Batteries will not charge-Abnormal Cells Voltage Error

[Rapidrob]

As I've posted on this forum, I just built two identical 39120S battery packs.
Each one producing about 13.2 VDC. The charging cables showed up today. 5 wire.
I hooked up the ISDT Air8 battery charger after hooking up the wiring to the Positive out put terminal and negative output terminal as well as three buss bars.
The charger throws out an error in a second or two " Abnormal Cells Voltage". I was able to take a photo of the instant I hook up the cable going to the cells for charging and you can see cell 1 on the lower left is 3.13 ( the red positive wire is on the out put + terminal, and one wire it on the negative - output terminal.) and the rest are 5.55 VDC, where the buss bars are. The charger is seeing these buss bar batteries as an abnormal battery voltage.( 6 VDC )
How do I hook up the 5 wires while the batteries are in the pack to be charged?
Please help.





Bottom of battery pack. Top two wires marked in silver 2 & 3 for charger cable. Other two wires are for BMS sense wires.


The red wire is on the lower left battery and the black is on the lower right battery terminal.
Disregard the 2nd battery pack on the right of the left four batteries.
The silver marked terminal is number 1 of the buss bar batteries.

Thank you for your help.

 

[sunshine_eggo]

I can't see how your BMS leads are connected relative to the 5 pin "harness".

Your 5 pin 'harness" needs to be on the same terminals or at least at the same potential as the BMS leads assuming you have wired your BMS correctly..

You can only charge 1 4S battery at a time with a 5 pin sensing lead.

5.55V is screaming at you that the sense harness is wired incorrectly, or the charger is defective. You can confirm this by using a voltmeter on the pins of the harness. If you measure the same as the charger, it's clearly a wiring problem.

Counting the wires right to left, 1-5 (poorly labeled), those wires need to be connected at the locations shown. Locations not on a terminal can be on either terminal on the bus bar.

 

[Rapidrob]

OK, really confusing. Let me take the wires off of the pack, take photos, and number the cells/wires. I very well may have the BMS improperly wired.
Thank you for your time and effort.

 

[sunshine_eggo]

it's often helpful to measure the harness starting at red, leaving the probe there and then moving the black to each successive pin. You should see the voltage reading increase by approximately the same per-cell amount, e.g., 3.3, 6.6, 9.9, 13.2. If you do not see that progression, the harness is wired improperly.

Each adjacent wire should be one cell different from the prior. It appears to me that pin 1 (red) and the adjacent pin 2 (black) are actually across the entire 4S pack with the red on the primary (+) terminal and the black on the primary (-) terminal.

Improperly wired sensing harnesses can destroy the hardware they are plugged in to.

 

[sunshine_eggo]

 

[Rapidrob]

OK, I took some more photos of the pack stripped of wires.
Both top and bottom are numbered the same.... so it would be wire one
(red ) goes to + output battery terminal
wire 2 goes to top or bottom # ?, etc. Please ID top or bottom.
Thank you for your help.
TOP OF BATTERY PACK 1 12VDC



Bottom of battery pack


Wiring harness

 

[TacomaJoe]

Your numbering on the cells is wrong. Looking at the photos cell #1 has two positive ends. I think your 1-3 and 2-4 numbers are flipped for the bottom photo. Check cell numbers, these notes refer to the numbers of the TOP photo. Wire 1 to #1 top, wire 2 to #3 bottom, wire 3 to #4 top, wire 4 to #2 bottom, wire 5 to #2 top. Then check your voltages.

 

[Rapidrob]

I numbered them that way. I just need which wire goes to TOP 1-4 and Bottom 1-4

 

[sunshine_eggo]

Wires #1 and #5 must go on the indicated terminal.

Wires 2, 3 and 4 may go on either terminal common to the bus bar:

 

[sunshine_eggo]

IN YOUR WIRING HARNESS PICTURE, YOU HAVE #3 AND #4 OUT OF ORDER. MY NUMBERING IS STARTING AT #1 = RED AND INCREMENTING 1 PER STEP LEFT.

 

[sunshine_eggo]

How we doin?

 

[Rapidrob]

I contracted Covid again. Been sick for the last week. Once I feel better I try the wiring way you listed. Thank you for you help again.

 

[Rapidrob]

Sunshine_eggo you are 100% correct on the wiring. Thank you!
Is it safe to assume the BMS is hooked up same? No instructions or pin-out provided by the seller/maker.
What threw me way off course was the individual voltage pin out readings of the 5 pins, I was looking for 3.2 VDC on each leg which is not right in the interface cable.

 

[Rapidrob]

Sure enough,one of the BMS's are bad. It got fried. It only allows 12.3 VDC out. If I Ohm the othe BMS back to the battery negative there is a direct path. The 12.3 BMS shows an open back to the - terminal.

 

[Rapidrob]

The new BMS showed up and shows all four batteries are normal. I turned on the ISDT Air8 charger and after and hour the Abnormal Cells voltage error showed up again. The voltage on all the cells are less than 3.4 volts. What is going on? Why the error?

 

[sunshine_eggo]

The new BMS showed up and shows all four batteries are normal. I turned on the ISDT Air8 charger and after and hour the Abnormal Cells voltage error showed up again. The voltage on all the cells are less than 3.4 volts. What is going on? Why the error?

Please elaborate.

 

[Rogerb]

@Rapidrob is it possible you have the Air8 set to the wrong chemistry, thus getting the error? Li-ion vs LiFePo?