Dead 90WH DELL battery investigation - Page 1
Forum section: electronics / projects

author: Spikee
author_rank: Frequent Contributor
timestamp: September 20, 2013, 03:47:45 pm
content: So the battery of my DELL XPS17 L702X suddenly died and that really sucks...Dell wants to get 150+ € for a new one and i don't have that money as a student at the moment.So i want to fix it myself.Brand: SANYO / DELLBattery type: R795X Li-ionVoltage: 11.1 VCells: 9Capacity: min 7.65 MahCode on battery cell: PEHZ914983Battery controller board TOP:High res :https://dl.dropboxusercontent.com/u/100819959/dell_batt/control_top.jpgBattery controller board BOTTOM:High res:https://dl.dropboxusercontent.com/u/100819959/dell_batt/control_bot.jpgBatt:High res:https://dl.dropboxusercontent.com/u/100819959/dell_batt/batt.jpgand a weird component:High res:https://dl.dropboxusercontent.com/u/100819959/dell_batt/batt.jpgSome sort of diode or something ?I'll have to test if i can charge these cells manually and look if they are still alive using my turnigy accucell 6.And if they are dead which one to buy and replace them with.

author: Clear as mud
author_rank: Regular Contributor
timestamp: September 20, 2013, 04:00:31 pm
content: There are aftermarket batteries available for less - maybe 1/3 to 1/4 the cost of a new Dell one. Search Amazon, and look at the customer reviews to make sure you get a good one. At least know that is another option, before you spend the time to repair that one. I am not sure if you can just replace all the cells, or if further work is necessary on that type of battery. Someone else probably can give you better advice, if you want to proceed with repair.

author: Kjelt
author_rank: Super Contributor
timestamp: September 20, 2013, 04:02:03 pm
content: That "weird" component is probably a thermal fuse (or switch) which opens when the temperature exceeds the safety temperature. Most common are these fuses in coffee machines as a last resort against fire if the thermostat malfunctions.If this component is not almost zero ohms (so conductive) it is dead. The more expensive version of these reset after cooling down.I hope it is as simple as one of the cells that died and not the controller hardware since that would be a difficult repair/replacement. Then you need to find an old version of your battery and replace the electronics.

author: Spikee
author_rank: Frequent Contributor
timestamp: September 20, 2013, 04:50:00 pm
content: I measured the thermal fuse and it is conductive so that is nog the problem. I have looked at some after market replacement batts and they are around the 80 euro mark.Maybe i can borrow the BK precision DC load at school and test the Batts when i have recharged the cells using my turnigy charger.

author: Unknown
author_rank: Unknown
timestamp: September 20, 2013, 05:30:09 pm
content: Quote from: Spikee on September 20, 2013, 03:47:45 pmThermal link. Goes open circuit at a preset temperature. As mentioned, generally used as a last line of defence in things with heating elements in, and apparently battery packs.

author: Rasz
author_rank: Super Contributor
timestamp: September 20, 2013, 05:53:39 pm
content: one of the batteries in the third stack needs replacementbut that wont be all, you said battery died = BQ8050 is locked = NO free tools to unlock it = keep 18650s, throw away the restcheap chinese replacement (~2/3 declared capacity) are extremely cheap, $30 will get you ~3000mah battery

author: Spikee
author_rank: Frequent Contributor
timestamp: September 21, 2013, 08:39:43 am
content: That sucks ... Guess I'll just have to buy a new battery.

author: Psi
author_rank: Super Contributor
timestamp: September 21, 2013, 08:57:46 am
content: First thing to check is if the electronics is ok.Simulate a battery of the correct voltage with a psu, or other batteries, and see if it will run the laptop.Don't connect AC power during the test though, you don't want it trying to "charge" your psu.Also, some of these smart battery systems learn the battery stats and can get confused if you screw with them.(Adjusting psu voltage while its simulating a battery etc)I would pick 3.9 x 3 = 11.7V as that's close to what the batters are now (except for that group of dead cells).

author: Kjelt
author_rank: Super Contributor
timestamp: September 21, 2013, 09:06:55 am
content: Quote from: Rasz on September 20, 2013, 05:53:39 pmYou're right I think: Here is a datasheet of a similar componenthttp://www.ti.com/product/BQ3050If you look at the 2ndary safety, there is a fuse and that can not be reset, blown is blown?Then they also have this SHA1 cryptographic authentication, so how come the chinese have batteries that are being recognized by the system, are these hacked?

author: amyk
author_rank: Super Contributor
timestamp: September 21, 2013, 11:14:14 am
content: Quote from: Rasz on September 20, 2013, 05:53:39 pmAt least that's what they *want* you to think... classic vendor lock-in scheme, like ink cartridges and whatever else.Quote from: KjeltI don't think it's the Chinese this time (althoughthey do some); it's the Vietnamese. Google for things like "BQ8050 reset", "BQ8050 unlock" and the like and the majority of the results are from the Vietnamese...this videofor example I have no idea what he's doing but it looks interesting.AIUI the "unseal password" on most of them is only 32 bits; bruteforcing won't take long. The claimed SHA1 authentication is likely either not used or there's some other backdoors, which the recellers have figured out long ago.

author: Rasz
author_rank: Super Contributor
timestamp: September 21, 2013, 02:31:01 pm
content: Quote from: amyk on September 21, 2013, 11:14:14 amno, its what I want you to think - NO free tools to unlock itthere are tools to unlock it, one costs $3500there are also free tools that can unlock earlier chips like BQ8030 (be2works)but BQ8050 is locked = NO free tools to unlock it

author: happylex
author_rank: Contributor
timestamp: September 26, 2013, 07:13:29 pm
content: Hallo Thijs,Alles goed? Wanneer ga je verder met je PSOC tutorials? Ik wil graag een usb geluidskaart maken, maar ik kom er niet uit.I wonder what makes you think the battery died. I have a Dell for about 18 months, and I just got a message to replace the battery.The first messages clearly states the battery is broken and needs to be replaced. However, what is wrong if I can watch four hours of youtube HD with this battery? When I click a bit more I get messages that are just suggestive like the battery might. ... bla ... you might consider to maybe buy a new battery fromwww.dell.no. So the first logical step for me was go to the police.But I wonder what you and others experience? Is this the Dell version of the famous telephone computer fix scam? Or do I miss something and will my laptop explode?OOOPS!Groetjes,Edit: The 57WH battery is €197! What? Do batteries of this price just live for 18 months? Rediculous

author: Spikee
author_rank: Frequent Contributor
timestamp: September 26, 2013, 07:18:31 pm
content: A part of the battery was actually dead so they don't bs when you get the message. If it is right or wrong that DELL disables battery charging is another thing ... But with a third party replacement of 56 € i'm not really complaining.As for the PSOC tutorials .... I have been using one in a project (Psoc 4 Gyro , accel , magnetometer , altimeter ) for a school project.And I'm close to finishing it. when it is done I'll make some more video's. Also a good place to learn:http://www.element14.com/community/thread/23736