Heath Robinson approach to solar

rugbyken

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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 ?
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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.
 
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
 
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?
 
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
 
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 (y)


*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
 
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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.
 

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