Hi, and am fairly new to electronics, but I found an old laptop which I'm attempting to fix and the first problem is the battery won't charge. When I cracked open the battery, I saw 5 cells and 5 pins but the cells were only connected to the first and last pin. 2 out of 3 other pins seemed to be connected but when I took my multimeter to test my theory it showed otherwise. Does anyone know what the 3 extra pins are for? Also when I tried hooking up 12 volts to the computers positive and negative leads it didn't detect anything so I'm thinking the 3 other pins have some purpose.

Patrick.

 

I see a temperature sensing bead and a meltable thermal limit fuse.

 

Thermistor, thermal fuse, what's the other item at the back out of focus,,, laptops usually monitor the temperature and charging current limit, and if it detects faulty cells it won't do anything..

 

Yes both seems to match the picture of a thermistor and thermal fuse I looked up, does the thermistor connect the 2 leads going into it? Also it seems that the thermal fuse doesn't connect to any of the pins. It connects the cathode of the first cell to the anode of the second. Also here is a better picture

 

The fuse will be in series with the cells, the thermistor will go to the terminals, easy to see which terminals the thermistor goes to, use an Ohm meter to check, should be around 10-25K and will decrease when you hold it between your fingers.

 

So the fuse is connected to the cells and the thermistor reads about 11 ohms and is connected to 2 pins so what is the silver box thing in the back? I tried looking up the modle number and had no luck. Here it is anyway, ISUZU IP385 AFC-B (78C) Is it a
Bimetal Temperature Control Switch Thermo Protector?

 

I also tested the thermistor with a air hair dryer and it is a NTC thermistor. Just in case that is helpful.

 

So you have all the information you need, you just need to connect the battery charger.

 

So you have all the information you need, you just need to connect the battery charger.

No just the battery still wont charge. Could it be a faulty cell? How can I tell?

 

Check that there is an output from the battery charger. Connect the battery charger to the battey pack. Check the voltage between the ends of the two cells that connect to the charger connections. (If you don't get a voltage reading there then there is no point in going any further.) Check the voltage between the ends of each stick of cells. (Each stick will probably contain 2 or 3 cells in series.) Report the results of your tests.

Les.

 

This is a Compaq LTE battery, is it not? I'm working on the EXACT same project for a Compaq LTE 5280! If you see this, I'd love to know if you got it working!

 

This is a Compaq LTE battery, is it not? I'm working on the EXACT same project for a Compaq LTE 5280! If you see this, I'd love to know if you got it working!

I never did get it working, but I think my laptop was just a dead. Good luck if you can figure it out.

 

I never did get it working, but I think my laptop was just a dead. Good luck if you can figure it out.

Oh, as in it didn't power on even with a power adapter? If so, that sucks... Did you end up throwing it away? Was it Compaq LTE laptop?

 

I never did get it working, but I think my laptop was just a dead. Good luck if you can figure it out.

For the record, the battery was actually a 10 cell NIMH battery (2 cells per 'stick') with, in your case, a capacity of probably around 3300 - 3800 mah. Each cell was a 4/3a NIMH cell made by Sanyo, I believe. In order to get the battery working again, you would need to replace the cells with new ones. Personally, I used cells made by PKCELL. Once you ordered the individual cells, you would need to attatch them to each other in a series. I would also replace the Thermistor and the Thermal Fuse.

 

Ya, I had a compaq LTE and did throw it out a while ago. I just found it in a junk pile and didn't want to spend any money or too much time fixing it as I didn't even know if the laptop was working.

 

Ah, that's a shame... Well, if you ever find yourself working on a battery or refurbishing an old computer again, hit me up, I've been doing it since I was 12 and I'd be happy to help!