OT Halfords Don't you just love 'em

This is the scenario Few days ago we had a power cut - went on for quite a while so decided to use gas stove in camper van by the house to brew up. Some time later somebody -let's not play the blame game here- well OK it was SWMBO, returned kettle to van, but didn't quite close the sliding door properly. Result this morning one totally flat battery.

Not to worry, get out Halfords Automatic Battery Charger, connect it up, switch it on and - nothing. Slight hum tells me power is on. There's a little orange light to tell you its charging and a little green light to tell you when its gone into maintenance mode. There's EVEN a little red light to tell you you've connected it the wrong way round - and blown the fuse. There's a switch to choose between normal battery and sealed battery and a switch for Bike or Other vehicle battery. What a clever charger.

Dead as the proverbial dodo. Not a single light on. Perhaps it's gone to meet it's maker. Auxiliary battery is right next to vehicle battery, so quick check, and connect it to that - and yes it works. Little orange light on - charging - soon followed by little green light - maintenance mode. Back to vehicle battery - nothing. Get out meter, no voltage. Rig up as ammeter, no current. Get out test lamp. Connect "earth" lead to + on vehicle battery and point to + on Aux battery and light comes on. So vehicle battery is not high resistance/open circuit, so why the f*** won't it charge.

Can't get other vehicle alongside to use jump leads, only way would be to tow out camper van onto road to get near it to use leads. Can't use aux battery to start - it would destroy it.

Solution - put a jump lead from + on aux batt to + on vehicle batt to see what happens. Just touched for an instant and charger which was still connected, burst into life.

WHAT F****** USE IS A BATTERY CHARGER THAT WON'T CHARGE A TOTALLY FLAT BATTERY?

Reply to
hugh
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It's the type of battery, most wet cells cannot be brought back from dead, they need a low voltage cut off & if the charger/usage circuit doesnt have one they die screaming mate. I think (going back in time) you need a switch mode charger for a very dead cell battery?

Again, an expert will prove me wrong!

-- Subaru WRX (Annabel)

Landrover 110 County Station Wagon (Tyson)

'"Say hello to my little friend"

Reply to
Nige

they need a low voltage cut

think (going back in time)

Nicads and Nimh are also well, damp, internally. and they can be resuscitated. Lead-acids can if they aren't left "Dodo dead" for long, they can be brought back, but it takes a great deal of care. If lead acids cells are left dead, the cell "sulphates" and it will not be the same again.

Steve

Reply to
steve Taylor

I can tell you feel better after getting that off your chest :)

I wonder if the flat battery was drawing too much from the charger and it had some sort of overload protection? Supplementing it with the other battery might have been enough for it to decide to play game?

Reply to
wayne

I have the same charger and one of those gel cell starter/aux/tyrepump thingies for emergencies. They both work the same as they sense the battery terminals for polarity, this is to protect them from wrong polarity or dead shorts. As such they will not drive a load off the clamps that has no voltage on it, bit of a b***** when I needed to run my 12V diesel pump and couldn't get a vehicle near enough.

Easiest solution is to connect a second battery in parallel to the dead one for a few seconds to fool the charger.

AJH

Reply to
AJH

I have the same charger and can tell you how this works...

If the battery has been left on a very low load for long enough to totally f*ck it, the Halfords charger will charge it, but you need to leave it connected for about a week (no really).

Alternatively, strap it in the aux position of a 101 and run it for 10 minutes (an electrical 'kick up the arse'). Then it will charge OK.

Reply to
Tim Hobbs

If it's a constant voltage battery charger, none at all. Modern battery chargers are no use at all in circumstances like these (and not a lot of use the rest of the time either) To ressurect batteries in that manner you require a constant current battery charger, and a lot of mucking about. While it is then technically possible to ressurect the battery, it may not be possible, and the battery may not be any good at all afterwards

Reply to
Alex

On or around Thu, 01 Sep 2005 23:45:22 +0100, steve Taylor enlightened us thusly:

they need a low voltage cut

think (going back in time)

yeah, but that's not "flat overnight", that's dead for months.

sounds like the chattery barger is a heap of s**te. I have a nice fattish Absaar one which just supplies power to the battery.

Reply to
Austin Shackles

Do you ever wish you hadn't binned something!

Lee D

Reply to
Lee_D

Never happens, the problem is just finding the bit I'd saved "just in case" amongst the piles of other debris I've saved. After an hour or so looking for a bit I know I have somewhere I have to go down the shop and buy a new one!

AJH

Reply to
AJH

they need a low voltage cut

I think (going back in time)

I've got one of the Haflrauds auto chargers. It won't start charging a completely dead battery, somthing to do with current sensors for the maintenance setting I think. I put a cheap 4 amp charger on to kick a dead battery in to life before connecting the Halfrauds special. Or put another battery in parallel to the dead 'un.

Reply to
Colonel Tupperware

On or around Fri, 02 Sep 2005 09:07:55 GMT, Alex enlightened us thusly:

I still thought that the problematic resuscitation of a dead battery was one that's been killed and left dead, not one that has just been run flat yesterday.

Mind, alternators in vehicles won't always recharge a completely dead one.

Reply to
Austin Shackles

In news: snipped-for-privacy@4ax.com, Austin Shackles blithered:

That's because alternators are not usually self exciting so must have a tad of current to start up. Dynamos on the other hand usually are self exciting because of residual magnetic field in the field armature.

Reply to
GbH

On or around Sat, 3 Sep 2005 21:50:28 +0100, "GbH" enlightened us thusly:

I knew that, wondered if anyone else did :-)

Reply to
Austin Shackles

But sometimes a dynamo can require a niad pulse convertor to excite the flux field in the star-point.

Alex

Reply to
Alex

On or around Sat, 03 Sep 2005 23:12:53 GMT, Alex enlightened us thusly:

also, the dymano can need converting to the other polarity if it's wrong. hmmm. just occured to me to wonder, do alternators have polarity? I realise the electronic regulator bit does, but the alternator itself shouldn't mind, so either a rebuilt regulator with the components arse-about-face or an external regulator like some alternators have should produce results.

Reply to
Austin Shackles

But I was under the impression that was only required if you didn't have the latest tri-lithium power convertor rigged up to the output terminals of the flux capacitor bank to ensure a tri-cyclic waveform output? :-) Badger.

Reply to
Badger

In news: snipped-for-privacy@4ax.com, Austin Shackles blithered:

IIRC the reason why alternators are made +ve earth is so the diode pack can be grounded to keep the poor bugger cool. I think you may run into a problemo just reversing the battery polarity, your starter motor is going to do its best to crank t'engine back'ards, which ain't going to happen with a bendix gear but could with a pre-engaged breed. I suggest your best bet would be to insulate (electrically) the alternator and connect it as a -ve earth. then you've only one bit of kit to bugger about with, all else remains unchanged. Except your charge warning light which is going to get awfully confused.

Reply to
GbH

In news:dfecfb$kk5$ snipped-for-privacy@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com, Badger blithered:

Just can't get the plutonium quality these days.

Reply to
GbH

The starter will work perfectly with the polarity reversed, it would only be a problem if it were a permanent magnet motor, but it's not. The a winding provides the magnetic field, and this is also reversed so the direction of rotation will be the same.

If the days around the transition from + to - earth many people swapped the polarity so they could use -ve radios etc.. Just flash the dynamo to re-set the residual magnetism and you were away.

Regards Jeff

Reply to
Jeff

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