Problem - not sure where it is from?

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Jonathanm
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Joined: 09/09/2008
Points: 141

Well I have an issue - at times disabling...periodically I get large fluctuations in the voltage display on the speedo (Lairds Software). When it drops to below 100V the bike obviously stops. Then it comes back and all is good for a while. When this is happening, when regenerating the voltage can go over 150V and then just as quickly under acceleration go below 100V.

This issue started when I abruptly cut the "cruise control" one day. I reset the plugs under the front fender and that seemed to fix things but it still happens periodically.

So I cannot work out if it a MC problem or a cell that is shot? I still have Ni Hy cells and nearly 40K km. Have not been here for a while - happy to see a few old faces....

Jonathan

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Sunder
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Joined: 10/10/2016
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Re: Problem - not sure where it is from?

Sounds more like a poor connection somewhere, rather than a bad cell.

The reason I give for this assessment is the sudden drops and rises.

When you get one bad cell, the pack voltage will drop, but otherwise should not sag or spike large voltages.

If your whole pack is shot, the voltage can sag and spike a lot, but will be consistent, and your range would be terrible.

If you have a bad ground or a poor connection, when the connection is good, the bike works normally. If the connection is bad, it acts as a high resistance resistor - Load will cause the "apparent" voltage to sag, and attempting to charge it - either by regen or by charger, will cause it spike. (I know this is counter intuitive, but think about what happens to a charger's voltage when you remove the pack (Infinite resistance) - it jumps to the highest the voltage the charger will do).

Look for any scorching around the battery and where it connects to anything high powered, would be my first step.

Jonathanm
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Joined: 09/09/2008
Points: 141
Re: Problem - not sure where it is from?

Well thanks for the update - the bike decided to tell me which was at fault after about 10 days of zero problem. Riding home today I got the big voltage drop then the bike stopped, then started then stopped again - all black and no life. My feeling is at the end I blew the main fuse. So it seems it was the motor controller all along!

Any way - full tear down coming up and now having to source another motor controller....

I can't really complain really 35K km without any problems...

Jonathan

Sacko
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Re: Problem - not sure where it is from?

If it is the fuse, could you not just replace it?

They're about £25.

Jonathanm
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Points: 141
Re: Problem - not sure where it is from?

Yes thats true but I think there was a lot of horrible things going on before the fuse blew....I will certainly need a new fuse amongst the other bits and pieces that hang on to it...

Thanks for your input.

Jonathan

Bikemad
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Re: Problem - not sure where it is from?

If you can measure full battery voltage directly across the fuse, it would confirm that your diagnosis of a blown fuse is indeed correct, but if any of the battery's 102 cells has somehow failed in an open circuit state (instead of the designed closed circuit state) this could also prevent battery power from reaching the controller.

A loose connection on any of the cells (or the battery connections on the controller or fuse) could also produce burning under load which could eventually cause an open circuit condition too.

If you include the contacts on the Anderson connectors between the two halves of the battery, there's a total of at least 210 physical connections that could theoretically produce the same end result as a blown fuse (no battery voltage reaching the controller).

It will be interesting to find out the exact cause of death after the post mortem has been carried out, as I am still not totally convinced that it is a fuse problem.

I would first make sure that full battery voltage is reaching the two battery output cables before dismantling the controller.
If you don't have battery voltage coming from the battery, try to measure the voltage flow through the battery in a methodical fashion as much as possible before disturbing any cables etc. as an open circuit fault is always easier to locate while it is still there.

Alan

Jonathanm
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Points: 141
Re: Problem - not sure where it is from?

Well Allan - you were right on the money - when I finally got down to it the fuse was NOT blown and the MC showed no obvious signs of burning. The phase connectors seemed loose but maybe that was only when I removed the phase wires. The aft battery was severely down on voltage - further digging down found one cell appearing to have almost blown up. It had bulged and burst. All other cells were within .1V of one anther so I am assuming they are all ok...So the good news appears that I only need to find a row of cells to replace the defective one. Then I should be good to go and I think range will be back to what it should be!

The thing that was strange was the way it failed...Anyway if this diagnosis is wrong I will report.

Jonathan

Bikemad
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Re: Problem - not sure where it is from?

Obviously, a complete row of cells will be a lot easier to replace, but a single second hand replacement cell is basically all that is needed to fix it.

To fit a complete row, you will ideally need to find a good row of 9 cells from a rear pack, as the front pack is smaller and only has 8 cells per row.

The open circuit voltage of the replacement cell/s should ideally be the same as your other existing cells before you fit it/them.

You can use a 12V car charger on the complete row of 9 cells to increase their voltage, or a single 60W 12V headlamp bulb to slowly reduce their voltage if necessary (multiple bulbs connected in parallel could also be used to discharge the cells more quickly).

A single cell can also be charged from a 12V charger by simply connecting a 12V bulb in series with it, but discharging a single cell using a 12V bulb will take a lot longer.

Alan

Sacko
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Re: Problem - not sure where it is from?

Where abouts are you located?

Jonathanm
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Joined: 09/09/2008
Points: 141
Re: Problem - not sure where it is from?

Thanks Allan....job will be for next week

Jonathanm
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Points: 141
Re: Problem - not sure where it is from?

Sacko wrote:

Where abouts are you located?

Normally south of France...away over the pond for this week but back next week.

Sacko
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Re: Problem - not sure where it is from?

I have lots of cells available, but shipping them is usually the issue.

Jonathanm
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Joined: 09/09/2008
Points: 141
Re: Problem - not sure where it is from?

Of course I would like a row from the rear battery pack...have no idea what the shipping is from UK to France though?

Sacko
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Re: Problem - not sure where it is from?

Private message sent Jonathan.

Jonathanm
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Points: 141
Re: Problem - not sure where it is from?

Sacko wrote:

Private message sent Jonathan.

Received with thanks!

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