Sorry in advance for the length of this post. Just curious if any of you have seen similar solar charging issues.
I’ve had the AC200max now for about a month. It’s been working great and does charge well most of the time (So Cal sun). However, about once every 3 days, the charge rate drops dramatically.
For example, yesterday morning, it started charging at sunrise at about 40w. PV charge was climbing until around 10:30 am and was producing 500w+. It stayed around that level for several hours, then as expected, it slowly dropped charge rate until the sun went down. That’s a “normal” PV charge day (no clouds and perfect winter sun all day).
Today started the same in the morning, then after about 30 minutes, charge rate dropped from 150w to 15w and stayed at that pitiful rate for about 20 minutes. No other indications as to why it dropped. I checked the panels and nothing interfering. I pulled the PV charge cable out of the AC200max and waited for the volts to drop to zero. Plugged it back and and after about 30 seconds the PV rate was back up to normal. After 10 minutes, it dropped down again to 15w. Pulled plug and repeated. It’s currently charging at 180w, so that’s a bit better giving the time of day. I presume this might just be the battery protecting itself, but it seems overly aggressive if that is the case (fans are not running, so it’s not hot).
BTW: I’ve also noticed that if I leave the PV cable attached overnight, it will read the wrong voltage the next day when the sun rises. I remove the cable and reattach it and then volts now read correctly.
Other tid-bits: 3 x 350w solar panels attached in series. VOC is 142 running around 8 amps and the PV usually reads about 130v input (that’s volts, not watts). Fans turn on based on AC usage or high charge rate, but not very often and it doesn’t appear to affect the charge rate. Firmware is up to date, and no alarms logged.
I typically use the battery between 85% charge, drain to 50% and let it charge back up – sometimes a bit higher or lower depending on the use case. Battery does seem to go into trickle-charge mode at around 90% charged.
I have a grid-tied solar system on my house, so I have some comparison data for charge rates based on current conditions. For example, if my house system is charging at 60% capacity, the Bluetti is usually around 50% (that’s OK because there is battery system overhead). This makes it easier to see what the Bluetti “should” be doing based on comparison to my house system.
Have you run into similar PV charging issues with your system?