Heath Robinson approach to solar

[rugbyken]

recently the tracker on my van activated I was able to check via a secreted phone that it was still in the barn a mile away ,all 3 batteries were flatter than flat I jump started it & bought it home & plugged in mot due Monday so been titivating , in the summer I had a VictronConnect fitted and I was able to check through the history that although undercover it does face south and an opening and had received some input on odd days so when I take it back I have jury rigged a mirror on a stand to see if that supplements the harvest , David is making up a box with a battery monitor so I will be able to tell if it does increase I have 2x125A batteries & the history shows that the batt level has been dropping at 0.4 v a day with only an I phone plugged in ?

 

[colinm]

Our van is parked up under cover. The leisure battery stays at a decent charge, but the vehicle battery drops over a few weeks. I got a 'cheap' 40w panel/controller package some years back and fixed the panel to end of 'van port' I clip this to vehicle battery if it's going to be standing for more than a week.
T'other year we took mains power to the 'van port', we started with EHU one day a week, but the EBL99 puts loads of charge into leisure battery and little into vehicle battery, so rather than leave it on permanently have gone back to the solar.

 

[rugbyken]

i didn’t bother using the 30w solar trickle charger you can see on the dash when i parked up last time i will also use this straight into a live cigar lighter

 

[r4dent]

Van is on drive so I charge my cab battery every 4 weeks. It is something to do during lockdown.

 

[wildebus]

0.4V drop in a day would suggest you either have a bit of a load going on or the batteries are not very healthy
Are you sure the iPhone is the only thing plugged in? inverter not on standby and drawing some power? Or something like TV booster left on?

 

[rugbyken]

yes david i was thinking along those lines the batteries are getting on 2.8 yrs old though i was hoping to get another year or so out of them then go the lithium route budget reasons only i’ll have spent best part of £3k on the van this year with a new fridge freezer & solar set up your box will be the last for now i hope , i thought i’d isolated everything on the leisure set up going to cover the panel a get some readings then if necessary i will disconnect the batteries when i next park up for a few weeks

 

[wildebus]

Some approximate maths would say that a 0.4V* drop on a 12V system would mean losing around 30% of the batteries total capacity in that time - so in a day for your 250Ah bank, that is 75Ah ( so around a constant 3A draw). Not impossible if something significant left on, but fairly hefty all the same.
The installation of the battery monitor I think will be quite revealing on if it is the load or the batteries


*starting from around 12.7V or so or lower - above that point the batteries would have a surface charge that would go on a load so a fast initial drop down to 12.7V should be ignored

 

[Veloman]

As an experiment I tried reflecting the sun onto a free standing solar panel connected to my van using a windscreen sun screen. I can confirm that reflecting sun onto a solar panel does increase its output but only by a fairly small amount.