T420 Battery Recommendation?

[abstract_username]

Hey there!
First post,
Just wondering if anyone has a recommended place to procure a new extended run battery for my Lenovo Thinkpad T420...
My current battery is a SANYO 42T4799

My system info reports:
ID-1: BAT0 charge: 11.0 Wh condition: 29.3/93.2 Wh (31%) volts: 11.6/11.1

I shouldn't get a battery replacement that is 10.8v?
I would prefer to have a battery that has the most Wh, Im guessing that is the 94 Wh battery.



Im new to the Thinkpad line! I love the retro style of my T420!

[atagunov]

T420...
My current battery is a SANYO 42T4799
ID-1: BAT0 charge: 11.0 Wh condition: 29.3/93.2 Wh (31%) volts: 11.6/11.1

Hi, welcome to the forum! I'm under Ubuntu so battery condition report looks a little different but here's my original Lenovo battery for T520L:

Code: Select all

/sys/devices/platform/smapi/BAT0/manufacture_date           = 2011-12-13
/sys/devices/platform/smapi/BAT0/first_use_date             = 2012-07-11
...
/sys/devices/platform/smapi/BAT0/design_capacity            =  86580 [mWh]
/sys/devices/platform/smapi/BAT0/last_full_capacity         =  73740 [mWh]
/sys/devices/platform/smapi/BAT0/remaining_capacity         =  72040 [mWh]
/sys/devices/platform/smapi/BAT0/remaining_percent          =     98 [%]
Charge                                                      =   97.7 [%]
Capacity                                                    =   85.2 [%]

So my battery was designed to hold 86.58Wh
By the estimation of battery's own microcontroller last time it was fully charged it managed to take 73.74Wh
This means the battery is 85.2% healthy
Of these 73.74Wh that the battery can presumably hold now it's currently charged to 72.04Wh, so it's 97.7% full
All by estimation of batteries own microcontroller - which can be wrong especially on non-original batteries

Looking at your numbers it appears that your last full charge was just 29.3Wh which means your battery is only 31% healthy
Better than no battery but yes ripe for a replacement indeed

I shouldn't get a battery replacement that is 10.8v?

I think Thinkpad can use battery of any voltage. I feel quite sure it can use both 10.8v and 11.1v batteries. The way it works - two of the contacts on the battery connector are used for a "conversation" over so-called SMBus protocol. Thinkpad's will ask: dear battery how would you prefer to be charged? To what voltage? With what maximum current? Then it will use this data to control battery charging circuits. So a battery that asks for 10.8v will be charged to 10.8v and a battery that asks for 11.1 v will be charged to 11.1v. On the flip side I think internally Thinkpad will be able to use a range of battery voltages to produce the voltages that it actually needs. Internally Thinkpad probably needs 5V, 3.3V, 12V. The external power supply provides 20V. The battery as you now know will give between 10.8v and some higher voltage. That's expected. Thinkpad will cope.

I'm a little less sure about 14.4v batteries.. But generally I think that so long as the battery is marketed as being "for T420" it will be suitable.

The big choice you've got to make is between original Lenovo batteries - they will in fact by SANYO, LGC or some other manufacturer - but those which were originally blessed by and sold by Lenovo itself and aftermarket batteries. Originals are all quite old, they haven't been made for a while. Ebay is probably the best source for them. They can be used or unused, but I'm not sure which ones are better. Just sitting on the shelf for 10 years doesn't necessarily guarantee the battery is still good. So it's a bit of a lottery. If you look at the stats from my T520 battery you will notice it's 10 years old but still going strong. It's not rare to hear such stories about original batteries. They often hold up quite well. In particular my machine was normally plugged all these years so I haven't been using the battery much. Not that it guarantees anything.. Even an unused battery can deteriorate.. There are on the other hand other used original batteries that are quite worn.. Worst thing is that sellers on ebay normally can't or don't want to tell you how healthy or worn the battery they're selling is. They rarely run `tlp-stat -b` under Ubuntu or another tool to check health levels. They just have this batt they want to get rid of.

