I have a bluesolar 75/15 controlling 200 watts of solar into a 550 AH battery bank.
It output rises to 16.5 volts in good sunlight. The voltage has been measured using 3 different meters. It was working fine last summer topping out at 14.4 volts for bulk charging. since then I have renewed the battery bank with 5 flooded lead acid batteries which involved disconnecting all the batteries from the output at once but with the solar panels still connected. What is wrong ?
Hi 36. There was some discussion on this recently, but I can't seem to find it right now.
Depending on the vintage of your 75/15, it's possible that when you disconnected the batts, the mppt has picked up the V of your panels and reset itself to target a 24V system.
Try completely isolating it from both pv and batts, go take a 30min break to let it dissipate any internal charge, then hook the batts up first so that it can power up seeing V in the correct range.
There may be more to this, but try it and report back..
thanks for that John, positives from the PV and the battery both disconnected kettle is on, Even with towels over the solar panels theyre still producing 30 volts.he s Twas 78 volts without the towels could this be a problem ?
Yeh, that's what panels do. Not delivering A, their V can peak at Voc spec with minimal light. They just can't deliver A. But the V can be picked up by the mppt.
Ok to disconnect just the +ve from the batts, but best to isolate both sides from the pv to be sure. My apologies, do both +/- on the panel(s). Pv can do strange V things..
Ok all done I disconnected PV negative too had another cuppa and then connected it all back up again. PV s are reading 13.2 volts which to my mind is realistic for mid April. earlier they were reading 15.5 with what to me (and i cant measure sunlight intensity independantly) looks to be about the same amount of sunlight. I wouldn't expect to get the full 14.4 V in April anyway as the panels are mounted flat and the midday sun is still at about 45 degrees to the horizon. So only time will tell but Ill keep you posted. I ordered the USB cable this morning so I can check out the settings properly but if it did default to 24 volts when I disconnected the batteries I may never know. According to the manual however the blue solar will only auto-detect the battery voltage once so therefore I assumed that the controller would remain set up for 12 volts during the battery change. Hopefully lesson learnt, if not watch this space.
many thanks all, keep optimistic
alas optimism was misplaced, reading 16 volts again today,so I put a plank over the panels to partially obscure them and still getting 13.5 volts. Guess ill just have to wait for the cable to arrive unless anyone has some other ideas
FYI
Using the victron cable I could see that the controller had set itself to charge a 24 volt battery bank. Set it back to 12 and all now appears happy
