8fun conversion kit

[andycoh]

Back in january I bought the 8FUN 36V / 250W e-bike conversion kit. and to convert my bicycle to electric. At that time did not know about this forum, wish I had! Anyway it worked great for 2-3 months, but recently it stopped working. When first switched on the power light on the LED panel glows for a couple of seconds, then goes out. The battery has been fully charged, and the motor was working fine up to that point. It has been ridden in the rain quite a few times, and during the day time is not parked undercover. So possibly some water has got in?

I'd be grateful for any advice on how to troubleshoot this. I have sent email to 8fun (no response) and tried the 0845 number, but no answer on that. Before trying the other numbers I thought it would be good to troubleshoot a little myself.


thanks for any suggestions,
Andrew

 

[amigafan2003]

What's the voltage on the battery when fully charged?

 

[KirstinS]

You'll need a multimeter to check voltages -I never owned one before I got the same kit you have

Invaluable tool less than a tenner on eBay or under 20 from halfords/maplins etc

Start with the battery and test for voltage there.

If not at 42v or close to then it's not getting charged which leads to next set of tests starting with the charger

I've done quite a bit of trouble shooting on this exact kit (even got the odd spare part including a controller ) I'm sure we can get you back on the e road

I would have been stuffed without this site and the good folk on it

I've gone from not even owning a multimeter or knowing how it works to building my own battery packs out of old laptop batteries !

I found 8 fun helpful when I was in warranty - they even replaced a battery (though it turned out not to be the fault). Mobile number was best bet and email

Cheers

 

[Deleted member 4366]

The 8Funbike UK guys are nothing to do with 8Fun motors. They just sell 8Fun hub-motor kits, so no point in ringing them.

You need to check your battery first, and then check that you've got 5v on your throttle. You need a voltmeter for that.

 

[KirstinS]

Yes sorry my assumption was you bought from here a few months ago

http://www.8funbike.com

 

[andycoh]

Thanks for speedy responses. I will dig out the multimeter (due to a recent house move its buried in a box somewhere), and let you know results.

Kirstin, you are right I bought the kit from the 8Fun guys in Birmingham, hence my contacting them.

 

[Deleted member 4366]

sorry, i thought you had a crank-drive kit. The UK guys are normally pretty good with warranty on their stuff. maybe they're on holiday. They are Chinese, so keep any communications simple.

 

[manalog]

I had the same problem last year, they replaced my Battery. Last week my Thumb Throttle stopped working and e mailed them twice - no response and the phone just keeps ringing.

 

[KirstinS]

I had the same problem last year, they replaced my Battery. Last week my Thumb Throttle stopped working and e mailed them twice - no response and the phone just keeps ringing.

Oh dear - hopefully just on holiday

 

[KirstinS]

Oh , I ended soldering my throttle directly - the connector was bit rubbish

Have you tested it ? Ie know for sure the throttle is gone rather than just bad connection ?

 

[Deleted member 4366]

It's probably easier to fix the throttle than contact the supplier as long as you can solder - and less stressful. If you want to have a go at fixing it, is it the plain type or one with a switch and LEDs? Then I can walk you through how to test and fix it.

 

[KirstinS]

Pretty sure they only supply the plain type - looks that way still

 

[manalog]

Oh dear - hopefully just on holiday

I hope they are, I'm about t o buy a new one but I don't use my E bike very often nowadays. The problem with the Throttle is the spring looks like it is broken inside I can still use it but the throttle is not returning to the original position. I might have to open it up and have a look.

 

[amigafan2003]

I hope they are, I'm about t o buy a new one but I don't use my E bike very often nowadays. The problem with the Throttle is the spring looks like it is broken inside I can still use it but the throttle is not returning to the original position. I might have to open it up and have a look.

The spring has two right angled "hooks" that latch into a hole - it's common for one of these ends to come out of the hole so the throttle doesn't return. Dead easy to have a look - just put a thin flat blade screw driver or knife between the part that rotates and the part that clamps to the bar and lever the "twisty" bit away and you'll be able to see inside. You can do this while the throttle is still clamped to the bars.

I remove the springs from thumb throttles - cheap cruise control

 

[andycoh]

What's the voltage on the battery when fully charged?

The battery is not taking any more charge, light stays green on charger,
Just got the multimeter on it, its hovering between 40 - 41 V.

 

[Deleted member 4366]

That doesn't look good. It should be at least 41.5v straight off the charger. If you want to fix it yourself or check what's wrong (or right), you have to take the top off the battery (3 screws),then unplug the wire that's still connected to it. On top of the battery is the BMS. You'll see one or two multi-pin plugs to it. These are the sense wires from the cells. Put your black probe on the BMS where a thick black wire from the cell-pack is joined. It should be marked "B -", then with your red probe, check each pin on the sense wire connections to get the incremental voltages, something like 4.1, 8.2, 12.3, ....etc. Write them down and post them here.

If you don't understand where to check, take a photo of the BMS and post it here. Make sure it's clear.

 

[amigafan2003]

Yeah - I agree with d8veh - I'd put money on a weak cell causing the BMS to shut off power.

 

[manalog]

The spring has two right angled "hooks" that latch into a hole - it's common for one of these ends to come out of the hole so the throttle doesn't return. Dead easy to have a look - just put a thin flat blade screw driver or knife between the part that rotates and the part that clamps to the bar and lever the "twisty" bit away and you'll be able to see inside. You can do this while the throttle is still clamped to the bars.

I remove the springs from thumb throttles - cheap cruise control

Thanks Amigafan, I'll give it a go.

 

[andycoh]

That doesn't look good. It should be at least 41.5v straight off the charger. If you want to fix it yourself or check what's wrong (or right), you have to take the top off the battery (3 screws),then unplug the wire that's still connected to it. On top of the battery is the BMS. You'll see one or two multi-pin plugs to it. These are the sense wires from the cells. Put your black probe on the BMS where a thick black wire from the cell-pack is joined. It should be marked "B -", then with your red probe, check each pin on the sense wire connections to get the incremental voltages, something like 4.1, 8.2, 12.3, ....etc. Write them down and post them here.

If you don't understand where to check, take a photo of the BMS and post it here. Make sure it's clear.

Update: one of the screws on battery cover is stuck, I cant get it off with the screwdrivers I have, so have ordered some more.

According to 8fun they say it should be ridable down to 30V, and they advise me to check the connections. Could anyone let me have a wiring diagram? I did ask 8fun , but no reply so far.

 

[KirstinS]

Just a comment - my 8fun cuts out at 32v - wether designed that way or not !