Generator: Xantrex use/battery charging

[DavidMort]

Generator: Xantrex use/battery charging

We are cool weather camping in national parks with no hookups. We normally have two hours in the morning and two hours in the evening to run the generator. We charge the batteries and use higher power AC devices while running the generator as well as use electric heaters to save propane.

The charging rate for the batteries is 100 amps for the first hour and then rate will drop off as batteries approach full charge. This puts about 80 amp hours into the batteries which will usually bring the batteries to close to full charge depending on how far we pulled them down. To do this the generator is putting out about 15 amps AC.

The problem I have is that the when I plug in my coffee maker, or tea pot, or heater, or use the microwave the Xantrex cuts the power to the charger and the charging current drops to around 2 amps. So if it’s cold and we want to run the heaters for an hour, make coffee, nuke something for dinner, etc., the batteries will not be charged.

The Xantrex does this when charging:

“Power sharing: The Freedom SW charger uses incoming AC or
shore power (see following note) to charge the batteries. The
charger shares incoming AC power with AC loads on Line 1 only.
The AC loads have priority, which means that the charger will
reduce its output with large AC loads and increase the output again
when the AC load decreases. The regulatory maximum for
continuous AC loads is 80% of the breaker rating (see “AC1
Breaker” on page 44) that the loads are connected to. The Freedom
SW senses pass-through current going to the AC load. The
difference between the pass-through (load) and 80% of the AC1
Breaker setting is the current that is available for charging the
batteries.
For example, if the AC input of the Freedom SW is from an AC
panel with a 30-amp breaker, the AC1 Breaker setting on the SCP
should be selected as 30 amps. Based on this, the charger will
control the charge current so that the total current draw is equal to or
less than 24 amps in this case. Should the load current be more than
24 amps, the charger output will reduce to 0 amp, but the Freedom
SW will continue to supply the loads. The Freedom SW will
continue to pass-through power to the loads, even if the load current
exceeds the AC1 Breaker setting. In this case, it will be up to the
user to remove/disconnect loads if tripping the AC input breaker
supplying the Freedom SW is to be avoided.”

The generator is capable of supplying around 50 amps and I would like to make use of the capability of the generator and charge at maximum rate and use appliances. Is there a way to do this? Is there a plug that runs off the line that the Xantrex doesn’t monitor? Where does line two go? Anyone have a functional wiring diagram for the Xantrex? I assume this problem would not be as severe if the correct higher power inverter was installed by dealer when the original inverter stopped working during the warranty period.

NOTES: This is normally a minor issue. Coffee pot and microwave use are intermittent. We use a low amp electric heater so the Xantrex doesn’t cut the charging current. The only times we have problems getting the batteries charged is when we use the convection oven to bake, because it is a large electric heater and the batteries do not charge when it is running. The new XTR31 batteries seem to be working fine. It would be nice to be able to turn on higher power electric heaters in the morning rather than turning up the propane furnace.

[Bill Davis]

Originally Posted by DavidMort

Generator: Xantrex use/battery charging

We are cool weather camping in national parks with no hookups. We normally have two hours in the morning and two hours in the evening to run the generator. We charge the batteries and use higher power AC devices while running the generator as well as use electric heaters to save propane.

The charging rate for the batteries is 100 amps for the first hour and then rate will drop off as batteries approach full charge. This puts about 80 amp hours into the batteries which will usually bring the batteries to close to full charge depending on how far we pulled them down. To do this the generator is putting out about 15 amps AC.

The problem I have is that the when I plug in my coffee maker, or tea pot, or heater, or use the microwave the Xantrex cuts the power to the charger and the charging current drops to around 2 amps. So if it’s cold and we want to run the heaters for an hour, make coffee, nuke something for dinner, etc., the batteries will not be charged.

The Xantrex does this when charging:

“Power sharing: The Freedom SW charger uses incoming AC or
shore power (see following note) to charge the batteries. The
charger shares incoming AC power with AC loads on Line 1 only.
The AC loads have priority, which means that the charger will
reduce its output with large AC loads and increase the output again
when the AC load decreases. The regulatory maximum for
continuous AC loads is 80% of the breaker rating (see “AC1
Breaker” on page 44) that the loads are connected to. The Freedom
SW senses pass-through current going to the AC load. The
difference between the pass-through (load) and 80% of the AC1
Breaker setting is the current that is available for charging the
batteries.
For example, if the AC input of the Freedom SW is from an AC
panel with a 30-amp breaker, the AC1 Breaker setting on the SCP
should be selected as 30 amps. Based on this, the charger will
control the charge current so that the total current draw is equal to or
less than 24 amps in this case. Should the load current be more than
24 amps, the charger output will reduce to 0 amp, but the Freedom
SW will continue to supply the loads. The Freedom SW will
continue to pass-through power to the loads, even if the load current
exceeds the AC1 Breaker setting. In this case, it will be up to the
user to remove/disconnect loads if tripping the AC input breaker
supplying the Freedom SW is to be avoided.”

