Battery: Let it hibernate?

[LuckyDuck]

For the last two years I’ve left the two batteries on our trailer, with no draw on them at all, through the winter. Same this year — they were fully charged when I parked it at the end of September. Today I checked the voltage and it showed 12.6. Unless I’m mistaken, a full charge is considered 12.7v, so they haven’t lost much. Dare I leave them for another three months or bite the bullet, pull them and bring them home to put on trickle chargers? Our weather rarely gets below freezing if that makes a difference. Another option is to bring the TT home from RV storage at some point and stick it on shore power for a day, which means uncovering it etc. Advice welcome. Thanks!

[stateboy]

I always remove them, charge them out in the garage, bring them inside and store at room temp. About three months later, I'll take them back to the garage for another charge (again at the lowest setting for my charger, which is 2 amps). I'll bring them back in until needed, which is usually another three months and run them for the summer.

I usually get about eight years from my batteries that way. That goes for the crappy riding lawn mower batteries too. The last mower battery went nine years before replacing with a 90-day warranty one from Wal-Mart. That one is on year four now.

This may not be the best way but it has always worked for me.

[JFlightRisk]

It's definitely a plus that they don't live in freezing temps. Yes, I believe a fully charged battery will show 12.65 volts, considering ambient temperature, and time at rest, so you're good. I store our TT next to our house, so it's readily accessible, but I still remove it, take it to the cellar, and hook up a battery maintainer in my shop. It's warm and happy, and although not a real concern, it's safe from anyone that believes it should belong to someone else.

I think yours will be fine, as there's no draw on it, and it sounds like it's still healthy. Just my opinion.

[Jagiven]

If it is under a cover, I would not bring the tt home.

Assuming your tt is at a public storage facility, I would bring the batteries home, put them on a battery maintainer, and return them when your ready for your next trip.

In 3 months down 0.1 volts, I would leave them on the tt, if it's in a safe environment.

[LuckyDuck]

Thanks all. The TT is in a safe RV yard a couple blocks away — part of our HOA community. I might be able to actually tow it the few blocks with the cover on — no public streets — but it would make more sense to pull them. I guess I’ll monitor and see how they hold. I’m thinking if they get to 12.4 or less, I should charge them for sure?

[MichaelO]

You could put a solar charger on it.

[mokurt]

This might help......
Observe the following values to assess the condition of the battery through the meter reading. A voltage value of 12.7 volts and above indicates a 100 percent charged battery. The voltage reading of 12.4 volts will indicate that the battery is only 75 percent charged. A meter reading of 12.2 volts or 12.0 volts will indicate a charge rate of 50 percent and 25 percent, respectively. Any readings below 11.9 volts will indicate a fully discharged battery, and damage may have occurred to the storage device. Voltage readings that are 10.5 volts and below show that the battery is severely damaged and needs to be replaced.

[TCNashville]

Originally Posted by MichaelO

You could put a solar charger on it.

This is what I do in the summer. In the winter I bring the battery home because we get well below freezing here, and leave it on my BatteryMinder trickle charger in the garage. This solar charger will keep your batteries topped off all year long in your environment. It's been a great little charger for me.
https://www.amazon.com/Battery-Porta...s%2C180&sr=8-6

[Grumpy]

Originally Posted by LuckyDuck

. I’m thinking if they get to 12.4 or less, I should charge them for sure?

Hook it up to your TV and let it idle for while and just sit and listen to the radio while topping off the charge.`

[LuckyDuck]

Originally Posted by Grumpy

Hook it up to your TV and let it idle for while and just sit and listen to the radio while topping off the charge.`

Grumpy — I thought about that, too! Wasn’t sure how much charge it would get from the TV just idling.

[Grumpy]

Your alternator output it is not dependent on speed only load.

Right from the web....

Alternator output is not rpm related. It is load related.

For example: when you start the car the engine is running approximately 1000rpm. This will be about 3000rpm for the alternator. The alternator senses battery voltage. When the battery voltage goes down the output of the alternator rises. If you turn on the lights or other electrical devices you will increase the electrical demand, the battery voltage will begin to drop. Again the alternator will sense the drop in voltage and increase its output. If you never raise the engine rpm the alternator would always keep the battery charged.

Alternator output is specified in volts and amps. The alternator is designed to keep the battery charged to at least 12.55 volts, with a maximum of approximately 14.5 volts. The amperage output is usually listed as the maximum output of the alternator. The latest alternators are capable of supplying at least 100amps with some vehicles equipped with alternators capable of 200 or more amps.

The physical size of the alternator limits the maximum amperage output no matter the rpm.

[LuckyDuck]

Originally Posted by Grumpy

Your alternator output it is not dependent on speed only load.

Right from the web....

Alternator output is not rpm related. It is load related.

