Sorry to bring this subject up again...BUT... EQ-10 set up with 2 A-123, 2300's, with JR balance tap leads...Why do I need to plug the individual charge leads into the EQ-10? Why can't I just plug the balance taps directly into the charge leads bypassing the "10" since I balance charge every time? I have read about the common ground thing but I'm no electrician and don't fully understand it...but...it appears to be the reason why I can't charge both batts at the same time...Then I read that if my chargers support "common ground" I can. I use FMA Multi-4's. Can I charge both batts simultaneausly with them?
Final stupid ??...If the common ground thing is causing so much turmoil, why not build these PE's without it?

Still confused...a little

Oops: 1 more... I'm using a Tech-Aero Ultra IBEC plugged into Aux2...anything I need to be careful of here?

Thanks in advance!

its not the power expanders that cause it .. its the separate leads the chargers have to each cell when both batts are connected to chargers at the same time. They confuse each other. a switch that will shut off both Positive AND negative to the batts, actually i think just one switch that cut off both + an - on one of the batteries will cure the prob. its not just Pe's that have this prob, dual batts into a rx run into this too. if yer tryin to charge em in parallel, well good luck. or just stuff the charger on fast charge and hope it works.

Multi 4 has to charge one at a time
It only takes 9 min or less to charge one A123

Hi,
Any time you use redundant batteries you end up with a common ground. This is because switches do not switch the ground lead. Because of this, even when a switch is off, the grounds of the two batteries are still connected. Since almost every charger on the market is build wrong, except Fromeco's chargers, this common ground confuses them and can cause charger damage, battery damage or even battery explosions. So it would not matter if you ran two batteries into a receiver or two batteries into a PowerExpander, you still end up with common ground. There is no way around this. The balance leads still connect to ground so you have the same issue with the balance leads as the main leads, they are all in a common circuit. You have two choices, either charge one battery at a time if both batteries are connected to the system or break the circuit somewhere so the grounds are not connected and then you can charge both batteries.

If you have BEC plugged into a PowerExpander then you must make sure it is not supplying power through that lead. If it is you MUST remove the red wire.

Originally Posted by billd3

Sorry to bring this subject up again...BUT... EQ-10 set up with 2 A-123, 2300's, with JR balance tap leads...Why do I need to plug the individual charge leads into the EQ-10? Why can't I just plug the balance taps directly into the charge leads bypassing the "10" since I balance charge every time? I have read about the common ground thing but I'm no electrician and don't fully understand it...but...it appears to be the reason why I can't charge both batts at the same time...Then I read that if my chargers support "common ground" I can. I use FMA Multi-4's. Can I charge both batts simultaneausly with them?
Final stupid ??...If the common ground thing is causing so much turmoil, why not build these PE's without it?

Still confused...a little

Oops: 1 more... I'm using a Tech-Aero Ultra IBEC plugged into Aux2...anything I need to be careful of here?

Thanks in advance!

Originally Posted by rrritchey

Hi,
Any time you use redundant batteries you end up with a common ground. This is because switches do not switch the ground lead. Because of this, even when a switch is off, the grounds of the two batteries are still connected. Since almost every charger on the market is build wrong, except Fromeco's chargers, this common ground confuses them and can cause charger damage, battery damage or even battery explosions. So it would not matter if you ran two batteries into a receiver or two batteries into a PowerExpander, you still end up with common ground. There is no way around this. The balance leads still connect to ground so you have the same issue with the balance leads as the main leads, they are all in a common circuit. You have two choices, either charge one battery at a time if both batteries are connected to the system or break the circuit somewhere so the grounds are not connected and then you can charge both batteries.

If you have BEC plugged into a PowerExpander then you must make sure it is not supplying power through that lead. If it is you MUST remove the red wire.

Nuff said.....from THE man himself...