inverter on load terminal of Prostar CC

wxh3

I've used my ProStar charge controller for a few years with a couple of different inverters connected to its load terminals. It was a bit more convenient for me and I liked seeing the load amps on the controller's digital meter. I had not noticed any problems at all. The manual said nothing about treating inverters differently...

However, I noticed recently while browsing the MorningStar website Tech Support:

"We do not recommend wiring inverters to the load terminals of our products because of current in-rush on start up. Inverters typically have large amounts of input capacitance (for input filtering). When power is first applied, these capacitors can draw very large currents in the 100's of amps, albeit for a short period of time. These current surges can stress our power transistors and will trip our short circuit protections. The inverter may start eventually after several attempts to reconnect from the short circuit condition, but this mode of operation is not normal.

For this reason, we do not recommend wiring inverters directly. Many inverters have their own LVD circuitry and will not allow the battery to discharge too low. However, if the customer requires load control and LVD functionality, they can switch the inverter through a relay wired in series between the battery and inverter. The relay is switched by the load terminals of the controller. Refer to the Related Documents list for load relay wiring diagrams."

Yikes. Hopefully I haven't damaged my controller...

BB.

Re: inverter on load terminal of Prostar CC

Ah--the wonderful world of solid state electronics...

You can beat the heck out of them--and one day they will up-chuck and die... And, unless you spend hundreds or thousands of dollars--you will never know for sure if you hurried it along, the Mfg. did something wrong during mfg., assembly, or in design, or it was just age/act of God.

At this point--there is nothing you can do one way or another. And most DC inverters have internal low voltage detection circuitry anyway--so you do not need the controller to perform that function. And if the LVD breaks--you might not even need it (unless you have a DC load--such as lighting--that could take the batteries dead if left connected).

And in any case, the circuitry is to prevent damage/fire in the inverter--not really to protect your batteries.

At some point--if you want to spend lots more money--it would be nice to get a battery monitor. Then you can really tell how you are treating your battery (you would still need a separate amp meter--or take the difference between the charge controller amperage and the battery amp reading--to see how much current the inverter is using).

-Bill