Hi
I have a B&Q 4:8v cordless screwdriver which is identical to this;
Can I get an 'in car' charger for it? Presumably I could pop into Maplins & get the right plug and a charger giving out 4:8v? Is it as simple as that?
Just buy a mains inverter. Then you can run all the wall warts you like off it.
Christian.
Depends.
The batteries in these beasts are really intended to be charged with a constant current, not a constant voltage. Of course, some just charge them constant voltage but this can be dangerous and shorten the battery life.
What you need to know is if there is any circuitry in the charger (or possibly the screwdriver) that provides a constant current. Can you look in side and take a photo? If so, Email to me on at the address on my website.
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73 BrianBuy a 12V dc to 240V ac power inerter (small one fits your car cigarrete lighter), and plug your home screwdriver charger into it.
How does it normally charge - the pic doesn't show. Do you remove the battery and put into a charger? And has that charger got a separate wall wart? As it really depends where the actual charging electronics are.
If, for example, it has a wall wart which outputs something like 9 volt DC unregulated a car supply will probably be ok. But if the charging circuit is in the wall wart it won't.
You have a charger that plugs into the drill. I wish it had a removeable battery, I'd buy a spare & solve the problem.
Sounds perfect. Where would I get one? Maplins?
What else would an inverter cope with? Could I run power tools with a bigger one?
Dave,
Splash out and buy this :- Bosch GSR10 cordless screwdriver. Good price from Screwfix and a fabulos tool with a fair bit of grunt. Screwfix part no is
61739. it will seem expensive at £79.99 + vat, but is it a very good piece of kit and all my electricains have been bought them.Regards
Steve
Shop around. TLC are reasonable.
You can, but don't expect the car battery to last long. 3 amps at 240 volts is 60 at 12. Ish.
I chesked out
I checked out TLC and they have just plain inverters - but the cheapest is aroud £23.
I'd only expect to pay a £5 -£10 for an in car charger for a phone or whatever. Is an inverter overkill?
It is, but unless a proper charger is available or you can make one it's likely to be the cheapest way.
Might be cheaper still to buy a drill that can be charged off the car battery.
In message , "Dave Plowman (News)" writes
Car Accessory shops and caravan/camping places sell them as well.
Might be a better idea to stump up the extra for a new driver with 2 batteries?
And most drills like this have the charging electronics built in to the charging base, so look out for one that has a 12 volt wall wart - you could then substitute this with the car battery.
Does the drill have a standard DC socket? If so why not make a lead.
Just use a cigar lighter plug, DC power plug lead and a power resistor to drop the voltage and regulate the current.
These drill usually have 1Ah batts, so a lead with a 3 ohm resistor will drop ~9v at 300mA, for a charge time of 3-4 hours.
You need to find out the polarity of the mains charger plug, this can be done with a cheap DMM.
Also a word of warning, get a 10W power resistor and superglue it to a plate of ali or small heatsink. Without this they get very very hot!
With a cigar plug with screw terminals and a ceramic terminal block or two, you won't need to do any soldering. Add a 12v LED or small bulb across the resistor to remind you it's on charge.
Don't leave it on charge for longer than needed, as the life of the batts will be shortened.
If this is too much hassle just get a cheap one that takes rechargable AAs and use as a backup...
cheers, Pete.
You mean 30 ohm!!! 3 ohm will blow up either itself or the driver or both.
Apart from that, there is no means to terminate the charge when the driver is charged up. This scheme will keep pushing 300 ma into the driver as long as connected, which won't do it any good.
It's easy enough to design a simple charger using an IC and very few additional components, and I daresay a search for "battery charger circuit" will turn up loads. Here's one
Oops, well spotted!
I daresay the mains charger works like that, the one for my driver does.
cheers, Pete.
And other low power mains things like other chargers. Very useful box to have.
They do have them. I'd look for one with sine output. I have a 300W invertor in the car, one plugin 4 x AA battery charger will only charge one pair of batteries when on the invertor but is fine on real mains. The phone charger is fine.
Yes but as Mr Plowman says the DC side currents start to get hefty and you'll have to wire it direct to your car battery with thick cable. You also run the real risk of flattening that battery leading to a few problems like not being able to start your car a severly shortening the vehicle batteries life. If going this route fit a seperate "deep discharge" leisure battery and split charge system. Decent power output invertors aren't cheap either.
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