Ebike not working with addition 12v battery

H

Highxtech

10 mW
Joined
Jul 24, 2018
Messages
23
Hey everyone,

This is my first post so take it easy 😂

I have an emmo zone ebike 72v 20ah 500w hub. I added a 12v 20ah battery yesterday and it was fine, rode it till it almost died, picked up an 84v smart charger and plugged it in overnight.

Woke up this morning and unplugged the bike, it turned on fine but there was no throttle.

Took it apart and removed the extra 12v battery, she runs fine, put the 12v back in, measured and got 98.7V but still no throttle, if I hold the throttle and turn it off at the same time it'll move for a split second.

Controller has 100v caps and 24 FETS with a pretty big heatsink, the DC-DC converter is rated for 72v but has 100v caps as well.

The controller looks fine, nothing burned out and no smoke or smells , all lights and everything works.

What am I missing? She's sitting outside with the lights on (trying to drain the battery a bit to see if she'll run)

Thanks in advance!
 
There's probably a high voltage cutoff in the controller. You could discharge the 12v one a little with a lightbulb or something and see if it comes on as the voltage drops.

Edit.. Just read that last paragraph.. That seems like a good idea.
 
First: Welcome to the Sphere.

2nd First: How on earth are you getting a reading of 98+ volts on a 72v pack? you should never exceed 84v as this = 4.2v max per cell.

Second: How and where is that 12v lead battery hooked up to the bike? with 98v it sounds like you have it hooked up to the wrong place 84v+12.6v=98+v

Load some pics of this setup and wiring, it will help speed things up.

Also: Not sure if this helps but some 72v controllers use a small 100v to 12v buck converter on the main board, then convert the 12v in to 5v for the motor halls and throttle signal.

If you have a controller with a 12v out wire say for brake signal or headlights and you are tying your larger 12v DC/Dc to that same line, there is a chance the larger 12v converter is pushing more like 13v or 14v, maybe be even 15-16v.

If it is pushing anything more than 12.6v the second 5v DC/Dc converter may be producing 6v or 7v. Meaning the controller may be seeing a false high throttle/PAS signal upon start up and kills motor output as a safety measure.

PROTIP: Even if your caps are rated for 100v, remember, there is always a + or - 10% tolerance for the actual voltage range of that capacitor. Shits printed right on the side. This means you can run 90v with very little concern for letting the smoke out. At 98v, you are asking/begging for a fireworks show.
 
2WheelsMovesTheSoul said:
First: Welcome to the Sphere.

2nd First: How on earth are you getting a reading of 98+ volts on a 72v pack? you should never exceed 84v as this = 4.2v max per cell.

Second: How and where is that 12v lead battery hooked up to the bike? with 98v it sounds like you have it hooked up to the wrong place 84v+12.6v=98+v

Load some pics of this setup and wiring, it will help speed things up.

Also: Not sure if this helps but some 72v controllers use a small 100v to 12v buck converter on the main board, then convert the 12v in to 5v for the motor halls and throttle signal.

If you have a controller with a 12v out wire say for brake signal or headlights and you are tying your larger 12v DC/Dc to that same line, there is a chance the larger 12v converter is pushing more like 13v or 14v, maybe be even 15-16v.

If it is pushing anything more than 12.6v the second 5v DC/Dc converter may be producing 6v or 7v. Meaning the controller may be seeing a false high throttle/PAS signal upon start up and kills motor output as a safety measure.

PROTIP: Even if your caps are rated for 100v, remember, there is always a + or - 10% tolerance for the actual voltage range of that capacitor. Shits printed right on the side. This means you can run 90v with very little concern for letting the smoke out. At 98v, you are asking/begging for a fireworks show.
Click to expand...

Thanks for the response. There is a second 72v to 12v DC to DC converter mounted under the controller. Should I grab an 84v to 12v DC to dc? Im hoping that's where the problem is but because the lights, signals, horns etc work I didn't think twice about the overvoltage cutoff.

I added the extra 12v 20ah battery in series to the existing series ran, 6 12v 20h sla batteries. Each of the batteries are reading 13.9v-14.1v right now, * 7 its around 98v. I know there's a 10 tolerance on the caps but from what I've heard the controller should be fine, the bike runs perfect when I take out the extra 12v battery.
 
Most likely the controller has an over voltage cutoff. Sometimes this can be changed with software. The crude approach is to reroute the ignition line so it goes to the 72v battery but the main (fat) battery wires go to the 98v. This way the controller logic only sees the lower voltage.
 
fechter said:
Most likely the controller has an over voltage cutoff. Sometimes this can be changed with software. The crude approach is to reroute the ignition line so it goes to the 72v battery but the main (fat) battery wires go to the 98v. This way the controller logic only sees the lower voltage.
Click to expand...

