3-Phase Adapter

[4Springs]

We are in the middle of converting a Mighty Boy, and the installed battery is starting to get low. Two of the LFP cells are down to 2.5V and the rest are also lowish. We have a 144V charger connected, and so we'd like to use that to charge them all up. But the charger draws 14 A, and there are no 15 A power points nearby, and the car isn't ready to be driven yet!
There is a three phase outlet nearby though, so I think we should be able to make an adapter?
Here is the outlet:

ppt1.jpg (2.53 MiB) Viewed 423 times

I think this should supply 20 A per phase, is that correct?
If so then I think we should be able to marry one of these:

15A.png (314.54 KiB) Viewed 423 times

to one of these:

20A.png (174.71 KiB) Viewed 423 times

This is urgent, as the vehicle is in a school that is about to close for the Christmas break. Hopefully we can get a few hours charge into it.
Are we on the right track? Which pins need to be connected for us to break out one phase and earth? Or I imagine we can look that up...

[jonescg]

Nothing wrong with pinching a phase and neutral from the plug, just make sure you pass it through a mobile RCBO.

[coulomb]

Unfortunately that 3-phase outlet only has 4 pins. So that will be 3 phases and an earth. You can't use the earth for carrying non-fault current, certainly not 14A continuous. So all you have is 400V+ phase to phase, which your charger will almost certainly not appreciate, and will likely get blown to bits.

So that outlet is for three-phase loads only. Are there other outlets with 5 pins?

[ Edit: 3 pins → 4 pins. I can count now :-O ]

[4Springs]

Unfortunately that 3-phase outlet only has 3 pins. So that will be 3 phases and an earth. You can't use the earth for carrying non-fault current, certainly not 14A continuous. So all you have is 400V+ phase to phase, which your charger will almost certainly not appreciate, and will likely get blown to bits.

Great, thank you, that explains it nicely.
I saw this this morning before I went shopping, and knew that I needn't purchase those parts.

So that outlet is for three-phase loads only. Are there other outlets with 5 pins?

It doesn't appear so, no.
Plan B is to charge the lowest two cells (the ones measuring 2.5 V) up to 3.1 V with a benchtop power supply, and disconnect the BMS modules from the remainder.

Once the vehicle is mobile then charging won't be a problem. There are 15 A outlets on site, but to get the vehicle to one of them would require several doors to be unlocked, plus moving the unpowered and unregistered vehicle along busy city streets to get it into an appropriate place.

[Bryce]

Hi there - I often use a constant voltage/constant current benchtop power supply for just that purpose. I set the voltage in gentle stages to bring the cell back to the rest of the pack and set the current to a suitably safe level to avoid cooking it. (2 or 3 amps max).
Cheers
Bryce

[OzSpider]

Non-electrical persons thought here. Could you make a double lead to take power from 2 separate 10A GPOs? Probably safer at a single phase only dwelling to avoid phase to phase short...

[antiscab]

We call those suicide leads, as it's easy to make the other male end live and exposed at the same time.

If on different rcbo it will also trip both rcbos

Note, you can usually get away with pulling 14A from a 10A point, as they're usually protected by a 16A rcbo.

[brendon_m]

Personally before I went down the path of making a sketchy adaptor like that I'd just plug the charger into a 10A gpo. It's only 14A, the wiring should be capable and as long as there's nothing else running off the same circuit the rcd won't pop. Fine for a short term, get out of trouble situation.

[OzSpider]

We call those suicide leads, as it's easy to make the other male end live and exposed at the same time.

Good tip, mental note to avoid ever doing that!

[Dean Williams]

would it not just be sensible to get a 15 amp outlet installed?

[brendon_m]

Yes but this was a short term, had to be solved quick problem