations to calculate the loads on the alternator and therefore match you more accurately to a battery to battery charger. To find out more send us a message and we’ll be more than happy to help!

5. Select an appropriate charger: Once you have calculated the charging current required, you can look for a battery charger that meets your specifications. Choose a charger that can provide the desired charging current and is compatible with your battery type.

6. Additional features: Consider any additional features you may need in a battery charger, such as multi-stage charging, built-in safety features, compatibility with solar panels or alternators, and user-friendly interfaces.

7. Seek expert advice if unsure: We at Tiny Build Electrics can help you with choosing the correct battery to battery charger. Once we’ve matched your requirements with the correct charger we can also supply the item.

Van pets
Tom Alderdice

Hey, I’m Tom – founder of Tiny Build Electrics

My mission is to help sustainable-minded folks develop their electrical knowledge, giving them the confidence to do their own tiny build electrics.

Book A Consultation  
Lithium Battery Types

Choosing the Right Battery Types for Your Van Conversion: A Comprehensive Guide

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If you have undertook even a small amount of research regarding batteries for your tiny build, then you have quickly come to realise it is a bit of a minefield.

Battery technology is developing faster than you can imagine. They are becoming lighter, more powerful and their life cycles are ever increasing.

So what’s best? Well… how long is a piece of string?

There are a few fundamentals that are worth understanding before we proceed with the types of batteries in which you could fit into your tiny build.

Depth of discharge

The first being depth of discharge (DOD). Depth of discharge is how far a battery can be discharged relative to its capacity. Different batteries have different depth of discharge ratings, some batteries can be discharged further than others.

Dod Diagram

We recommend that you always use a battery monitor, such as the Victron BMV, to accurately determine the depth of discharge of your battery. Not only do the battery management devices monitor DOD, they also give you an array of information regarding your battery. Once setup correctly these monitors become extremely useful in your tiny build and help prolong the life of your batteries.

State of charge (SOC)

A batteries state of charge is simply the amount of charge within the battery.

A fully charged battery would be 100% SOC whilst an empty battery would be 0% SOC.

State of charge is the inverse of depth of discharge. Put another way, if a battery is at 100% state of charge, then its depth of discharge is 0%. The opposite is also true. If a battery is 100% discharged, its state of charge is 0%.

SOC Diagram

Cycles

The second fundamental is a cycle. A cycle is when the battery has been fully charged, discharged and then fully charged again. Every time it completes this circle of events, that will be considered 1 cycle. Although by completing this cycle the battery is technically aging, it also keeps the battery active and healthy. Different batteries have different life cycles, some more than others.

The number of charge cycles a rechargeable battery can withstand before performance degrades is the method in which we use to measure how long our batteries will last, if taken care of properly.

Ohms Check

Battery Lifespan

A batteries lifespan is a time frame given by the manufacturer which depicts how many cycles a battery can perform in certain period of time.

Over time your battery monitoring system may tell you your system is at 100% charge but this isn’t necessarily accurate. This is a depletion in its lifespan, the battery will take longer to charge and be quicker to discharge in some circumstances.

Batteries coming to the end of their lifespan also struggle to hold a charge, so if everything is turned off in your tiny build and the battery is struggling to hold a healthy voltage you know your batteries are on their way out. If we look after our batteries, connect them in the correct way and use the correct equipment to charge them they will live long and prosper!

Cycle Complete

How can you increase the life of your batteries?

Once you begin to understand how different factors impact your battery’s life cycle, it becomes clearer how you can increase your battery’s life. Following some simple “best practices” can help you get the most out of your battery, regardless of whether it’s a lead-acid or lithium-ion battery.

Best Practice 1: As much as possible, use your battery in moderate temperatures. Of course, this may not always be possible but if you can keep your batteries in a moderate temperatures this can have a dramatic affect on its life cycles. Optimal temperature for most batteries is between 20 – 25 degrees centigrade. Lithium-Ion batteries are particularly sensitive to discharging and charging in colder weathers. To get around this you can surround your batteries with heat pads to keep them warm and operating efficiently.

