In all of these ideas, the power STILL has to go through the controller.
None of them can create power out of nothing. Indeed NOTHING can creat
power out of nothing.
Since POWER is the only thing that really matters, all of these ideas are
basically pointless, even if they did work. You are still limited by the
power you can get through the controller.
It doesn't really matter if we use a boost converter, or some other method
of boosting voltage, it still comes down to power.
Since, as I understand it, the basic point is to get more power from the
motor a more powerful controller solves the problem.
If you are limited to an 80V pack, then you have to make up the power with
higher current levels.
Power /out/ equals power /in/ minus losses. All of these schemes just
increase your losses, so you gain nothing by using them. In fact, you
actually loose a little.
>
> I like my third idea the best if it would work.
> 1. Well I have heard of it is possible to increase the field to say 72V
> (on
> a shunt motor) for 30 sec max to increase torque, so that you can spin
> tires. That could be used as booster switch. Though, torque is increased
> to
> extreme levels at 72V, but top end speed would be slower. The problem of
> course is burning out the field wiring inside the motor. Which would mean
> getting stuck and possibly repairing the motor. Of course you could also
> try
> say 48VDC booster switch. So the car would go from say 24VDC on take off
> to
> to 48VDC and then turn it off after you get going and then it goes back to
> 24VDC. How you get the 48VDC could be an issue. I suppose you could tap
> into
> the traction pack. I read you are using 24VDC separate battery pack, so to
> get 48VDC from this you could use an 115V AC car inverter and then convert
> this to 48VDC with a household 48V power supply. Say you need 30 amps max
> at
> 48VDC and this is 1440 watts. So your inverter needs to be 1500 watts
> continuous and maybe 3000 watts peak. Now you would need to win this
> auction
> http://tinyurl.com/2j3t8k . As it is a 99 cent auction and how many people
> really need such a 3000 watt 48VDC power supply. Of course now you have
> two
> big boxes to place on the vehicle. Plus, you'd probably have to power on
> the
> inverter and then the power supply when you start the car. That way
> switching from 24V to 48V would be flawless. I sure there is a more direct
> way to do this by building some simple circuit.
>
> 2. Another simple solution is to put 4 smaller batteries equivalent in
> size
> to the two already on the vehicle or just add two. The two you add don't
> have to be the same size, since you just need an increase in voltage. Just
> adding two 12Ah-18AH 12V batteries would work. Now you need to have
> batteries switch from 24V to 48V. However, it is important that it do this
> instantly without dropping the field. I think I have a contactor diode
> circuit for this. Check this out
> http://img525.imageshack.us/img525/7324/pg4fa7.jpg Figure 5-7 is what
> might
> work. Notice is says the relays have to be interlocked. Which means a
> reverse based diode on each switch.
> 3. Thirdly, I think you'd be fine with simply connecting the 4 batteries
> in
> series and then tapping off what you needed. Since the battery pack will
> tend to balance. Maybe you could build a lead acid battery balancer. So
> the
> negative will come off the end of bigger Ah side of the 48V pack. Then
> then
> + 24V tap will come off counting from the negative and connect to the
> motor
> field +. Now simply run a + from the 48V end of the battery pack and add a
> heavy duty switch in between here and motor field or use cheap $15 curtis
> contactor from surplus center. If you don't think this will work, then
> tell
> me because positive's being connected together?? So when you turn the
> switch on you have Turbo take off. You could even use one of the switches
> with a spring, so when you release your hand the boost is always gone. I'd
> use a contactor for this type. Maybe a solenoid would work, but contactor
> is
> a lot better in my opinion. Here is a pic of what I am talking about
> http://img150.imageshack.us/img150/7603/48vdccu7.jpg .
>
>
>
> Michael Barkley wrote:
>>
>> Hello all, as many may be aware, but for those who
>> aren't, I'm legally limited to no more than 80vdc for
>> my EV conversion.
>>
>> I had a brain @!#$% last night and wondered if this
>> would work:
>>
>> Place a heavy duty transformer between the motor and
>> controller, so that the controller is feeding one
>> winding of the transformer, and the other is feeding
>> the DC motor. If the transformer was wound to boost
>> the output voltage in relation to the input voltage,
>> would this accomplish anything for the EV, or just let
>> the smoke out of something?
>>
>> Figured, you all needed something CRAZY to think about
>> on a Friday.
>>
>> M.Barkley
>>
>>
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