Electric Drill-drivers with dead batteries

[Enough!Participant @enough]

Posted by richardandtracy on 16/01/2017 15:48:16:

I had a Lithium battery electric screwdriver (3.6V) and that died in 2.5 years, so I've had no more success with Lithium batteries.

My experience with Lithium batteries has been that the chargers are overly fussy at times. I suppose it's natural for them to err on the side of caution with this technology but I ended up with 2 batteries for my 18V Lithium tools that were rejected by the charger and wouldn't charge. It would charge a third battery just fine.

Then I got a "special" on a kit of two new batteries plus charger …. and the new charger charged the old "dead" batteries just fine. Now I've got 5 good batteries, one good charger and one questionable one.

[Martin 100Participant @martin100]

I've rebuilt a few Bosch 14.4v NiCd battery packs using NiMh (the standard Bosch charger being compatible with both) They use sub-c cells, originally 2Ah, I fitted cells rated at 3Ah. With the drill costing around £250 in 2007 and battery packs from the manufacturer at around £90 a piece rebuilding was an economic proposition and a relatively sound idea around five years ago.

At £60+ for a couple of sets of cells, plus the time and effort involved you really have to have a drill that is worth keeping alive. Plastic cased rebranded plastic junk will remain just that. Old cordless drills from a quality manufacturer will probably have an all metal geartrain with decent bearings and even now reasonable spares availability for brushes etc. On the downside they are very significantly heavier to handle than todays Lithium powered offerings.

While the AA and AAA Sanyo (now Panasonic) Eneloop NiMh cells have very low self discharge, with large capacity NiMh cells used in power tools it remains a significant issue, and it's often higher than the equivalent NiCd. Leave the battery packs for a couple of months and they will be unusable until they are topped up, leave them too long or discharge too much in use and you run the risk of one or more cells failing and reducing the overall capacity and voltage of your pack. Such a conditon is unfixable without removal from the housing, individual cell voltage measurement and charging in situ.

A brand new Lithium Ion drill with two 3Ah batteries from a quality manufacturer is available around the £120 pricepoint, it'll be faster lighter and easier to use, with the benefit of instant use after a few months sat on the shelf.

The cell supplier I used was batteriesplus No connection etc

[pgk pgkParticipant @pgkpgk17461]

I make no pretence at knowing the real figures for NiHM discharge rates/duration but I built a R/C Gasser heli that has some quite demanding servos on it as well as simple voltage indicators and it's own on-board charging system so it really just needs the batteries to run things until it gets towards take-off speeds and for landing.

Everyone advised sub C packs for that but I found that on the bench testing heavy servo usage caused my voltage indicators to flash low whereas dual parallel eneloope packs came in at much the same weight but didn't ….If memory serves they were 2300Ma cells.

[Ian S CParticipant @iansc]

I'v got a collection of dead and dying battery drills, one an 18V one is powered by my workshop low voltage supply, another is wired up to run from the 12V of my emergency power supply.

Ian S C

[Howard LewisParticipant @howardlewis46836]

One pack on my 18V Lidl drill is dead, and the other is terminal in all senses.

Took a quick look (TOO quick) at the pack and ordered 30 off NiMh C celss.

The originals are, I think 4/5C so have made up two boxes and stated soldering tinplate straps across the C cells.

The drill will be mains free, but connected by a 2.5M cable to the new battery boxes. Will have to connect into the original battery cases a) to power the drill b) to charge the new batteries, when completed.

When completed, (Don't hold your breath!) should have 3 Ah instead of the original 1.5Ah capacity, so it should be worth the work involved.

If it works, there is another one lurking in the garage awaiting being refreshed.

Well, it stops me getting bored!

Howard

[MuzzerParticipant @muzzer]

Posted by Andy Ash on 16/01/2017 17:35:42:

If you want to keep your NiCad or NiMH batteries alive, try keeping them warm.

I realised if I leave them in the car or in a cold shed, they die pretty quick.