For example: when you start the car the engine is running approximately 1000rpm. This will be about 3000rpm for the alternator. The alternator senses battery voltage. When the battery voltage goes down the output of the alternator rises. If you turn on the lights or other electrical devices you will increase the electrical demand, the battery voltage will begin to drop. Again the alternator will sense the drop in voltage and increase its output. If you never raise the engine rpm the alternator would always keep the battery charged.

Alternator output is specified in volts and amps. The alternator is designed to keep the battery charged to at least 12.55 volts, with a maximum of approximately 14.5 volts. The amperage output is usually listed as the maximum output of the alternator. The latest alternators are capable of supplying at least 100amps with some vehicles equipped with alternators capable of 200 or more amps.

The physical size of the alternator limits the maximum amperage output no matter the rpm.

Interesting! Another dumb question: Does it matter if I keep my battery disconnect switch closed while charging, or should I open it? Thanks!!

[TCNashville]

Keep it closed. All you want to do is charge the battery. If you open it all those little annoying parasitic draws will take the charge away from what you're putting in there.

[LuckyDuck]

Ah, of course. Thanks!

[ruralIN]

Originally Posted by MichaelO

You could put a solar charger on it.

That is what I do. A cheap one from Harbor Freight direct to the battery with one terminal detached so the charge stays at the battery.

[gypsmjim]

I don't believe in trickle chargers or battery maintainers as long as I have access to the trailer. But that's just me. Y'all can follow the consensus or do your own thing.

I have several garaged vehicles (boats and cars) that are in freezing garage temps all winter. They are still installed but disconnected. I charge them up with a smart charger religiously on the first of each month.

My last boat battery was 12 years old when I sold the boat. It was still good. My old car battery was just replaced last Spring even though it still checked out good. I do the maintenance but hadn't really checked dates and stuff. When I checked and found out the battery was 24 years old (a Sears Die Hard) I replaced it "just because".

My RV battery is installed in the trailer, which is kept on a mountaintop in southern NY. I don't bother with it because its not accessible to me, but I have a 100 w solar panel on it. The solar panel will still provide minimal charging as long as the snow depth is less than about 2 inches. Yeah, likely that's gonna happen.....LOL. At any rate, the battery is still 100% after 5 years.

[RetiredOne]

Originally Posted by gypsmjim

I don't believe in trickle chargers or battery maintainers as long as I have access to the trailer. But that's just me. Y'all can follow the consensus or do your own thing.

I have several garaged vehicles (boats and cars) that are in freezing garage temps all winter. They are still installed but disconnected. I charge them up with a smart charger religiously on the first of each month.

Your batteries are disconnected, which means there isn't any parasitic draw on them, like a chassis or house battery. As such, they will hold stable voltage for months in that situation. Then, once a month you put them on a charger, even though there's been no draw down.

Many people here leave their batteries connected, which is why they need a constant trickle charger, or leave their rigs plugged in.

My RV battery is installed in the trailer, which is kept on a mountaintop in southern NY. I don't bother with it because its not accessible to me, but I have a 100 w solar panel on it. The solar panel will still provide minimal charging as long as the snow depth is less than about 2 inches.

Wouldn't that be considered a trickle charger, since the battery is getting constant recharges from the solar panel every day?

[gypsmjim]

Originally Posted by RetiredOne

Wouldn't that be considered a trickle charger, since the battery is getting constant recharges from the solar panel every day?

Sort of. Half of the winter it is covered with more than 2" of snow, so its not charging at all. When it is uncovered, it only gets direct sunlight about an hour a day.

The solar was only installed because I don't have the ability to charge it once a month like the rest of them.

[ruralIN]

I'm talking about the $14.99, 1.5 W model. Just enough to keep it topped off without worry of overcharging. A minute or two to take it out of the basement compartment and hook it up and not worry about. Cheap enough I don't have to worry about somebody taking it.

[gypsmjim]

Originally Posted by ruralIN

I'm talking about the $14.99, 1.5 W model. Just enough to keep it topped off without worry of overcharging. A minute or two to take it out of the basement compartment and hook it up and not worry about. Cheap enough I don't have to worry about somebody taking it.

First of all, I am assuming that the battery is disconnected, because I doubt that 1.5 W will "top off" a battery that has a parasitic draw.

Secondly, you have to remember that solar only works less than 1/2 of the day, and even then during daylight hours with clouds and such the overall efficiency is relatively poor. My unit is just a single 100 watt unit and it barely keeps up in the Summer. Even under the best of conditions it doesn't put out 100 watts.

My objection to trickle chargers is that whenever I did that in the past (with a quality unit) I always had some fluid loss. In my case, although solar wasn't a perfect solution, it was better than nothing.

Why don't you give the 1.5 watter a try and report back the results. It would be interesting to view the monthly voltage data to see how its doing.