Hi guys,
Hope you don't mind my sticking my nose in, I have two nine month old Ping batteries, One 24 volt 15 a/h and a 36 volt 10 a/h.
When preparing these batteries for use, and after soldering the XLR plugs to the charger output leads, I remember that I checked the polarity was correct.
These checks were carried out WITHOUT the charger connected to the batteries. The open voltage measured at the charger lead XLR pins were: 39.9 volts for the 36 volt charger. 28.9 volts for the 24 volt charger. It may well be Jeremy, that the chargers in fact do not need to see a voltage as you thought. I'm not very good with electronics, so please don't be offended if I'm wrong.
The chargers are a bit suspect regarding quality, but in fairness to Li Ping, I would be inclined not to be too critical of them. After all, they are £20 chargers.
I remember when my 24 volt pack arrived, as soon as I unpacked the charger, I could hear something rattling about inside. This proved to be a reverse current diode which had "fallen off" the PCB. With this component re-soldered to the board, the charger worked fine, except, it sometimes needs a "barney flinstone" tap to persuade the cooling fan to start.
I hope this may help in some small way.
Regards
Bob