I keep them in the house during the winter now, and I get much longer life.

Yes, I'm afraid it is bumkum. Self discharge is particularly bad for NiMH chemistry. It's a result of an unwanted chemical reaction and like most chemical reactions, it increases with temperature. Basically, leakage current will double for every 10C increase in temperature. It's one major disadvantage of NiMH chemistry but at least it doesn't contain heavy metals like cadmium.

Murray

[Paul LousickParticipant @paullousick59116]

A modification to a cordless drill that does not require batteries.

**LINK**

[Andy AshParticipant @andyash24902]

Posted by Muzzer on 18/01/2017 15:24:31:

Posted by Andy Ash on 16/01/2017 17:35:42:

If you want to keep your NiCad or NiMH batteries alive, try keeping them warm.

I realised if I leave them in the car or in a cold shed, they die pretty quick.

I keep them in the house during the winter now, and I get much longer life.

Yes, I'm afraid it is bumkum. Self discharge is particularly bad for NiMH chemistry. It's a result of an unwanted chemical reaction and like most chemical reactions, it increases with temperature. Basically, leakage current will double for every 10C increase in temperature. It's one major disadvantage of NiMH chemistry but at least it doesn't contain heavy metals like cadmium.

Murray

They've been going for four of five years now, which is the best I've ever done, so I'm not planning to stop keeping them in the house.

I don't doubt what you're saying though. My batteries are NiCad, but I'd always assumed that NiMH would be similar if not slightly better.

I've not been able to find much about self discharge with temperature, but I do know there are fairly strict limits on charging at lower temperatures. Maybe you know something about that too?

Edited By Andy Ash on 19/01/2017 16:18:24

[richardandtracyParticipant @richardandtracy]

As it happens, in the cold weather my 4yo car battery is struggling & as a result, my drill-driver is going to have a new (ish) 12V lead acid battery. Strange how things turn out.

Regards,

Richard

[Ian S CParticipant @iansc]

If you build model engines, steam, IC, or hot air, the motor from one of these drills can be used as a generator, or if the motor is one of the newer brushless ones, an alternator.

Ian S C

[MuzzerParticipant @muzzer]

Posted by Andy Ash on 19/01/2017 16:17:55:

They've been going for four of five years now, which is the best I've ever done, so I'm not planning to stop keeping them in the house.

I don't doubt what you're saying though. My batteries are NiCad, but I'd always assumed that NiMH would be similar if not slightly better.

I've not been able to find much about self discharge with temperature, but I do know there are fairly strict limits on charging at lower temperatures. Maybe you know something about that too?

Edited By Andy Ash on 19/01/2017 16:18:24

Not sure what the problem is although I have my suspicions. I just googled "NiMH self discharge temperature". The first hit was this. Seems to cover most of the stuff you don't seem to understand?

Murray

[John CParticipant @johnc47954]

I followed up this tip from page 1 of this thread:

Posted by Bikepete on 16/01/2017 10:05:14:

– or this one with 12.1V, 69A, £8.54 inc postage! Often there are instructions on the web for hooking them up e.g. here.

and very quickly received said power supply. Modifying it was easy, although not quite as straightforward as the link. I used a junior hacksaw blade to saw through the plastic socket and then nibbled away at the plastic. I snipped off all the leads apart from 3 and 4 which I soldered together – I din't bother with a switch. I made plugs for the 12v out by milling down the pins of a standard 13 amp domestic plug.

Good one – thanks Bikepete!

[Gordon WParticipant @gordonw]

I made connecting plugs from 2 pin plug and sockets as sold for mains electric lawnmowers and suchlike. You can make them polarised by cutting one pin short and putting the sawn off piece in the socket, you will have to work out how much to cut off depending on the make of coupler.

[BikepeteParticipant @bikepete]

Glad it was of use John C. Have you tried using it to power a drill?

If you can find some cheap, Speakon connectors are good for high DC currents, if a bit bulky.

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