Question re: solar and lithium battery

ColinLarkin · September 10

Hello. We recently purchased a new Tab400 and have been loving it. I am happy to be part of this awesome community,

Last weekend, we were out camping off-grid and our trailer’s power basically quit working. The Alde system said it was because we were at 10 volts.

I’m still learning about the new system and I guess I’m confused.

Why would the voltage be so low that the systems wouldn’t work even though our battery was showing a charge of 65%?

Do I need to change some settings so things will still function below a charge of 65%?

Thank you!!!

Tabnero · September 10

what type batteries do you have

ColinLarkin · September 10

We have one Battle Born 100AH Lithium battery.

AnOldUR · September 10

ColinLarkin said:
Why would the voltage be so low that the systems wouldn’t work even though our battery was showing a charge of 65%?

How are you determining that your at 65% charge? If it's from a shunt, chances are you need to reset the state of charge to 100% after fully recharging.

pthomas745 · September 10

What year trailer is your "new" trailer? Most 400's would have at least 200 amp hours of battery available. And, in your trailer, you should have a Victron solar controller, and along with that, you have access to the Victron App, which will show you information about the status of your battery.

If you have not done it...open up the complete battery area and see exactly what you have: take pictures if you want. Tell us if you have the Victron app. Or, a multimeter.

ColinLarkin · September 10

Thank you for your input. It's appreciated. I have a 2025 400. I do have the Victron App and a Victron SmartSolar and a SmartShunt and the1 100AH battery.

Marceline · September 10

ColinLarkin said:

Hello. We recently purchased a new Tab400 and have been loving it. I am happy to be part of this awesome community,

Last weekend, we were out camping off-grid and our trailer’s power basically quit working. The Alde system said it was because we were at 10 volts.

I’m still learning about the new system and I guess I’m confused.

Why would the voltage be so low that the systems wouldn’t work even though our battery was showing a charge of 65%?

Do I need to change some settings so things will still function below a charge of 65%?
Thank you!!!

Your Victron battery monitor was probably not properly synchronized and is giving you bad data. As someone else said, when you get home, plug in your trailer, and then synchronize only when you're 100% sure that the battery is fully charged.

https://www.victronenergy.com/upload/documents/SmartShunt_IP65/9172-Manual_BMV_and_SmartShunt-pdf-en.pdf

ColinLarkin · September 10

Thank you!
I will try that.
So, that would potentially result in low voltage even at 65%? Would that cause the 65% to be inaccurate?

Marceline · September 10

ColinLarkin said:

Thank you!
I will try that.
So, that would potentially result in low voltage even at 65%? Would that cause the 65% to be inaccurate?

The battery monitor measures the current going in and out of the battery. The default setting on the monitor assumes that a battery is fully charged when it's first connected to the battery. So if the battery wasn't fully charged when first connected, the monitor was never giving you correct readings.

WayneW · September 10

The monitor certainly needs to be correctly synched to know where you’re at, but perhaps the bigger issue is that the battery voltage was at 10v. Regardless of what the monitor thinks, the battery was low.

Battery management while off-grid is a whole new learning curve. Was the battery fully charged when you left? Were you getting full sun and did the solar panel get the battery recharged each day? How many days were you out? Did you use your inverter? Did you run the stereo and/or television? Did you pre-cool the fridge? Ambient temp?

The single 100ah battery doesn’t have a lot of capacity, and depending on the answers to the questions above, maybe you simply ran out of juice. As I said, off-grid camping and power management will take some time to learn. Getting the monitor synched is just the beginning!

Bill&Suze · September 10

@pthomas745 mentioned checking the battery with a multimeter. This would be very helpful and if you don't have one, it's something you should have. Use it to check the voltage of the battery prior to plugging in to shore power and then after it's been plugged in for a day. Our T@B 400 charges fully to 14.2 volts during active charging daily via solar and then settles down to around 13.27 at rest so use either of those numbers to determine with a multimeter when you think you're fully charged during active charging or resting and then synchronize. See p.16 of the SmartShunt manual that @Marceline provided above. If the Alde actually indicated your true voltage as 10V your battery was just about fully depleted.
12V Lithium Battery Voltage graph

Lifepo4 4s Voltage Chart Sales Shop wwwafaqcmcom

ColinLarkin · September 11

Thank you all! What a great community!
We previously had a 320S for 8 years camped off the grid around pretty much exclusively and didn't have many power issues other than having to replace the lead/acid battery every few years. BUT, we didn't use the refrigerator. I think our power needs were pretty minimal. Compared to our fancy new 400.
I was wondering, did some of you add another battery? Looks like there's room under the bed.
I appreciate all of your input and will let you know how things go!

Gomers2 · September 11

@ColinLarkin, just to say it another way: the victron smartshunt does not measure the voltage of the battery, it counts how much current flows into and out of the battery, so it keeps track of how much charge you have. But in order for this to be accurate it needs to be calibrated, or synchronized as they say. Plug in and charge your battery until it is fully charged, then go into the apps battery settings menu and tap the Synchronize button (sorry I'm not with the camper or I could send you a screenshot but it's fairly easy to find). At this point the smartshunt should read 100% and that matches your full battery. With respect to adding a battery, of course you can add another and it is recommended to add the same make and model. They are not cheap. Before you do that try managing your usage a little more effectively to see if you really need it. It certainly depends on where you camp, whether you have power at most places etc. You can also add a portable external solar panel which helps tremendously because those flat panels are quite effective, especially in direct sunlight, and you can move them around to get some charging in a shaded site.

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Question re: solar and lithium battery

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