Battery Conditioners - any good?

Hi All,

does anyone use one of those "battery conditioners"? I'm thinking of the little solar powered things that either plug into the lighter socket, or in some cases will connect to the battery direct. I'm not convinced myself as most don't have much of an output.

Asking for a friend who's having problems with his battery draining slowly on his lightly used car. It's not parked near enough the house to plug a mains charger into it, and removing and putting the battery on and taking it into the house to charge isn't really that convenient. Car gets used maybe once a week at the moment. Was thinking one of these could help, but I think they're probably snake- oily type things.

Am I right, or will one help?

cheers

Reply to
Mike P
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As a very crude estimate, a solar panel will deliver nominally 16v at

200mA per square foot when in full UK sunlight. So ideal for maintaining the charge for a lead-acid 12v battery feeding something like a motorway emergency phone (such as frequently seen on the continent).

If the car is lightly used but the battery is losing charge, first thing to check is for continuous loads. The remote control locking receiver might take a few mA, but otherwise the load should be virtually zero, when the vehicle is switched off and locked.

So the issue is whether the actual use will support the loss incurred in starting. If running properly, the car should start within 5 seconds of cranking - I would expect significantly less. Assume this is 500A - so the charge taken is 2500 amp-seconds. When running, the alternator should be able to charge at 25A, so 100 seconds of running should replenish the battery. Even if the charge efficiency is only 10% that means 1000 seconds, or less than 15 minutes driving.

Years a dynamo feeding every available electrical load (lighs, heated rear window, fan, foglights, etc.) and with the engine running at tickover would have struggled to meet that demand, so short-run city commuting might then have been a problem; but alternators are designed to meet that demand.

By contrast, a solar panel might replenish this loss in 12,500 seconds, or about 4 hours, before accounting for the inefficiency of the charging process.

So probably the solution is to get the car working properly, no electrical leaks, and good starting.

Reply to
Graham J

Of course you are. They are too small to be of use. I have one he can have free if he wants. It was useless s**te.

The ones on the boat worked well, they are 4ft x 2 ft, two of them knocking out 150W and they need a sophisticated battery charger unit to avoid overcharging the batteries. Cost about £1000, a cheap one foot by one foot panel doesn't stand a chance.

Reply to
Steve Firth

One which is the size of the windscreen will probably be ok on the average winter's day.

Reply to
Dave Plowman (News)

It's a mutual acquaintances 3.0 24V Carlton that's having the problem.. leaves it a week, it struggles to start. Battery was new in December..

Thanks for the confirmation that they are bollocks. I don't really want to start messing with his car electrics, but I don't want to see him stiffed by a garage again..

Reply to
Mike P

The best solution is one of those electronic float chargers that Lidl/Aldi sell from time to time. Which does rely on the car being parked on the owner's premises. I can't recall if that is possible in this case.

Reply to
Steve Firth
[...]

Is the new battery of suitable capacity for such a large engine?

If the vehicle is used once a week, could the length of journey be increased? If so, using it once a week for a reasonable run (IOW not in heavy traffic) for 10 miles should keep the battery charged. If it doesn't, there is a fault either with the charging system, or something is draining the battery. Otherwise, could the engine be left running for

15 minutes at the end of a run?

When it struggles to start, is it cranking at normal speed, but turning over for a long time without firing? Perhaps the problem with non- starting is not battery related, but extended cranking is discharging the battery.

Anything with an alternator should cope with infrequent short journeys. In the winter, my car sometimes only gets used once a week for a three mile trip to the supermarket and back. The battery is 10 years old, yet it always starts OK.

Chris

Reply to
Chris Whelan
[...]

The car in question should indeed have a low quiescent current, but note that some modern cars have a high enough drain to reduce a well-charged battery to a state of charge that will not start the car if left for two weeks. VAG cars with a peripheral alarm and keyless entry are particularly bad in this respect.

Chris

Reply to
Chris Whelan

It's worth checking the actual car. One that old could well have had things added - and some aftermarket alarms and ICE are particularly power hungry at 'rest'. And some of the original equipment too. On my SD1, the original factory central locking took 20mA just sitting there. ;-)

Reply to
Dave Plowman (News)

Forget it. Money down the drain.

Reply to
Sam

The minimum size of panel you need is 15W. Any less is a waste of time, as most of the time it will be delivering a fraction of its potential.

Reply to
Grimly Curmudgeon

Larger maybe better if you look at the figures.

15W at 12V is 1.25 amps which is not much when you consider a small trickle charger is 2-2.5 amps. Solar panels are not very efficient at making consistent power all day due to weather factors.(as mentioned).

Using a larger realistic 40W panel (3,3A) then becomes uneconomical cost wise. (4x the price of a 15W unit)

You may be better off with a small mains powered charging unit.

Reply to
Rob
[...]

ISTR the OP said that wasn't possible due to the location of the vehicle WRT the house.

Chris

Reply to
Chris Whelan

fair enough wasn't in the post to which I replied.

Reply to
Rob

Having saved a new battery from the scrap for four years, I speak from experience. A 15W amorphous silicon panel, mounted on the inside of the south-facing windscreen, kept the battery topped up all year round. Charging current varied from a miserable 30 to 50mA on claggy winter days, to 170/200mA on bright days. I unrecall what the peak sunny charge was. This was on a vehicle with no parasitic loads, save an LED clock. If I were doing it longer term on a modern car, I'd think seriously about a quick-disconnect battery switch.

Reply to
Grimly Curmudgeon

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