Car solar panel battery conditioners / chargers

Honest John Back Room » Motoring discussion
What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks
View Threaded
Sat 14 Jan 2023 14:11
Car solar panel battery conditioners / chargers - Engineer Andy

I've been thinking about buying a portable solar panel car battery charger, given my car mostly sits around for long periods and the cost (fitted) of car batteries is now around the £150 - £200 mark, especially as my car seems to go through batteries around every 4-5 years, whatever the usage (I've never detected any electrical issues, including lights on in the boot, etc).

I did a very coursory web search, and came across the usual never-heard-of, seemingly shed-built cheap Chinese tat, as well as seemingly better quality units, including one(s) sold with the AA brand (though similar to the Halfords one) for between £25 - £40.

Has anyone used them before? Are they any good, especially on older cars like my 17yo Mazda3, where I'm unsure whether connecting the unit to anything other than directly to the battery would be wise - with the AA one, you have the option of also connecting the unit to the OBD port or the cigar lighter, though again I'm not sure if that would work (it supposedly needs a 'live' connection) but which my car has.

I'm wondering, even if they do / could work, whether tha cables are long enough, given how I need to park the car means that the rear window is where 90% of the sun comes in.

Reply | Report as offensive | Link
Sat 14 Jan 2023 15:08
Car solar panel battery conditioners / chargers - kiss (keep it simple)

I bought a cheap one of these a few years ago. It was completely useless. In full sunlight it would deliver about 20mA. No doubt a larger modern one would do perhaps 200mA. But then consider how many hours of sunlight actually hit the part of the car where you place it, and the angle required to get the best insolation. Knock off another 25 or more percent because of the tinted glass. Then the hours of daylight and the chances of a sunny day happening more that twice a week on present form. I think I would take the car for a run every 2 weeks or simply disconnect the battery if it's going to be a long lay-up. Can you get a charger onto it occasionally? 20 minutes a week should be sufficient.

Reply | Report as offensive | Link
Sat 14 Jan 2023 15:15
Car solar panel battery conditioners / chargers - elekie&a/c doctor
Very much the same with me . Cheap 10w solar panel , and I don’t think it did any charging of any use . I’ve got a 20 year old Bmw cabriolet that sits around for weeks. I bought a maintenance charger that plugs into the 13amp socket, leave it on for a few days and this seems to do the job ok .
Reply | Report as offensive | Link
Sat 14 Jan 2023 16:21
Car solar panel battery conditioners / chargers - Engineer Andy

Unfortunately I cannot occasionally charge up the battery myself because I live in a flat, and we're not allowed to use communal area sockets with trailling cables for both safety and security reasons (leaving the communal doors open).

I tend to use my car once a week at this time of the year and once every two weeks in warmer weather in the summer (perhaps once every three weeks occasionally then), mostly to get grocery shopping in another town's supermarket about 12 miles awy precisely to keep the battery topped up as much as possible.

Given the price of fuel, it seems less worthwhile using it more often, especially when I have no excuse of doing the weekly shop.

The AA unit looks like it's a bit bigger at around the size of an A3 sheet of paper or perhaps a bit bigger. The problem as you've both described is that precisely when it's most needed is the time of year with the least daylight hours and sun strength.

Maybe a trickle charger (internal so I don't have to have the bonnet open with me in attendance) with a decent sized lithium battery I can recharge itself inside my flat and leave 'trickling' for a few days in the car. I suspect that battery would itself be quite sizeable and thus not cheap.

Still, maybe also useful (if it can do 230V AC as well) as a power backup for the landline phone in the event of a powercut, given the 'new' digital-only phones can't operate in a powercut, unlike the old analogue ones.

Reply | Report as offensive | Link
Sat 14 Jan 2023 16:54
Car solar panel battery conditioners / chargers - Chris M

Alternatively:

youtu.be/gmzQvhF5iq8

Reply | Report as offensive | Link
Sat 14 Jan 2023 18:16
Car solar panel battery conditioners / chargers - Adampr

I've had one of the 1.5w ones. I reckon it used all the power it generated to make the LED flash. I think you'd need at least 10w to make any difference and it needs to be pointing right at the sun.

When I had a car I barely used, I bought a thing called Dis Car Nect that went on the negative terminal of the battery and meant I could disconnect the battery by opening the bonnet and turning a little handle.

Reply | Report as offensive | Link
Sat 14 Jan 2023 18:20
Car solar panel battery conditioners / chargers - paul 1963

Andy, could you not just take the battery off and keep it indoors with a trickle charger?

