A bit OT - battery charging advice please

[Penners]

I have an old B&D 18V battery drill, which has lain unused for a year or more. It's a bit knackered but can still do a bit of rough-and-ready duty (cue funny remarks about its owner).

I've just dug it out and tried to charge the battery. However, the charger refuses to work properly. The principle is simple - you shove a flat battery into it and it shows a red light until the battery is charged. It then shows a green light.

However, although the battery has been uncharged for around a year (maybe more), when I put it into the charger the red light flashes briefly and then the green one comes on. I've tried leaving the battery in the charger for a few minutes with the green light showing, and I've smelt hot plastic, although neither battery nor charger feels remotely hot to the touch.

Any ideas how I can get this battery to charge, please?

 

[robgil]

Are the contact points clean?

 

[Penners]

Yes, Rob. To be certain I've just given them a slight rub with wire wool. No change.

 

[MdB]

Duff cell. I doubt that there is much you can do to bring it back to life.

 

[Flyfisher]

How old is 'old' and do you know the battery type e.g. NiCd or Lithium?

If the battery has not been used for a long time then there are various methods that might revive it, some more complicated than others. In general, the idea is to slowly discharge the battery, then recharge it and repeat this process a few times. In practice, the optimal process depends on the battery type and includes things such as controlling the discharge rate and discharging to a specific voltage etc. More information here: http://www.buchmann.ca/article10-page1.asp

MdB's suggestion of a duff cell is quite likely though. In extreme cases of discharge and non-use, one or more cells within the battery may become faulty, perhaps even reverse polarity. In a battery of series-connected cells, this will affect or even prevent the battery charger from working correctly, but it's difficult to know what's really going on without a multimeter to check battery and/or cell voltages and charging currents.

All of which may (or may not!) be vaguely interesting but doesn't really help with the basic problem.

I presume that the battery will not operate the drill at all. In which case, I would leave the battery in the charger for 10 minutes or so, even with the green light showing. Then attempt to discharge the battery using the drill. If this doesn't work, bang the battery pack fairly hard onto a solid bench a few times. The idea is to break up any internal crystals that may have built up within the battery, which may be causing problems. Then try charging again. Admittedly, this is a bit of a desperate measure but without opening up the battery and checking what's going on with a multimeter then the options for revival are limited.

The 'burning plastic' smell is a little curious - the green light on the charger suggests that the charging is complete, implying that there should be little current flowing, yet significant current would be required to 'burn' plastic.

Is it possible to say where the burning smell is coming from? Perhaps the charger itself is faulty, rather than the battery?

 

[AMc]

I'd try Flyfishers approach - 'conditioning' the battery by trickle charging and discharging can bring NiCad batteries back to life.
I bought a very expensive Powerex charger to charge some 1100mAh D cells for a DAB radio which were taking days to charge on another charger. It's conditioning mode revived a bunch of old nicad AAs that I'd written off and had been intending to take to the recycling centre.

B&D do supply spare batteries and chargers http://service.blackanddecker.co.uk/ but when my old 12V drill/driver wouldn't charge the cost of a new battery or charger was more than the cost of the equivalent replacement drill driver and I wasn't convinced which was at fault so I replaced it.

 

[Penners]

How old is 'old' and do you know the battery type e.g. NiCd or Lithium?
limited.

It's a NiCad battery, 1.7 Ampere-hours. I neglected to mention that the drill in question has two batteries, so I've just put the second one into the charger. Same result.

Would it be unusual for two batteries to show the same problem?

I've tried discharging the first battery by running the drill from it - I got a couple of minutes of half-hearted rotation. I then tried it in the charger again - same result.

The second battery doesn't have enough oomph in it to produce any response at all in the drill.

I'm now going to try both batteries in the charger for 10 minutes or so, then see if I can get anything from them in the drill. I'll report back.

Thanks very much for your responses, chaps.

 

[Flyfisher]

Hmm. With one charger not being able to two charge different batteries I'd have some doubt over the charger, though it's hardly conclusive and in the grand scheme of things I'd expect a not-used-for-a-long-time battery to be more likely to fail than a charger.

If you could track down the burning plastic smell to the charger it might provide more evidence.

Alternatively, could you beg, borrow or steal a second suitable charger to see if that makes any difference? (well, maybe not the steal option :wink: ).

