Leisure Vehicle.

It really depends on what else you want to run at the same time, and how frequently you expect to have to charge the battery.

There are two key issues to consider.

First, storage capacity

The battery capacity (when new) is 1.3 kWh.

On average, this equates to 750 kWh over the life of the battery (for lead-acid types).

Which means it could (theoretically, with some losses taken into account) run a 600 W microwave oven for roughly 1 hour, on average, over its lifespan (more when new, slightly less when older).

So, with few other loads, thinking about "ready meals" ... perhaps 6 to 12 runs of a 600 W microwave for 5 minutes a time before the battery needs charging.

Second, drive current and voltage drop

To run a 600 W microwave oven, the output current of the battery will be 40-60 A (depending on inverter losses).

This should be within the capability of most leisure batteries, but again it depends if (and what) other loads you want to run at the same time.

There are some other options out there, including using solar panels on the roof of the vehicle ... and also deviating from a standard leisure battery, especially if it's not a 'tight budget' consideration. For example: https://www.claytonpower.com/

It is possible for sure, but if it is much more than a 2 minute pot noodle, I'd keep the engine running to be sure of starting next day, as some of that 110Ah capacity is needed to crank the engine in the morning. Also a battery that makes 110A at 20 hour discharge rate will not make the same amp-hour product at higher currents so do not expect 110 A for one hour - half that may be a better aspiration if you want it to last more than a very few cycles of charge and discharge.

there are dedicated 12 or 24 V microwaves made for caravan and truck use, but they still need the chunky wiring that a separate inverter and microwave need, Be aware that the input power of say a 700 watt microwave is about 1400 watts - the mains or DC to RF conversion efficiency  is ~ 50% and at 12V that is over 100A, so think in terms of 6mm singles or fatter - car wiring is singles and usually based on 120C copper temp so the ratings are  a bit higher than the house wiring equivalent, but voltage drop dominates after a meter or two. As ths article notes, an inverter near the battery and a normal microwave on a  mains lead is less restrictive, but even so, keep the power down.

Mike

It might be just about possible, but a larger battery is needed for other than VERY brief use. A "600 watt microwave" generally means 600 watts into the food or about 1,200 watts from the supply. 1,200 watts from an inverter is about 120 amps input at 12 volts. A 110 amp hour battery can just about supply 120 amps but only for a very few minutes.

Running the engine will help, as would a bigger battery.

This is probably not a good idea, the battery is far too small for it to be more than an emergency cooker. A better choice would be a nice quiet small generator of 2kVA or so, Honda make some nice ones. The best question is why a microwave, normal propane cookers are probably a much better bargain overall, unless you are addicted to ready meals. Do they have a fridge too, presumably gas? My friend has a (large) RV but this has 1000Ah of backup batteries and a generator (key start diesel) for proper power, its very comfortable including the aircon! Charging this battery will also be a problem, in parallel with the vehicle battery is not a good idea, both being flat is not a good problem to have, and diode split charging will need a fair bit of work and an unusual alternator to deal with the volt drop and dual sensing.

The leisure battery might be separate from the vehicle starter battery (caravan style, although either option is possible for a campervan), In any event you usually don't want to discharge a lead acid below 50% if you're going to get a decent life out of it - so perhaps think more in terms of a maximum capacity of 660Wh rather than 1.3kWh - and reduced again for the high discharge rate.

   - Andy.

Thanks Graham.

Z.

Indeed, the motor starting "traction battery" is separate from the leisure battery.  There is though a battery charger hidden under the driver's seat that supposedly charges the leisure battery when the engine is running. The vehicle had a gas fridge. At first glance the battery charger looked to me to be an inverter. It has the same finned case and appearance. I think the  new owners of the camper van want to live "at home" with all mod cons whilst driving about. That is until reality kicks in.

Z.

Often a DC-DC converter yes., In the old days the leisure battery was just connected across the ignition circut to charge it but that often confuses modern engine management systems as they then think that the main traction battery isn't charging as it should....

Not sure about motorcaravans but with towing caravans there's normally a 'habitation relay' too - that switches off all the caravan's circuits when the ignition is on (but allows the leisure battery to charge from the traction battery/alternator and the fridge to run on 12V from the traction system) - the idea being that stuff in the caravan can't then interferre with the engine operation.

   - Andy.

at the shallow end, rather than dual alternators

and or diode switching diode example, a  simple relay that parallels the auxiliary battery to the cranking one when the latter is at more than 13.5v i.e. pretty much  charged is common. However a single car grade alternator may struggle with a flat battery and the loads of a dark winters night,  example relay. It also confuses those  stop and go systems that cut the engine at traffic lights etc. Fine for doubling up 2 similar batteries but not anything seriously heavily loaded.

Mike

FWIW, my previous motor car had two batteries - the system battery and the starting battery. The latter always remained available, but if the former had run down (which it did due to inactivity during the covid lockdowns) the central locking and keyless start failed. Interestingly, my current one has only one battery (and stops at the lights).