Re: Battery Trailer

["VanDerWal, Peter" <vanderwp@fhu.disa.mil>]

>    For example say I have a 15 US8vgc for 120volts on board and want
>to have a trailer with a set of 20 US145 6volts for 120volts to extend
>my range.
>    Would it be safe (i.e. healthy for batteries) to parallel them
>while discharging and separate them for charging?
>    Would it be possible to use lighter wire/connector for the trailer
>since it would always be in parallel and seeing less amps?

I'm not entirely sure, but I think you'll find that the trailer pack you
describe is significantly stiffer than the EV pack.  This means that during
high current draws, the bulk of the current will come from the trailer pack.
I suppose you could deliberately undersize the cables, this will increase
their resistance and reduce the current pulled from the trailer pack.
However your trailer pack has roughly twice the energy storage capacity (at
1hr rate) as the ev pack so you'll really want at least 2/3 of your current
coming from the trailer pack.

I think if you did this and wanted it to work properly, you'd actually want
cables on the trailer pack to be LARGER than the normal cables to keep
resistance down and insure that 2/3 of the current comes from the trailer.

P.S. Doing this will almost double the weight of your vehicle so you'll end
up using more current under all circumstances than without the trailer.
Make sure your motor, controller, cables, etc. are up to it.