Solar battery charger advice

victorgte · 7th January 2021, 09:40

I’m looking at Solar Battery maintainers to top up idle vehicles.
I’m staggered by the wide range of types and suppliers. Is there a simple formula to use and decide which one to buy? Obviously we are talking about a 12v car battery that needs maintaining.
One point that cropped up on one advert was that the cigarette lighter plug in type will not work if the ignition is off and the cigarette lighter is then no longer live. True?
Recommendations welcome.

SD1too · 7th January 2021, 13:19

Quote:

Originally Posted by victorgte

One point that cropped up ... was that the cigarette lighter plug-in type will not work if the ignition is off and the cigarette lighter is then no longer live. True?

That depends upon how the car manufacturer decided to wire it. In the case of the 75/ZT I believe that this was changed at some point during production but it's easy to find out!

The most important thing to bear in mind is that only cars which are used frequently for long journeys will have their batteries at a full state of charge. For most of us, the reality of life is that the battery will be partially discharged. This is particularly true of the 75/ZT whose communication systems draw a constant current from the battery at all times, and this is quite significant each time the car is unlocked.

Solar powered devices are not very good at charging a battery because this requires a current of up to 3 amps. They may however be able to maintain a fully charged battery because that process demands very little current. Their output does of course depend upon available light and that is in short supply in the winter when you'll need the maintenance ability the most.

Simon

COLVERT · 9th February 2021, 22:16

There are inexpensive solar battery chargers for cars that can work in low light.---However, in all cases as Simon says above, they are really only to keep fully charged batteries topped up. The idea is to supply any low internal discharge of the battery and any current used by the system in sleep mode.---Any charge above those requirements is absorbed by the battery without causing any harm.

7th January 2021, 09:40	#1
victorgte I really should get out more....... MGTF, MGZT, Range Rover Join Date: Sep 2013 Location: Cheltenham Posts: 2,802 Thanks: 395 Thanked 633 Times in 446 Posts	Solar battery charger advice I’m looking at Solar Battery maintainers to top up idle vehicles. I’m staggered by the wide range of types and suppliers. Is there a simple formula to use and decide which one to buy? Obviously we are talking about a 12v car battery that needs maintaining. One point that cropped up on one advert was that the cigarette lighter plug in type will not work if the ignition is off and the cigarette lighter is then no longer live. True? Recommendations welcome. __________________ MG TF 135, MG ZT, Range Rover P38

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9th February 2021, 22:16	#3
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	There are inexpensive solar battery chargers for cars that can work in low light.---However, in all cases as Simon says above, they are really only to keep fully charged batteries topped up. The idea is to supply any low internal discharge of the battery and any current used by the system in sleep mode.---Any charge above those requirements is absorbed by the battery without causing any harm.