Portable Battery Chargers

[SHAKTER]

I have a car that rarely gets used and battery is regularly going flat. I either buy a new battery when it's totally knackered or jump the car the traditional way (total hassle).

Anyway I came across these portable chargers (http://www.amazon.co.uk/dp/B00YDZR3ZI/?tag=amazon0e9db-21)

Does anyone know if they're any good? I don't intend to use regularly but on the odd occasion I take the car out, it would be nice knowing there is an emergency boost of power in case the battery dies while I'm out.

I've bought a Master Disconnect Switch that I hope will prove to be a more long-term solution. But again, any views appreciated!

 

[The _Don]

Disconnect the battery whilst not in use?

 

[SHAKTER]

Disconnect the battery whilst not in use?

Yes - or that! How much does a battery lose through standard discharge when disconnected (if anything)?

 

[OneForTheRoad]

Buy a big solar charger and leave it on the dash . They plug into the fag lighter socket.

 

[whitenemesis]

How about a maintenance/trickle charger? The Ctek is good. Leave charging, battery in perfect condition whenever you need it..

 

[SHAKTER]

Buy a big solar charger and leave it on the dash . They plug into the fag lighter socket.

The car is parked in an underground park so am not sure how effective this would be.

 

[SHAKTER]

How about a maintenance/trickle charger? The Ctek is good. Leave charging, battery in perfect condition whenever you need it..

I have looked into these but there is no access to a power supply where the car is kept unfortunately (underground car park).

 

[whitenemesis]

I think I would remove the battery and leave on charge at home?

 

[190]

.....How much does a battery lose through standard discharge when disconnected (if anything)?

Depends on battery type and age and storage temperature.

A 70 AH wet cell battery will lose at least 2 or 3 amp hours a week while AGM's which have very low internal self discharge should be below 1 amp hour per week. High storage temperatures increase the self discharge rate and a battery towards the end of it's life may have much higher rates.

I only use my C180K which has a wet cell 2 consecutive days per week so I give it a couple of hours top up on the charger in between as much because the "see you to the door lights" and the going to sleep mean that you can never end a journey with a truly fully charged battery.

 

[bob6600]

I asked about the same product a couple of days ago, some info here

http://www.mbclub.co.uk/forums/ot-off-topic-forums/202120-these-any-good-just-gimmick.html

 

[kungfupanda]

I got this one from Costco.

PowerStation 12 Volt Portable Jumpstart - Model PSX3EU | Costco UK -

Had it for my Porsche 996 C4S and it started it every time. Also got a light and a tyre compressor too.

 

[OneForTheRoad]

solar ones wouldn't be any good if not in daylight , strangely enough .

 

[190]

We talked about solar panel chargers recently on another thread. My experience was that a small one was inadequate even in full sunshine and in the winter it was utterly hopeless. It was so bad that I had to remove the led indicator circuit that flashed when the panel was charging as it was consuming too much of the available power !

I toyed with the idea of getting a larger panel and mounting it on my south facing roof with the wires run down into the garage. This was some years ago and at that time a waterproof panel was too expensive to be worth the bother.

 

[SHAKTER]

Thanks all I took the car out for a good 2hr drive today so hopefully that's charged the battery up sufficiently (it was fried when I first started the car - needed a jump).

 

[190]

If the battery was truly flat a 2 hour drive will have put a substantial charge into it and it will be enough to start the car next time but it won't be 100% fully charged. To charge a 70Ah battery in 2 hours the charge rate would need to be in excess of 40 amps which the alternator can't deliver. Not because it isn't rated at 40 Amps or above, it will be, but it's also limited to a maximum safe voltage which is not high enough to drive 40 amps through the battery. Even if it were possible a charge rate of 40 amps is too high and will damage the battery.

Putting just enough charge in so that it starts the car is a recipe for early battery failure through sulphation. The only way to get maximum life out of a battery is to keep it fully charged at all times and inevitably that means using a charger on infrequently used vehicles.

 

[guydewdney]

even a long run wont bring a battery to full charge. ive done lots of research into chargers and charging. you need something like the ctek. there must be power, as theres lights! is it a private car park? could you talk to the owner and get a small 1 amp fused spur put in off the lighting circuit? then connect the trickle charger to that.

 

[SHAKTER]

If the battery was truly flat a 2 hour drive will have put a substantial charge into it and it will be enough to start the car next time but it won't be 100% fully charged. To charge a 70Ah battery in 2 hours the charge rate would need to be in excess of 40 amps which the alternator can't deliver. Not because it isn't rated at 40 Amps or above, it will be, but it's also limited to a maximum safe voltage which is not high enough to drive 40 amps through the battery. Even if it were possible a charge rate of 40 amps is too high and will damage the battery. Putting just enough charge in so that it starts the car is a recipe for early battery failure through sulphation. The only way to get maximum life out of a battery is to keep it fully charged at all times and inevitably that means using a charger on infrequently used vehicles.

Or disconnecting it?

 

[Aussie Baz]

Don't muck around, buy yourself a Ctek smart charger as Gel batterys today require a smart charger to do the correct job..

 

[190]

Or disconnecting it?

That would obviously eliminate the discharge due to the cars quiescent current of 30 - 50mA or what ever it is. But it wouldn't eliminate the batteries own internal discharge of 2 - 3 amp hours per week for a wet cell battery. An AGM battery would be very much better though. A disconnected AGM would lose less than 1 amp hour per week and could be safely left for for several months.

I have an AGM type battery on my 1979 motorcycle which of course is very simple electrically and therefore has zero quiescent current. Compared to an old wet cell the AGM has been a revelation when it comes to holding it's charge.

 

[vito-dork]

ok, this what i did in the same situation a few years back and it worked for me

i found a location for another battery
and piggy backed them
buy 2 new ones and try to connect them close together
you may have to have some leads made up
its not difficult

or
lithium batterys (expensive)
but i do like that charger