OXYGEN S-Cross CB -intermittent cut out.

[DBye]

What could be causing this:
When cycling the display initially shows full battery charge (41.5V, the battery has been charged earlier in the day), initially all seems normal, assisting as it should.
Then the assist stops, display remains on, but the display suddenly shows anything between 33v and 23v.
Power off and restart sometimes fixes it.
Removing the battery and plugging it back in fixes it.
Sometimes, on cut out, the display slowly creeps back up to normal operating range (above 37v) and the assist kicks back in.
Sometimes the assist kicks in when the display is showing less than 25v.

Pressing the charge indicator on the battery itself shows 4/4 lights i.e. close to full.
Reading the battery terminals with a multimeter when home shows 37.8v after intermittent ride home.

I'll check the battery again when it is hot off the charger, I suspect it will be fine as I checked it last weekend and it read 41.7v.

 

[Nealh]

First thoughts are a poor battery/contact connection or poor wiring connections. Though a faulty a lcd may also be the issue .
Is it under warranty ?
If so back to the dealer.

 

[Deleted member 4366]

Inspect the battery contacts in the frame and the battery carefully. if they're OK, remove the battery connector and catch (two or three small screws) and look at the connection on the back of the connector to see if they're soldered properly, and follow the wires to the controller to see if they're connected properly. The controller sits in the frame just above that connector. It's tight, but you can pull it down for inspection.

 

[DBye]

@Nealh -Thanks, I was under the impression that the warranty was 2 years for mechanical components and the battery (just checked my manual and it is as stated). So I assumed the electrics was statutory 1 year. But Looking on the Oxygen website it says 2 years for electronics too.

I'll take it back but first I need to remove my "additions" to the controller... also it doesn't seem like 5 mins since I was last on the phone to them about that crack in the frame.

The -ve battery electrode seems a bit mucky/corroded -any suggestions on how to safely clean this?

I suspect this is not the fault though as I can read 41.7V on the multimeter:
1. Across the terminals themselves easily (I don't need to dig through the muck for the probe to take a reading).
2. Across the connector from the battery to the controller, when the connector is plugged into the battery.
3. With the battery unplugged I've plugged the connector into the controller and using the continuity setting on the multimeter I can tell that both the +ve and -ve connections are continuous from the connector to the controller.

The connector is shrink wrapped so I can't inspect the solder joints without further deconstruction, however there is continuity there. Looking at the controller I can't see any dry joints, although I have spotted a surface mount LED which is flashing red when the battery is plugged in.

Of course, now it is sat in my office at work everything appears to be fine but the ride in to work, wasn't

 

[Deleted member 4366]

What were your additions to the controller?

 

[DBye]

That'd be these resistors to the shunt.

 

[Nealh]

Two likely faults possible then, your solid state shunt mods may be asking to much of the battery and can't supply the amp load demanded. Or the contacts need cleaning and a bit of non conductive grease applied, use a light emery grade on the contacts and wipe with isopropanol. Corrosion can and will give poor or intermittent continuity.

 

[Deleted member 4366]

If one of those shunts wasn't soldered properly, I can imagine all sorts of problems. You should check them. There can't be anything wrong with what you did because it worked for a while. Something has changed. I still think that the most likely cause is something on the wires between the controller and the battery. Did you check everything on that route?

The dirty connector could still be the problem even though you can measure full voltage there. your probe can pierce through surface contamination, but the blunt pin on the connector can't. You should clean them as best you can to see if the problem improves.

The red flashing LED means that everything is working properly when the flashing is even. When there's a problem, it changes to a flashing pattern. The pattern tells you what the problem is.

 

[DBye]

Thank you both.

I had it apart yesterday for a good clean, I used emery cloth and a small needle file.
I removed the fuse from the battery to start! -Made working on it much easier as far less fear of getting a shock.

Anyway, I'm pleased to report I've made it worse -which is good!
It now seems clear that the battery it is struggling to maintain contact with the terminals on the bike. If I tape the battery tightly down in place it makes OK contact, but if I don't then the slightest bump results in disconnection.

The socket on the battery looks like one of these. I'm finding it difficult to get the negative pin nice and clean. Any suggestions? Looking at the socket my cleaning efforts don't seem to have touched it, so I've got some contact cleaner to see if I can remove some of the residue better.

 

[Deleted member 4366]

If it were my bike and I wanted to run over-current, I think I'd remove both connectors and fit something like Deans connectors. That would be less convenient if you wanted to remove the battery every day, but at least it would give a more reliable connection.

Those connectors are used on a lot of E-bike batteries, but I have some questions about whether they're up to the job. Already, I've heard of several problems with them. All you need is a bit of contamination on them, which then causes over-heating, melting, etc. They, or similar connectors, are used on the various downtube batteries at up to 25 amps. I've not heard of problems with them there though. Maybe there's differences. I'd prefer to see more metal in the connectors, whichever ones are used. Most people never remove the battery, so it shouldn't be a problem for them.

Heat goes up with the square of the current, so going from 15 to 20 amps would make an 80% increase to any heat in the terminals from bad contact.

 

[DBye]

I agree with you. I'm not impressed by this connector at all.

The socket on the bike is connected to the controller with a Deans connector (irony?).

I did pop the cover off the battery to see if I could easily replace the socket as I have noticed a lip of plastic building up around the -ve terminal on the battery. But it appears to be soldered on (I need to do some more digging).

 

[DBye]

Sorry I should say that I remove the battery every day to charge as there is no power where I keep the bike.

I'll give the contacts a clean and see how I go. I've put a watch on these on ebay:
AMASS T PLUG
AMASS T PLUG INSULATED CAP

 

[Deleted member 4366]

Sorry I should say that I remove the battery every day to charge as there is no power where I keep the bike.

I think that's the problem. There's no switch on those batteries so every time you reconnect it, you get a spark from the controller's capacitor inrush, which gradually erodes and contaminates the terminals.

 

[DBye]

That makes sense. I can only imagine it being exacerbated if the battery is rattling about too.

This has got me wondering if I could incorporate a switch if I were to replace the connector.
I had thought of replacing the 30A blade fuse with one with a manual circuit breaker but I think it would be hard to keep dry.

Is there such a thing as a Deans connector with switch or would i be looking to add in some in-line thing?

 

[Deleted member 4366]

A switch on the battery main cables is tricky for the same reason. You need an electronic switch like they have in the BMS. these are what I used to use:

 

[Mal69]

How did you get a crack in the frame?

 

[DBye]

@d8veh -thanks, not as simple as I'd hoped, but will bear in mind. The contact cleaner appears to have done the trick for now, but there is clear pitting on the -ve contact, so will see how long I can get away with it for.

@Mal69 -not sure. Full details here. I was using a Suntour NCX post at the time and current thoughts are that the frame couldn't take the rocking motion. According to Oxygen the seat tube has been beefed up in later frames "for asthetic reasons".

 

[Mal69]

@Mal69 -not sure. Full details here. I was using a Suntour NCX post at the time and current thoughts are that the frame couldn't take the rocking motion. According to Oxygen the seat tube has been beefed up in later frames "for asthetic reasons".

I remember now, yes, so it will take the Suntour now.