Intermittant Power Shutdown While Riding

[quasimodo]

Hi Folks: I installed a 1000 watt front wheel motor kit on a Schwinn Meridian 3 Wheeler and built my own 52 volt battery from used 18650's. (14s8p) It worked great for a month or two then it quit on me, no power showing on the on off button next to throttle. After I got it home, I checked battery voltage and it was ok. I have a connector that is between the controller and battery so I can disconnect the battery when I want. I plugged the connector back together and turned the power on and it worked. I tried riding again and it would do the same each time but would come back on each time I reconnected. I thought it might be the connectors, so I changed them. Same thing. The motor kit is one of the cheaper imports and it runs great when working. Just wondering, before I start looking again for the culprit, if someone else has had this problem and might shorten my diagnosis time. Thanks .....

 

[AHicks]

This sounds to me like your controller is shutting the power down due to low voltage getting to it (low voltage controller/LVC). That's the only thing I know of that will kill the power completely, then reset when the power to it is cycled (turned off, then back on again).

So that in mind, you might want to go over your charge level, assuring you're something over 3.7v or so per cell. There's also a chance you may have a bad connection internal to the battery, or somewhere between the battery and the controller.

I've seen defective chargers that shut down early as well (for various reasons). Those are generally easy to trace as the battery level will be left much lower than what it should be at the end of the charge.

 

[quasimodo]

Thanks AHicks....That is what I have been thinking also. May be a bad solder joint where I soldered the connections together. I am not a very good solderer. I am going to replace the joints with crimp connectors and try that. If not, I will need to carry my tester with me and try to catch it doing its thing.....

 

[AHicks]

I hate erratic problems! My bike hit a bump a while back, and did the lights out thing. I jiggled some wires, pulled the battery and plugged it back in, and the power came back on. Very thankful for that, as I was quite a way from home. About 2 weeks later the same thing happened, only this time the power would not come back on. I remember thinking, now I can fix this issue! We're in a hilly coastal area, so it was a miserable ride home, even had to push the bike up a couple of hills as I was wiped out.

Anyway, my issue turned out to be the key switch on the battery. Power in, but nothing coming out. Switch is now bypassed, and a year later I trust the bike again.....

Best of luck! -Al

 

[harryS]

Quasi- when the bike shuts down because of intermittent battery connection, or a temporary voltage sag, it can be restarted from the on/off switch used to start the bike controller.

When the battery shuts down because the BMS saw too much current or the internal LVC alarm went off, it usually has to be reset by disconnecting it from the bike controller.

The difference between the two situations isn't that obvious, but it sounds like battery.

Is the battery spot welded, soldered, or a compression kit? Using a BMS? Have you checked the balance of the 14 groups?

 

[tomjasz]

Well, I’d stick a wattmeter inline and see what’s happening. sadly recycled batteries can be nothing but issues.
what are you pulling for amps!? What IS the pack voltage?

 

[quasimodo]

Well, I cut all my battery connections that I had soldered off and redid them with crimped connections. Rode the bike to the Dollar Store, which is just a couple blocks away, and no problems at all. Before, it would shut off about every 50 feet or so. Don't know for sure that was the problem, but will ride it to the grocery store Saturday, which is a mile away, and see what happens. My battery pack voltage at full charge is about 58 volts. Don't know exactly what the amps are, but I have them eight across in parallel. Probably average about 2.2 amps each. Never have been low on power. Just power and no power. Thanks everyone for the input. Will let ya know what happens Saturday. I would like to put a inline disconnect shut off switch on the battery line so I wouldn't have to unplug it each time I stop for awhile. Was wondering if a regular dc
switch would handle the voltage ok?

 

[AHicks]

Voltage is not the concern. It's WAY more about the amperage! You don't want to create an amperage bottleneck!

 

[quasimodo]

Well, I rode my bike to the store and back, roundtrip of approx. 2 miles, last week and it worked perfectly. I rode it a couple days later to same destination and noticed a split second interruption of power, once on the way and then again on the way back. It did not completely quit like before. Now its back to its old self of completely losing power (voltage) after short distances. Unplugging and plugging back in restores power as before. I think this weekend I will remove battery and tear it down to check its connections. As I said before, the connections are all bolt on and it may have loosened up some connections. Also, I bought a controller tester that may help in analyzing the situation. Any more thoughts would be helpful...Thanks...

 

[quasimodo]

Quasi- when the bike shuts down because of intermittent battery connection, or a temporary voltage sag, it can be restarted from the on/off switch used to start the bike controller.

When the battery shuts down because the BMS saw too much current or the internal LVC alarm went off, it usually has to be reset by disconnecting it from the bike controller.

The difference between the two situations isn't that obvious, but it sounds like battery.

Is the battery spot welded, soldered, or a compression kit? Using a BMS? Have you checked the balance of the 14 groups?

