currie electrodrive question

[aljsk8]

Hi

will my 24v 450w (peak 750) brushed DC currie electrodrive motor
get me 3 miles of flatish road

using 2 x 12v 3700mah vapextech r/c nimh batterypacks

hope you can help

thanks

Alex

 

[andys]

those are very low capacity batteries you are using. Most e-bikes need at least 10 AH to get a respectable distance ability.

 

[aljsk8]

thanks for taking the time to reply

im really after someone to work out the maths

i dont want to go a reasonable distance - 3miles max
2 miles would be ok

can anyone tell me how far id get before loosing power using these batteries?

thanks

Alex

 

[Miles]

Alex,

You battery will be fine for that journey.

24V x 3.7Ah = 89Wh available from the battery.

@ 60% system efficiency = 53.4Wh

So, for instance, that's about 200 Watts power available for a 15 minute journey (12 mph for 3 miles).

On the flat, without headwind, you will need something like 55 Watts to maintain 12mph.

On a 5% gradient, you will need approximately 300 Watts to maintain 12 mph.

Travelling at 20mph on the flat will take about 200 Watts.

 

[aljsk8]

THATS GREAT

Do i need to worry about voltage sag?

bear in mind the system is currently using 2off 12v 12ah sla

im also guessing that it is a claimed 3700mah and probably more like 3400mah

i think i can manage the maths now but a reply about voltage sag would be super

cheers Miles

 

[deardancer3]

Hi

will my 24v 450w (peak 750) brushed DC currie electrodrive motor
get me 3 miles of flatish road

using 2 x 12v 3700mah vapextech r/c nimh batterypacks

hope you can help

thanks

Alex

Yeah I think voltage sag willl be an issue.


Not many reasonalbly priced C NIMH cells can deliver 15 amps without appreciable sag.
Acceeleration from a stop, hill limbng and end of trip loads will be your trip points.
Moderating your throttle and having a voltage montor on the handle bars will help.
Or, get a second pack for using in parrallel, or, a cyle anayst set to maximum current.

But training yourself to stay out of the big sag zone with a simple voltage is probably the chaepest.

my 5 watts worth.

d

 

[Miles]

Alex,

Did you see this thread?
http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=5339

 

[aljsk8]

yeah i saw that thread but i didnt know what effect only running 2 batterys in series would have

it says the batterys can handle 30 amps - i think thats about the max for my setup so i assumed it would be fine

i might just get 2 and try it at £50 even if it didnt work im sure id find a use for the batteries

any more hep would be great

thanks

Alex