[etischer]

I drive my TDI Touareg about once every 3-5 months, and the battery is just barely able to start. Last time I hooked up a charger to it, I put in about 50Ah. Decided to add a solar panel to keep it topped off. I have a cable going though the panel to hold it in place, and prevent it from easily being stolen. I put a hole in the cover for the cable, and crimped a grommet to prevent tearing. Should be able to put in about 1-1.5 Ah per day. The charge controller has bluetooth, so I can monitor the battery voltage without having to take the cover off. I stuck the bluetooth transmitter under the plastic cowl at the base of the windshield.

 

[etischer]

That's a pretty cool set up. Why don't you drive it more?

I have a Tesla Model 3 dual motor as my daily driver. We only use the Touareg when we tow our travel trailer. The solar panel seems to be doing its job. The Touareg battery was at 12.3v three days ago, up to 12.5v today just with the sun.

 

[etischer]

Do you have VCDS to check the charge level on the battery? My original that I just recently replaced was down to 11.5v and only 15Ah and it was still usable but I never had it sitting for months... a week or two max, and not often.
You have a lot more sun over there, but I'd be curious to see just how much you can really get the battery up to with that little guy.

I have an old VDCS (2000s) and a crappy Windows XP netbook, from the same era, not sure it's worth trying to get it working. I drove it yesterday, so the battery was able to come up to a full charge, and today with full sun, it's sitting at 12.6V (~85% charge). I think 1Ah per day should be plenty to keep it topped off. I'll report back after a month of not driving and see how it goes. It is quite nice being able to see battery voltage from my phone inside the house.

The App shows 0.43A going into the battery, but it's more like 0.25A. It's a basic PWM controller.