Best Practice 2: If you have a lead-acid battery (FLA, AGM, GEL) ensure that you minimise how often you discharge the battery below 50% of its capacity. Ideally, the depth of discharge on each cycle should be between 10% and 50%. If you have a lithium battery, you can likely go down to 80% DOD and, in some cases, 100% DOD. Refer to your battery manufacturer’s recommendations to be safe.

Best Practice 3: If you have a flooded lead-acid battery, make sure to keep the electrolyte solution topped up.

Best Practice 4: Ensure you use the correct charging equipment for your batteries. Better yet, ensure the charge equipment that you are using has the correct charge parameters for your battery type. These parameters vary from battery type to battery type and needs to be done correctly. This is something that we, at Tiny Build Electrics, can help you with.

Battery Types

Batteries is a stage you want to get right, after all, no one wants to be sat in the dark sipping warm beers, right?!
Understanding the types of batteries available, the capacity you need for your van lifestyle, the relative cost and how to take care of them will help when it comes to choosing the best camper van batteries for you.

The four battery types we will be considering are:

Each type has a different make up and because of this perform differently under different circumstances.

Flood lead acid (FLA)

Flood lead acid batteries consist of two lead plates, one positively charged, the other negative. The battery is then flooded with a liquid electrolyte, sulphuric acid which covers all internal parts. When charging commences the acid and lead plates react to store electricity.

Pros

  • Low cost
  • Resilient to occasional over charging
  • Proven technology
  • Lifespan can be 4-8 years with regular maintenance and careful charging
  • Less susceptible to temperature differences

Cons

  • As the batteries age the performance will degrade to the point where the battery won’t hold a charge
  • Should be stored inside an enclosure (battery box)
  • Battery can only be drained to a maximum DOD of 50%, otherwise you’re likely to incur damage.
  • Must be vented in an enclosed area as some FLA batteries will emit gases.
  • Stricter regulations on how FLA batteries are fitted and how close they are installed to inverters and chargers.
  • Require regular maintenance
  • Heavy

Gel

Gel batteries use the same technology as FLA but instead of liquid acid they are filled with Gel. Gel gives us more advantages than FLA as you will see below.

Pros

  • Doesn’t emit any nasty gases
  • Sealed so can’t leak or produce any gas
  • Maintenance free
  • Operates in a wider array of temperatures than AGMS.
  • Ideal for vans that are stored over winter and not used for long periods of time

Cons

  • Very sensitive to depth of discharge
  • Do not recover well from a low DOD
  • More expensive than conventional FLA and AGM
  • Heavy


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Absorbed glass mat (AGM)

AGM batteries work in a similar manner to FLA and Gel. Instead of acid or gel they have electrolyte soaked glass fibres between the positive and negative plates.

Pros

  • Long shelf life
  • Maintenance free
  • Ideal for vans that are stored over winter and not used for long periods of time
  • Can be installed sideways as its a sealed unit and cannot leak (unless damaged)
  • Smaller than the conventional Gel equivalent

Cons

  • Very sensitive to depth of discharge
  • Do not recover well from a low DOD
  • More expensive than FLA
  • Heavy
  • Poor performance in colder temperatures


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Lithium LiFePO4 / Lithium-ion / Li-ion

The famous lithium-ion battery. If you have done any sort of research on tiny building or off grid systems then it is highly likely you have come across the lithium battery, currently at the top end of the battery technology market. This is a battery you should be considering for your build, there’s just one downside… £££!

Pros

  • 30% lighter than FLA, GEL & AGM
  • Smaller frame size than FLA, GEL & AGM
  • 90% of their capacity is usable meaning you need less batteries for the same amp hours as FLA, GEL & AGM
  • Low internal impedance (resistance) mean these batteries also charge a lot quicker than the other types of batteries.
  • Can be installed in various orientations
  • Maintenance Free
  • Long life cycles if charged and discharged in accordance with manufactures instructions

Cons

  • Very sensitive to charging in low temperatures
  • Expensive, although prices have started to drop over the past few years
  • A battery management system is required to protect the lithium-ion battery bank from excessive discharging, over charging and to control the load and balancing of each internal cell. Most of the time this system is built into the battery itself.
  • Some extra monitoring may be required such as battery temperature monitoring

Lithium-ion batteries (LiFePO4)

Can I use a vehicle engine battery as a leisure battery?

