Don’t Be Like Me: Turn Off Your Inverter

TNOutback

I have a label I printed out not long after purchasing our 2020 400.  It says “turn off before leaving camper”, and affixed right above the nondescript button under the front seat that turns off the inverter.  Fast forward to sometime in the past week or two, and I had unplugged shore power to our camper and turned off the battery switch because it didn’t look like the weather was going to cooperate for a winter camping trip.

Today, my wife was walking past the camper in the driveway, and said she heard beeping coming from the camper.  Upon investigation, there were actually two alarms going off simultaneously:  the inverter was emitting a solid tone, and my Victron battery monitor was beeping a low battery alarm intermittently.  It took a while to figure out what was going on:  I had left the inverter button depressed, and over the course of 10 days or so, had drained the batteries down to 27% state of charge.  The inverter apparently has a low battery alarm in it, and I set the Victron to alarm at 50% SOC.  We apparently haven’t had enough sun for the solar to keep the batteries topped up against the slow drain of the fan in the inverter, owing in part to the fact the panels are pointing north with the camper in the driveway.

For reasons that still escape me, NuCamp wired the inverter directly to the batteries, in front of the battery switch, so turning the switch  off still does not isolate the inverter from the batteries.  I’m going to have to make a more prominent reminder and stick at eye level on the back of the door!  Don’t be like me; keep that inverter turned off unless you are using it or need power to those plugs.

Interestingly, even with the batteries drained that low, once I plugged in the shore power again, the power converter/charger still only put in 22 amps into the batteries; I would have expected a higher bulk charging rate, but that could be the line losses for having the converter so far away from the batteries. A mod is definitely coming soon to put a charger closer to the batteries!

Denny16

The inverter is mounted next to the battery, because of their high amp draw, they require a fairly short wire connection, routing this to the battery cut of switch, would require an even larger wire size, and a bigger battery cutoff switch to handle the extra amp draw.  It is best to leave the inverter turned off, unless you are actually using it, then turn it off afterwards.  

Even when not used, the large inverter in the TaB400 draws about 1 amp hr of power.  Without a load, the inverter is in standby, and some of its circuits are drawing power.  Fan kicks on when heat is generated from a load, not sure if it runs without a load present.
cheers

jrhamel

I make that mistake once also. Now I always keep mine off unless we need it. 

ColoradoSun

I had a similar experience with our new T@B 400. The inverter had been left on during our orientation at the dealer. After several days at home, with the battery switch turned off, I noticed the solar charge controller was never reaching the float mode even with plenty of sunshine. I finally realized the inverter was still on and after switching it off it immediately began reaching the float mode every day. 
I was surprised that the inverter even with no load was using that much power. I hope this won't be an issue using the inverter to power a CPAP machine plugged in every night for 7-8 hours. In our previous pop-up pickup camper we plugged the CPAP with a 12V adapter into a 12V DC (cigarette lighter type) and never had a problem. The T@B does not have that type of plug near the rear berth so the using inverter and 110 outlets by the bed seem the only option.

TNOutback

I at least know now that the inverter has its own low battery alarm, and I’ve now heard/seen for the first time the alarm from the Victron battery monitor.  I’ve also placed a more prominent reminder to turn off the inverter at eye-level on the inside of the camper door; if you are exiting the camper, the reminder is right in front of you!  

It also appears that the best the power converter can do for bulk stage charging is right at the minimally-acceptable level for the Harris 6V batteries.  I will be working on a mod solution like @rh5555 has done to place a charger closer to the battery bank.

Tampakayaker

ColoradoSun said:

I had a similar experience with our new T@B 400. The inverter had been left on during our orientation at the dealer. After several days at home, with the battery switch turned off, I noticed the solar charge controller was never reaching the float mode even with plenty of sunshine. I finally realized the inverter was still on and after switching it off it immediately began reaching the float mode every day. 
I was surprised that the inverter even with no load was using that much power. I hope this won't be an issue using the inverter to power a CPAP machine plugged in every night for 7-8 hours. In our previous pop-up pickup camper we plugged the CPAP with a 12V adapter into a 12V DC (cigarette lighter type) and never had a problem. The T@B does not have that type of plug near the rear berth so the using inverter and 110 outlets by the bed seem the only option.

If you're handy you should be able to install a 12 volt outlet.

Or you can purchase a 12 volt extension cord.

Michigan_Mike

ColoradoSun said:

I was surprised that the inverter even with no load was using that much power. I hope this won't be an issue using the inverter to power a CPAP machine plugged in every night for 7-8 hours. In our previous pop-up pickup camper we plugged the CPAP with a 12V adapter into a 12V DC (cigarette lighter type) and never had a problem. The T@B does not have that type of plug near the rear berth so the using inverter and 110 outlets by the bed seem the only option.

I have used a Resmed 9 CPAP and now have the Resperonics Dreamstation and have used both on the inverter in my 2019 T@B 400.  I also noticed the power draw and had contemplated power consumption while boondocking and in the event of extended cloudy weather.  To offset this I installed a cigarette lighter style plug in that corner, purchased the 12V DC adapter and use that for my CPAP unit while traveling or boondocking.  Works like a champ and that eliminated that concern.  Nothing worse than inadequate power, a drained battery and the panic that sets in when you can’t use your CPAP.  I learned long ago to be prepared, have a backup or spare plug that stays in the trailer.     

rh5555

I'm going to re-post the following, from an earlier thread, which might clarify things:

Our 2020 TAB has an AIMS PWRIX120012S inverter.  It powers 3 outlets (at bed, at front door and in bathroom). These outlets are dead, even when connected to shore power, unless you turn the inverter "on".  This can lead to problems:  You're on shore power and want to use one of the aforementioned outlets, so you turn the inverter "on" using the button by the front door.  When you leave camp, you disconnect shore power and the inverter now powers the outlets from the battery, drawing 1.2A even if you have nothing plugged into the 120V outlets.  You have to remember to turn the inverter "off" when you break camp!

AIMS has now superseded this inverter with the PWRIX120012SUL.  I haven't played with one of these, but my understanding is that it now automatically powers its outlets when on shore power, so no need to turn the inverter "on" in this circumstance.  Much better.  I don't know if any of these inverters are installed in TABs, but it will certainly add to the confusion when they do!

ColoradoSun

Michigan_Mike I have thought about doing that. Where did you wire the cigarette lighter style plug into power? We have some USB outlets* in that cubby by the bed so I know there is some 12V power nearby. 
* I've seen adapters going from USB to a cigarette lighter style plug but I doubt they have the capacity to power a CPAP.