Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[digger.9]

Hi all,
I'm kinda new too this as you will quickly learn and looking at my first ev. managed to get  a cheap gsx-r '92

looking at what i will need to achieve hopefully somewhere near 40-50 range and top end 50-60mph.
then stumbled on these electric fence batteries?    
Hotline Electric Fence 6V 40Ah Battery
one site says they use them for golf carts, ev's etc but the are Alkaline (rechargeable)
At 1kg each seems very light too..

was thinking of 12 of them thus a 72v system. 40*12=480ah? does it work like this and if so how would I be looking for range?
thanks for the help

[Gregski]

hi the gixxer will make a fantastic platform for a conversion with it's lightweight aluminum frame, if you can make a battery tray out of aluminum that will be a bonus

40Ah batteries will not give you a range of 40 miles, especially not at the 50 MPH speed, maybe 10 miles with a top speed of 40 mph depending on gearing ie number of teeth on your sprockets

you connect batteries in either one of two ways (well you can do a hybrid but lets keep it simple)

First way... Series

12 x 6 volts = 72 volts (the amp hours stay the same so 40 Ah is the total amp hours)

Second way... Parallel

12 x 40 Ah = 480 Ah but volts stay the same and at 6 volts you are not goinng anywhere, lol

Third Serial Parallel solution could look something like this

6 x 6 volts for a 36 volt system then parallel that with the other 6 batteries x 6=36 volts also  so then 40 AH x 2 = 80 AH

you would end up with a slow bike that goes twice as far, lol

[Bogan]

+1 to Gregski's Ah explanation.

With batteries you primarily need to get some that can handle the power output, this is generally given as a C rating, which can be multiplied by the Ah rating to give max current output. For example, if that batteries you listed above have a 1 C Discharge, you can draw 40Amps from them. Some of the more common motors require 300 to make full torque, so you are looking at 8 in parallel to generate that. Those 8 would then need to have more sets of 8 added in series until the correct voltage is reached. You get more Ahr, but more weight and space and cost too.

That is most of what you need to know regarding the electrical performance, mechanically you want light and small. Budgetly, you want cheap.

Just a matter of finding the right balance between all the parameters.

Personally, I did some investigation recently, and would go with either of these two batteries.
http://currentevtech.com/Lithium-Batteries/Thundersky/Thundersky-90ah-cell-p23.html
http://currentevtech.com/Lithium-Batteries/Headway/Headway-40160S-16ah-cell-LiFePO4-p42.html
The first for distance stuff (like a 60mph street bike) and the later for lightweight power (like a dirtbike). But as always, what you want to build, dictates what you want to use!

[digger.9]

thanks guys really appreciated!
right first step
1) more research
2) lots more research
lol

[frodus]

From what I've found, those are just normal alkaline batteries and aren't rechargeable.... and I can't find a weight. Can you share more info on these? The "manufacturer" doesn't even have a datasheet on them.


And for range, don't think in Ah, think in Wh.

6V * 40Ah = 240Wh

240Wh * 12 = 2880Wh for the pack...... you'd get over 20 miles with a 72V 40Ah setup. Let me explain..... After taking into account some losses, and assuming that you'll only get 75% out of them beause I can't find any information on Alkaline Air discharge curves, so assume they're like SLA batteries.... you'd have about 2160Wh to pay with, and assuming you're under 50-60mph, you'll be running around 100Wh per mile (wh/mi).

So 2160Wh / 100wh/mi = ~21miles, give or take some if you're light or heavy on the throttle respectively.

And I don't think there'd be a problem getting to 50+ MPH on a 72V system. Gregski uses 48V in his and tops out around ~38mph or so. With 72V, you're at 50% more voltage, and voltage is directly proportional to RPM, so you're looking at ~55mph give or take a few MPH.

Just remember:
Volts is RPM.
Amps is Torque.
You want to stay as low current as possible while accelerating to conserve batteries.


If you have questions, post it here, we'll help!