Zantrex RS2000

[Bill Schneider]

I made the mistake of replacing the inverter that came with my coach with another Zantrex (RS2000). To its credit, the battery charger is excellent, but the inverter function is the problem. Within 5 to 10 min after switching to invert, I get a low voltage fault. I set the low voltage at 12V. The initial battery voltage was 12.6, So the batteries were fully charged. the batteries are 2 years old, top of the line Interstate deep cycle. I keep them well maintained and clean. All connections are free of corrosion and tight. All individual battery voltages are in spec and equal. With virtually no A/C load on the inverter, I am pulling 10 to 12 amps. I know the Zantrex uses a lot of amps on invert, but even this amp draw should not cause this problem. My house batteries (4) have 464ah of reserve power . As soon as I disable the inverter, the battery voltage returns to 12.6V. I believe there is some problem in the inverter that is shunting the voltage, but if that were the case, I would expect a much higher amp draw. I wanted to see what thoughts anyone else had before throwing this thing in the dumpster and buying a Magnum 2800, which I should have done in the first place.

[Steve Huber Co-Admin]

Bill,
Couple of things to check;
1. Is Load Sense Mode on? It will shut off invert function if no AC load exists, saving battery drain.
2. Is Battery Type set to Flooded?  If not, batteries are not getting correctly charged. (Flooded is default setting).
3. Low Voltage set point at 12v is too high. Range is 10-13v. Default value is 10V. Consider setting it there.
4. What is current draw in charger mode? Even with batteries at 12.6v, you could have a weak cell that will cause batteries to discharge faster than normal. Consider checking specific gravity of each cell. Should be 1265 or greater if fully charged.
Steve

[Bill Schneider]

Steve,
Thanks for the quick response. Other than the low voltage setting, all other settings/readings were as you suggested. I was trying to keep my original post as short as possible so I didn't elaborate too much. Taking it further, I even did an equalizing charge and let the batteries rest before taking gravities and measuring voltage just to eliminate the battery bank from the problem. After verifying the batteries, I enabled the inverter with a small load and monitored the DC voltage. The DC voltage degraded rapidly even with the small A/C loads. I know it has all the indications of a weak battery bank, but I think I have done all I can to eliminate it as the cause. Also, the A/C output of the inverter is at the correct level during this test. After doing this test, I "disabled" the inverter and charger from the remote panel ( I also turned the A/C breaker "Off" to the unit). I then monitored the DC voltage while cycling several DC loads and the battery bank maintained normal DC voltage levels with minimal voltage degrade for several hours which seems to eliminate the house battery bank. I still think my problem is in the inverter function. The part that has me stumped is the rapid DC voltage drop with only a 10 to 12 amp current draw being indicated. I guess this may be just an exercise in theoretical troubleshooting seeings how this model is not considered repairable and there are no schematics for it. The consensus on the Forum seems to be for Magnum anyway.
Bill

[Steve Huber Co-Admin]

Bill,
You may be right re the inverter. However, If you haven't done so, you may want to try disabling all the AC and DC loads at the breaker panel and turn the charger off. this should tell you what the inverter is drawing itself with no loading. Then check the current draw of teh inverter with no loading. Should be very low.
Steve

[Edward Buker]

Bill,

Make sure that the DC cable going to the inverter has really clean ground and positive connections points through the whole run. There are battery terminals, maybe a switch depending on how it is wired, a fuse with contacts (check that the fuse is good and not deformed from heat), possibly a shunt to measure DC current, and the inverter DC connections. Series resistance in the path can explain voltage drop under load and poor capacity performance.

You can get a sense of this by turning the inverter on with about a 50 amp DC load and measure DC volts at your house battery bank and then measure across the DC wiring connections at the inverter. The voltage should be nearly the same and not have more than a few tenths of a volt drop in the wiring between the battery bank and the inverter if all was well.

Later Ed