Hi Harry.....It's a compression kit, which may be the problem. It seems to have started after a hefty bump in the road.

 

[harryS]

In my opinion, compression kits can be problematic, which is why they're only used by do-it-yourselfers.

 

[jfar48]

Hi guys
I have a sun lite e bike. I’m not real mechanical so would like some possible in site before taking in to repair shop. My bike has started to disengage at the chain sprocket and motor hub or not in gage the hub at all for know reason I can see pedals just spin yet the motor assist still works as well as the throttle ....this usually happen after a few miles I’ve had bike for little over a year and just now have been having this problem. Any ideas

 

[tomjasz]

Hi guys
I have a sun lite e bike. I’m not real mechanical so would like some possible in site before taking in to repair shop. My bike has started to disengage at the chain sprocket and motor hub or not in gage the hub at all for know reason I can see pedals just spin yet the motor assist still works as well as the throttle ....this usually happen after a few miles I’ve had bike for little over a year and just now have been having this problem. Any ideas

Instead of jumping into an unrelated thread, I'd suggest you start a new thread. You'll get more reads and rsponses typically. Also, list ALL you know about your bike. Motor type, brand, battery voltage? Anything that can help us troubleshoot. Help will be along soon!! Welcome!

 

[quasimodo]

Well, I found out a weird kind of thing today on the ebike. If I charge it all the way up (58 volts) it runs fine. No problems. But if I try to run it a little undercharged (51 volts) That's when I have the shutting down problems. Since the motor is a 48 volt motor, it seems to me that it should work fine at 51 volts. But, I am not familiar with the mechanics of electric motors. Any ideas?

 

[AHicks]

I would guess that with a charge at that level, your voltage is dropping way below 51 volts when under any type of substantial load. Low enough where the BMS or controller is shutting you down, probably with good reason.

 

[indianajo]

You can test the battery at home with a 5 amp load, say 10 ohms 500 watt resistors. Build that out of a bank of smaller resistors. Tests at 250 W. Resistors parallel to a voltmeter. If you use any 14 ga wire or log resistors, solder with 130 W iron or propane iron. Otherwise use crimp connectors from dorman (oreilleys) 3m, panduit, T&B, Ideal. Only. A more stringent test is 5 ohm resistor 1000 W, which is more expensive. Tests at 10 A or 500 W.
If the battery fully charged will pull that load for an hour without dropping below 50 v, you may be able to get somewhere, slowly. I proved a battery that was dropping out on the road at about the 5th mile was at fault, not any of the other wiring, the controller, or the motor. Unfortunately I'd had the battery for 3 months so I didn't get my money back from Ebay.
Do this outside on concrete, you don't want to set fire to anything.
Buy batteries from Lunabikes, is my advice. You're in California where they are. They are expensive, but worth it IMHO. TJ has another vendor he likes in California but he's never published the URL. Other reliable vendors are out of the country, where the FBI will not investigate if your debit card # is hacked. If you use EM3ev or ebikes.ca, use a one time use debit card.

 

[tomjasz]

Well, I found out a weird kind of thing today on the ebike. If I charge it all the way up (58 volts) it runs fine. No problems. But if I try to run it a little undercharged (51 volts) That's when I have the shutting down problems. Since the motor is a 48 volt motor, it seems to me that it should work fine at 51 volts. But, I am not familiar with the mechanics of electric motors. Any ideas?

Does your display have settings for battery voltage? Without any other details, motor? Controller? Display? It’s a guessing game. Are you riding in volc weather? The devil is in the details!


EDIT, SORRY I DIDNT READ BACK IN THE THREAD...

How are you getting voltage readings? First thought is a low voltage cutout is in play...

 

[tomjasz]

TJ has another vendor he likes in California but he's never published the URL.

Thanks. I don’t post it because it’s who I work for. I come here to help snd learn. It’d be unfair for me to use this as a sales platform.

 

[tomjasz]

Indiana Joe is an incredibly resourceful guy. An easier and very reliable Toll for battery maintenance is a $25 or so dollar Turnigy Wattmeter. I set up all my builds so that I can put one infineon a bike a get troubleshooting data.
There are cheaper clones. I prefer to pay 20-30% more for the Turnigy. Like Soshine usually reliable brands.

Turnigy 180A Watt Meter and Power Analyzer

There is no better or easier way for you to measure your power system than by using a watt meter. This handy little device takes the guess work out of it by reliably and accurately measuring watts amps and volts.

hobbyking.com

 

[harryS]

A 14S8P made with used 18650's with compression contacts is going to be problematic.

Now that you said it started after a bump, I understand. You probably should probe every cell in each 8P group to see if they're at the same voltage as their neighbors. That might reveal any bad contacts.

Check your balance. Are all 14S groups more or less at the same voltage?

You have a weak series group in there sagging below the BMS' LVC (low voltage cutoff). Maybe it will be spotted with your series voltage test.