Oxydrive battery seems dead, what to do?

[nosmo]

Hi,

Today I was driving my bike to work at power level 2, I still had 2 energy bars left while standing still. The last part of the trip I switched to power level 4, it worked for a second and then the system died on me.
This isn't special, I know that a high power draw can make the voltage drop and the protection shuts down the system if the battery goes beyond a certain point. It happened to me before, I just turn it off and on again and I can drive in power level 3 without any problems.

Today I though I would just leave it, I was close to work anyway. At work I tried to charge the battery but nothing happened, also the internal battery checker didn't do much.
At home I measured the voltage and its about 8V, doesn't matter if I turn it on or off.
I know 8V is way too low for a 36V system.

So what gives, whats going on, why cant I charge anymore? I don't believe I did something wrong...
Anyone with an answer?

kind regards
Ido

 

[Zebb]

Have you checked the battery charger.? even so it does sound very ill.!! possible the BMS is causing the
problem, perhaps Dave will stop by and give you some advice on how to check it out.

 

[Deleted member 4366]

The BMS has shut down for some reason.

How old is it?

Could you measure the voltage at the charge socket? It's a bit fiddly, and you have to be careful not to short between the pin and the side contact.

Do you want to have a go at fixing it yourself, or do you want to send it somewhere to be fixed?

 

[trex]

by the description (8V at the output), it looks like the power switch FETs are shorted possibly due to motor seizure. Can't be easy to fix.

 

[nosmo]

Strange, I subscribed myself to this thread but didnt get an email, oh well.

Dont think its the charger, I measured it and its about 40V coming from it.
The battery age is... don't really know, I bought the set 2 months ago, there is a number on the plastic of the battery that looks like a date 2010 2, which seems like its an old battery if thats the case.

And trex, what do you mean due to motor seizure, how can fets be shortened out by this?

I rather want to wait what the guys from oxydrive have to say, otherwise I dont mind opening it up to have a look.

 

[Deleted member 4366]

Please measure the voltage on the battery charge socket, not the charger, then I will be able to tell you what's wrong with it.

If it's under warranty. Oxygen will just ask you to send it in, so you'll be without it for a few days. If you're competent, you can fix it yourself.
Amdrew, the Oxygen proprietor, is at Eurobike in Germany at the moment, so there might be a bit of a delay in communication, but normally he's pretty good.

 

[nosmo]

will measure it tonight when i am home again

 

[nosmo]

btw, also thanks for mentioning Andrew from Oxydrive is not at home. I was wondering why he wasnt reacting on my email

 

[nosmo]

I measured the voltages
Charger gives: 41.8V
Battery gives: 8.5V
Battery charger lead gives: 8.4V

 

[Deleted member 4366]

That means that your BMS is completely switched off. The reasons I've seen for that on bottle batteries are:
The connector on the BMS squished by the top piece because it was in the wrong position.
The connector not fully in.
A cell voltage below the minimum 3.1v.
BMS needs a reset because a cell temporarily went too low

It's dead easy to check. Just remove the three screws from the top and lift it. Look out for the "o" ring around the plastic part. You need to re-seat it when re-assembling.Once you've lifted the top, you can get a bit more access by removing the two screws in the LEDs circuit board. Pull it out and tape it to the side of the battery while you investigate.

If the connector looks OK, pull it out, wait a few seconds and plug it back in. That resets the BMS. If that doesn't bring it back to life, you need to measure all the cell voltages. Place your black probe on the "B-" connection, then on each slot in that connector, The results should go up in steps of about 3.5v. Write down all the results and then do the sums.

This might sound like a lot, but It's very easy to do and takes less time than to box up the battery to send it back. I know Andrew, and he won't have any problem with keeping the warranty even though you opened it.

 

[nosmo]

Thanks for the reply dave, I didnt check the fuse as I dont want to void warranty, if the guy from oxydrive say its ok to take a peek without loosing warranty...

8.5V is way to low ofcourse, could it be the internal protection thats it not charging, because the cells are below a minimum voltage? I dont understand why it would be this low, I didnt discharge that much, it still had 2 power bars left.

But it could one if the things you suggest. I guess I'll wait what Andrew has to say, hopefully he will react quickly.

 

[Deleted member 4366]

Re-read my post. I edited it because I misread your results. It won't be the fuse. Andrew is my friend and colleague. I went to China with him. If I say that it's OK to open the battery. He will agree, so go ahead if you feel competent. It'll save a lot of messing about for everyone. If it turns out that your cells are knackered (highly unlikely), then you'll get a new battery. I'll personally guarantee that.

 

[nosmo]

thanks dave, I opened it up, I replugged the connector, soldered a wire that was/came loose, the one for the internal battery checker and put everything back together. btw, didnt find an "o" ring around the top.

Now its measuring 34.7V again, yippie, its also charging again. It sure saves some shipping around. Don't really know what the problem was, resetting the BMS or the loose wire, which was or came loose, not really sure. But good thing its working again


The black wire came loose

 

[Deleted member 4366]

Another happy ending. Sigh!

 

[Oxygen Bicycles]

Hi all,

Sorry for the delay in responding, just posting from Euro Bike so very limited access to the net. Hotspot at the show totally does not work and after buying a sim, 10 Euros of credit has gone in 5 minutes so not so pleased shise . Anyway I'm glad that battery has been fixed now. Big thanks to Dave for all the advice given and indeed sometimes battery problems seem to be be very easy to fix. We off course don't encourage anyone to open them and repair on its own but for competent users that feel comfortable, removing the cover will naturally not void the warranty. Its all about common sense here.

All the best
Andrew

 

[nosmo]

Thanks for replying Andrew, I was wondering why no reply came to my mail, but now I know why. All is working again.