Battery storage and charging

[Capt Blue]

I have solar on my 16' Bambi. Will that keep the AGM batteries sufficiently charged during the Winter. I keep my rig outside and gets afternoon sun.

Any thoughts?

[tjdonahoe]

It should

[uncle_bob]

Originally Posted by Capt Blue

I have solar on my 16' Bambi. Will that keep the AGM batteries sufficiently charged during the Winter. I keep my rig outside and gets afternoon sun.

Any thoughts?

Hi

It might. Better to simply disconnect them.

Bob

[ROBERT CROSS]

^
X2

Why folks want to charge batteries that aren't being used is a mystery.
The 'mantra'.....Charge fully and disconnect.

Bob
🇺🇸

[Capt Blue]

So, turning the battery disconnect switch to off inside the '21 Bambi would be sufficient? I'd prefer not to physically disconnect the battery cables.

[uncle_bob]

Originally Posted by Capt Blue

So, turning the battery disconnect switch to off inside the '21 Bambi would be sufficient? I'd prefer not to physically disconnect the battery cables.

Hi

It very much depends on which switch we are talking about and how your particular example is wired. If we're talking about the use / store switch then the answer is always no. If we're talking about a big red rotary switch then the answer might be yes (depending on how it got wired).

Bob

[SlowPokePete]

Originally Posted by ROBERT CROSS

^
X2

Why folks want to charge batteries that aren't being used is a mystery.
The 'mantra'.....Charge fully and disconnect.

Bob
🇺🇸

So as a new AS owner, I really do find the conflicting information frustrating.

Colonial told me when I left with my 2020 GT that no problem, the solar would keep my batteries charged.

Then, a phone call a few days ago to the tech department I was told that I should plug it in using a dogbone to get my 50 amp down to 15 amp outlet because of cloudy days or when the snow starts to fly.

Bob, I like your answer the best but just want to clarify...

Can I simply disconnect the negative terminals on both fully charged AGM batteries, leave them mounted in the battery box all winter, and sleep at night without worrying?

Thanks...

SPP

[Silvr_Bullet]

If your Airstream is outdoors in upstate NY I wouldn’t leave them in your trailer especially with no Solar or electric hookup to keep them monitored and charged. If they are not kept fully charged they can freeze. Me speaking, I would and I did remove them, I recently upgraded to Lithium’s and I remove them too.

[ROBERT CROSS]

Originally Posted by SlowPokePete

So as a new AS owner, I really do find the conflicting information frustrating.

Colonial told me when I left with my 2020 GT that no problem, the solar would keep my batteries charged.

Then, a phone call a few days ago to the tech department I was told that I should plug it in using a dogbone to get my 50 amp down to 15 amp outlet because of cloudy days or when the snow starts to fly.

Bob, I like your answer the best but just want to clarify...

Can I simply disconnect the negative terminals on both fully charged AGM batteries, leave them mounted in the battery box all winter, and sleep at night without worrying?

Thanks...

SPP

With my Lifeline AGM's I ended up doing just that.
For the first couple years of use I schlepped'em down to the basement.
That got to be a real PITA, I ended up charging fully, removing them from the circuit, (I have a full disconnect switch) and waited 'til Spring. They lasted 11 yrs and are still in use as back-up for the sump pump.

The BB Lithiums are following the same routine.👍
I do keep track of the SOC, better safe than sorry.

Bob
🇺🇸
31* today.

[SlowPokePete]

Originally Posted by ROBERT CROSS

I do keep track of the SOC, better safe than sorry.

Bob
🇺🇸
31* today.

Assuming SOC means state of charge, how do I do that with the batteries disconnected?

SPP

[ROBERT CROSS]

Originally Posted by SlowPokePete

Assuming SOC means state of charge, how do I do that with the batteries disconnected?

SPP

I use a 'disconnect' switch which isolates the batteries from all loads.
The Victron 712 reads battery state before the connection to the AS.

Bob
🇺🇸

[dznf0g]

I run 3 cutoff switches. The victron battery protect cuts off the house loads, leaving solar and brake actuator live. I have a solar cutoff, leaving all other systems active. And the OEM switch which is pictured by robert cross, is now a battery isolation switch, which shuts the trailer down completely.

[uncle_bob]

Hi

Yes batteries can freeze. A fully charged lead acid will freeze somewhere around -80F. That's not the wind chill temperature, it's the thermometer temp. If you expect your storage location to get that cold and stay there, indeed you should take precautions. Indeed there are a *lot* of things in your trailer that are not rated for -80F ....

You will find all sorts of statements like "below -45F" (since the thermometer rarely / if ever goes that low ) for the damage temp when fully charged.

Battery self discharge slows down when the battery gets cold. If the battery is disconnected, self discharge is all you need to worry about.

Discharge due to parasitic loads only stops when the battery is fully disconnected. Parasitic discharge can flatten a battery in under a month.

Bob

[Buckless]

Right on Mr. Bob