What's the consensus of opinion on whether it's OK to leave a car battery on continuous (float) charge? Wikipedia says 'batteries kept on continuous float charge will have corrosion in the electrodes and result in premature failure' but other sites seem to recommend the practice when the vehicle is in infrequent use.
Richard.
Float is fine, but check that the voltage is spot-on for floating that exact battery technology and also that the float voltage is temperature compensated. Most "float" chargers sold are just normal chargers with a ballast resistor to limit current. Fine for leaving on accidentally for a few days, but they aren't a real float charger.
Generally for single car batteries that are stored in a shed nearby, protect from frost, charge them on a decent auto charge once a month and ignore them otherwise.
On the subject of batteries, whats the best way of rejuvinating a sulphated dead battery, whack it with rectified mains with a bulb for a load ?
We used to do similar to that for blowing crap off crt guns.
Fully charge it at the ten hour rate, take it off charge for a couple of days and repeat. Sometimes helps, but not a lot.
You used to be able to buy pills to drop into the electrolyte (EDTA = ethalene diamine tetra acetic acid), which helped a bit.
If they were *really* bad and refused to take a charge any other way, we used to whack 'em across a heavy duty 24V start/ charge unit on flat out for a minute or two, (About 100 amps...) then charge as normal. That often got another week or two of use out of them. It was kill or cure, though.
Otherwise, flog 'em for scrap and buy new ones, which often have more capacity in a smaller case, anyway.
There's an American unit by Pulse tech, which claims to do the job.
Richard Russell laid this down on his screen :
I have three batteries kept almost permanently on a float charge and I have done this for many years without any problems. Just make sure the float charger outputs an accurate float voltage.
I bought a couple of the Lidl chargers on sale a few weeks ago - judging by the tests I carried out, these charge fully, then fall back to an perfectly accurate float charge voltage.
I missed the Lidl offer. Any idea whether these are any good:
Richard (G4BAU).
If you fancy your hand at a bit of electronics, there are plenty of desulfator [sic] circuits around. Essentially they work by sending short, high voltage pulses into the battery. The theory is that the high voltage does some magic (technical term) to the plates which removes some/all of the insultaing material that builds up and prevents them from retaining a charge. I haven't tried one, myself but I'd be interested in knowing if this is just hokum or if there's some truth in the claims.
geoff used his keyboard to write :
Pulse charging - a series of pulses of high current is supposed to help shift the sulphate.
on 06/02/2011, Richard Russell supposed :
I would suggest waiting for one of the Aldi/Lidl ones to come back on offer - much better spec., water resistant and you could almost buy three for the B&D price.
The only source I have of 100A is another battery
Just want to put an old battery on an old car to flog it
Yeah - seems to do what I typed above
which is why I typed it
bit of flex and a 10A bridge rectifier it is, then
couple
I bought one of the pulser units a couple of years ago to revive the deep cycle batteries in an electric 'factory truck'. I was rather skeptical as the truck had been idle/unused for a year. :Left it on for a few days then did a discharge test (roll of fence wire wrapped round an asbestos flue pipe as a load) Amazngly 90% of full capacity on a 10 hour rate test..
AWEM
A sulphated battery will have such a high internal resistance, you'll not 'whack' high current into it with any charger. What you do need is fairly high voltage - 30 or so - to speed up the chemical process. An old basic charger with no regulation is likely to achieve this rather than a modern one, unless the modern one is designed to pulse charge.
Or check out the one that CostCo and possibly Makro have that is very similar.
Well, our 24V jump start/ rapid charge unit was high enough voltage to give us an indicated 60 rising to 100 amps going into a 12 volt battery. Maximum one or two minutes, before the electrloyte started either boiling or gassing. As I said, kill or cure, but we were doing it for a fleet of rather tired old coaches, which *had* to be out on the road
*now*. This charger would start a vehicle with completely flat batteries within seconds of being connected, too.The 22 to 24 volt bit is what the modern pulse power units do, except they don't ouptut that much current, and they're controlled by a microprocessor and not a fitter reading a meter. They also take rather longer to do the job.
It wasn't sulphated, then.
We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember John Williamson saying something like:
Or, for fraction of the price...
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