SoloRock Electric Bike (moped style) looses power while riding.

[atactic]

Hello,
I'm looking for some help troubleshooting my "project bike" I have a working converted mountain bike, but took on this other bike as a project. It's a "SoloRock" moped style ebike, Not sure how old it is, but assume that it is over 10 years as it has a drum brake on the front.

I purchased it used for $125, without batteries. Was told it was in working condition.

I put my 48v (20ah) Lithium Ion battery in it. Worked well, and went on trips up to 5 kilometers without problems. Unfortunately, the battery from my other bike is a triangle battery and did not fit in the battery box.

Ordered and installed a 52v (20ah) LiFeO4 battery. Installed it, and the bike died on the test ride after about 1 km. Loss to power and the battery meter goes to 0%
Put the 52v battery in my mountain bike conversion and ran it hard on full throttle for about 4 km, and it was fine.

I replaced the motor controller with this: https://www.aliexpress.com/item/100....order_list.order_list_main.17.65ff1802zgjvyv and it still gives me the same result. Tested a couple more times and distance to failure became shorter every time. After loosing power, I measured the battery voltage at ~5 volts, after disconnecting the battery, it returned to 52v.

My guess is that there is a short somewhere in the system and (thank heaven) the BMS in the battery cut out to save the day! Can a short in the motor do this? Should I rewire all the power cables in the bike?

Thanks for any suggestions on what I should do next...


Peter

 

[amberwolf]

Solorock appears to be a general reseller of assorted goods, and their website has no information I can connect to the description of this bike. Can you post more details (as complete as possible) of what this bike has on it? It may help us help you narrow down the problem. If you're not sure of what various parts are, post clear pics of them and we can try to figure out what they are.

If you put a multimeter set to it's highest A setting (usualy 10A for typical meters), with the leads in the correct place on the face of the meter for A (not V or ohms), and connect it between the battery positive and the bike positive, what does it read with the bike just sitting there doing nothing?

If you then have the bike's powered wheel offground, and very slowly increase throttle from zero to full, what does the multimeter A reading start at and change to and end at?

 

[atactic]

Thanks for the suggestions. Further testing of the battery shows it is the problem. The sad part is that it's the most expensive part of the system. Battery runs well and then the voltage drops after a random amount of time. Less than 20 minutes. Searching forums for battery troubleshooting now...