Direct Drive motor power consumption increase

[mutmost]

Morning All,
my direct drive motor which has covered approx 12000 miles has recently started consuming alot more AH for my commute, it use to use about 11 AH for 22 miles but recently this has jumped to 17AH.

It still seems to run okay although there does seem to be a lack of top end power but no juddering or noise that is different to normal.

I changed over to a new bag at the weekend hoping that checking all the connections and soldering them all would fix the issue but it is still the same.

Any suggestions of what to check first?
Thanks

Mutmost

 

[Deleted member 4366]

What are you using to measure the consumption? My first suspicion is that the measuring device is giving an error. That would be confirmed by the pack voltage. Is the pack voltage going down 50% further too?

 

[mutmost]

The consumption is via a cycle analyst which I have used for the whole life of this set up.

The pack voltage seems to be behaving normally in terms of fully charged value and LVC.

The LVC and total AH consumed ties up both on the bike and a drain test with 3 x 12V light bulbs, ie the LVC cuts out at the same AH consumed.

i hope that answers your questions?

Thanks for your help.

 

[danielrlee]

There's not much to go wrong with a DD motor, so that behavior is pretty strange. First thing to check is that your brakes aren't rubbing. Assuming they're not, I'd look at your motor phase connections. Are you noticing any more heat than usual in the motor or controller? A motor of that milage could possibly be suffering problems with a bearing. Does the motor turn as freely as it has previously?

 

[Deleted member 4366]

The consumption is via a cycle analyst which I have used for the whole life of this set up.

The pack voltage seems to be behaving normally in terms of fully charged value and LVC.

The LVC and total AH consumed ties up both on the bike and a drain test with 3 x 12V light bulbs, ie the LVC cuts out at the same AH consumed.

i hope that answers your questions?

Thanks for your help.

That doesn't quite answer my question. Let's say you have a 36v 20ah battery. To use 11ah, it would go down to about 37v resting voltage. To use 17ah, it would go down to about 34v. Did you see that difference? Is your CA the SA version (separate shunt) or the one that plugs invto the controller?

 

[mutmost]

It is a 36v 20ah ping battery which recently had some cells replaced (December 14).

The Cycle Analyst is the SA one.

When the battery was failing my 22 miles hit the LVC at 13AH consumed. To check I charged the battery and did a discharge test and got the same readings 13AH LVC hit . On repairing the battery my commute went down to 11AH and the discharge test went back to 16AH, so until this week all seemed normal until the ride which hit the LVC at 20 miles and 16AH, I can't honestly say i have ever paid much attention to the resting voltage once I have got home and put it back on the charger.

 

[mutmost]

As an update I have checked the hall sensors with a volt meter and they are all working okay, I have checked the phase wires with an ebike tester (the little box with all the wires and lights on) and they seem okay.

I have ordered some new bearings to fit so hope that works.

i'll let you know.

 

[mutmost]

new bearings fitted. I have now ridden it twice with the new bearings and it seems to be more or less back to normal.

The old ones didn't seem to be rough or knackered when in your hand though.

It does seem to not quite have the full power it use to have but that could be me. The battery has done 13,000 miles on 615 cycle charges so it could be getting a bit tired generally.

thanks for your help / suggestions.