I had the same experience as AMc regarding buying spare batteries though. It was cheaper to buy a complete new kit - very annoying! Having said that, the new kit had lithium batteries and these have lasted far longer than the older Nicad ones - though I do use them on a fairly regular basis.

 

[robgil]

I have an old AEG drill, had it for years and years ,it's now got three dud batteries and I cant bring my self to chucking it out.

 

[AMc]

I have an old AEG drill, had it for years and years ,it's now got three dud batteries and I cant bring my self to chucking it out.

It's telling that the dead drill driver is still in its box behind me despite it dying 2 years ago.
I also have a corded B&D drill which has a 6mm masonary bit stuck in it. Drilling in a tight corner I mangled the twist lock chuck and can't release it and the only way to get the chuck off appears to need access to the inside of the jaws. At one point I'd hoped to cannibalise both drills to make one good corded drill but in the end time pressure meant I've bought replacements for both

@penners - I would expect to need several discharge/recharge cycles to get any real performance from the batteries.
I tried to test my charger with a multimeter but I suspect it being "intelligent" meant it wouldn't respond to the meter without the battery and I couldn't easily rig jump leads between the charger and battery.

 

[Penners]

Update:

I put the battery back in the charger, intending to leave it for about 10 minutes. The red (charging) light steadfastly refused to come on - the green (fully charged) still came on.

However, events intervened and I was unable to get back to it for about an hour. I put the battery into the drill and got a good 2 hours of steady work out of it!

I've now put the battery back into the charger. It's still showing the green (fully charged) light. I'll leave it for a couple of hours then remove it from the charger - it'll be interesting to see whether it holds a charge overnight.

So thank you very much, battery experts. It looks as though I may still have a useable old drill.

Inspired by these events, may I ask you one more question? My newer drill - an identical B&D 18V job - is about a year old. When it was new, the batteries would give full power for a fair length of time, then their charge would very quickly drop away to nothing. When they had insufficient power to do any work, I would just run the drill unloaded for a couple of minutes until the chuck virtually stopped rotating, then put the battery in the charger.

Now I find that the loss of power is a much longer, slower business. The drill reaches the point where it has insufficient power to carry out useful work, but the chuck still rotates at reduced speed, getting slower and slower over a long drawn-out period. This goes on for at least fifteen minutes (or until I lose patience and bung it into the charger anyway).

Is there any way that I can "condition" the batteries to get them back to peak performance?

 

[philpjuk100]

If you narrow it down to the batteries it is often far cheaper to prise the battery casing open and source some new cells (ebay works for me!) and solder them in the case glueing the case back together afterwards,my old bosch drill is now over ten years old and on its second set of cells and this laptop is running on a set of lithium/metal cells that came from ebay for less than a fiver! Most batteries are made up from standard size cells.phil.

 

[Penners]

Hmmm - that sounds a bit above my pay-grade, Phil!

 

[Lime]

When my drill's battery failed I didn't want the expense of a new one.
I wasn't impressed with it anyway.
It never had enough life in it to finish any job on the land rover.
(One large hole in aluminium and thick steel plate and that was that, almost.)

However it has another life now.
I found myself faced with having to make repairs to a heavy trailer stuck in a field in the middle of nowhere.
The job required making several large holes through the very thick (¼") steel subframe/chassis.
In a fit of desperation, I took out the dead battery from the drill and soldered a long two-core lead to the drill's interior battery connections.
I put crock clips on the other end of the lead to connect to a car battery.
Bingo! A drill that goes on and on almost forever.
I wouldn't be without it.

 

[philpjuk100]

Yup! done that,I found a drill in the skip at the marina and even though it said it was 9.6 volt it works great on the boats 12 volt battery!phil.

 

[Penners]

Sounds great, Lime, if you have a 12V drill. Unfortunately mine is 18V, so a 12V supply would tend to leave it a bit underpowered, wouldn't it?

 

[Flyfisher]

Update:

I put the battery back in the charger, intending to leave it for about 10 minutes. The red (charging) light steadfastly refused to come on - the green (fully charged) still came on.

However, events intervened and I was unable to get back to it for about an hour. I put the battery into the drill and got a good 2 hours of steady work out of it!

