Reviving LiOn Batteries & managing hardly-ever-used batteries

[Julian]

Does anyone know if the following is good advice?

https://sciencing.com/revive-lithium-io ... 82537.html

Basically it says fully discharge the battery into a reasonably heavy load, seal it in an airtight bag and put it in the freezer for 24 hours, thaw for 8 hours and then charge it again. I wonder if anyone who knows a bit more about the science/chemistry behind LiOn batteries than I do might have an opinion or other suggestions. Any experience from people who have actually tried this rejuvenation technique would also be appreciated.

I have a couple of cordless drill batteries that will only charge to about half capacity. It's not a huge surprise because I probably haven't used them for about 5 years, give or take a couple of years (it's been sufficiently long ago that I don't really know). I suppose that I should actually be relieved that they still take charge at all. After charging I did get enough charge into one of the batteries to do the 5 mins of drilling that I needed with no sign of the battery dying at the end but I'd rather not buy brand new batteries at about £70 a piece just to put them back in the cupboard and have the new ones deteriorated to a half-chargeable state by the time I first use them which might well only be in a few years time.

Do others have any tips/tricks for keeping the batteries in very rarely used LiOn-powered devices healthy? Two ideas that I can think of are...

1 - Permanently connecting the device/battery to a charger and plugging the charger into a timer set to something like on-for-4-hours-every-month but that's a pain because it takes up quite a lot of room. This is probably only practical for a small device such as a backup phone that could be sat in the boiler cupboard or some out of the way place that has power.

2 - Put annually recurring reminders into one's calendar (I use Google calendar) with the calendar entries set to send a reminder email on the day of each entry to get out device-X and recharge its batteries. This idea is probably better at least for bigger devices. Assuming that a device is totally switched off all year so the only drain is via internal battery discharge then how many times a year should a reminder for that device appear in one's calendar in order to best keep the battery healthy? Every 6 months? More often? Less often? Or is that a bad idea in general?

Any other thoughts/suggestions etc?

- Julian

[UncleEbenezer]

I guess a crucial question is, what's your startingpoint? If a battery's on its last legs, it's unlikely ever to look like new again! Though I'd be very happy to be proved wrong!

As I understand it, at least some chargers are smart enough to know their target battery, so leaving your device permanently on charge is recommended. One such is my roomba.

[Julian]

I guess a crucial question is, what's your startingpoint? If a battery's on its last legs, it's unlikely ever to look like new again! Though I'd be very happy to be proved wrong!

As I understand it, at least some chargers are smart enough to know their target battery, so leaving your device permanently on charge is recommended. One such is my roomba.

And therein lies another question I suppose. Is a LiOn battery that has only been through maybe 10 charge cycles but has been left unused for a few years "on its last legs", i.e. did the years of disuse irreparably damage it or can it be rejuvenated? I realise that a smartphone battery that has gone through hundreds of charge cycles will simply be at the end of its life and there are no clever tricks there to bring it back from the dead, a (possibly) thriving industry is built around replacing such batteries, but is a pretty much unused LiOn battery dead or just sleeping after years of inactivity?

I'm a huge Roomba fan by the way, I got my first one in 2009 and it's still going strong to this day (I got a second one for the bedroooms a year later). Mine are a model before iRobot started using LiOn though so are Ni-MH not LiOn and have had numerous new batteries over the last decade. Luckily there is a good third-party market supplying clones of the Roomba batteries that I need at a fraction of the price of official iRobot spares so even if I occasionally get a dud that only lasts 6 months it's still not too onerous a cost.

In answer to the question about my starting point, I would guess that the Li-ion batteries in question have been through about 10 recharge cycles in their lives and I've had them since 6th February 2013 at which point they were presumably new, plus however long they sat in warehouses along the supply chain. (Searching Gmail for stuff like "when did I buy X" is so convenient, it took me all of 5 seconds to find the purchase date of these tools.)

- Julian

[jfgw]

From your link,

Take a healthy battery, rated at the same voltage as the dead one, and connect them with crocodile clips. Make certain to connect positive to negative to create a working circuit.

Do this only if you want to discharge the battery further, wreck both batteries or create a fire and burn your house down. To charge one battery from another, you need to connect positive to positive. (I have emailed them.)

Do you need cordless? I think my cordless Makita is great for most jobs but I use it very regularly. You can get a corded drill (plus an extension lead if you need one) for a lot less than the cost of a battery. It will be more powerful, probably last you a lifetime and you will never have to worry about the battery being charged. Compare the amount of time you have spent faffing about with batteries, searching the 'net and posting on TLF with the amount of time it would have taken to to plug in a mains drill (which would probably drill faster in any case). What were you drilling that took 5 minutes?

Julian F. G. W.

[Julian]

...
Do you need cordless? I think my cordless Makita is great for most jobs but I use it very regularly. You can get a corded drill (plus an extension lead if you need one) for a lot less than the cost of a battery. It will be more powerful, probably last you a lifetime and you will never have to worry about the battery being charged. Compare the amount of time you have spent faffing about with batteries, searching the 'net and posting on TLF with the amount of time it would have taken to to plug in a mains drill (which would probably drill faster in any case). What were you drilling that took 5 minutes?

I actually already have a power adaptor that turns my cordless tools into mains-powered so if the batteries totally die then I can revert to that. It's just that with 2 x £69 batteries already purchased it would be nice to keep at least some capability in them since despite what you say it is sometimes more convenient to use a cordless drill or screwdriver. The power adaptor is actually quite clever, it looks like a power/battery handle that clips onto the tool but instead of having a battery in it it is simply a plastic handle with a trigger and cable coming out of the bottom (about 2m long I think and pretty chunky to minimise voltage drop) that runs to an AC to DC converter so that the tool sees a solid and undepletable 17V or whatever it is coming in from what it thinks is the battery.

My 5 minutes of work was related to a flue issue that I posted about last week on the DIY forum (viewtopic.php?f=40&t=17570) so was out on scaffolding. As it happens the location I was working on was about 1.25 metres away from the window I climbed out of so my convert-to-mains handle would have worked but it was just a bit more convenient to use the drill/driver cordless.

Ooops re your first paragraph that I snipped! I was never intending to try that bit of the advice since my batteries at least have enough voltage to be seen as chargeable by my charger so I didn't read that bit very carefully. Hopefully it's simply a typo since it is such an obvious error that, if the author really thought that what she was typing was correct, it doesn't bode well for the quality of the rest of the advice.

- Julian