What is the baseline power draw, and how can it be reduced?

JHornby · December 2025

I have a 2021 T@B 320S. I notice when I have "everything turned off" (no lights, no refrigerator, no Alde heating, no TV monitor on, etc.) so long as the master battery connect is on, there is still a drain on my batteries. I am guessing it is about 1 to 1.5 amps based on how fast the batteries are discharging. When boondocking, if there is effectively no solar, this can drain all my battery capacity in a few days or so. Other than disconnecting the battery connect switch, is there something I am missing that I can still turn off to minimize this drain? Is this estimate of baseline power draw about right? Thanks.

AnOldUR · December 2025

We have a slightly older 320S, so there will be differences, but our parasitic drain is in the same range as yours. Other owners will surely give recommendation on devices that can be turned off or fuses pulled, but my opinion is that these are mostly convenience things that I'd rather have available. My suggestion is to upgrade your battery capacity to match both your parasitic and camping usage.

JHornby · December 2025

Thanks for the confirmation around what I have been thinking. We actually have 200 AmpHours of capacity via two lithium batteries, so normally that has been enough if the trip is less than 5 or 6 days even with just occasional solar. With good solar they don't get drained at all. We normally sleep in the towing truck, so I'm thinking that in many cases I can just disconnect the master switch when not using the camper as long as we are not needing to run the refrigerator. We just got back from a week in Mammoth Hot Springs in Yellowstone and had been counting on just using the fridge as an "ice box" with bottles of frozen water to keep things cool, but it rained all week and never got cold enough to even do that! And of course almost no solar the entire week! Crazy stuff. I think my solution is turn off the switch if necessary.

swiftwave · December 2025

The baseline power draw on my 2020 T@B 400 has been reduced to 0.15 amps according to my Victron shunt.

The stereo used to draw power even when it was off. After installing a switch on the power supply line to the stereo, that parasitic draw was reduced to zero. Before I completely removed the television, it also had a parasitic draw. Installing this inline switch enabled me to reduce that draw to zero as well:
https://www.amazon.com/dp/B01D66D9PM

I believe the remaining 0.15 amps is being consumed by the two propane / carbon monoxide detectors connected to the battery. The propane fridge also has a tiny 12V draw.

pthomas745 · December 2025

If you have installed solar, the Victron app will show you the "parasitic drain". With everything "off", you will be able to see the negative values for "current" and "watts" and have a specific value.

In my 2017, the "current" value from my Victron shunt, with the battery switch on and everything I can turn off is off, my "current" is a -.24 of an amp, or about 3 watts. So, about 6 amp hours per 24 hours.

Back in the "old days" when the campers were made of iron and we only had 40 amp hours of "usable" power from our 80 amp hour lead acid batteries, this was a "lot" of parasitic drain.

So, have a look at your Victron devices (if you have them) and you can get a pretty big idea of your "drain".

With 200 amp hours of lithium, and a 6 amp hour a day drain.....your battery could probably last a month before reaching 180 amp hours from that setup.

What fridge do you have? The two way fridge's power use is pretty well established at "around" 25-35 amp hours per 24 hours. As you say, that gives you several days of fridge usage with "occasional" solar. Even if you just replaced half of that 25-35 amp hour fridge usage, your 200 amp hour lithiums should be still in a decent state of charge for even more than 5-6 days.

Not a bad strategy to turn the fridge off overnight if you need to save power.

So: what fridge do you have? Do you have a Victron shunt? If you can show us a photo of your Victron solar controller status page, we can help you decode the numbers you see with the "battery switch on and everything off".

JHornby · December 2025

I have the newer fridge that only runs on electric. I don't think I have a shunt. (Not really great at this electricity stuff.) I have a victron app that can see whatever the NuCamp installed Solar Controller puts out, which I mostly use to see how many amps are coming in off solar, but when it comes to figuring out the state of charge of the batteries, I just push some button on the Lion Safari batteries that has some sort of idiot lights on top of them that shows state of charge wherein 5 lights - full charge and 0 lit up would be zero, and there are 5 lights total on each battery. So if you get down to say 1 or 2 lit up on each battery, you are in danger of running out of power. I am attaching a snapshot of the app output after I turned off the electric heat I have running off shore power in my garage right now to dry the cabin out after our last trip. Obviously there is no solar input because the 320S is inside the closed garage.

Grumpy_G · December 2025

The way the solar controller is installed in the T@b (and pretty much all RVs) is that it only connects the solar panel and the battery, the load terminals are not connected. The loads (lights, fridge, TV etc.) connect directly to the battery (via the fuses) so the solar controller is in the dark (see what I did there ?

) about how much current flows out of the battery. Hence the load output is always zero and it doesn't help with troubleshooting. Depending on the exact model of battery it might have bluetooth monitoring which can give you a pretty good reading of actual current draw.

As for a baseline current draw that depends a bit on what is installed in the trailer. My 2015 "idles" just shy of 0.3 A with TV, Radio in standby, CO/propane detector, a simple battery monitor and the "night light" in the bathroom. The solar charge controller consumes a little power from the battery when the solar panels do not work.

