I have a laptop computer (Dell L701X) which requires an 11.1 V battery with a rating of 8400 mAh (Battery Type R795X, 9 cell, 11.1 V, 90 Wh, 8400 mAh, other battery ID are: R1122J-733 & B052R796-9021).

If I place a new 11.1 V battery with the same physical dimensions in the computer, but with a rating of 5200 mAh the computer doesn't like the battery. On start-up the computer beeps & gives a text warning on the black start up screen. The on-keyboard battery indicator flashes between white & amber when both my old & new battery are in the computer. After boot up, the battery icon in the task bar acknowledges the 5200 mAh battery but the computer will not charge the battery - the battery is new and it only has a charge of 17%.

Does the computer need a 8400 mAh battery or is there a fault with the battery charger in my computer?

  • $\begingroup$ Can you please list name model of the computer and batteries? $\endgroup$ – Mahendra Gunawardena Jan 13 '17 at 11:40
  • $\begingroup$ @MahendraGunawardena: thanks for your comment. The additional information has now been included in the question. $\endgroup$ – Fred Jan 13 '17 at 11:52
  • $\begingroup$ Have you checked you bios? can you post a image of the system bios infomation as it relates to the battery. BTW I have update the answer $\endgroup$ – Mahendra Gunawardena Jan 14 '17 at 12:28
  • $\begingroup$ Did this work for you? $\endgroup$ – Mahendra Gunawardena Jan 18 '17 at 1:04
  • $\begingroup$ @MahendraGunawardena: it helped, but my problem still persists. Your answer served as a good reminder of things to do - recently replaced the hard drive in the computer & restored the system, but I forgot to update all the drivers, particularly one for the BIOS. I think the battery may not be compatible with the computer so I've ordered a 8400 mAh one - very difficult source & get delivered here. If that doesn't work I get another power supply. If that doesn't work the mother board is the problem & I'll leave it at that. My computer will then have to work without a battery back up. $\endgroup$ – Fred Jan 18 '17 at 6:41

If dell recommends the use of a 5200mAh battery then it should work. There is something else not in sync with the laptop. I would suggest that you update the BIOS firmware. All thought the computer recognizes the lower capacity battery, there might be some parameters that need to be updated. Below is link that might help you.

Although highly unlikely your power adapter might not match in new battery. If you a getting error similar to the one below you might want to follow the direction.

enter image description here

There might be some discrepancies between your laptop BIOS, power adapter and the new battery. Here is an example where there was inconsistency between the power adapter and the BIOS.


Batter adapter not recognized

After replacing the power adapter.

enter image description here

I have listed the links to help you further perform root cause analysis.



*first draft, which I will edit with more details

The capacity of battery is usually not the parameter you look at to determine battery compatibility.

Sometimes batteries with different capacities can be used by the same product with no problems, but often ignored parameters for compatibility would be the C and E rates.

C- and E- rates – In describing batteries, discharge current is often expressed as a C-rate in order to normalize against battery capacity, which is often very different between batteries. A C-rate is a measure of the rate at which a battery is discharged relative to its maximum capacity. A 1C rate means that the discharge current will discharge the entire battery in 1 hour. For a battery with a capacity of 100 Amp-hrs, this equates to a discharge current of 100 Amps. A 5C rate for this battery would be 500 Amps, and a C/2 rate would be 50 Amps. Similarly, an E-rate describes the discharge power. A 1E rate is the discharge power to discharge the entire battery in 1 hour



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