| [GMCnet] Interesting electrical/battery issue [message #259627] |
Thu, 21 August 2014 16:29  |
glwgmc
Messages: 1014
Registered: June 2004
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I have four large golf cart batteries as a house bank for the Royale. The bank is rated at 460 amp hours and is five or six years old. I decided to run the microwave off an inverter so changed out the modified sine wave inverter and installed a Xantrax SW 2000. It is a full sine wave inverter and says it will put out 2000 watts for five minutes and 1800 watts continuous. The microwave is a modern Panasonic inverter based unit so it modulates output directly rather than time slicing to get lower outlet like older microwaves. It is rated to draw 12.7 amps at full power and runs easily from a 15 amp wall plug.
The problem is, it will not run at full power off the inverter. It stays on for only a few seconds before the inverter shuts down with an overload message. It will run at up to 80% power level, but not beyond. At 80% the voltage sagged to 11.3 volts while running and was drawing 153 amps for 1729 watts according to my Xantrax battery meter. According to the plate on the microwave it should only be drawing 1524 watts at full power. As soon as the microwave shut off the battery voltage moved up to 12.4. At 50% power the battery voltage sagged to 11.5 and the unit was drawing 93.5 amps. At 70% power voltage sag was to 11.6 and amp draw was 122. In both cases the battery voltage returned to 12.3 to 12.4 volts as soon as the microwave stopped.
Thinking the interconnect cables might be adding too much resistance I changed out all the cables from 1ga to 00. The battery interconnect cables are wired to properly balance the load across all four batteries and none are longer than 18". The battery to inverter cables are also 00 and 30" long. All the connectors are soldered in place, the mounting studs are clean and the batteries fully charged. I even swapped the Iota 75 amp converter/charger that was in the Royale for the 60 amp PD that was in the Clasco just to make sure there was no issue there. With those cables in place the 80% power voltage sag was still to 11.7 volts while drawing 150 amps.
I added a second automatic transfer switch to switch between shore/generator power and the inverter power for a series of new power strips installed around the inside of the coach. I did not want to tie into the current house panel to avoid any grounding issues plus the existing wall plugs are not where we need them for the way we live in the coach. The microwave is plugged into a dedicated 120volt line running from that second transfer switch. That line is a 12-3 appliance extension cord 25' long. The microwave runs just fine when I plug the coach into a 15 amp shore power plug.
So, whats up? We had a similar set up (four 6vdc golf cart batteries and a 2000 watt Heart converter/battery charger/Inverter) in our old Beaver Patriot and it ran a similar size microwave off the inverter just fine. The only thing I can think of is that the battery bank may be nearing the end of its useful life. Any of you electrically minded folks have a suggestion or an idea as to how I might go about testing the battery bank itself? Can you think of anything else I might have overlooked that would cause this issue? Thanks.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
Visitors always welcome!
glwork@mac.com
http://jerrywork.com
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Jerry & Sharon Work
78 Royale
Kerby, OR
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