Parallel Charging Lipos

Does anybody here do this?

There are a few things to consider obviously and the consequences of getting it wrong are potentially disastrous but it seems a good way of getting multiple lipos charged in reasonable time.

Does anyone have any charger boards that they've used and would recommend? one with replaceable fuses would seem be a good idea.

Do cells maintain their balance when charged multiple times this way?

Apart from lipo charge state and lipo type symmetry requirements and charge current/power calculation, is there anything else to consider?

Yes. I charge 4×5000mAh 6s batteries this way. I check that the batteries have reasonably similar voltages...seems to coincide with 15% to 35% on my battery checker. It's not necessarily quicker but you don't have to keep going back and swapping batteries all the time.
It could also be argued that it is kinder to the batteries...if I charge my 5000mAh batteries at 1C that is a 5A charge. But my charger only does 10A max so if I charge four in parallel that's only 2.5A each which is 0.5C and could arguably extend battery life.

Mike how do you physically wire up the batteries? you can't balance charge them can you.
Where do you charge your batteries it's been stated many times that lipo's should be never left unattended while charging. I charge mine in the garage on a metal shelf and on occasions forgotten about them and left them overnight on charge, relying on the charger to stop charging when full, perhaps a accident waiting to happen.

Yes, John. They are balanced using something similar to this

HK parallel balance board

I'm using a different one now with fuses but cannot find a link to it...Chris001 might have it.

I charge my batteries in the morning before I go flying, so there is no chance of leaving them overnight

With a balance board you can balance charge a number of batteries like Mike says. I only use the ones with fuses on both the main power lines and with polyfuses on the balance lines. Like Mike,I individually check each battery before I connect them.

Unless using XT60 or Deans your probably going to need adaptor leads and It's helpful to have balance extension wires too, depending on how generous they are on the batteries.

I charge 4 x 5000mAh packs on this at 7.4 Amps (my power supply is the limiting factor here) I have done this will all my batteries since day one and they have always been balanced when checked afterwards.

John, I charge mine in an ammo can on its side, with the lid off on the concrete floor of the garage. If the worst happens I'll loose all batteries and the balance board, but the ammo can should direct the flames outside as I leave the garage door slightly open.

I think you need to be sure that your battery packs are discharged to a very similar level every time and that you don't have any 'low' cells in any of the packs. My own personal experience of using a balance board with a pair of 5K 6S batteries was a huge flash and two of the balance tracks on the balance board evaporated. I know others have had a less dramatic experience!
When you think about it logicaly, all you are doing is paralling each cell with its parter in another battery(s), and the higher potential cell is going to try and dump its contents until the cells are at the same potential - you are relying entirely on the internal resistance of the cell and the tracks and connectors to stop this happening in an instant (i.e hundreds of amps want to flow from one battery to another).
P.s it puzzles me why jump leads don't evaporate when jumping a car, but maybe there is a scientific reason that I don't understand!

Chris001 wrote: John, I charge mine in an ammo can on its side, with the lid off on the concrete floor of the garage. If the worst happens I'll loose all batteries and the balance board, but the ammo can should direct the flames outside as I leave the garage door slightly open.

Having had the unfortunate experience of a lipo fire when charging, I will never charge inside again, it's not just the fire you need to worry about, the smoke damage in my shed was horrendous. Also after the initial jet of flame from the pressure build up, the volume of flame which develops as the fire takes hold really surprised me. When I had my fire which was only from a 3s 2200mah pack, by the time I put the garden hose to it in desperation, the flames were a foot across and at least 2 feet high and the heat did lots of damage even to stuff at the other end of the shed 10ft away.

Chris001 wrote: With a balance board you can balance charge a number of batteries like Mike says. I only use the ones with fuses on both the main power lines and with polyfuses on the balance lines. Like Mike,I individually check each battery before I connect them.

Unless using XT60 or Deans your probably going to need adaptor leads and It's helpful to have balance extension wires too, depending on how generous they are on the batteries.

.

Which board is this Chris? does it have the replaceable car type fuses for the main connectors as well as poly fuses? Would you recommend it?

Hi Jon,

I guess It's one of those things that unless you've personally seen a lipo go up in flames you don't really know the potential damage that can be done. I did start charging outside after your experience, but I guess I got complacent and compromised to the garage.

Time to build a charging station with an element of weather protection and that is easily portable so that it doesn't become an onerous task to set it up.

Hi Alan,

I got one from America, RC Buddy (I think) and the one in the pic from HK, I can't see any quality difference. My batteries originally had Deans so that's what I went for, but would now choose XT60s over Deans, even if using adaptors: hobbyking.com/en_us/hobbyking-safe-40a-p...packs-2-6s-xt60.html

I can only recommend it in so far as I've not tried anything else, and I've not had any issues with it. The main power line has replaceable car fuses on each socket and also a master one where the main wires go in.

It might have been overkill, but I did go over them with a multimeter just to check continuity, they were fine!

Thanks for that Chris. After hearing of Jon's experience I now do all my charging outside especially as my garage and workshop are attached to the house!

I've just spotted that the charger board has a couple of 4mm bannna plugs on the input - what could possibly go wrong there! I'd better stock up on fuses.