JHornby · December 2025

That makes sense. The batteries I have are pretty good, but just a bit too old for the direct monitoring via the bluetooth app that comes with the newer ones. All I really have are the idiot lights, but that's ok. I somehow estimated that the refrigerator could draw up to 1.8 amps, which over a few days can wipe out a lot of my 200 amp-hour capacity if not replenished in some way. Normally not an issue, but I think just not using the fridge if I can avoid it and shutting down the who master switch are the keys to my plan of attack now if there is not enough solar. If I try to rewire a bunch of stuff or switch out the Jenson and so on I'll end up screwing it all up and then I'll really be in a bind. Thanks again for the tips.

Maxcamp · December 2025

Some more sources of phantom power draw including Alde and 2cd solar controller:

https://tab-rv.vanillacommunity.com/discussion/18242/alde-phantom-power-draw-0-11-amps-or-18-4a-week#latest

pthomas745 · December 2025

If you have a Victron controller, that monitor is lightyears better than any of the bluetooth "monitors" in the batteries, especially if your Lion batteries are "old" as you say. The way that lithium battery voltages "drop" make any "blinky light" display or even various voltage readings very misleading.

The best investment to make to sort this out would be a Victron shunt. This would simply remove any question about "is 13.2 volts 70 percent of capacity or 30 percent capacity" of my lithium battery.

The shunt will give you much more and better information about exactly where your batteries are.

The next thing we should look at is the setup of your Victron solar controller. If you are not very familiar with the workings and readouts of the Victron devices, we should have a look at them with you and make sure your solar setup is correctly set up for charging a lithium battery. Show us the setup page.

Marceline · December 2025

JHornby said:

I have the newer fridge that only runs on electric. I don't think I have a shunt. (Not really great at this electricity stuff.) I have a victron app that can see whatever the NuCamp installed Solar Controller puts out, which I mostly use to see how many amps are coming in off solar, but when it comes to figuring out the state of charge of the batteries, I just push some button on the Lion Safari batteries that has some sort of idiot lights on top of them that shows state of charge wherein 5 lights - full charge and 0 lit up would be zero, and there are 5 lights total on each battery. So if you get down to say 1 or 2 lit up on each battery, you are in danger of running out of power. I am attaching a snapshot of the app output after I turned off the electric heat I have running off shore power in my garage right now to dry the cabin out after our last trip. Obviously there is no solar input because the 320S is inside the closed garage.

If you do a lot of camping without shore power, I recommend that you consider installing the Victron SmartShunt. It measures all power going in/out of your battery, removing the guesswork. I have an older Lion Energy battery with the idiot lights and they aren't really that useful. If your battery is in the tub at the front of the trailer, it would probably be better to get the IP65 (more waterproof) version. The 300A version of either shunt is fine for a T@B.

(Links included for information, only. I'm not necessarily suggesting purchasing from Amazon)

More information here: https://www.victronenergy.com/battery-monitors/smart-battery-shunt

JHornby · December 2025

pthomas745 and Marceline,

Thanks for the advice. I am pretty sure I have the Victron controller that connects the T@B solar panel to the batteries set up correctly for Lithium. When have decent solar it has not problems keeping full charge on the batteries. I couple things I have not mentioned: 1) I installed an port for a second portable solar panel into the diamond box that feeds into these batteries, and that has it's own controller. It seems to be working, but I usually don't want to bother hooking that up due to weather and theft considerations. We almost always are boondocking. 2) I had the NuCamp dealer install the two batteries inside the trailer, under the sink, as you can see in the photos attached. I did that so we had more room in the diamond box for other stuff, but also because I was concerned about theft of those valuable batteries. So I don't have to worry about moisture in terms of a shunt. It was a bit of a pain to get the wires necessary fed from the diamond box into the inside to the trailer where the batteries sit, but it's working. I will attach the photos so you can see the setup. I'll start looking into the shunt idea in the meantime. Thanks so much!

pthomas745 · December 2025

That is a nice setup! The shunt will help....and when ever you get the chance, the portable solar will definitely help out on helping the batteries keep up with that fridge power use we have been discussing.

JHornby · January 2

I ordered the Victron Shunt. Now watch me screw up the installation and burn down the house (trailer).

qhumberd · January 2

Have faith. It is just like working on a car battery with pos and neg terminals. I put in a shunt a while back and have limited electrical experience and it has worked just fine.

Victron has good support from all I have read so you will be surprised how straightforward it will be. the only downside is how often you may find yourself checking on those electrons! My wife tired of it real quick.

pthomas745 · January 2

@JHornby there is plenty of help available....relatively easy once you get your head around it. It took me a while, but I sorted it out. When you get your shunt out of the box just let us know and we can help.

Look this over.

https://tab-rv.vanillacommunity.com/discussion/9100/need-circuit-diagram-for-hooking-up-victron-battery-monitor

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What is the baseline power draw, and how can it be reduced?

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