Inverter Woes

[Frank P]

My xantrex prowat 1750 inverter died after 12 year of service. I replaced it with a new xanrtex prowatt SW 2000 and new batteries (4 Trojan T125s’s). My old batteries (9 years old) and old inverter worked great. I could operate my microwave or coffee maker etc when on the hook for 24+ hours (i.e. batteries not fully toped up). Now the new system, with the inverter located much closer to the battery bank and larger cables, does not perform well at all. I can only run these high draw items when the batteries are at 90 to 100%. If I try to run the microwave after24 hrs on the hook, the inverter faults out on low votage. I have equalized the batteries and still have the same result.
Has anyone had this issue with the prowatt SW 2000?

Thanks
Frank

 

[Don S/V ILLusion]

The surge capacity of the 1750 is 3000w. The 2000 surge cap is 2000w according to the Xantrex manuals.

 

[Chief RA]

Don, maybe he needs to check on the at rest current draw on that new 2k. That could be the problem. Maybe keep it off until he needs it, unless he already is doing that. Chief

 

[Stu Jackson]

Frank, did you upgrade the wiring between the bank and the inverter when you went larger?

 

[Chief RA]

Stu: He indicates he shortened and enlarged them. Chief

 

[Maine Sail]

Frank,

#1 Check the voltage at the inverter terminals under high load then check the voltage at the battery terminals. If you have more than a 3% difference between bank and inverter this could be causing part of the issue. You don't say what gauge these wires are? Note: Xantrex expects far less than a 3% voltage drop in the wiring.

#2 If you notice too much VD measure the positive & negative wires between inverter and bank individually. Place one DVM lead at the battery end of the cable and the other at the inverter end and see what the DVM says. Compare the voltage drop in both wires. If well made, well terminated and similar in length these readings should be very similar. The positive may have slightly more due to a fuse or switch..

#3 A pure sine inverter will use more current while running the microwave than your old modified sine inverter did.

#4 if your batteries are brand new they may not yet be sufficiently broken in and suffering from voltage sag. They may just need 20-30 full deep cycles before they begin to hold voltage better.

#5 You could have a weak battery. Under load measure the voltage of the "series" batteries individually. They should be well balanced.

#6 Your SOC may not be what you think it is..

#7 Your inverters low voltage cut off may be set higher than your old one... Xantrex cut off is usually 10.5V but the alarm point is closer to 11V....

 

[Frank P]

All...thanks for the input

Off hand I don't recall the gauge cable I used but it was what Xantres recommended, it was larger than the old wire and a shorter run (by only 2') the new cable length is 4'.

I have been dealing with this since last summer and I use my boat on a regular bases for weekend trips with the discharged down to 50% many times already.

Mainsail, can you describe the process recommended for #6? Do I isolate the two sets of batteries into two banks (i.e. bank 1 and bank 2). Load up each bank (how many amps for this?) and compare Voltage? Also, what does SOC in #6 mean?

Thanks,
Frank

 

[Benny17441]

Some users of the Xantrex Prowatt SW 2000 have made reviews that the unit does not produce the claimed output. A user measured the continuous output at 1500W and the surge output at 3000W which is short of the 2000W/4000W claimed by the manufacturer. The reality is that even with the measured and confirmed outputs the unit should be able to perform well in driving a wide array of appliances. This unit is a True (Pure) Sine wave inverter designed to operate more sophisticated electronics. Digital clocks and computer chip controlled appliances mostly require pure sine wave a/c power while a Modified Sine Wave inverter is more efficient in starting and driving electric motors and heating elements. I think your old inverter may have produced more raw power and was better matched to your microwave unit. Perhaps looking for a new microwave oven that better matches the reported confirmed specs might solve your problem. Look to the new unit as an upgrade that provides more capabilities to be able to operate more sophisticated electronics. I looked at the specs of the 1750W unit and the low voltage shutdown was listed at 10V. The newer 2000 model is listed at 10.5V and that difference is huge in % of battery charge status. It is likely the more sophisticated electronics need a more stable power supply.

 

[Chief RA]

Send that sucker back if it doesn't perform as expected. Sounds like you need solar as well. Chief