I recently , i.e. 2 months, joined the ebike crowd by impulse buying a used cargo bike with an electric hub motor. The Bike is an ex-food delivery bike built by Thrust bikes which is out of business. I knew nothing about ebikes but took the plunge due to impossible parking situation at my kids school. I have been very happy with the bike. It has exceeded all my expectations. I have been using it daily without problems. Last night I got around to fixing a couple of things on the bike one of which included replacing the brake lever out with a new one which had a working cut out switch. Today on the way home from the school I smelled burning electrics and the bike shut down. the breaker on the controller was not tripped. I could not find any problem with the controller and the battery smelled burned so I removed the battery from its case and found a battery which looks like many of the ones I have seen trying to learn more about ebikes since my purchase. Once I peeled back the shrink wrap I was able to determine that the voltage from the actual batteries was pretty good at a little over 51 volts. There was however 0 voltage from what I am guessing are the terminals on the output side of the BMS. Is there a way to test the BMS? I could feel that the BMS was hot. I can not diagnose anything further as this particular unit is potted in resin. So my questions are: all the batteries 78 CGR18650CH 6 per group 13 groups measure pretty closely to each other within .2 of a volt. I do not see any arcing melting etc... Anything else I should do to check them out? I think its clear I need at a minimum a new BMS so what kind should I get? It appears if I have done my math properly that the current setup is 48v/13.2AH. I have an idea to get another battery which would be 48v/20AH lifepo4. Also the cells while fairly closely matched seem like they could be better balanced. The wheel I have now is a rear mounted 20" rim with an ampedbikes ( also apparently out of business ) direct drive motor. I am uncertain about the wattage rating. Although one place I saw on the web where it was mentioned that it may be a 750watt. The controller is labeled for 36v/22A, its generic and not much other information is available. I cruise at 18-19MPH faster a little if alone. I would like to change my setup in the future to a 1000watt front mounted wheel with a nexus style rear 20" internal gear hub. I hooked up the battery directly to the controller with some jumper leads and the bike turned on and ran although I did not ride it or put a load on it. Finally it seems that this must be related to the brake lever I installed which is a switch to shut the motor down during breaking? This is what I was told by the PO. Does it in fact do something different? My wife really wanted that hooked up. Many thanks for any help that could be offered. George
Newbie problem with battery on ebike
- Thread starter verbryck
- Start date
Hwy89
10 kW
I think you are on the right track as far as the BMS being the problem. I doubt that the brake switch was the cause. If you had improperly installed it you would have known immediately and the failure would have been the controller not the BMS. Try searching with the terms BMS, Besttech, and Dnmun. If you are comfortable doing a little soldering you should get all the help you need here on ES. Post photos if you can.
Well I had a more extensive look and this is what I found out. The controller is a Smart controller 36v 22A phase angle 120 degrees . Also it is Function: E-ABS, Energy feed back and mute. Now I am wondering if the BMS is/was not compatible with the abs/feedback of this controller i.e. maybe it was not connected on purpose? The controller also indicates it has a cutoff voltage of 31.5 volts, can this be changed easily to 33 volts? If the controller has a cut off then the only thing the BMS does is to keep the pack from over charging and over heating? The way the controller is assembled it is not easy to access but I could make out that the Transistors are K4145 and ten are present . I am not sure I understand exactly how the controller works but event tough this one is labeled for 36 volts it can run higher voltage ? The transistors are rated for much more voltage and all the caps are 105c 63v. This seem pretty tight to me there is not even a 20% margin with a full charge of 52 volts. Would an 48 volt controller have 80 volt caps? Should I just install 80v caps? In any case the controller looked good no burned spots or failed caps. Some wires are not hooked up to anything I have searched the web but have not been able to find anything like a diagram/schematic or picture that matches the look of my controller. I am going to include a picture.The 2 small plugs yellow/black wires are what I hooked up to the brake levers. The red and black plug wires is the battery , Yellow, blue, green are I assume phase wires, red, black , white, green are hooked up to the throttle , the red, red wire is not hooked up, the red, green, blue, yellow, black is hooked up and there is a white and black wire which are clipped close to the controller. So I assume the white and black wires are the speed limiter eliminated? Is the red, red possibly a on?off(mute)? The five wire plug goes to the motor along with the phase wires. The 4 wire plug that goes to the throttle, the actual throttle has a twist grip and 3 leds ( full, half, empty and a on/off switch. The led's , all of them are always lit and the on/off switch does nothing. I figure that one is ground, one voltage level, one for the throttle input, one on/off. But since only one function works can anybody tell me the wire code so I could get it properly hooked up? The motor is a XF40 750watt/48v. I feel like since I bought this used and there is not any kind of standardization if I could get a grip on all these questions then I could comfortably move forward with this gear. On the other hand should I just start over and get a new controller throttle and BMS to start fresh with known components. If that is the recommendation which ones should I get? Reliability is the most important part of this bike for my daily use to get the kids to school. From looking on the web it appears that the motor is an acceptable choice and durable, beyond that I am ignorant. Again many thanks for any input, George
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dogman dan
1 PW
IMO it's just the BMS. The brake thing is just the coincidence that makes you go down the wrong path with troubleshooting. Nothing to do with the battery problem.
Meanwhile, it is possible for you to charge and run the battery bypassing the bms. But you will have to manually check that all is well, as a human bms. Check the voltage of each group of cells after they charge, and maybe even watch as they charge the first few times.
And, if your daily commute is long enough, be very careful not to over discharge the pack. You need a real voltmeter display on the bike to run a naked battery and not screw up.
No need for a new throttle or controller yet. If you do eventually replace a controller, getting one with a cycle analyst direct plug in would be ideal Then you can set some limits on the controller at the CA display.
Meanwhile, it is possible for you to charge and run the battery bypassing the bms. But you will have to manually check that all is well, as a human bms. Check the voltage of each group of cells after they charge, and maybe even watch as they charge the first few times.
And, if your daily commute is long enough, be very careful not to over discharge the pack. You need a real voltmeter display on the bike to run a naked battery and not screw up.
No need for a new throttle or controller yet. If you do eventually replace a controller, getting one with a cycle analyst direct plug in would be ideal Then you can set some limits on the controller at the CA display.
