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Here's an explanation for that.frozencaptain wrote: ↑Mon Mar 17, 2025 1:22 pmHello! I am once again asking for guidance regarding my T400. A few weeks ago I bought a Greencell brand battery from Ebay and it seems like bad quality overall and the capacity has already degraded to 88% according to TLP. Could anyone recommend where to get a better battery, thanks.
Thank you for your replies. Sorry for taking so long to reply. I'll go the re-celling route. I was already thinking about buying a spot-welder and other tools to make a battery for a different project. Could you link the guide(s)? I was searching your profile, but couldn't find a post about the T400. Is one of the other ones applicable?kfzhu1229 wrote: ↑Tue Mar 18, 2025 1:59 pmHere's an explanation for that.frozencaptain wrote: ↑Mon Mar 17, 2025 1:22 pmHello! I am once again asking for guidance regarding my T400. A few weeks ago I bought a Greencell brand battery from Ebay and it seems like bad quality overall and the capacity has already degraded to 88% according to TLP. Could anyone recommend where to get a better battery, thanks.
Typically for extra reassurance that the aftermarket battery is compatible with the original batteries, manufacturers put ratings equivalent of 2200mah per cell (which is what most laptops of the era used, though not T400 which was 2600mah), so 6 cell would be rated for 4400mah and 9 cell would be 6600mah.
But the catch is, most of the cheapest crap no name cells are in fact 2000mah cells, or 4000mah for 6 cell out of the box.
The difference is "small enough" they hope most end users won't notice. So effectively you only have 90% of promised full charge out of the box.
And unfortunately also, these cells degrade much faster than even name brand Chinese cells, hence 88% after a few of your calibration cycles.
My experience with battdepot no name cells for example is that they seem to degrade as much as 1Wh per cycle on average, if you keep on doing full cycles.
if you want better batteries, your only hopes are to either see my guides on the unlock/rebuild original batteries that I've shared free of charge and do it yourself. Or that you'd have to pay up some for others to do this job.
There are actually better built batteries on aliexpress as well, I've come across a T530 battery that worked well, but they seem to be buried around a bunch of crappy options that it's hard to pick out.
EDIT: I think I've actually bought from them before, but directly from their display shelf at the Shenzhen HQ-mart. It was DIRT CHEAP if you buy there directly, I believe 90 CNY for a 9 cell or like only 13USD. But yeah no, those are definitely 2000mah crappy cells, which isn't a surprise given that even a nice quality Chinese EVE made 18650 cell is like 12 CNY each which is clearly over the budget.
I wrote one about a T43 one and another about an X61 one I believe. The X61 one is actually similar enough in unlocking procedures to the T400 battery. I have opened that one before, it's pretty easy to open. But you need to see which manufacturer the genuine battery is from, a Sanyo one vs a Panasonic one vs a Sony one vs an LG one will have different procedures for working with the BMS.frozencaptain wrote: ↑Sun Mar 23, 2025 2:24 pmThank you for your replies. Sorry for taking so long to reply. I'll go the re-celling route. I was already thinking about buying a spot-welder and other tools to make a battery for a different project. Could you link the guide(s)? I was searching your profile, but couldn't find a post about the T400. Is one of the other ones applicable?
My original battery is a "Panasonic 42T4645" according to the XFCE power manager. This one is a 6-cell, I was thinking of buying a used 9-cell from ebay and rebuilding that.kfzhu1229 wrote: ↑Sun Mar 23, 2025 2:34 pmI wrote one about a T43 one and another about an X61 one I believe. The X61 one is actually similar enough in unlocking procedures to the T400 battery. I have opened that one before, it's pretty easy to open. But you need to see which manufacturer the genuine battery is from, a Sanyo one vs a Panasonic one vs a Sony one vs an LG one will have different procedures for working with the BMS.frozencaptain wrote: ↑Sun Mar 23, 2025 2:24 pmThank you for your replies. Sorry for taking so long to reply. I'll go the re-celling route. I was already thinking about buying a spot-welder and other tools to make a battery for a different project. Could you link the guide(s)? I was searching your profile, but couldn't find a post about the T400. Is one of the other ones applicable?
Oh, I think I have exactly that battery in my 14.1 widescreen T61 (which has the same battery as T400). Mine is working but was already previously apart as I corrected a cell imbalance before it would lock the bms. I can have a look at the BMS IC on that thing if you wishfrozencaptain wrote: ↑Sun Mar 23, 2025 2:43 pmMy original battery is a "Panasonic 42T4645" according to the XFCE power manager. This one is a 6-cell, I was thinking of buying a used 9-cell from ebay and rebuilding that.
That would be very helpful. Thank youkfzhu1229 wrote: ↑Sun Mar 23, 2025 3:26 pmOh, I think I have exactly that battery in my 14.1 widescreen T61 (which has the same battery as T400). Mine is working but was already previously apart as I corrected a cell imbalance before it would lock the bms. I can have a look at the BMS IC on that thing if you wishfrozencaptain wrote: ↑Sun Mar 23, 2025 2:43 pmMy original battery is a "Panasonic 42T4645" according to the XFCE power manager. This one is a 6-cell, I was thinking of buying a used 9-cell from ebay and rebuilding that.
I had a look at mine, which is a 42T5265, but should be similar enough to yours if yours is also Panasonic. It has a M37512 FC200 IC, which is going to be more intimidating for beginners to work with. BE2Works that I have seems to support it fine theoretically, according to this forum, but some hardwiring on the IC itself to force it into boot mode is required before you can write anything to the chip: https://forum.be2works.com/viewtopic.php?f=2&t=79frozencaptain wrote: ↑Mon Mar 24, 2025 1:37 pmThat would be very helpful. Thank youkfzhu1229 wrote: ↑Sun Mar 23, 2025 3:26 pm
Oh, I think I have exactly that battery in my 14.1 widescreen T61 (which has the same battery as T400). Mine is working but was already previously apart as I corrected a cell imbalance before it would lock the bms. I can have a look at the BMS IC on that thing if you wish
Thank you. I will look into itkfzhu1229 wrote: ↑Tue Mar 25, 2025 2:20 pmI had a look at mine, which is a 42T5265, but should be similar enough to yours if yours is also Panasonic. It has a M37512 FC200 IC, which is going to be more intimidating for beginners to work with. BE2Works that I have seems to support it fine theoretically, according to this forum, but some hardwiring on the IC itself to force it into boot mode is required before you can write anything to the chip: https://forum.be2works.com/viewtopic.php?f=2&t=79
where are these guides man?
The detailed guide on how to reprogram these differs by each controller chip found in each battery manufacturer. You need to determine the FRU and your battery manufacturer first.