A little bit of help with electrics!

[weedyt]

I am in the final stages of converting a Citroen HY Van into a mobile cheeseshop, and I'm looking for some experienced advice to try and confirm my t'internet trawling.
I'm trying to power the shop side of the vehicle with a battery bank (due to the high peak load of two chillers and a water heater, a generator that can handle the load is a: big, b: heavy and c: very expensive!).
I'll be drawing approx. 9amps at 240v for 6 to 8 hours. (the peak load jumps to about 15amps)
By my workings, a bank of 6 to 8 deep cycle, 240ah leisure batteries with a beefy 2.5kw inverter will either run it perfectly or crash and burn after a couple of hours. Oh the joy of trying to figure this out with the Internet as a guide!
Anyone out there with any helpful nuggets of advice would be very, very welcome!

[Toltec]

Given 15 Amps at 240V is 3.6kW you are going to need more than a 2.5kW inverter, something like 5kW would be safer and it is going to need decent cooling so you may need to allow for the fan load on the batteries as well.

Don't forget you will be lugging 400kg or so of batteries as well so watch your axle loads.

Edited by Toltec on Thursday 18th October 16:34

[geeks]

By the time you have payed out for the number of required batteries and an inverter that will cope you probably would have been better off buying the generator! Inverters are also notoriously inefficient as well.

[Who me ?]

As toltec says- 15A @ 240v IS 3.6kw, but that is with a 100% efficient invertor system. Wat you might be looking for is the connection between the input and output voltages and currents. For a 100% efficient system, Ampsxvolts is a constant. i.e for a drain of 12A at 240 v ,12v batteries ( on a 100% efficient system) would need to provide (240/12)x 12 = 240 A . At 90% efficiency this would be about 266amps. And the efficiency of the cooling would depend on the output of the invertor as motor efficiency varies dependant on the voltage waveform. So you might need to look at a higher input voltage for the invertor and possibly a trailer for the batteries and invertor, or simply a towed generator

[bearman68]

You'd need a much bigger inverter for a fridge - prob 8kw due to the inductive loads from the motors.

Check out these batteries though

https://www.ebay.co.uk/itm/12V-Ultra-Plus-220AH-Le...

Each of these is a max of 2.6kwh - say 1.8kwh useable - so you'd need about 10 of these to run your van for 8 hours. (All approx figures)

Ouch, expensive.

[Mignon]

I don't think you're calculating much of this right. Firstly you don't really want to discharge batteries more than 50% so you'll need twice as many as you think. 12 x 220 amp 12v batteries at £170 each = £2040 and at 42 kg each that's half a ton. Secondly you'll need a huge battery charger to recharge them in 8 hours overnight or multiple smaller chargers and have to pull your battery bank apart every time which will get tiresome. I can't even see a big enough 12v charger to do the job online. I figure about 150 amps of 12v charging is needed. Usually chargers that big are 24v or 36v. So even if you can find one that's another several hundred quid plus the inverter at maybe £200. Electricity cost will be about £3 per day to recharge them.

A diesel generator which will run on cheap red diesel will cost a fraction of this and be simple to use. Red diesel cost will be about £6 per day so more than using batteries but not a huge difference. A petrol generator will cost about three times as much to run so that's right out.

This might do you for £1,100.

https://www.machinemart.co.uk/p/warrior-5kw-silent...

[Penelope Stopit]

The usage time is far too much for a battery/inverter setup, the same setup was not up to powering one Electrolux aircon unit for any reasonable length of time, I can't remember the power consumption of the aircon but I expect your chillers and whatever else will consume more

The problem is that there is no such thing as free energy and as mentioned above, inverters aren't very efficient

[Toltec]

Is there anything like a storage chiller, i.e. the opposite of a storage heater?

Something with a big thermal sink you can chill on mains overnight an use to keep a well insulated stock compartment cool for many hours? Perhaps investigate propane chillers too.

[weedyt]

Now I can finally reply, thank you all for the help! It looks like it was too good to be true, so it's on to plan C.

Who me? - towing is not an option, unfortunately, as the van doesn't have a hitch and I don't have a license for towing!

Mignon - as I said in the original post, I've spent the last couple of months trying to pick through conflicting information on the Web, and have had wildly different results. That's why I posted here, looking for people with experience in this area to try and clarify matters.

Toltec - an insulated compartment with a thermal sink is fine for storage, but to display the product for sale, the chiller needs to be open to view, unfortunately!

Thanks to everyone who's taken the time to respond!

[Mikey G]

I think for it to work you would have to rethink your chilling/heating requirements.
Maybe a smaller display chiller, I assume your going to use an open one and not one with a glass door which would be more efficient?
I have a 70AH leisure battery and 1kw pure sine wave inverter and on camping trips it has powered a small beer type fridge for 12 to 16 hours between charges without the inverter breaking a sweat, I have tested it on my full size under counter freezer and it starts and runs fine, for how long dont know, was only on for about an hour while doing electrical work in the house. So i would imagine the same size under counter fridge would also be fine. If a bigger fridge took twice as much power as my beer fridge then i'm sure another 70AH battery would do fine for an 8 hour stay off grid. This could be charged via a split charger or a second alternator on the main engine.

Do you need an electric water heater? maybe a small gas boiler as an alternative?
You could combine them all for say battery/inverter for storage, gas for water heater and a suitcase generator to keep the display chiller cool? and maybe electric hookup for those times its available or to keep everything running when parked up at home?

[TooMany2cvs]

weedyt said:

towing is not an option, unfortunately, as the van doesn't have a hitch and I don't have a license for towing!

Fitting a towbar to an H isn't hard, and you do have a towing licence... Just not a "full-fat" one.
https://www.pistonheads.com/gassing/topic.asp?t=11...
Look at your chassis number plate - the weight given as PTC or Poids Total en Charge is the GVW (you need to check you're not overloaded with all the kit + stock, anyway). Subtract that from 3500kg, and that's how much you can tow, or 750kg, whichever's higher.

[OldGermanHeaps]

The ice cream vans i work on all have diesel generators in a sound insulated compartment at the back of the van running on cherry, then a commando socket for when they are back at the yard. I doubt thats by accident.

[TooMany2cvs]

OldGermanHeaps said:

The ice cream vans i work on all have diesel generators in a sound insulated compartment at the back of the van running on cherry, then a commando socket for when they are back at the yard. I doubt thats by accident.

Indeed. The old-school way was a big generator on the engine, left idling.