OBD2 Solar powered battery chargers?

B0bbyEwing

https://forums.moneysavingexpert.com/discussion/comment/81977678#Comment_81977678

100% sure.

1. For the reason I've already given. Sure, electricals can go funny at any point but I would be willing to bet that had it remained in the car it was in then it wouldn't have given any issue whatsoever.
2. The battery has been tested by a (HGV) mechanic with his testing gear. Gear said battery is fine.

B0bbyEwing

https://forums.moneysavingexpert.com/discussion/comment/81977804#Comment_81977804

Hmm, attached to a roof rack maybe? :D

I get the point though - knock this idea on the head.

facade

20 miles a day ought to keep the battery charged.

The actual best solution is to get the parasitic draw reduced, but you'd have to pay someone to troubleshoot it, and if you are shortly getting rid, it isn't worth it.

I don't suppose it is one of those keyless monstrocities? If your keys are in range the car won't go to sleep (they get all excited about going for a drive, like a dog when you are holding his lead).

I used to charge the battery on my Citroen virtually every Sunday (unless it was absolutely pouring) and I'd just put the charger inside the engine compartment and not fully close the bonnet so as not to damage the mains cable.

I have a rainproof outdoor extension lead, but I could have shoved it far enough under the car to keep the rain off it if it wasn't.

knightstyle

I would put a meter between one battery terminal and the wire, then pull fuses till the meter reads zero. This will show where the fault is and probably you can use the car without the faulty circuit connected.

B0bbyEwing

https://forums.moneysavingexpert.com/discussion/comment/81977982#Comment_81977982

Yeah if it's used daily then the 2x10mile trips are fine to give you some days safety net.

And no the car isn't anything of the sort. It's a 21 year old VW.

Regards charging, that's pretty much what I do. Run the single socket extension to the engine bay, have the charger connected up with the plug dangling down a gap so that if it rains then it's not where plug meets socket & I lower the bonnet so it's just & so latched, which doesn't trap the cable. Or I put a block of wood underneath the bonnet so it actually can't come down.

It's only because it's a bit of a rust bucket that I'll be looking to replace it. It'll be at the stage where to get it through many more MOTs it's going to need too much thrown at it.

First things first though, I need to get it through the upcoming MOT. Had it in for pre-mot recently & they thought it'd only need a tyre to get it through so fingers crossed.

B0bbyEwing

Yeah this is what I was doing but the reading was bouncing round like a don'tknowwhat. It certainly wasn't like the guy on YouTube was showing with his.

Goudy

Turn everything off in the car, wind the window down and close the door.

Set a multimeter to read (small) amps and remove the neg cable from the battery.

Bridge the gap between the neg cable and neg battery terminal with the multimeter and see what it's pulling amp wise.

Normally, modern cars will pull something like 0.04 or 0.05 amps in this completely "off" state.

If it's flattening the battery in a couple of days because of a parasitic drain, then yes around 0.50 or 500mA would do that.

If your figures are around this, you just got to find what's pulling 0.45 or so amps.

First thing I would look at it the head unit. Is it factory or has someone fitted an aftermarket one? It's the most common cause of parasitic drains.

Head units usually have two power feeds to them. A switched and unswitched live.

The switched live is only live when the ignition is on, so the head unit will only power up when the ignition is on. When it's turned on, it will pull nearly have an amp.

The unswitched is there to store the settings, so all your preset setting, channels etc need power to store them. This pulls very little, just fractions of a mA.

Get these the wrong way around and the head unit will pull around 0.40 amps or more all the time, even with the ignition off and head unit turned off.

Some cars used a different colour wiring to the factory head unit which effectively made it look like these two lives were easy to match when fitting an aftermarket head unit, but they were actually the wrong way around.

So the quick check is just to unplug the head unit and test the drain again at the battery.

If that is not it, it's now down to trial and error. Pull one fuse at a time until the drain drops significantly. Remember the normal pull of a car with everything off it around 0.04/5 or an amp, so you are looking for a drop on a lot more than that.

Now you have what it's drawing, any charger needs to put that back. This means if you just want to ignore it and use a solar chargers, you need something that's going to put the drain back, but that will be difficult with a solar charger as the drain is 24/7 and the sun is only out 12ish hours a day at the moment.

MattMattMattUK

Just a thought, didn't you post before about having an aftermarket dashcam hard wired into your car?

Mildly_Miffed

There's three things getting conflated here…

1. Car won't start after a few days, flat battery.
It's either a duff battery or something drawing too much power. Easy to diagnose which with a multimeter, then track it down to a specific circuit.

2. Fix or workaround?
Obviously, fixing is preferable… Chucking a solar panel on to workaround it is a bodge that won't work in the long term.

3. Small behind-glass panel connected to eOBD port, or something else?
A panel the size of a sheet of A4 behind tinted glass is going to be useless. Which is just as well, because trying to push non-trivial current into battery via the eOBD port is going to have… consequences.

Goudy

https://forums.moneysavingexpert.com/discussion/comment/81978420#Comment_81978420

I think I might have missed that.

A Dashcam can pull around 0.2 to 0.5 amps.

They are generally just attached to a switched live, which means they come on and go off on the ignition.

With devices designed to come on and go off via a switched live, they tend to still pull power if they are connected and turned off on the device, so just turning/pressing the off button doesn't always stop the power being drained.

If in any doubt about it's wiring, unplug it from the source and see what happens to the drain.