🟢 Airstream Lithium battery drain

This seems to be a real problem with new Airstream trailers…

Hi Mike,

I have a lithium battery question for you.

The following summarizes our battery situation that occurred after our return from the International Rally in Rock Springs, WY:

1. We placed the Airstream in a covered storage area that is completely dark, on or around July 3, 2023.

2. We have two Lithium Viper Power Cell Batteries (Expion EV-V120-2A) providing 240 Amp-hours.

3. We also have two solar panels on the roof of the Airstream.

4. When the Airstream was placed in storage, the battery indicator was at 100%.

5. I turned the battery disconnect under the front right bed (passenger side) to “off”.

6. I returned to the Airstream on September 27, 2023, and turned the battery disconnect to “0n”.

7. The battery indicator showed 8% battery capacity.

8. My understanding is that a lithium battery loses 2-3% of charge/capacity each month when turned off, so I was surprised at the lack of capacity.  Based on these numbers, I thought I would only lose about 6-9% capacity over the 3 months it was in storage.

9. I left the Airstream in the totally enclosed shop area and did turn the fridge on with propane.  I went back the next day and the battery showed 0% and the front jack would not operate.  

10. I then manually operated the front jack and hooked up to the Airstream and took it home and plugged it into shore power overnight.

11. By morning, the battery indicator showed 100%. 

12. We have traveled with the Airstream since then and have not had problems with the battery staying charged.

13. I am thinking the lithium battery should have had more charge in the short period of time it was in storage and wondering if I should be doing something differently.

14. Any thoughts you may have would be greatly appreciated.

Thanks, Jerry

Hey Jerry,

Great summary of what you’re experiencing, and you are not alone. I’ve received at least half a dozen emails and posts from other Airstream owners complaining about the same problem.

Every Lithium battery I’ve studied online as well as in my shop has a very low self-discharge rate. In fact, most of them lose only 1% to 2% SoC (State of Charge) per month. So you should be able to park your Airstream for the winter, turn off the battery disconnect switch, and not worry about it. In fact, if that disconnect switch actually disconnected all 12-volt loads in your trailer the Lithium batteries should lose less than 10% SoC (State of Charge) after sitting unused for 5 months.

Here’s what the manual for your Expion battery states

As you can see, they’re suggesting you can do at least 6 months of storage without significant loss of charge. So something elsel is using that power.

You must have a substantial 12-volt parasitic current

To lose 92% of your battery charge in 3 months suggests a SoC loss of around 1% per Day. Since you have 240Ah of battery storage, that’s 2.4Ah per day. Divide that by 24 hours in a day we come up with 100mA (100 milliamperes or 0.1 Amperes) of parasitic current. That’s the typical parasitic current I’m calculating from other Airstream owners with this problem.

In theory, every 12-volt load is turned off in your trailer when you use the battery disconnect switch. But something is still drawing power. And I’ve not been able to figure out exactly what that is.

I’m sending this to my Airstream engineering contact

I’ve not been able to determine exactly what is drawing this parasitic amperage, but it’s not obvious. So either Airstream has an answer as to what’s doing this, or someone needs to get an AC/DC Clamp Ammeter on their Airstream battery conductors to find out where the current is going.

Do you have an Airstream with this problem and an AC/DC Clamp Meter?

If so, contact me and I’ll walk you through a test procedure that should reveal what’s drawing this parasitic current, and hopefully a way to disconnect it. Until then you’ll need to disconnect the battery in your Airstream while in storage. If not, then you will need to add a small battery charger (1 amp or so) to keep your Lithium batteries charged. But that should be a last resort.

I may have a battery disconnect switch workaround

But I don’t want to publish this info until I know for sure. So please email me any details on your own Airstream battery discharge problems and I’ll try to make some sense of it all.

Let’s play safe out there… Mike