Check Battery Level

rcwoodhams

Hello new owner here so feel free to mention any basics! Tag XL 2020.

We recently got caught out Boondocking on our third night (during the BC heat dome) without any power. The trailer has the built in solar panel and was in full sun so we were not expecting it to run out of charge as all we run is the fan, a few lights, phone chargers and the water pump on occasion. Maybe the radio too (and those lights never go off).

Before a trip, we plug into a standard outlet in the garage overnight but perhaps this isn’t charging enough?

Simply, I don’t think we have any way of checking the charge of the battery. I’ve finally started to get my head around the solar controller app (but doesn’t seem to tell me the battery charge level) and I’ve read about intergrating BMS but we’d like to try a cost considerate approach first. Also not really in a position to purchase a

Heading out on a 2 week adventure next week but quite nervous about our battery!

Sharon_is_SAM

You need to understand that you are simply using more Ahrs than your battery and solar combo can supply. That means you at least need more battery capacity. It is also helpful to understand how much power you are using. That means knowing how many hours you are using the fan and at what setting. I think there is a discussion here that identifies the number of Amps per fixture/appliance.

Basic battery: how many Ahr is your battery? Typically the dealer supplied battery is pretty stingy - 75 Ahr or less. Frequently using more than 50% of the capacity will reduce the lifespan of the battery, so you are limited to 37 Ahr before requiring recharge.
Many TaG owners use a100 Ahr battery with solar. Lithium allows you to discharge the battery beyond 50%, so you get more usable Ahr.

If you plan to Boondock you must monitor your battery. Monitoring voltage is not ideal as you must have a rested battery to get an accurate measure. A shunted battery monitor is your best bet and it will give you a real-time state of charge reading.

MrGGBrown

Sounds like you need a simple battery monitor, like this one --> Cigarette Lighter Voltage Meter LED/LCD Display Battery Low Voltage Warning (Black)(https://smile.amazon.com/Palumma-Charger-Adapter-Display-Battery/dp/B0773BYS6P/ref=sr_1_14?dchild=1&keywords=12v+battery+voltage+meter&qid=1627648456&sr=8-14)

It's not as good as a shunt-based battery monitor, but relatively cheap and easy.

rcwoodhams

Thank you both, yes being able to know the battery level will be very helpful and in the future we will look to upgrade the battery or have a generator.

This is our battery (as supplied): https://www.interstatebatteries.com/products/srm-24. Not too expensive to maybe just get another for the short term! Will the charge hold in storage though? Not sure what the Ahr is though? Amp hours is 81 (is that it?). Also, does the battery shut off at 50% or do we need to make sure we don't let it drop that low (hence the need for a monitor)?

On the battery monitors, I was looking at the Victron Battery Monitor with shunt (no LCD) which I'm happy to purchase ($100 CAD) but getting it in time for our trip seems to be an issue. There's some cheap options on Amazon I will look into today and hoping its simple enough to install myself! Cigarette lighter voltage reader seems like an easy and cheap solution, do you just plug it into the cabin outlet?

PS I think i actually have a 2021 tag XL (not 2020 as noted before). Sorry for all the questions!

HikinMike

Yes. Or you can plug it into the 12v in the galley.

I have this one: https://www.amazon.com/MOTOPOWER-MP0514B-Voltmeter-Charging-Indication/dp/B073VN9L3M/ref=sr_1_6?dchild=1&keywords=multimeter+for+car+battery&qid=1627673339&sr=8-6&th=1

When I get where I'm going, I open the battery box and lay it on the battery. I dont leave it connected because of phantom drain. I check the battery periodically.

rich67

We recently upgraded to a lithium 100ah battery. We also have the factory solar setup. One thing I have noticed is the battery charges up incredibly fast when hooked up to shore power or the tow vehicle...MUCH faster than with the original lead acid deep cycle that came with the camper. We are going to have a crash course in battery usage when we go on our year long trip coming up in a few months. We are going to be doing a lot of boondocking, but we also have a small generator with us for those times we need to top the battery off-if the weather is lousy or we have to use more power for whatever reason. To prevent some drain, I bought a shutoff switch for the TV so that LED doesn't stay on all the time, and we also will be keeping the hatch closed when not cooking in the back because of the propane solenoid drain. We have LED lanterns for outside when we are not inside, and we will only be using the minimal lighting inside (the small reading lights) at night. Charging phones and other items will be tasked with power banks. Those should keep those items topped off until we head to sites with hookups, then we re-charge the banks and are good to go for the next off-grid location. I'll keep you updated as we go about our trip to see how well the lithium performs with the factory solar setup.

rcwoodhams

Would love to upgrade to lithium but a bit pricy for us right now. I’d love to hear how it works out for you.

Following the advice above we were able to install a battery monitor before our trip. Thank you. It told us our battery is charging just fine but dies overnight with no additional draw (did a garage test). Since being away it shows us how good the solar panel is too (even when cloudy) but is down at 20% before we go to bed. Again not using any fans, lights, outlets as we came prepared but thankful the heat dome in BC is over! Posted a few more notes on a recent post on the same trailer and battery.

Pretty sure now our battery is a dud.

Also learnt that the Victron solar app tells you the battery voltage and aligns with our battery monitor but no percentage so I guess you need to know a bit about batteries to translate!

Sharon_is_SAM

@rcwoodhams - sounds like you need a new battery. https://teardrop-trailers.vanillacommunity.com/discussion/comment/11565#Comment_11565

Michigan_Mike

As Sharon noted running the fan at varying speeds will deplete your battery, as will running the pump, TV/DVD, etc. 50% puts you at around 12 volts DC and that becomes the danger zone. Repeated episodes of 50% and below will kill a battery. But there is hope as although you are new to solar you are paying attention and learning at the same time. If you have an AutoZone store nearby pull your battery, take it up to them and they will check your battery cells for free. At least you will know the health of the battery before buying another one.

Another thing to consider is how best to conserve energy when camping. Luci lights (available on Amazon) are excellent solar powered lights and provide a means of conserving battery power. Another thing about solar charging is that using power during the day is better as your solar will replenish it and continue to charge during peak sunlight hours. You could also add an additional battery to bolster your energy supply and remove some of the anxiety that arises from issues like this. And even though you have a roof mounted panel you could also add a additional portable panel to improve and supplement the charge rate. I know firsthand how quickly a battery bank can be charged up after having spent 4 years out in SW Arizona off the grid. We had 470W of solar and 4 batteries and were able to get fully charged by 9:30-10 AM daily.

Good luck and am sure you will figure it all out as monitoring the voltage and getting acclimated to better means of conserving energy pays dividends. I know the feeling as I use a CPAP unit and panic sets in when the power is in short supply.