photohc said:
You may want to checkout this
Kickstarter for Solar/Battery Management device made for Lithium's. His previous version did very well and is available for purchase, or you can get the new one he is developing for release this October.
I have looked into that one before and the issue is that I have a battery with an existing BMS so I don't actually need to purchase a controller/BMS - I just need the controller.
I spoke with Bioenno today and run though a ton of diagnostics (it's only 109 outside so it's ok). They believe something in my unit has failed and they are sending a replacement.
The unit reads
18.5 Volts (close circuit) from the panels (aka normal)
Full battery reads 13.5 volts (aka normal)
Charge voltage (absorption) is 14.5 (aka normal)
Everything works fine until the battery reaches a full charge - then things get weird.
Voltages on solar stay at 18.5 (normal) - but cycles between load and no load.
On the battery side voltages vary from 14.4 to as high as 17.0 very quickly.
The "load" connection on the controller - which is unused in my setup - turns on and off in sync with the solar array switching between load and no load.
I even ran only a single panel and received the same results.
Attaching a heavy load to the load side of the controller did not change the results.
A full reset did not change the results.
Finally directly wiring the controller to the battery (bypassing the Xantrax Link shunt) did not change the results.
A new box is on the way.
I am not sure this will be a fix however - my gut tells me the solar controller and my BMS are fighting each other. I hope I am wrong.
If the replacement controller does not solve the problem I plan to install a large capacitor between the solar controller and the battery to "smooth the spikes" or get a different brand of controller.