Forcing Trace Inverter SW4024 from Bult to Float

[travelite]

Donny Myers mentioned an inverter cheat sheet to do this on our Vantare and Parliament coaches. I have all my coach documentation from the original owner and the second owner, I'm the third owner. Guess what I found in the documentation? The Inverter Cheat Sheet! The method described in this document allows the user to coerce one inverter to the float charging mode. This fixes the problem of one inverter in bulk while the other is in float. When this condition exists the inverter in bulk charging is attempting to raise the DC voltage to 28.8 by lowering it's AC output voltage while the inverter in float charging is attempting to lower the DC voltage to 26.8 by raising it's AC output voltage and adding power back into the AC voltage source (shore or generator). The inverters are kinda fighting each other; one is charging while the other is inverting. This can result in imbalances on the Leg 1 and Leg 2 ammeters. (Leg 1 is supplying power to 3 CruiseAirs while Leg 2 is supplying power to 1 CruiseAir even though the CruiseAir wiring splits the four evenly across both legs). By coercing the bulk charging inverter into float the DC voltage is held at 26.8 by both inverters and the battery bank is no longer a conduit for moving loads from one Leg to the other. :)

[Donnie Myers]

That is definitely my steps that I created at a Bus N Biker rally in Cedar City when we were blowing transformers! I like to see bulk at 28.6 and float at 26.6 with the temperature sensors disconnected and removed and placed in the trash. I put the sheet along with the settings I like to see in your coach before you left.

[travelite]

Thanks Donnie, I appreciate it.

Here's what I have on the charging voltage levels, but nothing on the temperature sensors.

Thanks,
David

[Donnie Myers]

That's because when a coach comes in here or every coach I see, I pull temp sensors and trash them! You cannot have two different temp sensors connected to two separate charging sources monitoring the same bank of batteries. The temp sensors are poor quality and read differently and will cause one inverter to charge and the other inverter to discharge while both are on the same cycle, ie, both are in bulk but one will discharge because it's sensor thinks the charge rate is too high for the temp. This causes the batteries to sulfate due to improper bulk/absorption cycle and really cuts the life of the battery. If anyone has two inverters and temp sensors are connected, save yourself some money and disconnect both of them from the inverter and toss them! I had a letter from Trace years ago (mid to late 90's) backing me on this but our (Vantare) engineers would not listen. I finally got through to them around the end of 2006 and tens of thousands of dollars worth of toasted batteries.

[travelite]

Got it. Thanks Donnie.

[TG Transport]

I periodically experience the same charging condition so I will unhook the temp sensors and observe what happens. Regarding the "procedure" to trick the second inverter into float, is this something that needs to be done each time you find your inverters in opposing modes or are you altering the settings when you make these changes the first time?