Fixing a Li-ion battery pack for a laptop

[Alec_t]

Is it possible that removal of the battery has set some flag so that only a genuine OEM battery replacement will work?

 

[Bumblebee001]

I thought of that but the specs might be different. Most batteries I have seen have a higher voltage than this battery. Would the board of such batteries be good? Also I am not sure if they have the same 4 battery leads as this board has...

View attachment 53178

Also, the connector is likely to be different....

 

[Bumblebee001]

Is it possible that removal of the battery has set some flag so that only a genuine OEM battery replacement will work?

I have tested the new batteries: all are charged. I tested the assembled "pack" connecting the voltmeter (automatic) to the two outmost slots in the connector: only resistance is measured - no voltage reading

 

[Alec_t]

no voltage reading

The BMS could have turned off an internal switch, requiring some resetting incantation known only to the OEM.

 

[Harald Kapp]

Of course you'd have to find a battery pack of the same type to match the specs.

 

[Bumblebee001]

What's even more confusing is that even if I could order a complete battery with the same compatibility and numbers (codes) the voltage of the new batteries is 14.8V (old one is 10.95V)!

 

[Audioguru]

An older style lithium 18650 battery cell is 4.2V when fully charged, 3.2V when the voltage is low and its load should be disconnected then 3.7V is when it is half discharged. Three cells produce 12.6V when fully charged.

If a cell is charged to a voltage higher than 4.2V then there is a risk of an explosion and fire!
You said the new batteries are 14.8V which is four 3.7V cells.

A multimeter cannot measure voltage and resistance at the same time. Set it to DC volts.

 

[Bumblebee001]

An older style lithium 18650 battery cell is 4.2V when fully charged, 3.2V when the voltage is low and its load should be disconnected then 3.7V is when it is half discharged. Three cells produce 12.6V when fully charged.

If a cell is charged to a voltage higher than 4.2V then there is a risk of an explosion and fire!
You said the new batteries are 14.8V which is four 3.7V cells.

A multimeter cannot measure voltage and resistance at the same time. Set it to DC volts.

I said that the original battery had 3 cells and I replaced all 3. I never added a fourth. My diagram and photos illustrate clearly what I did.

Furthermore my meter automatically sets itself to voltage / resistance. I never expected to get two different types of readings on any meter at the same time. When I set directly to the cells, the correct voltage appears on the meter whereas when I test the outer two slots in the connector, the meter shows a resistance value. No Voltage. When I connected a bulb (car lamp or LED) none light up showing that there is no current.

 

[Audioguru]

In your post #26 you said a new battery is 14.8V which is much too high for three Li-Ion cells. 14.8V/3.7V= 4 (four cells)
Your photo shows 10.95V (3 cells of 3.65V), 12.6V (3 fully charged cells of 4.2V) and 19.5V (used by very old laptops).

 

[Alec_t]

when I test the outer two slots in the connector

What measurements do the other slots give?

 

[Bumblebee001]

In your post #26 you said a new battery is 14.8V which is much too high for three Li-Ion cells. 14.8V/3.7V= 4 (four cells)
Your photo shows 10.95V (3 cells of 3.65V), 12.6V (3 fully charged cells of 4.2V) and 19.5V (used by very old laptops).

I was referring to the great majority of new laptop batteries being sold on eBay and Amazon.

 

[Bumblebee001]

What measurements do the other slots give?

I could not establish a pair of stops that produce a voltage difference. There are eight slots (contacts) in the connector and it would be best to know what the standard output of each is. I am still attempting to learn more from the internet when I get some time to spare.

 

[Bumblebee001]

What measurements do the other slots give?

None gave any voltage reading