Fw: (ET) pack not isolated from frame??

["Ralph & Elaine Vogan" <ralphgv centurytel net>]

Note;  If you measure the voltage from the positive 36 volt to the frame 
and
get a reading of 18 volts then the short is in the lift motor circuit.

Ralph V
ralphgv centurytel net


> That is true.
>
> But remember, we are talking about a system that is supposed to be
> totally isolated frome the frame. You can't think of it in
> familiar terms like a car were you have positive and ground. You
> have a pack that is only positive and negative in relationship to
> itself and nothing else. If you connect any part of it to the
> frame of the tractor then you introduce the frame into the pack.
> If you connect the positive side of the frame then you have whats
> commonly referred to as a positive ground systems and all voltages
> are measured as negatives.
>
> The fact that the pack is isolated is an advantage when you are
> looking for pack induced ground faults. If you know you have a
> fault you can measure a voltage between any terminal and the
> frame, this voltage and its polarity will tell you exactly where
> your fault is. Another option is to use the light bulb method, it
> better be a 36v light though. Connect one lead to the frame and
> start touching the other lead to the battery terminals each one at
> a time. The one that does not light is the source of the leak.
>
> If you leave a lightbulb connected from the pack to the frame,
> then the pack is no longer isolated, until the light blows which
> won't happen until the pack connects somewhere else.
>
> Stay Charged!
> Hump