Solar Trickle charger

[Tonyfarmer]

Hi,
just got 4.8watt solar trickle charger to keep battery topped up on Merc GLC220d 2020yr.Has anyone used the OBD connection tha comes with these chargers?.

 

[Chrishazle]

Some Halfords clown connected a 12V battery to the OBD port on my S204 when doing a battery change - cost 2-3 days hassle and £174 for my indie to sort it - which Halfords had to reimburse. I will never again allow a power source to be connected to the OBD post on my car!!

 

[Bobby Dazzler]

I’d also avoid charging through the OBD2 connector. Is there not an option to connect to the charging points under the bonnet?

 

[markjay]

I’d also avoid charging through the OBD2 connector. Is there not an option to connect to the charging points under the bonnet?

Agreed, however leaving the solar panel on the dash inside the car, connected to the OBDII port, seems like the simplest option, as it does not require running wires into the engine bay.

E.g.:

AA 4.8W Solar Battery Charger | Saxon Brands | Experts in Brand Distribution

The AA 4.8W Car and Caravan Solar Battery Charger is designed to maintain the vehicle battery by converting light energy from the sun into electricity. The charger provides peace of mind that your vehicle will start if it has been left unused over a period of time. This product should not be...

saxon-brands.com

(The OBDII port has an always-on live feed at pin no. 1)

 

[FiveAlive]

Some Halfords clown connected a 12V battery to the OBD port on my S204 when doing a battery change - cost 2-3 days hassle and £174 for my indie to sort it - which Halfords had to reimburse. I will never again allow a power source to be connected to the OBD post on my car!!

What damage was caused?

 

[190]

One possible risk with an unregulated solar charger is that the open circuit voltage can be as high as 21 volts so that could cause damage to the cars electronics when the battery reaches 100% full charge. That isn't remotely going to happen with a 4.8w charger though but it's a risk with bigger solar panel unless they have a regulated output.

My experience of a 5W panel inside the car was it was a waste of time. I did find a permanent live connection in the boot and had the panel on the rear parcel shelf which was a neat solution but being inside the car caused a big reduction in output. The chance of getting 5 watts out of one of those things inside the car even in high summer is zero. The output was so weak that little blinking LED circuit consumed half the power that the panel was producing until I disconnected it.

 

[Chrishazle]

What damage was caused?

Initial problem was that after the new battery was installed, although the car would start I could not change the transmission from P to anything else, ended up using the emergency release (remove the bottom of the gearstick gaiter, it's then a push thing drivers side) to get mobile and to my german car specialist. He immediately found the OBD port was dead so his diagnostics would not do anything, had to go back to first principles, find wiring diagrams and eventually figure that IIRC Fuse 12 had blown. Main part of the £174 was his time, took him 2 hours to figure it out. Replaced the fuse and that fixed the problem. However, I spent an hour at Halfords with the manager trying everything he could think of, including changing the main battery again, then was without the car for a day while Ben fixed it, than another trip to Halfords with Ben's bill, which was too much for the manager to authorise for refund so he had to refer it to head office, that took another couple of days to sort out. I was told this escapade resulted in a company wide alert to all Halfords shops to never connect a 12V battery to the OBD port!

 

[Bobby Dazzler]

Agreed, however leaving the solar panel on the dash inside the car, connected to the OBDII port, seems like the simplest option, as it does not require running wires into the engine bay.

E.g.:

AA 4.8W Solar Battery Charger | Saxon Brands | Experts in Brand Distribution

The AA 4.8W Car and Caravan Solar Battery Charger is designed to maintain the vehicle battery by converting light energy from the sun into electricity. The charger provides peace of mind that your vehicle will start if it has been left unused over a period of time. This product should not be...

saxon-brands.com

(The OBDII port has an always-on live feed at pin no. 1)

It would certainly be a neat solution, however the OBD2 isn’t designed to accept a charge and so there’s a risk of causing damage. It would probably pass a tiny amount of charge anyway as the output would be reduced further if it’s inside the car, but personally wouldn’t risk it.

The safer and more effective option would be to have the solar panel outside, connected to the charging point under the bonnet.

 

[Chrishazle]

See Post #2 and my subsequent posts!! No way would I connect a 12V input to my OBD2 port!!

 

[markjay]

See Post #2 and my subsequent posts!! No way would I connect a 12V input to my OBD2 port!!

The OBDII-shaped plug probably has just one pin, and it only connects to pin no1 in the OBDII socket, that's a 12v always-on feed, with a low-rated fuse (from memory 5A or 7A). It won't connect to any of the data pins on the OBDII socket.

 

[markjay]

It would certainly be a neat solution, however the OBD2 isn’t designed to accept a charge and so there’s a risk of causing damage. It would probably pass a tiny amount of charge anyway as the output would be reduced further if it’s inside the car, but personally wouldn’t risk it.

The safer and more effective option would be to have the solar panel outside, connected to the charging point under the bonnet.

No doubt this is a better option, but it will only work if you have off street parking... leaving the solar panel attached to the roof or bonnet when parked on public roads doesn't sound like a good idea.

 

[Wolfie1]

A 4.8w solar panel isint going to be enough to charge your battery, my first attempt at a solar panel to keep my battery charged on a car was a 10w and that was only enough with the battery disconnected in the summer months, 2nd attempt was a 25w which was enough in summer with the battery connected for all year round i found a solar panel of 50w along with a solar charge controller was needed for all year round use