Wisper 805fe battery

[isla]

Hi, my partner bought a second hand 805fe but never realised its only a 24 or actually 25volt battery. Would this have been the original battery as we thought they were 36 v bikes.

More importantly can he replace the battery with a 36v one he already has? Would this be compatible with the motor or would it do damage because if the voltage difference.

Many Thanks

Sandra

 

[Benjahmin]

Earlier bikes were 24v, how old is it? The motor would be alright on 36v however the controller wouldn't, there are capacitors in it rated for 24 and will release the magic blue smoke if 36 is applied. He would need a new controller/display combo fitted before usung the 36v battery.

 

[isla]

Earlier bikes were 24v, how old is it? The motor would be alright on 36v however the controller wouldn't, there are capacitors in it rated for 24 and will release the magic blue smoke if 36 is applied. He would need a new controller/display combo fitted before usung the 36v battery.

Thank you for the quick reply. We have no idea how old it is, it didn’t really concern him because he thought it was 36v and knew he had a good spare 36v battery. I’m now guessing if he needs a new controller he might be as cheap just to sell the bike again and look for another. We can google the price. Thanks so much for your help.

 

[Nealh]

Isla you may find it might work at 36v if originally 24v but checks need to be made first, the controller will need opening to check the actual voltage rating of the capacitors (small cannisters) written on them. Other wise as mentioned they will pop if voltage rating is too low.

 

[isla]

Isla you may find it might work at 36v if originally 24v but checks need to be made first, the controller will need opening to check the actual voltage rating of the capacitors (small cannisters) written on them. Other wise as mentioned they will pop if voltage rating is too low.

Thanks, will get him to check it .

 

[isla]

There are 2 separate purple wires 1male ,1emale funattached and also a black and blue stripe female one. Please can someone tell us what they are for, should any be connected to each other?

 

[Andy-Mat]

Isla you may find it might work at 36v if originally 24v but checks need to be made first, the controller will need opening to check the actual voltage rating of the capacitors (small cannisters) written on them. Other wise as mentioned they will pop if voltage rating is too low.

Good point.
For safety reasons, the voltage written on the caps should be far higher than the battery voltage. For 36 volts, I would recommend above 60 volts, and 72 volts should preclude failures, for example.
The replacement of a controller, is for a committed DIYer, no Biggy, but for someone with less talent in that direction, selling the bike may still be the best and safest option...
regards
Andy

 

[Nealh]

36v bikes use 50v caps and 48v use 63v ones.

 

[Nealh]

View attachment 36246
There are 2 separate purple wires 1male ,1emale funattached and also a black and blue stripe female one. Please can someone tell us what they are for, should any be connected to each other?

The purple might be a speed restriction wire or even a cruise wire, the other one is a brake wire like the other in the pic. One is for low side brake input and the other type is for high side brake input, ebikes use mainly low side brake input.

 

[isla]

36v bikes use 50v caps and 48v use 63v ones.

Thanks for this. And do you know what 24v uses?

 

[Andy-Mat]

36v bikes use 50v caps and 48v use 63v ones.

Good to know exactly, thanks.
Andy

 

[Andy-Mat]

Thanks for this. And do you know what 24v uses?

They can use either of the ones mentioned, as long as the area on the PCB can accept them, but the original manufacturer might use something in the range of 36 volts (guessing), as they are probably a tiny bit cheaper for him.
But as long as the working voltage is higher than the actual voltage, and the type and capacitance values are correct, it will still work fine.
Andy

 

[isla]

Thanks both for your replies.,

what does low side and high side brake input mean?

 

[Andy-Mat]

Thanks both for your replies.,

what does low side and high side brake input mean?

I do believe its a 5 volt signal, or lack of, from the brake levers, to the controller, that turns off motor drive when braking.
Also used on some controllers, to light brake lights at the rear of the bike.
Which is which I cannot say.
Look here:-

Andy

 

[Nealh]

Low side is usually a Reed switch that doesn't use 5v , only using Gnd and current.
High side is Hall which uses Gnd, signal 1v & Vcc/ 5v.

 

[Nealh]

Thanks for this. And do you know what 24v uses?

You would have to open the controller to look some 24v models might only use 30v rated caps some might use higher rated ones.

 

[vfr400]

That old controller will be really bad compared with modern ones and 24v bikes are nearly always crap. If it needs a new battery, get a 36v one and a modern controller to transform it into a nice bike. In the meantime, I'd put the 36v battery on to see if it works. If the controller smokes, you haven't lost much! Most of those old 24v controllers can work at 36v.

If you do use a 36v battery, remember that the controller won't cut off when the battery is flat and any battery level lights on the handlebars will be permanently on. The battery itself has a cut-off system, but they're normally set a bit on the low side for continued battery health. Basically, keep an eye on the battery and don't run it anywhere near flat.

Make sure you connect the battery the right way round. Use a meter to check. If you put it the wrong way, the controller will definitely smoke..

 

[isla]

Is it just the big black capacitor on the top right of photo that needs measured. Its showing 50 v.

 

[Nealh]

Yes Isla that is the main input charge capacitor you will be safe, the other small ones should be fine as all the other stuff is 5v.

 

[isla]

Thankyou. You are all so knowledgeable and helpful here.