D620 Battery problem

I have recently purchased a D620 from eBay and am experiencing the following problem with charging the battery:
Battery charges normally to 29% and then charge rate falls back and charge will not exceed 31% and charge light goes off.
MobileMeter gives battery wear rate of 21%
When the laptop arrived the battery had a 100% charge but once used it will not charge over 31%.
I have tried different charger.
At 31% I can get 40 mins of power normal use.
Is the problem with the battery or internal control of the charging rate? If the latter it could explain why the battery arrived fully charged if it had been charged on another computer or commercial group charger.

 

This is unusual behaviour. It might be the charging circuit or something has got out of calibration. You can check the BIOS for any battery calibration option.

If there's nothing there then I suggest a couple of full discharges. Do this by disabling the Critical Battery Action in the power properties and then letting the computer run on idle until it goes off, then recharge as much as you can and repeat the discharge / recharge.

John

 

Hi John, thanks for quick reply, I have checked BIOS but there are no calibration options.
I will try the 100% discharge and report back
Malcolm

 

I tried a couple of 100% discharges but no improvement.
I think the battery is ok because when you continue to hold down battery indicator button only 1 light shows which I am led to believe indicates a 20% degrading of battery health which would match with the MobileMeter report.
Does anyone know if this means a new Motherboard?

 

That was quick, something is definitely wrong since two full cycles should have taken lots of hours.

AFAIK each battery light represents 20% charge: A full battery will show 5 lights and 31% charge is less than 40% so only one light would show.

Are you sure that the battery had 100% charge when you received it? Did you get lots of battery run time? It would be reasonable for a 2 or 3 year old battery to be down to 20% charge.

It's difficult to debug this further without access to another D620 (or something which uses the same battery). The D620 service manual is here but doesn't show a separate power module.

I would be tempted to look for another battery first. They always come useful.

John

 

Thanks John, I have reported the problem to the Seller and it appears that there is still some dell warranty left so they are going to arrange for an engineer to visit next week.
I am pretty sure it had 5 lights when I received it but i ran a dvd and did not get much run time.
However the battery wear indicator light only shows 1 light which according to dell would indicate reasonably good condition.
I have 2 other dell batteries for my D600 which mobileMeter tell me have 27% and 35% wear the indicator lights on the battery would also seem to back this up with 2 lights and 4 lights showing respectively.
I will let you know the outcome next week after Dell have had a look at it.
Malcolm

 

AFAIK the indicator lights show the current amount of charge, not the wear. See here. My 3month old E6400 battery shows all 5 lights. I think this means 100% charged, not 100% worn.

Anyway, getting a Dell tech round should get to the bottom of the problem. However, the warranty on the battery is most likely only 12 months although the computer itself may be 3 years (being a Latitude).

John

 

I am not familiar with the "wear level" indicator in MobileMeter. Can you please post the following values from MobileMeter: "Remaining Wattage", "Designed Capacity" and "Fully Charged Capacity"?
Note that some batteries doesn't report a correct value for "Designed Capacity". Sometimes you have to read the label on the battery itself to get the correct value.

Örjan

 

John, if you continue to press button the next number of lights give indication of degredation. If you get no lights then battery in great condition - continue to read the link you posted from dell.
Orjan - capacity on Battery - 56000
capacity given by MobileMeter - 57720
fully charged - 45088
wear level 21%

 

Thanks. I didn't read that far, so I have learnt something new today.

John