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Author Topic: Volts = Speed, AMPS = Torque, AH = Range, So...  (Read 3101 times)

Gregski

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Volts = Speed, AMPS = Torque, AH = Range, So...
« on: August 23, 2011, 10:55:21 AM »
I have a 48 volt system on my motorcycle conversion. Four 12 volt 55 AH 22NF-AGM Lead Acid UB12550 Batteries in series. An Alltrax AXE4834 300 AMP controller. A MARS ME0709 18 HP / 300 AMP peak motor (8 HP / 125 AMP continuous).

My current (no pun intended) top speed is 45 MPH.

To go faster I plan on adding 2 more batteries which will give me a 72 volt system. Of course I will have to upgrade my controller to either the AXE7234 200 AMP or the AXE7245 450 AMP.

To increase the range I need to up the AH, and that's where I am confused. I know in the parallel configuration the Amp Hours are added up, but where do the extra Amp Hours go when I add the additional two batteries like I am planning to do? I realize I will be carrying the additional weight.

If I limit myself to 45 MPH top speed Is my range going to increase at all?

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Bogan

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Re: Volts = Speed, AMPS = Torque, AH = Range, So...
« Reply #1 on: August 23, 2011, 11:57:09 AM »
In series the voltage adds and amp hours stay the same, in parralel the voltage stays the same but the amp hours add, total kWhr is same for both.

If you up the voltage with more batteries, it also increases the range, as the battery current is less, for the motor current at a given speed.

The problem with lead acids, is you will not get 55ah out of them, unless it's at very low discharge rates. The quicker you go, the more power you need; the more power you need, the less capacity you have available. It's to do with the cell chemistry I guess.
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frodus

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Re: Volts = Speed, AMPS = Torque, AH = Range, So...
« Reply #2 on: August 23, 2011, 10:37:29 PM »
So you have 55Ah batteries and they're all 12V and you have 4 of them.

55 * 12 * 4 = 2640 Watt Hours

If you add 2 more:

55 * 12 * 6 = 3960 Watt Hours


Now, bogan is right, you won't get all of that out of lead, expect 75% or lower. Adding 2 55AH batteries increases your capacity 50% though. What range you get out of it, well it'l be SLIGHTLY more than 50%, because the current is lower at 72V, but that's only if you keep that 300A peak in the controller. If you get a larger controller, and suck more amps, then you can't guarantee that you'd get more than 50% range increase.


If you want an alltrax, there's one over on elmoto.net for sale, $450 it's an AXE 7245 I think.
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Travis
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