OBD2 Solar powered battery chargers?

B0bbyEwing

Until last night I wasn't even aware these things were a thing. Saw someone suggest it to another on a car group I'm on.

I have a car that has a parasitic drain. If you use it daily then there's no problem but if you let maybe 3-5 days pass then you could have an issue starting it. In the end I got a starter pack & just left that in the boot.

Car is going for MOT next week & tbh it's just a stepping stone car while I look for something more long term. I've had a YouTube on how to determine parasitic drain but can't determine what the cause is … and it's not the battery. As the car can certainly make 24 hours & the fact I'm not looking to keep it overly long, I don't want to spend an endless amount on an auto electrician.

But then I saw these things mentioned.

Now I know solar panels are best out in the open in direct good sunlight rather than sat in a windscreen … but then you leave it open to some idiot just taking/damaging it.

I also guess if you buy the cheapest of the cheap then you're going to get poor results.

So if you buy a decent (whatever that is) unit, are these things actually much good? Just chancing someone here may have experienced these & can comment either way.

It's not to charge the battery from dead, it'd be to just keep it ticking over so that I can finish using it on a Friday & have no concerns come Monday morning.

These kinds of things but not necessarily specifically this one.

MattMattMattUK

If you are having starting issues after not having driven for 3-5 days then your battery has almost failed, get it replaced.

B0bbyEwing

https://forums.moneysavingexpert.com/discussion/comment/81977624#Comment_81977624

No problem, please explain this…

Car A has starting trouble. Think it's battery. Put an apparent good battery in as a replacement (but used) - problem persists.

Car B comes to an end but has a compatible battery. Battery is within warranty still & gives absolutely no starting issues whatsoever in the couple years its been in use. Battery was bought brand new.

As soon as this battery gets put in car A from car B the problem persists - battery drains when left for a few days.

So bearing in mind the battery was giving absolutely no trouble in car B whatsoever and it immediately caused trouble in car A, please explain how the battery has failed (or almost failed).

subjecttocontract

There are different types of battery. Battery from car A may not be comparable with car B.

facade

If your parasitic draw is high enough to prevent starting after a couple of days it must be around 500mA or so, or you only run the car for a short time every day and the battery is never getting recharged.

The best solution is to get a £12 charger from Lidl/Aldi and put the battery on charge every Sunday, but I guess if you are considering a solar charger that you can't get mains power to the car.

I had a solar charger about 10"x6" in my LandRover, and it only put out about 50mA behind glass in direct sunshine, so it was really a waste of money.

I can't imagine that anything affordable is going to make a significant difference if you have a continual 500mA discharge, you will only get a decent output for a couple of hours a day from a panel on top of the dash/rear parcel shelf.

born_again

https://forums.moneysavingexpert.com/discussion/comment/81977656#Comment_81977656

Put an apparent good battery

How sure are you that it is good?

As you have looked on car groups, then perhaps look on one for your car (which is?) & you might get a answer to what the cause of the drain is.

If the battery is constantly going flat, then the issue needs sorting & battery replacing. The more a battery goes flat, the quicker it will do it in future, as the internals get damaged.

paul_c123

The way to test a battery is to use a voltmeter as a basic check; a battery tester to determine state of health; and an ammeter to help diagnose parasitic draw issues. Swap-testing isn't that useful.

It does sound like a parasitic draw here.

What was a good battery can be damaged by being discharged then not recharged for a length of time.

QrizB

If your parasitic draw is high enough to prevent starting after a couple of days it must be around 500mA or so, or you only run the car for a short time every day and the battery is never getting recharged.

Agreed.

If the drain is 150-200 watt-hours a day, even in the summer months you're going to need a chunky solar panel to keep up.

I've got a 10W solar charger (the exact same Eco Worthy one that the OP has linked to) and that's likely to only add 20-30 watt-hours a day, even in good April weather. My car takes 3-4 weeks to go flat (in the summer, when I'm cycling to work instead of driving) and it's perfect for me.

The OP however is going to need something like a 100 watt panel, which might not even fit in his windscreen.

Something this size:

https://www.ebay.co.uk/itm/196732108984

Iceweasel

It may be make specific, but if you leave anything permanently connected to a BMW OBD port then they start to throw fault codes after a few days.

A known problem according to BMW owners forums.

Some folks have had success with a solar charger connected via a cigarette-lighter socket.

B0bbyEwing

Car B comes to an end but has a compatible battery.

https://forums.moneysavingexpert.com/discussion/comment/81977661#Comment_81977661

I suppose I should've put it in bold. I've done that now though.

B0bbyEwing

https://forums.moneysavingexpert.com/discussion/comment/81977675#Comment_81977675

Thanks.

This is why I wanted to ask others because I've no idea. You can pull numbers because I'll assume you know what you're talking about. All I see is x-days = need for a jump, I can't break it down beyond that & so wasn't sure if one of these things would be any good for my situation or not.

So thanks for the reply.

The journeys are 10 mile a time, 20 mile a day. Like I say, if I run it each day then there's absolutely zero issue with the charge, it wont lose it.

I could get away with running it Saturday, having Sunday off & coming back to it Monday - that's also fine.

Running Friday, having Sat & Sun off, back on Monday will more than likely be fine.

But once you start getting much beyond that the chances get less & less. I have before started it 5-7 days after it last ran & it struggled a bit but then started. Likewise I've tried it 3 days after it last ran & it needed a jump.

As for a charger, I have one. a Ctek something or other that was around the £80-£100 range. It just means running the extension lead from the outdoor socket over the drive, positioning it all in case it's a rainy day & then getting it all back in later in the day. Not the end of the world but I was thinking if I could do away with that kind of faff then all the better.