Car Battery

[Stinsy]

Thank you for your replies. We removed the battery from the car and connected it up and has been charging since around 4pm - 10pm. The battery charger has a pointer and the scale is 0 - 2 - 4 - 6. The pointer was half way between 0 - 2 and it looked pretty much the same when I switched it off, if anything the pointer may have been very slightly below the half way mark between 0 - 2. I know the charger is working because new crocodile clips were put on it and it was tested by charging up an old battery. I have switched it off and unplugged the charger for the night and will put it back on charge tomorrow. Would you have expected the pointer to have moved in 6 hours? The charger is 4amp output 12v, input 220/250v 50Hz.

The maths is simple! You have a 4A charger and a 110Ah battery it will take 27hrs to charge. I’d just leave it on charge for a few days. Check with a multimeter across the battery periodically, it should show something between 13.8-14.4V while charging.

However if the battery has been drained to dead a few times, particularly if has been in the drained state for an extended period then you can only expect a temporary reprieve at best. At worst you’re flogging a dead horse.

[JR]

I switched the charger off overnight. I switched the charger back on, on Monday and the pointer soon went to 0. On Monday the battery was put back on the car and it started up first time, had a drive round the block then left the car running on the driveway for a short while. I shall have to make sure I use the car more and keep a check on the battery and if necessary, I shall have to buy a new one. Thanks for all your help.

[JR]

So here we are again, hardly using the car and on Thursday the car would not start. I have shopped around for a new battery (prices range from £48 - £110) and as I speak my battery is on charge. I am thinking of buying a solar trickle charger and try it on my old battery to see if it helps - I have seen one in Halfords for £15 and it plugs into the cigarette lighter. (I have tested the cigarette lighter with a decorative Christmas tree and it does work). If the solar trickle charger doesnt help then I will buy a new battery and then I think the solar trickle charger would be a good investment to keep the new battery charged. Halfords have a solar trickle charger for £35 which includes an OBD power cable. What puzzles me is how can a gadget be plugged into the cigarette lighter and charge the car battery? Any help would be much appreciated.

PS. When I first found my battery flat, my local garage kept my car overnight and fully charged the battery for me and it was all good until I used the car less and less.

[nowty]

Halfords have a solar trickle charger for £35 which includes an OBD power cable. What puzzles me is how can a gadget be plugged into the cigarette lighter and charge the car battery? Any help would be much appreciated.

Because the cigarette lighter is directly connected to the battery (via a fuse), so the Solar trickle charger will simply run at a slightly higher voltage and force some leccy back into the battery.

Very similar to using Jump Leads and connecting your battery directly to another cars battery, but in a much smaller way.

[JR]

Thanks for your explanation. Have just spoke to Halfords as I wondered what the size was of the solar panel. On the dearer one the size is 2.4w and on the one for £15 the solar panel is 1.5w. I asked because a link was provided on one of the posts and the panel was 10w. So not sure how effective a solar trickle charger with a 1.5w panel will be.

[Mr Gus]

Not all vehicles have live connection via the fag socket when the key is removed.
You will need to research this in relation to your vehicle.

[Countrypaul]

How long do you leave your car unused and does it have anything runing whilst you do, eg. clock, alarm, temperature sensors?

If you leave it for say 100 days, 24 hrs/day means 2400 hours use. If the battery is 48 Ahr then it could only supply 10mA (48/2400) before it is flat. 10mA x 12V would be 0.12W. How much the battery would use through self discharge I have no idea.

How much average daily charge could you expect to put into a car battery from say a 10W solar panel in your location over winter?

Obviously use your own figures for the above calculations, but you should be able to get a better idea of what size panel you might need. Someone on here might be able to give you an idea of the self discharge a car battery consumes.

[Stinsy]

For these cigarette chargers to work they need the socket to be always-on. Most aren't. Sometimes you can move a fuse and make it always-on, otherwise you might need to tap into an always-on supply.

However you don't get much power from solar chargers when they are perfectly orientated, in summer. In winter these little solar panels are useless. My suggestion would be to connect the car to a mains "battery maintainer" or trickle-charger if it isn't used for weeks at a time. Alternatively if the car is used for a few short trips a week and connecting/disconnecting a trickle-charger each time would be inconvenient, I'd suggest a 20-30A charger is used for a few hours once a month.

[Stinsy]

Thanks for your explanation. Have just spoke to Halfords as I wondered what the size was of the solar panel. On the dearer one the size is 2.4w and on the one for £15 the solar panel is 1.5w. I asked because a link was provided on one of the posts and the panel was 10w. So not sure how effective a solar trickle charger with a 1.5w panel will be.

Just seen this: neither 1.5W nor 2.4W will do anything at all!

They are chocolate teapots!

[JR]

Thank you for your replies. My car is a 2008 1242cc Ford Zetec and I have had it from new, (done under 24,000 miles) a new battery on in 2017. I have a 4 amp charger and it is charging now, had it on charge for 4 hours yesterday and 4 hours last Thursday.

Used car on 11 Oct and went about a mile, 12 Oct went about 8 miles and 25 Oct under 5 miles. Try to start it on 4 Nov and it wouldnt start. I thought a solar trickle charger would keep the battery topped up and I have no idea about sizes of solar panels and what they will achieve.

Halfords are saving me the solar trickle charger as they have very few left. If it is unsuitable after 28 days I can return it and get my money back. But it seems that with a 1.5 or 2.4 watt panel, it wont do anything but I didnt realise that and thanks for telling me.

I have no idea how much average daily charge I could expect to put into a car battery from a 10 watt solar panel or any sized solar panel ..... Sounds like I need a bigger wattage panel and to spend more money. Perhaps I might as well just buy a new battery and not bother with the solar trickle charger .....