Two hours of steady use sounds pretty good to me, especially from a first cycle after such a long period of no use. It may even improve with another cycle or two. The only thing to be slightly wary of is the charging time. There's clearly something not quite right with the charger so I don't think I'd leave a charging battery completely unattended until I was confident that nothing would seriously overheat - no need to actually sit and stare at it though, just be in the vicinity. :wink:

Inspired by these events, may I ask you one more question? My newer drill - an identical B&D 18V job - is about a year old. When it was new, the batteries would give full power for a fair length of time, then their charge would very quickly drop away to nothing. When they had insufficient power to do any work, I would just run the drill unloaded for a couple of minutes until the chuck virtually stopped rotating, then put the battery in the charger.

Now I find that the loss of power is a much longer, slower business. The drill reaches the point where it has insufficient power to carry out useful work, but the chuck still rotates at reduced speed, getting slower and slower over a long drawn-out period. This goes on for at least fifteen minutes (or until I lose patience and bung it into the charger anyway).

Is there any way that I can "condition" the batteries to get them back to peak performance?

Can you tell if you're actually getting a reduced working time or an extended 'residual' period? If it's an extended 'residual' period with little or no loss in 'high-power' time then it's possible that the battery is close to peak performance anyway. If it's the 'high power' time that is reduced then a few deep cycles might improve things.

If you don't have a compatible 18v torch to discharge the battery pack then car light bulbs can be used instead of actually working the drill (if you're handy with a bit of wiring and preferably a soldering iron).

If you narrow it down to the batteries it is often far cheaper to prise the battery casing open and source some new cells (ebay works for me!) and solder them in the case glueing the case back together afterwards,my old bosch drill is now over ten years old and on its second set of cells and this laptop is running on a set of lithium/metal cells that came from ebay for less than a fiver! Most batteries are made up from standard size cells.phil.

I'd agree that DIY repairs to battery packs can be very cost-effective but do be very, very careful when soldering directly onto batteries as overheating them is not to be recommended! Some cells have solder tags already welded to their terminals and are ideal for such applications.

Perverse as it may seem, it is often safer to solder such cells with a powerful (high wattage) soldering iron rather than the sort of iron more suited to general wiring or circuit boards. This is because the cells have a large mass of metal that will draw heat away from the iron; a small iron will not be able to locally heat the cell terminal enough to melt the solder joint. The temptation is then to leave the iron in contact with the cell for a long period of time until the solder eventually melts, causing the entire cell to get very hot - and possibly explode :shock: - whereas a sufficiently powerful iron will quickly cause sufficient local heating to make the solder-joint before the rest of the battery heats up.

 

[Lime]

Sounds great, Lime, if you have a 12V drill. Unfortunately mine is 18V, so a 12V supply would tend to leave it a bit underpowered, wouldn't it?

I failed to mention that it was a 9 volt drill and works a treat on 12 volts!
(and, no it doesn't overheat)

 

[philpjuk100]

If you narrow it down to the batteries it is often far cheaper to prise the battery casing open and source some new cells (ebay works for me!) and solder them in the case glueing the case back together afterwards,my old bosch drill is now over ten years old and on its second set of cells and this laptop is running on a set of lithium/metal cells that came from ebay for less than a fiver! Most batteries are made up from standard size cells.phil.

I'd agree that DIY repairs to battery packs can be very cost-effective but do be very, very careful when soldering directly onto batteries as overheating them is not to be recommended! Some cells have solder tags already welded to their terminals and are ideal for such applications.

.

Yes the cells that i purchased have solder tags fitted but if you are using interconnecting cable it has to be able to carry the current (or double up some five amp) the drill not being continuously rated.the cases may be a little "tight" for cells with solder tags but can usually be "dremmeled" a bit.Used to service metrology instruments and replaced customers batteries that would not hold a charge and used the better cells from their old batteries to build replacement batteries for "hire" instruments! phil.

 

[philpjuk100]

Sounds great, Lime, if you have a 12V drill. Unfortunately mine is 18V, so a 12V supply would tend to leave it a bit underpowered, wouldn't it?

Im sure it would still work quite well,even though the no load voltage may be 18 on load it will "droop" considerably when giving it some "welly" if you wire it to a car battery with some sturdy cable should be ok.