Image CaptionWhile charging from the grid overnight (00:30-04:30) I’m finding the batteries don’t reach 100% and the charge current drops from about 125a to 120a with about an hour to go. I have it set up with 2 x 25mm √x cables so able to take over 300amps but has a 150a mega fuse which does get hot up to 80°c last night, could this be causing a spike in resistance or is it an imbalance of the batteries ? I’ve tried to increase the charge current to 135a but it does make it better.
Add more cable to the pylon setup. Put them in pairs.
Your crimps may be the problem on your cables there.
DC bus in your setup is long with plenty of joins. So you should upsize your cables for that.
25mm² cable is not rated for 300A without loosing power to heat so inefficient (50mm² yes) unless you are trying to make a heating element.
From memory, the Pylontech supplied cables are rated for 100A max. Might be better to use power cables from each battery to a POS and NEG busbar. And not piggyback.
Current might be dropping because the multis are downrating due to heat. Usually the Pylontechs control the charge, through the GX.
Pylontech BMS will reduce the charging current limit as SoC approaches 100%, is that what you are seeing? What does the CCL trace look like?
Thanks for your help. One would expect the cable sizes to give consistent errors which doesn’t happen. Joints are soldered. Sometimes 100% sometimes 95%, I’ll run it a little longer and put a 250A fuse in to see if that makes any difference. Thanks all.
Referring back to the victron/pylon config docs:
