Xiongda kit intermittent fault

[LithiumFan]

I have had this kit on several bikes over the last few years and it has been giving great service until the other day. I was going up a steep hill and the motor had switched into low ratio when after a minute or so power stopped and the display indicated no battery then varying amounts of battery before turning itself off completely. After continuing with leg power only for some 10 minutes it worked again OK for 5 min or so before cutting out again. This cycle repeated several times before it wouldn't turn on at all. Back at home I recharged the battery, checked all the connections and headed up the hill. It cut out again but then restarted.
I have tried doing some multimeter checks on the controller and everything looks okay. I also tried cycling with the high/auto/low button in different positions. No difference. Sometimes the positive battery lead comes apart but not on the last occasion it happened. Any ideas before I send off for some new wiring

 

[Nealh]

One suspects one or more controller mosfets have failed, the slow going up hill causes heat to build up. Mosfets have an upper temp before they thermally cut out once cooled they work again, it sounds likely as this occurred more then once. Finally they probably shorted permanently.

Did you test for ohms resistance with your meter on the phase wires ?

 

[LithiumFan]

Yes I did and all had the same resistance. Does this mean I need to buy a new controller?

 

[LithiumFan]

I've just had a thought. I could try going up the big hill again but in low ratio all the way and see if it cuts out.

 

[Tony1951]

I've just had a thought. I could try going up the big hill again but in low ratio all the way and see if it cuts out.

Is the battery OK? I know you re-charged it, but if I am right in thinking you have used the same kit for a number of years, rather than that you have used various different iterations of this kit on your bikes for a number of years, it could be that the battery has just collapsed from old age and use.

 

[Nealh]

Did you do both sets of phase tests , high and low side ?

 

[Nealh]

Is the battery OK? I know you re-charged it, but if I am right in thinking you have used the same kit for a number of years, rather than that you have used various different iterations of this kit on your bikes for a number of years, it could be that the battery has just collapsed from old age and use.

Agree this is another avenue to check out, wire up a meter so you can watch what the voltage does.

 

[LithiumFan]

I can try with a different battery. The oldest one was being used both times and only charges to 41V. The volts are shown on the display and just went to 0 although the indicator bars went a bit up and down before showing blank.
I'm not sure what Nealh means by testing the high and low sides.

 

[Nealh]

A mosfet has two channels to test the gnd high side and the V low side.

 

[Nealh]

The 41v means that the battery is weak, badly out of balance or a combo of both.

 

[LithiumFan]

The bike behaved perfectly today using a different battery so it sounds like it's time for a new one. Thanks for your help.

 

[Tony1951]

The bike behaved perfectly today using a different battery so it sounds like it's time for a new one. Thanks for your help.

Great. Glad you solved it.

 

[Nealh]

Battery might need balancing but if it is old (6/7 years or more) then recycle it, at 41v it sounds pretty good but may just have a cell group out of balance.