Aftermarket batteries can be divided into completely no-name and some sort of a "brand". The "brands" I'm aware of are KingSener and GreenCell. The worst thing that can happen with an aftermarket battery I guess it won't hold charge at all. What more commonly happens is it holds some charge but not as much as advertised. I've got a 6-cell KingSener on my X220 for 1.5 years. For a while it has been behaving like this: I charge it, it works normally then after reaching around 30% charge it "tanks" - goes to close to 0% in less than 3 minutes. I think it may have snapped out of it now, but I'm not sure.. Funnily I was seeing the same on a battery which I think is original on the same X220.. I also own a KingSener 9-cell battery for X201. I have just received an X2100 - an X201 with a new custom motherboard fitted in. It's a disaster with battery, but I don't know where the fault is - in KingSener in X2100 or in both... The disaster is battery charge reported is dithering between 100% and 33% on a fully charged batt. But that may be specific to X201 or X2100. The issue that you commonly hear wrt aftermarket batts is "tanking" similar to what I'd seen on X220. I may still recommend a KingSener batt - they are sold on AliExpress, they are relatively cheap (£30), they arrive within a month and even if it tanks after 30% - hey you get a battery that holds 70% charge. Way better than 31% you're getting now! But in summary aftermarket batteries are a bit of a lottery too.

I would probably advise against completely no-name aftermarket batteries. But we have a member on this forum from Greece who has been buying aftermarket no-name from some shop in Greece - not sure if brick and mortar or online - which was offering unconditional returns within a year if the buyer doesn't like the batt - and he says they work for him those aftermarket batts.

There is probably a tiny little bit more peace of mind associated with original batts. The original batts are more certain to have more proper protections built in - the original batts will get completely switched off if the built in controller thinks situation is dangerous - overcharge etc and they have fuse that will blow on its own on overcurrent.. But then even original batts are faked and one cannot always be 100% sure looking at an ebay listing if its truly an original or a carefully created aftermarket replica that pretends to be original.

I would prefer to have a battery that has the most Wh, Im guessing that is the 94 Wh battery.

Sure, get yourself a big 9-cell battery of the same size and weight like you have now. I think batteries can generally be 6-cell or 9-cell. A cell is a round Li-Ion batt which looks similar to AA, they sit within those round "tube-shaped" compartments inside your batt. I'm a little surprised T420 has 94Wh batts while my T520 batt is only 87Wh, but that's entirely possible. Just look for something in that range.

Please note that KingSener batts for some strange reason are denominated in Ampere-hours not Watt hours. I think you divide watt-hours by voltage and you get ampere-hours. That's to help you choose the right battery on AliExpress since a single listing often offers a choice of 6-cell and 9-cell. I've actually made a mistake when ordering that X201 batt - I wanted a 6-cell but accidentally ordered a 9-cell because of this amp-hours confusion.

Im new to the Thinkpad line! I love the retro style of my T420!

What do you mean by "retro"? T420 much more modern compared to a T60 Just make sure it's got a decent SSD and at least 8Gb RAM and it will be a good runner!! I actually run all my *20 machines with 16Gb of RAM - mostly just because I can.

My T520 should be about as powerful as your T420. The setup I have is I'm running Ubuntu and on top of it Win 10 in a KVM VM. When support for Win 10 runs out and Win 11 becomes the only option I plan to run it the same way. It's not a gaming setup by any means but it has been sufficient for me to do light tasks that can only be done under Windows. I'm even able to have mostly glitch-free audio/video conferencing - even if that requires some extra effort to setup. The challenge here is of course not that T520 is generally not powerful enough for conferencing, the challenge is to have glitch-free sound in a virtual machine. I'm currently on I5-2520M cpu, I think your T420 might be running the same or similar.

P.S. It seems to me the website you linked to is selling what I would classify as "no-name aftermarket" batteries.

[abstract_username]

Woah! @atagunov

Didn't expect quite such a reply!
Yes my partner warned me of the laptop battery minefield!

I didn't actually link a website... but i will now
https://www.laptopbatteryexpress.com/Ge ... n-70xt.htm
It seems to be a little expensive, but apparently, it is a Samsung!?
It is also 94 Wh.

I suppose I should pay a little more, so i get what i pay for...
Ill keep looking around for now. Ill try a look at some of those brands you posted about!

