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Which battery is suitable for the camper?

batteryCouple charging their electric van at the charging station

Vehicle and utility batteries don’t like the cold. Whenever the temperatures approach the frost line, weaknesses come to light. Our living area battery also adhered to this rule and reduced its capacity considerably in the autumn.

The weakness didn’t surprise me because the first indications had been around for a long time. Self-discharge increased, and capacity decreased. An AGM battery can fail after four years of mobile home use.

The selection of the battery market is very confusing. Shippers, battery dealers, and mobile home workshops offer various solutions. But which solution is best suited to our habits?

Some basic requirements were quickly established. After all, a battery change shouldn’t lead to a total remodeling of the electrical system.

  • Installation location under the passenger seat
  • Secure attachment without new drilling or screw connections
  • No modification of the existing cables
  • No conversion of the charging technology (AGM and gel possible)
  • Inverter operation or solar system not provided

This reduced the selection considerably. Only one type of battery fits neatly under the seat. However, many manufacturers have a lot of choices for this size. Even lithium RV batteries are offered for this installation location.

The required capacity

The next step was to determine the required size. So far, a 95Ah battery under the seat has done its job. In winter, the capacity in heating mode was not sufficient to be able to spend 48 hours in the vehicle without energy-saving measures.

In addition to the fan for the heating, it is the television, radio, and computer technology that determine our needs for us. LED light only makes a negligible contribution to consumption.

Compared to other crews, we have two major consumers. The refrigerator runs on gas, and we make the coffee using the tried and tested method with the filter. Our energy requirements are therefore limited.

Based on our previous experience and estimates, we calculated a requirement of around 35 Ah per day. With our goal of being self-sufficient for two days, even in winter, we need a lithium battery 12v with a removable capacity of around 80Ah.

When we last bought a supply battery about 8 years ago, there was little to think about. We replaced the gel battery with an identical model without much thought. Thanks to technical progress, there are now several alternatives.

The AGM battery

So far, a 95Ah AGM battery has been in service in our van. AGM accumulators are similar to the classic lead acid battery. The main difference is that the electrolyte is bound in a fiberglass mat. (AGM = Absorbent Glass Mat).

The batteries are capable of high currents and are also used as starter batteries. Therefore, AGM batteries can cope with the great energy hunger from coffee machines or hair dryers.

Some manufacturers offer special designs for mobile homes that withstand a higher number of charging cycles. AGM batteries require an adapted charging technology to achieve the stated life expectancy.

The gel battery

The gel batteries also work according to the well-known principle of the lead-acid battery. Only the electrolyte is no longer liquid but geo-shaped.

Due to the high charging cycles achieved, gel batteries have been the standard battery in mobile homes for a long time. In the meantime, however, they have lost their importance because the batteries do not reach the amperage of lead or AGM batteries. They are only suitable for inverter use to a limited extent.

The lithium battery

The various LiFePO4 batteries are still very new. These batteries are available in different types. In my opinion, the development is not over yet.

This type of battery offers many advantages over the different lead batteries. Weight savings, a very high number of cycles, and insensitivity to deep discharges are the main arguments for these cells.

The main disadvantage is still the purchase price. Added to this is the high electronic monitoring effort of the cells. However, there are now ready-made blocks that can be used without knowledge of electronics.

The Lead Crystal Battery

Some time ago, the lead-crystal battery was considered a panacea on the Internet. Some writers in the forums propagated the special design of an AGM battery as a cheap and very powerful alternative.

In the meantime, the first of the batteries is already on the scrap heap. The reason is simple. The design requires high-quality charging technology with very high charging currents to achieve a long battery life.

So far, our considerations have been logical. The future belongs to lithium cells.

So I started to take a closer look at the individual offers. There were several offers on the market for the installation location. What they all had in common was the design with built-in battery management. The outer shape of the batteries, mostly from Asian manufacturers, corresponded to the classic battery. So a simple change should not be a problem.

It didn’t take long, and I had found my favorite battery. The offer was tempting. For less than 1000$, there was a 12v lithium ion battery that could be easily installed in place of the defective battery without any conversion. There was only the small disadvantage that charging in frost would not be possible.

The change of mind happened overnight. I slept one more night before the shopping cart went to the checkout. This time the final considerations led to a rethink. An economical and a technical reason led to the change of mind.

A battery system with two gel or AGM batteries, dimensioned for our technical requirements, is available for less than $400. With a gel battery life expectancy of four years, the lithium battery must last at least 10 years. Our vehicle with a Euro5 diesel will soon be 4 years old.

In addition, I recognized a small error in reasoning. It is always assumed that the capacity of the lithium battery can be used almost completely, while only about 50% is available with AGM or gel batteries.

This is not entirely correct because, in emergencies, conventional lead-acid batteries continue to supply energy even below the 50% mark, while the lithium battery has already switched off. This way, the living area’s basic functions can be maintained for a while. Of course, a deeper discharge harms the life of the battery.

The good experience determined the choice of battery

Except the 12v battery system, if your energy needs are over 1,000 watts, you can also choose a 24v or 48v battery system. Ultimately, it was common sense that triggered the switch from the technically innovative solution to the tried and tested standard battery. The decision between Gel and AGM was made quickly. Since I don’t need the high currents of AGM batteries, I decided to use gel batteries. In the past, I’ve only had good experiences with this design.

Now I’m waiting for the friendly DHL driver, who will put 50kg of lead in front of my front door in the next few days. Hopefully, DHL will give him a hand truck.

Then nothing stands in the way of the conversion. The electrician can finally do manual work again. A corresponding report will follow.

An important note: work on the electrical system of a motor vehicle is reserved for suitably trained specialists. The high currents that occur can lead to fires. Special tools and measuring devices are required for the work, which is not available in every hobby workshop.

 

 

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