I kind of see what you're saying, I don't think my controller is programmable by myself. I don't have a wiring diagram for it either but they're just be a cutoff if that's the case
 
Alrighty then... your setup appears to be fine. It's better than I was first thinking from your description.

I'm with Fetcher here, my guess is the over voltage. It's probably set from the factory at 85 or so. I'd try his theory first and tell us what happens.

fechter said:
Most likely the controller has an over voltage cutoff. Sometimes this can be changed with software. The crude approach is to reroute the ignition line so it goes to the 72v battery but the main (fat) battery wires go to the 98v. This way the controller logic only sees the lower voltage.
Click to expand...
 
2WheelsMovesTheSoul said:
Alrighty then... your setup appears to be fine. It's better than I was first thinking from your description.

I'm with Fetcher here, my guess is the over voltage. It's probably set from the factory at 85 or so. I'd try his theory first and tell us what happens.

fechter said:
Most likely the controller has an over voltage cutoff. Sometimes this can be changed with software. The crude approach is to reroute the ignition line so it goes to the 72v battery but the main (fat) battery wires go to the 98v. This way the controller logic only sees the lower voltage.
Click to expand...
Click to expand...

So would a new DC to DC converter solve it (84V to 12V instead of my 72v to 12v), or would I be better off wiring everything manually? Any tutotkm here how to do so?
 
nah.

Most of those DC/DC converters for 72v systems are actually rated for something like 24v to 120v and always output the same 12v -14v.

At least that's the acceptable voltage range on the DC/DC 12v 20A converter I currently use.

If you search on Ebay for 72v or 84v buck converter your gonna get the same results.
 
I guess I'm looking at a high voltage cutout then. So it's either a new controller or run the batteries down until it works and not charge the bike over that voltage...

I appreciate the responses everyone. Anyone have any other ideas?
 
It appears she's running now. Ran the bike a bit with just 72v and ran the other battery in a power wheels toy. She cuts out around 90v. Looks like I'll need a new controller.

Also what should the low voltage be for 84v 20ah sla batteries? I don't want to damage anything by running it dry
 
Also, can anyone recommend a 84v+ ebike controller with regen? Without regen is ok too but If I'm upgrading I want to try the regenerative braking functions
 
ummm not sure... what kind of amps are you pulling at speed? or what amps or wattage is the controller rated for?

Do you have a voltage display on the dash?

maybe you could wire up a multi-meter and see how much the voltage sags/drops under acceleration?
 
Highxtech said:
Also, can anyone recommend a 84v+ ebike controller with regen? Without regen is ok too but If I'm upgrading I want to try the regenerative braking functions
Click to expand...

I use a Kelly KLS7230S controller but my bike is built for 60mph. The KLS series has just about any and every feature you want except a display panel or HUD.
 
2WheelsMovesTheSoul said:
ummm not sure... what kind of amps are you pulling at speed? or what amps or wattage is the controller rated for?

Do you have a voltage display on the dash?

maybe you could wire up a multi-meter and see how much the voltage sags/drops under acceleration?
Click to expand...

Usually drops 1-3volts under full acceleration depending on how fast I'm already going. I'm not sure what the controller specs are I can't find much info on it
 
First post said 500w hub, so most times that is what the controller is. The hub motor is not limited to 500w since the controller controllers that. the hub will take more power but will over heat sooner if too many watts are pushed thru. How fast does it go with stock battery voltage and is the controller stock?

Dan
 
DAND214 said:
First post said 500w hub, so most times that is what the controller is. The hub motor is not limited to 500w since the controller controllers that. the hub will take more power but will over heat sooner if too many watts are pushed thru. How fast does it go with stock battery voltage and is the controller stock?

Dan
Click to expand...

Stock it'll go 52km/h, I'll get around 30km range (up and downhill riding, I weight around 175lb), with the extra 12v it'll go 60km/h
 
It's hard to see exactly in your picture, but the skinny orange wire from the controller looks like the ignition line. This usually goes to the key switch, then to the fat red wire. The trick is to reroute the key switch connection to cell 6 instead of the main fat red wire. This way the logic circuit will only "see" the 6 cell voltage, but the power stage gets the full voltage.

Downside of this is the 7th cell will have slightly less drain than the rest and won't stay balanced. If the 7th battery is being charged with a separate charger, this won't be a problem.
 
Thank you everyone for the information!

I got extremely lucky today and got an 84v 1000w Bluetooth programmable controller. Wired it up and it's running mint.

For anyone who reads this, looks like my controller has a high voltage cutoff and doesn't let the controller run over 89.9V. I had to run it down to this and the bike worked fine. However this only leaves around 14v before you should cut the power before killing your batteries, which isn't much.
 
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