Well, I ordered the ThunderPower TP-210 balancer and a
HV UBEC.
I know I could have simply gotten another LBA10 and networked them, but didn't like having to use the network cable, not to mention the added mess from the input/output Y adaptors for the main charge current.
The choice between balancers was between the
DimensionEngineering HVBEC and Western Robotics. The WR BEC was kinda pricey, but is capable of higher current (3.5A vs 2.5A for the DimEng one), and the components on the WR looks beefier. Once the BEC comes in, I'll perform a test on it like I did with the other BECs. The other option I was tossing around was to daisy-chain 8 diodes in series to drop ~5v to bring the 10s battery voltage down from a max of 42v to ~37v. This would have allowed me to use the KoolFlight UBEC (which tests out and performs quite well). The KF BEC has a max input of 40v - actually, the switching IC is rated for an absolute max voltage of 45v but that's pushing it.
Now I'm looking for connectors. I was going to use Deans, but they don't handle the current I'm expecting. I don't want to use bullet connectors because they are a PITA to connect/disconnect IMO. What is available that is polarized/keyed, rated for 100A+, connects both poles at the same time (like Deans), yet is still small/light?