The generator is capable of supplying around 50 amps and I would like to make use of the capability of the generator and charge at maximum rate and use appliances. Is there a way to do this? Is there a plug that runs off the line that the Xantrex doesn’t monitor? Where does line two go? Anyone have a functional wiring diagram for the Xantrex? I assume this problem would not be as severe if the correct higher power inverter was installed by dealer when the original inverter stopped working during the warranty period.

NOTES: This is normally a minor issue. Coffee pot and microwave use are intermittent. We use a low amp electric heater so the Xantrex doesn’t cut the charging current. The only times we have problems getting the batteries charged is when we use the convection oven to bake, because it is a large electric heater and the batteries do not charge when it is running. The new XTR31 batteries seem to be working fine. It would be nice to be able to turn on higher power electric heaters in the morning rather than turning up the propane furnace.

When I run my generator I turn the inverter off. I’m confused why you need to invert when the generator puts out A/C current to all your appliances including the converter.

[DavidMort]

Originally Posted by Bill Davis

When I run my generator I turn the inverter off. I’m confused why you need to invert when the generator puts out A/C current to all your appliances including the converter.

Inverter is not running, Xantrex automatically shuts off inverter when on generator or shore power. Turns it back on when external power is lost. The question is about power management which the Xantrex does when running on generator and charging the battery.

[Whalenss]

Hi David,
Electrical stuff not my strong suit, but I think I understand what you are asking.

Interested to see if someone knows.

Pat

[FOURWHL]

I noticed my 110v loads deduct from charging amps as well. I assumed its limited by the cable / 30A breaker feeding the xantrex. Regardless of what's supplying the AC it's still wired through that breaker and therefore limited.

[DavidMort]

Additional information: This morning it was warm enough so that we could use the heat pump option on the AC unit. It draws around 10 amps when the compressor is running. This had no effect on the current draw shown on the Xantrex. Xantrex was charging @100 amps DC and small appliances running so about 24 amps AC.

The Plex monitor apparently is looking at current readings from the generator itself and it show 34 amps.

Implies that the second line is pass through as described in the Xantrex manual and powers the two AC units. For my purposes would be nice to have plug powered off that second line.

[mookieblaylock]

The AC units are wired direct to shore/generator...they do not connect through the inverter at all. There are two 30A A/C circuits feeding the inverter, and downstream A/C loads can pass through on either one. I believe these two inverter outputs/buses are generally split with the driver’s side GFCI outlets and the microwave on one and the passenger side GFCI’s and the fridge on the other. The only thing I can think of that might help (short of moving circuits around in the breaker panel) would be to try plugging in your coffee pot on the other side of the coach. If you’re seeing them charger output drop when you use both the coffee pot and the microwave, then that implies those circuits are on the same 30A bus. See if it drops when the coffee pot is plugged into an outlet on the other side.

[joet19711]

Originally Posted by mookieblaylock

The AC units are wired direct to shore/generator...they do not connect through the inverter at all. There are two 30A A/C circuits feeding the inverter, and downstream A/C loads can pass through on either one. I believe these two inverter outputs/buses are generally split with the driver’s side GFCI outlets and the microwave on one and the passenger side GFCI’s and the fridge on the other. The only thing I can think of that might help (short of moving circuits around in the breaker panel) would be to try plugging in your coffee pot on the other side of the coach. If you’re seeing them charger output drop when you use both the coffee pot and the microwave, then that implies those circuits are on the same 30A bus. See if it drops when the coffee pot is plugged into an outlet on the other side.

X2 Except for me the outlets were not split, so i split them.

Drivers side: Dinette, bathroom, and one in the bedroom
Passenger side: one in the bedroom and two in the kitchen, + one in a storage bay.
For me,I plug toaster/coffee pot on dinette side and have no problem.
Check and see if they are split so you can compensate for the load.

[DavidMort]

Thanks for the ideas. I’ll check the outlets tonight when we run the generator.

[DavidMort]

All the outlets are on the Xantrex circuit. If you split circuits off would they be powered when running on the inverter? Best solution would be to have the correct 50amp Xantrex installed. That would give me at least another 25 amps to use without effecting the charging rate. Around $1500 if I install it myself.

[mookieblaylock]

There are two separate inverter output A/C buses that map directly to the two incoming 30A A/C feeds. The suggestion was to balance the loads between the two such that you could put some high load appliances (e.g. coffee pot) on bus 2 so the charging capability (sources from input 1) was not impacted. All the outlets in question should be off the inverter and would remain there.