Bongo Fury

Does anyone know if a duff second battery will eventually take the SB (starter battery) with it when used in the willinton kit? The AA man who diagnosed the battery problem said a bad battery will always take the good one out with it. So is the SB protected by the kit ?
I had two batteries but converted successfully to one. Problem is the two batteries that came off both seem fine to me, so one of the two is in situ and all seems fine.

Thanks all.

It doesn't directly do any harm if the L/B is not up to scratch. The whole reason for using a Voltage Sensitive Relay (VSR) is that the L/B isn't charged until the voltage on the S/B has risen to around 14volts, after the relay operates then the charging current is shared between the two batteries - however if they L/B is really knackered and isn't coming up to 12.6volts at rest then it may be taking more than its far share of current getting hot and hence being further damaged! The best way to check is to disconnect BOTH batteries, let them sit for an hour or two and then measure the voltage of each, they should both be in 12.6-12.8 volts if they are reasonable, if either is below 11 volts then put it on charge from a mains charger for at least 48 hours and then repeat the voltage test (including letting the battery rest for a couple of hours off the charger), if it still isn't coming up to 12.6volts then replace it. There can be other problems with batteries but that is the easiest check to make.

Thanks.