Incorrect inverter Dc input voltage reading

Damo

Hi please save me on this.

I have my own built myself 25kw 24v lithium ion 288p 7s battery pack. Been running over a year now not one problem. I know the charge on my pack, it is critical that i do. I max charge it to 28.4.

I have 4 solar controllers. All show the same voltage andare never more than 0.2v above the battery voltage. 

I have one of my dc inverters that even when load drops voltage it matches the voltage on my battery. Everything perfect so far. BUT

On my latest inverter the dc input voltage reading is literally 1.5v higher than the lot. My battery is 28v, my usul inverter 28v, my solar controllers 28.2v, but this damn new inverter shows 29.5v. It is driving me nuts. 

How can i adjust or calibrate this inverter to show me the correct voltage so it does not exceed maximum and cut out when the system isnt even actually anywhere near where this inverter thinks it is? Can i fix this dodgey thing?

mike95490

if it's a new inverter under warranty, return is your best bet, unless you have a shop manual for it.

Damo

Yeah I looked at the PCU hoping to easily see a voltage divider circuit that they might use to then reference from the lower voltage output, hoping it would be a simple trimpot and a five second fix with a screwdriver. But the only adjustment I could find was a trimpot that adjusted the internal fan start based on amount of load. I can in a way deal with the unit as it isn't actually cutting out, its high voltage cut is 31v, I have 4 BMS units in parallel with controllers that max at 28.4v. so it gets to 29.9v highest reading, what it does do though is beep that drives me over the bend so I tinkered with unit. It's only a 500w unit for led lights to separate them from inverters doing heavier tasks. Right now I set the fan to stay on constantly and replaced the tiny one with a 8cm quiet magnalev fan, then literally removed the buzzer from the circuit board. IpI an Arduino with a voltage reading code and relay across the power to the inverter also with a temp sensor so if temp or voltage go beyond the inverter parameters it will cut the unit without hearing its original buzzer giving me a 1.5v false alarm. Seems to work amazingly well. A lot of messing around though, wish it was as simple as I first imagined. If it has a manual it would be in Russian or Chinese. It's a cheap unit but has proven so far damn reliable, even my best pure sine wave inverters can't handle light dimming as well as this little sucker. Absolutely no flicker, total control of dimmers, not even grid power could deal with dimming as well as this unit. Very surprised by it.