Momentary 24 volt dc to 36 volt dc question

[frankie]

Guess I am getting old and rusty. I would like to be able to add 12 volts in series with 24 volts to feed 36 volts to
the 24 volt 450 watt motor on my Ezip. I already have the two 24 volt wired in parralle which gives me 24 volt at 18 ah.
My idea is to add the 12 volt in series just before 24 volts dc reach's the 24 volt motor. The motor would only see 36 volts when
switch was on, otherwise it would see the 24 volts. You would be bypassing the controller.
Anyone understand this old man and have an idea. I was thinking of a DTDP switch.

 

[amberwolf]

If you're going to "bypass the controller" you're going to need a switch capable of handling full motor/battery current at the highest load it will draw. That switch will have to be a "break before make" type, as well, meaning that it will have to break the 24V connection *and* the motor-controller-battery connection, before it makes the 36V motor-battery connection.

The most surefire way to do this wihtout spending too much on the switch is with multiple switches that are locked together with a physical bar across them (like circuit breakers often are) so that pushing one triggers the pushing of others at teh same time. That will allow you to use DPST or DPDT switches for everything, at most, or SPST at the simplest (but several of them).

Otherwise, you need a switch that will
--disconnect 24V from controller
--disconnect motor from controller
--connect one side of 12V to one side of 24V
--connect other side of 12V to motor
--connect other side of 24V to motor
The first two have to happen before the last three can happen, or you might end up smoking something if your controller can't handle 36V (or whatever your 36V pack really is when it's fully charged).

 

[liveforphysics]

The optimal way to do this would be to tweak the controller to take 36v input.

 

[frankie]

Thanks for the inputs on my post, but I think I will leave things as I so far modified them. Keeping my battery mounting pack contacts
sanded, gives me enough take off power (the two 24 volt batteries wired together for 24 volts and 18ah.) and 15mph or so, all this
old man needs. I played around today with feeding that 24v/18ah direct to the 24 volt motor via an on/off switch. Had it all designed
then decided that might now be good idea also. anyway, I like reading the forum.

 

[neptronix]

If you have an 08+ ezip, it won't take anything over about 28 volts.. they have protection in the controller :/

If you have a much earlier one, you could have the controller that has 63v caps... in that case, 36v away!
However, do know that you are shortening the motor's life at that voltage :\
I've heard of some guys who run 30-32v with an additional 6v SLA or converted to lithium entirely, they seem to have great results.

Anyway, i have a mongoose currie bike and i know how it feels. that bike definitely has a brick wall of speed.