Off-the-shelf battery packs

[CelestialMechanics]

Hi There
I'm an engineer sorting out a novelty (not in a bad way!) EV system for a TV production and I'm trying to find a short lead-time power supply system in the UK. Nominally in the 7kwh, 50 volts range, but the deisgn can be flexed around available units. Can you recommend any suppliers? It seems to be too much of a kooky one-off for the British companies I've spoken to (who are understandably focused on supporting fullscale commercial ventures. But I was thinking that there must be something out there now, especially as we don't mind the shape, volume, size (within reason) and we can juggle voltage to to some degree.
Any ideas, including second-hand units?
Best
Robin

[timpootle]

Sounds like a job for Lead-Acid batteries. How far and how fast are you trying to get?

Have a read through this thread:
viewtopic.php?f=3&t=3217&start=0

160Ahx12Vx4= 7.68 kWh @ 48V

Using lead, you won't need a pack as such, just 4 batteries connected in series and charged with a simple 48V charger from a golf buggy or similar. I have not done this. Hopefully someone who has will be along in a moment to confirm what I have said.

[GregsGarage]

For an off the shelf solution maybe 4 of these marine battery packs. They are 25.9 volts each and 2.6kwh, so 4 of them connected 2P2S would meet your requirements depending on how quickly you are going to be discharging them.

Otherwise you need to build it yourself or get it built. The trap with lead acid batteries is that the stated capacity is for a 20 hour discharge. When you use them on an EV with say a 1 hour discharge you will lose capacity through the Peukert effect. The amount varies, but as a rule of thumb, say 50%. So your 160ah cells are suddenly only good for 80ah. Then when you look at cell life vs. depth of discharge you find out that more than 50% discharge starts to shorten life, so now you are down to 40ah of usable capacity from a "160ah" pack. Of course if its a TV production with a few weeks of shooting then maybe you aren't bothered by cell life.

The other option is a lithium pack. Unlike lead acid, lithium cell capacity is usually rated for half to 1 hour discharge. 16x 160ah cells would probably suit your requirements. Add a bms and charger, build a case and you would be ready to go. I might be able to help you out with this, pm me.

[CelestialMechanics]

Thanks for the direction, I was thinking to "Production engineering" and looking straight to Lithium!
Looks like lead acid will be more than good enough for the job, much cheaper and the mass will actually be useful in this case.
Best
Robin