I have just bought a standalone UPS for my pellet stove home heating system as we live in a rural area so we get a lot of blackouts. It's the type that you add a large deep cycle battery to externally.

If my understanding is correct, a leisure caravan, camper battery is a deep cycle battery for starting and auxiliary so it's okay to be regularly drained but not 100% though and should last a couple of years. But a true deep cycle usually sealed AGM battery is a high-end version that will be fine with many hundreds or thousands of cycles.

Firstly have I understood this correctly, the differences I mean? And my main question is would I be okay with a standard camper van leisure battery? If it is an open battery that requires hopping up, and my right that these give off fumes and should not be inside the house?

In this region, a 100 Ah Leisure battery is around €100 but the equivalent AGM or gel battery is €300.

It's intended to be used frequently but most of the time it will be short uses so it should only be drained 5 to 20% maximum if the power is off for a long period I would then use my inverter generator. Really appreciate the help and advice. Thank you.

  • \$\begingroup\$ These days it's worth looking at LFP which will live longer than either. But the "LFP batteries" are still sold at a huge margin over the actual cells + BMS. \$\endgroup\$
    – user16324
    Feb 26, 2022 at 13:01

2 Answers 2


First, while and AGM battery is better than a regular Lead-Acid battery it still is not a good idea to let it discharge. An AGM battery is an upgraded Lead-Acid with some gel in it which exhibit some durability advantages. The Deep-Cycle battery, which is usually utilized in recreational vehicles is a better handler of full discharge ( although never recommended). Since you have power most of the time and the UPS will keep your Deep-Cycle battery fully charged pretty much all the time, I personally would go for the cheaper option.

Now, as far as fumes are concerned, I would certainly not park it near my night bed but since the fume emanating from a battery is mostly hydrogen and oxygen and H2S ( sulfur), H2 and O2 not poisonous gases but H2S is. H2S will only excape if your battery is being overcharged. I would not worry about a battery being inside the house since your UPS will never overcharge the battery ( unless becomming defective)

Here is a good reading about your question: Hazardous Gases

  • \$\begingroup\$ Never heard about H2S from lead acid battery. Mostly it is hydrogen and oxygen, which makes combustion hazard. Your link mentioned it is not usual case. Please provide more information about H2S coming from lead acid battery. \$\endgroup\$
    – user263983
    Feb 24, 2022 at 19:34
  • \$\begingroup\$ Really appreciate your help and advice, thank you \$\endgroup\$
    – Euphoria
    Feb 25, 2022 at 23:27

In vehicles working condition to battery is very tough, temperature changes, often charge-discharge cycles. By that reason demands to quality and working parameter is much higher. UPS is works occasionally, temperatures is not a big range. Just choose exact capacity and type, according to manual. Charger is designed to specific type, even same chemicals but different construction may have difference in critical values.


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