CellPro 10S Parallel Charging Confusion.

[Jermo]

I've been googling and searching around and seem to be missing something.

Based on my knowledge and experience I see no reason that the CellPro 10S wouldn't be able to charge packs in parallel as long as both the discharge leads and the balance leads on the packs are connected in parallel. This would Just make the pack appear to be double the mAH capacity but the same cellcount and voltage.

Example:
Two 3700mAH 5s 18.5V 25C packs in parallel would become:
ONE 7400mAH 5s 18.5V 50C pack.
Charging at 1.4C rate = 10.36A (7.4A * 1.4C) rounded down to the Cellpro limit of 10A.

The Only thing I can think of would be the 10A limit of the Cellpro preventing a charge at 2C


What am I missing?

[Gregor99]

Any charger can parallel charge. I have parallel charged with my Cellpro10s and even with my old Cellpro4s.

The real issue with the Cellpro10s is one of power. Compared to most modern chargers, its a little light on total wattage output. To make the best use of the charger's power, its important to run the numbers for different scenarios. Here are some examples using your pack's cell count.

For 5s pack the total fully charged pack voltage is 21v. Multiply that times the charger's current limit of 10 amps and the total peak wattage is 210 watts. This is the peak wattage for a 5s pack configuration whether its 1 pack or several packs in parallel.

210 watts is not quite at the charger's limit of 300 watts. And to perfectly fair that limit requires 16v and good external cooling. The practical limit on 12v in 70f ambient is closer to 250 watts.

Next lets look at two 5s packs in series. This is how the Cellpro10s chargers two packs at a time. Its a series connection with safety switches to prevent shorts common to serial charging. Total voltage is now 42v. Multiply times the charger's current limit and now we are up to 420 watts. This is well above the charger's wattage limit which means we are able to get the charger to fully max out its total wattage capabilities. With the parallel charging example above, we are hitting the charger's current limit before we hit the charger's wattage limit. So the total output of the charger is slightly reduced in that scenario.

Also when serial charging, each cell gets a full 1 amp of balancing bypass. When charging in parallel, the 1 amp is divided between the packs in parallel and the other 5 balancers in the charger are idle.

On the plus side, if your packs are largely different states of charge, parallel charging would end up being faster than letting the balancer take care of it.

[Jermo]

so without buying a new charger is parallel charging worth it for me? I'll be charging 2 5s packs at the most.

[Gregor99]

Originally Posted by Jermo

so without buying a new charger is parallel charging worth it for me? I'll be charging 2 5s packs at the most.

I can't answer that question for you. There are pros and cons to either approach.
Personally I like to experiment. So if were me, I would try it both ways and see which works better for my scenario. My suspicion is that serial charging as you are doing now will be the safest and fastest method.

Read my reply again and let me know if I can expand or clarify any points.