Advice needed - Controller kit, Panda ECO from Pandaebikes

[Andrew Wingrove]

I have just replaced the complete electrics on my ebike with only the 24V 250 watt Currie motor and the battery being from the original bike. The new components 24V 250W Electric Bike eBike Controller kit, Panda ECO from Pandaebikes. https://www.pandaebikes.com/shop/control-systems/24v-250w-electric-bike-ebike-controller-kit-panda-eco/

After connecting it all up I have an issue with the LED 880 control panel. When I press the On/off button all 7 red lights along the bottom of the display and they then fade away quickly and then nothing at all. Pressing again results in nothing lighting up. Disconnecting the brakes, throttle and pass makes no difference. I have tried with another identical LED 880 control panel that is brand new and I get the same problem,

I have contacted Pandaebikes, but wont hear anything till Monday, so though I would try here.

 

[Deleted member 4366]

That's what happens when you try and switch on when your battery's switched off.

 

[Andrew Wingrove]

Hi, battery was 100% turned on and power was going into the controller. If I left it and came back an hour later, having left it turned on it would do the same thing again.

 

[Deleted member 4366]

Can you check your battery voltage where it's connected to the controller before and after pressing the "on" button on the panel? I expect that one or both readings will be anomalous.

 

[Andrew Wingrove]

So checking battery voltage on the cable leading from the controller box to the LED unit. When I first plugged my leads into the cable connector I had a reading of 4.7 volts that slowly crept up to 24.7 volts over 6 or 7 minutes.

I have uploaded a video showing the results of what you asked me to do onto YouTube.

 

[Deleted member 4366]

Your problem is in the battery. The BMS has switched off the power for whatever reason. The voltage you're measuring is just leakage. It climbs slowly because it's charging up a capacitor, and it's the discharge from the capacitor that provides the power to blink the LEds.

 

[Andrew Wingrove]

So...... Besides, ordering a new battery, is there a fix for this problem? I get a feeling that the answer is no, as you have not offered one.

 

[Deleted member 4366]

You need to tell us which battery you have.

 

[Andrew Wingrove]

Its a Lithium Ion Li-ion Battery 24v 10ah Silver Fish

 

[Deleted member 4366]

Take the the bottom and top off. Turn the bottom sideways-on and use it to push the cell-pack up a couple of inches, peel off any tape and heatshrink until you get to the BMS's multi-pin connector. pull it out and measure the voltage on each pin. Put your red probe on the positive terminal on the bottom of the battery and use your black probe to check each pin. Write down the results. There should be 10 results in steps of about 4v. if you only get 9 results, use the point where the black power wire from the cell-pack joins to the BMS to get the last one.

 

[Andrew Wingrove]

Okay I am off to the garage to carry out these instructions.

 

[Andrew Wingrove]

Okay! So I made my way into the battery casing and it seems to be very well made inside. The shrink wrap around the battery casing was very hard to get into. I initially took some readings on what I could first see.


Top left green wire was 10.34 volts with a little fluctuation between 10.2 and 10.5V Top right with small yellow wire was 6.6 Volts and the black wire bottom left was 3.15. Bottom right with the three red wires gave me no reading at all.


I then realised that the BMS must be hidden further back inside and I cut back the green shrink wrap and then bent the yellow plastic sheet back until I could see the thin unit with wires. This must be the BMS, but the wires going inside its case seem to be surrounded by a resin making it impossible to take a reading. it is also glued down, and the screws holding the two plates together seem to have no heads on them.

Should I keep prising away the yellow plastic sheet to get this BMS free from the battery?

 

[Deleted member 4366]

Basically, you need to measure B1 to B7. put your red probe on B7+, then probe with your black from B6+ to B1+, and finally B1- to get seven readings. I said 10 before, but that was wrong for a 24v battery. Note that B1+ is the same as B2-, B2+ the same as B3-, etc.

If you need to re-insulate everything when you've finished, you can use gaffa tape.

 

[Andrew Wingrove]

So these are the results of the test.

B1= 24.4
B2= 20.3
B3= 16.2
B4= 12.2
B5= 8.1
B6= 4

 

[Deleted member 4366]

One missing. where's B7?

 

[Andrew Wingrove]

Red tip on B7 and black on B1- gives me 4V

 

[Andrew Wingrove]

Sorry 25.6 V

 

[Deleted member 4366]

That makes more sense. All cells are at 4.1v except one, which is at 1.2v. if any cell goes below something like 2.8v, the BMS will switch off.

Something is still confusing me though. It should go like this:
B1-, B- Black power wire connected
B1+ joined to B2- (4v approx)
B2+ joined to B3- (8v approx)
B3+ joined to B4- (12v approx)
B5+ joined to B5- (16v approx)
B5+ joined to B6- (20v approx)
B6+ joined to B7- (24v approx)
B7+, B+ Red power wire connected. (28v approx)

It looks like your red power wire is joined to B1+, which doesn't make sense.

Can you check your measurements again bearing in mind the above logic, just to make sure.

I think I've figured it. They have all the numbers reversed, so B1+ = B7+, B1- = B7-, B2+ = B6+, etc.

 

[Andrew Wingrove]

Hi,

I get the same results with the red tip on B7 and then moving the black tip from B1 to B6 and then last,y to B-

Photo showing wires running in.

With the one at 1.2V is there a fix for this to stop the BMS switching off?

 

[Andrew Wingrove]

Don't know if it makes any difference, but this battery has what I believe are LiPo cells inside. Flat rectangular battery packs.