Reply | Report as offensive | Link
Sat 14 Jan 2023 18:31
Car solar panel battery conditioners / chargers - Bolt

This may be worth trying, my fil used it to keep his Yaris battery going during spells of 3 to 4 months of illness, and it kept his battery fine from Amazon AA 5060114614185 solar charger I recommended to other people as well who said it worked well.

connects both to battery direct or through the obd port.

just a thought.

as he no longer has the car I use it on a double A battery charger works well

ps works ok in cloudy conditions as well

Reply | Report as offensive | Link
Sun 15 Jan 2023 14:48
Car solar panel battery conditioners / chargers - Engineer Andy

Andy, could you not just take the battery off and keep it indoors with a trickle charger?

Rather a pain having to do that at least once a week, then having to reset all the in-car electronics (radio, trip computer, odomoeter etc) and the car running rough every time because the ECU has gone back to factory settings and unlearned the best engine timing, etc.

Only worth it if I literally laid it up for months, which then means I'll get probablems with the brake shoes and discs, which are far more expensive to rectify. Besides, having a lead-acid battery on charge inside my flat doesn't sound like the safest thing to do. Not so bad if you have a shed or outhouse away from your home.

Reply | Report as offensive | Link
Sat 14 Jan 2023 20:23
Car solar panel battery conditioners / chargers - Brit_in_Germany

You could use a portable power station to power a trickle charger. If you wanted, you could even rig it up with a 100W solar cell.

Reply | Report as offensive | Link
Sun 15 Jan 2023 10:05
Car solar panel battery conditioners / chargers - John F

If you use it so infrequently I would just disconnect the battery. That's what I always do on the TR7; its batteries have lasted for ages. No spanner required, just a firm push and twist ensures adequate contact for the starter motor surge. If you keep the terminals clean you don't even get your fingers dirty.

I had a similar problem of short battery life with the Audi which stays 'alive' after switching off. I've rigged up a battery charger in the boot on a weekly time clock which gives it 4hrs on Mon Wed and Fri.

Reply | Report as offensive | Link
Sun 15 Jan 2023 10:39
Car solar panel battery conditioners / chargers - badbusdriver

If you use it so infrequently I would just disconnect the battery. That's what I always do on the TR7; its batteries have lasted for ages. No spanner required, just a firm push and twist ensures adequate contact for the starter motor surge. If you keep the terminals clean you don't even get your fingers dirty.

I was thinking along similar lines assuming no problems would come of it?. I know Andy's 3 isn't a young car, so possibly just losing preset radio stations?

But what I was thinking about specifically was something a guy I knew years ago had. The battery terminal on his car had an extra bolt in it which, when removed (easily and no dirty fingers), effectively isolated the battery. I went to a car show with him and after parking the car, he popped the bonnet, removed the bolt and put it in his pocket. Not sure if it was something he bought or if he made it himself though.

Reply | Report as offensive | Link
Sun 15 Jan 2023 13:52
Car solar panel battery conditioners / chargers - corax
But what I was thinking about specifically was something a guy I knew years ago had. The battery terminal on his car had an extra bolt in it which, when removed (easily and no dirty fingers), effectively isolated the battery. I went to a car show with him and after parking the car, he popped the bonnet, removed the bolt and put it in his pocket. Not sure if it was something he bought or if he made it himself though.

Adampr mentioned it further up the thread. Discarnect immobiliser or equivalent. I had one and it was useful to stop a battery drain that I had on a car while I tried to find the cause. They are still available.

tinyurl.com/44ywz5w9

Reply | Report as offensive | Link
Sun 15 Jan 2023 14:51
Car solar panel battery conditioners / chargers - Engineer Andy

If you use it so infrequently I would just disconnect the battery. That's what I always do on the TR7; its batteries have lasted for ages. No spanner required, just a firm push and twist ensures adequate contact for the starter motor surge. If you keep the terminals clean you don't even get your fingers dirty.

I was thinking along similar lines assuming no problems would come of it?. I know Andy's 3 isn't a young car, so possibly just losing preset radio stations?

But what I was thinking about specifically was something a guy I knew years ago had. The battery terminal on his car had an extra bolt in it which, when removed (easily and no dirty fingers), effectively isolated the battery. I went to a car show with him and after parking the car, he popped the bonnet, removed the bolt and put it in his pocket. Not sure if it was something he bought or if he made it himself though.

See my reply to Paul 1963.

Reply | Report as offensive | Link