What is the difference between starter and supply battery?

Starter and supply battery: The difference

Starter batteries are designed for the brief delivery of high currents when starting the vehicle . They are less suitable for permanent power consumption and continuous charging cycles.

In contrast, a supply battery is designed to deliver lower currents over a longer period of time. If both batteries are installed on board, both are also charged by the vehicle's alternator while driving.

In addition, the second battery can also be charged on the go via a solar system on the roof of the mobile home. In the stand, of course, suitable chargers and the normal 230V power supply can also be used.

The more electrical consumers are connected, the greater the capacity (Ah) of the supply battery must be.Danger! Deep discharge of the second battery must be avoided. Otherwise there is a risk of a significantly reduced life expectancy or even total damage to the battery. The installation of a so-called battery warning is therefore a sensible investment.

Why a second battery at all?

Fridge, radio, heating, light - especially in mobile homes, the permanent power requirement is higher than in a normal car. However, a second battery can also make sense in a car for powerful audio systems or other demanding electrical consumers. A second or backup battery is a simple and economical solution

for the reliable power supply of many electrical consumers on board . This applies in particular to older or self-converted mobile homes.

A solar panel on the roof can be a good support as an electricity supplier. In connection with the suitable inverter, your smart energy management can then be optimally adapted to personal requirements when travelling.

However, if you want to be supplied with on-board power for a few days, even with only a low to medium power requirement, regardless of the weather, you can hardly avoid a good second battery.


Gel, AGM, Lithium: Which battery should you choose?

Gel batteries: The reliable all-rounders

Gel batteries are very cyclically safe and therefore well suited as a second battery. This type of battery is leak-proof and also has a longer life expectancy than the classic, somewhat cheaper lead/acid batteries. In order to optimally charge and care for gel batteries , the supply from the alternator is usually not sufficient. 

It is therefore advisable to charge them regularly every 2 to 4 weeks via the 230V mains. There are special chargers for this . You can usually read off their suitability for you on the type plate of the device. If you use the wrong charger over a long period of time, for example if the end-of-charge voltage is too high, this can result in irreparable battery damage.

 See our Gel batteries 

AGM batteries: For demanding purposes

In principle, the structure of an AGM corresponds to that of a gel battery. In the AGM version, however, the battery acid is not gel-like, but bound in layers of fleeceIt does that – even if it is damaged! - Virtually leak-proof compared to other battery types. So if you consistently focus on robustness and safety when expanding your mobile home , you are very well served with an AGM. 

The AGM battery also requires a special charger. For maximum life expectancy, it should be fully charged regularly. In contrast to the gel battery, higher currents can also be drawn from the AGM battery.

 Explore AGM batteries 

Lithium batteries: The ultimate in camper batteries

This is what the profile of an ideal camper battery looks like: fast charging, light, maintenance-free. Leak-proof and relatively resistant to damage from deep discharge. And ambient temperature doesn't matter to battery capacity as long as it doesn't go below freezing.

Only lithium iron phosphate batteries (LiFePo4) are used in commercially available motorhomes. However, they are also the most expensive variant of a supply battery . These consist of four cells connected in series, each with a nominal voltage of 3.2 or 3.3 volts.

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