By retro I meant it had a design meant for computer enthusiasts, and still had its physical mouse click buttons under the trackpad, the T420 is basically the same design as my Z61t I received last week, but with more modern specifications, maybe 'retro' was the wrong choice of words!
I would definitely say this laptop is 'old-school'

I popped a 1TB Crucial MX500 and an 8GB Team Elite DDR3 in the back (taking me to 10GB Ram)
And once I find a good battery... I will be ready to study computer science at Uni! Yay!

Thanks for the reply!

[EDIT]
BTW, Im using Linux Mint, the battery report came from System Reports, System Information

[atagunov]

https://www.laptopbatteryexpress.com/Ge ... n-70xt.htm
It seems to be a little expensive, but apparently, it is a Samsung!?

Hi, I think Samsung is actually the brand of cells inside the battery that they are promising. I'd say it's impossible to check which brand of cells you have unless you open the battery, but if you open it you can't close it back neatly and it would look "funny" at boarding an airplane etc. One of the main concerns when buying cheap non-original batteries is that they are actually fitted out with poor-quality cells. Reasonable level of assurance that cells are good is one of the reasons people prefer original batteries - even if they are used or unused but have been sitting on the shelf.

I didn't realise T420 (yours) and T520 (mine) actually share battery models, but it seems you're looking to buy batteries that are very similar to those which I have in my machines.

At $140 it doesn't look cheap but those which I purchased at £30 as I described don't look absolutely perfect. I certainly won't be talking you out of buying from that shop. On the flip side I don't know the shop and cannot be vouching for them either. Whichever way you go would you mind sharing your experiences here?

BTW, Im using Linux Mint, the battery report came from System Reports, System Information

Ah, fellow Linux user then Please be sure to install https://linrunner.de/tlp/ This is the tool to have on a T420 under Linux. I'm not sure what the best way to install on Linux Mint is. On my T520 under Ubuntu it's

Code: Select all

add-apt-repository ppa:linrunner/tlp
apt-get install tlp tp-smapi-dkms acpi-call-dkms smartmontools linux-tools-generic powertop

Powertop here is just for fun, it's able to show me exact current power consumption when on battery and I do not find it useful for anything else. If you didn't come across TLP that is the tool that is able to tame power consumption when the notebook is on battery. /etc/tlp.conf contains the settings. You can for example limit CPU performance when on battery etc. It will do a decent job out of the box too with default configs. And you get tools like 'tlp-stat -b', 'tlp recalibrate BAT0', 'tlp discharge BAT0', 'tlp fullcharge BAT0' (I believe recalibrate is basically a 'discharge' followed by a 'fullcharge' - that is how battery controller re-learns true full battery capacity). Battery charge thresholds are an attractive feature and can be set with /etc/tlp.conf but I find them controversial. One theory is that setting upper threshold (not charging fully) might be confusing battery controllers into reporting wrong charge %, I am actually setting it now to 100%. I'm still using charge start threshold at around 60% or 70%:

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# note that you still need to set STOP.. to 100 in order for START to take effect; 
# you can't just omit STOP and only specify START
START_CHARGE_THRESH_BAT0=62
STOP_CHARGE_THRESH_BAT0=100

I find this setting fine for a usually docked machine. If I need to take machine and go somewhere, okay it will always have at least 62% charge, enough for me. Batteries are said to live longer if kept around middle charge (probably 30-70% range?) as opposed to empty or full.

P.S. do other forum members have opinions of this shop selling 9-cell T530/T430 batteries (which obviously also fit T520 and T420) in the US for $140?

[abstract_username]

@atagunov
Thanks for the tool recommendation! The battery threshold option seems enticing!

Considering the exchange rate USD-AUD I will probably steer clear of the shop i found...

Im in favour of buying this:
https://www.ebay.com.au/itm/35349909187 ... SwEP5gokoj

Its 94 Wh, 11.1V, and it is a LENOVO, apparently they advertised the T530(dont quote that) at 15 Hours of battery life! (Maybe at 0% Brightness! ) They came with the 70++
The T420 came with the 55++ and does not support Rapid Charge, and therefore is not available for use in the T530(or other models supporting Rapid Charge functionality)...

70 Bucks AND I will have it before I start classes!

[atagunov]

Hi, I've never actually yet purchased a battery on ebay separately from a Thinkpad, so no first-hand experience. Generally I quite like buying items from private sellers who take photos of the actual item they sell.. but then again this is lottery either way.