Start batteries are the type of batteries that are used in cars, boats, lorries, buses and generators. Start batteries are not suitable for uses where they are discharged and then recharged again, also known as a cyclical use.
They also cannot be used in connection with an inverter, although technically they can the batteries make up means that it will not last very long while feeding an inverter.

The reason that start batteries are not suitable for frequent deep discharging is because of the way they have been constructed. They have thin plates with a large surface area. They are designed purely for short-term high discharge currents like engine starting.

During an engine starting the battery is exposed to high current draw in a short period of time. This high current draw turns a starter motor which in turns causes the engine to turn over and start. It might be tempting to use start batteries in a battery bank in smaller inverter systems, but please don’t do it. It will only cause trouble in the long run.

Car

Price comparison

Battery Type Average Life Cycles @ 50% DOD Price (£) (TBE SHOP) Cost per Cycle (£)
Victron Energy 110ah AGM Battery 850 £316.99 0.37
Victron Energy 100ah LiFePo Battery 5000 £1,275.6 0.26

The table above clearly shows us that whilst the lithium-ion battery is more expensive than an AGM battery, it certainly is cheaper when you consider the cost per cycle over its lifetime. The life cycle of the lithium-ion battery is certainly unmatched and is something to seriously consider if you want a ‘fit and forget’ electrical system in your campervan.

Scales

Summary

If you are wanting the cheapest method of powering your tiny build then Flood Lead Acid is for you.
These batteries are as cheap as chips and can be picked up in various frame sizes as well as amp hour sizes. But please note, these batteries need ventilation and you need to monitor them to ensure they do not leak. We advise against installing FLA deep in your build. They need to be installed with in a battery enclosure and well vented should they need to vent or worst case, leak. When they vent, FLA batteries will emit dangerous gases into your campervan or motorhome.

If you are wanting a ‘fit and forget’ system with efficiency and a long cycle life then Lithium-ion is for you.
The lithiums are expensive, but, they are slowly coming down in price due to their popularity. When you consider the price of the lithium you must consider its lifecycle and DOD. Considering a AGM battery will enter in at around 500 cycles, lithiums are 5000+ cycles. Not only will they last longer (if installed and charged correctly) they’re a LOT lighter which is important when it comes to conversions such as vans, motorhomes, buses and lorries which have weight limits.

Tiny Build Electrics’ experience

I upgraded my campervan system from absorbed glass mat (AGM) to lithium-ion at the end of 2021. The main reason for this change was to save weight as I knew my self built van conversion was starting to get heavy. I removed my AGM batteries and weighed them. Both batteries weighed in at a whopping 35kg each! 70kg of batteries being pulled around by my van. It is not only the weight though, as the maximum DOD was 60% for my two x 100ah batteries which meant I only actually had 80ah of usable power.

Well, each lithium battery weighed in at… 11kg, yes 11kg! 70kg swapped out for 22kg. My van certainly thanked me! The weight saving was fantastic but what was even better was the power upgrade. My two 100ah lithium batteries now gave me 180ah of usable power, this is because the lithium batteries can be drawn down to 10% DOD without causing any damage. (They can theoretically go to 0% but most manufactures do not recommend this) I had literally doubled my power bank whilst saving two thirds of the weight!

I haven’t had any power worries since and because I have an electric hot water system the batteries take a beating. They cycle regularly but with a manufacture rating of over 5000 cycles this is not something I’m yet worrying about.

Tom Alderdice

Hey, I’m Tom – founder of Tiny Build Electrics

My mission is to help sustainable-minded folks develop their electrical knowledge, giving them the confidence to do their own tiny build electrics.

Book A Consultation