Battery Charger on dual batteries?

[ARedmon]

My 2014 RAM diesel sometimes sits for a few weeks between drives. I was thinking of using a "trickle" charger on it while it's sitting. I'm guessing that I should simply hook the positive clamp to one of the two batteries and the negative clamp to the opposite battery in order to keep both batteries charged?

 

[w6pea]

I have a friend that put a solar panel with a 12v Cigarette Lighter plug on it. He attached it to the sun visor and wired it directly to the battery under the hood. It works great he is on a Sea Going Tug. He's out on the water several weeks at a time.

Look here; https://www.batterystuff.com/solar-chargers/
Good luck.

 

[DavidC]

A Battery Tender would be a better idea. Have had one on mine for years.

Dave

 

[BigPapa]

No need to hook up both batteries to the charger. They are already connected. You charge one, you charge them both. Just look at the alternator. It's only connected to one battery, correct?

 

[Mingoglia]

Yes, hooking to only one is all that's needed. The batteries are hooked in parallel, positive to positive, negative to ground so you charge one, you charge both.

 

[TCDiesel]

I use 2 watt solar charger on front dash, I made My own disconnect to remove, works great. It won't be long and the solar panels will be installed in the windshield OE. the security systems needed to stay power up over long term take there toll on the batteries, AGMs batteries are just not made for slow drain life.

 

[kthaxton]

AGMs batteries are just not made for slow drain life.

No starting battery is, it is not an issue specific to AGMs.

 

[TCDiesel]

AGMs just cannot take the slow drain and High voltage charging form drain/dead state like other battery types, If you don't keep those AGMs fully charged YOU will be replacing them often if you live in 20F or lower temps.

 

[kthaxton]

Again, no "starting" battery can handle repeated discharges, AGM or otherwise. If there is a slow drain and repeated discharges, one needs a deep cycle battery.

While I have not experimented with slow draw on an AGM vs. wet acid starting batteries (cuz they aren't made for that), I lived in the mountains for 19 years (read: cold), in typical use (NOT constant draw however), AGM's typically lasted 3-5 times longer than wet acid batteries. In fact I found they were better in every way even with occasional discharge where they always recovered better than a wet acid.

In my old off-road truck, I had a dual battery setup. One Optima Red Top for regular starting/operating duties and one Optima Blue Top (Deep Cycle) for an electric cooler and air compressor. I basically drained that battery every night (on multiday, off-road excursions) running the cooler and I did this many, many times and it lasted me a long time. But, it survived this treatment.....because it was a deep cycle, the fact that it was an AGM, made it a better deep cycle.

I'm not sure why our results differ, but this is the first I've heard anyone state what you've experienced.

 

[TCDiesel]

Optima batteries don't survive in MN -0 temps, I already replace My AGMs last year under warranty. 2 cold winters in My 13 thus the solar charger, this year I can tell its working in -0 temps after leaving it sit for a week it fires right up.I don't leave it sit much longer then 10 Days W/O starting and drive around. the only time it get used is our trips out west during winter Months, in the summer it used weekly or daily.

 

[kthaxton]

For reasons I can't explain, my results have been the exact opposite (except I do not have a slow drain on my batteries, if I did, I'd use a deep cycle).

Wet cell batteries were fairly consistent at lasting me only two years. I've had anywhere from six to over ten years (sold the truck before battery died) on my Optimas.

 

[TCDiesel]

Its the extreme cold and slow drain that kills em. then if you don't fully charge VIA trickle charge they prematurely died, slamming a bunch of energy into a dead cold battery doesn't sit well with em.

 

[kthaxton]

Its the extreme cold and slow drain that kills em. then if you don't fully charge VIA trickle charge they prematurely died, slamming a bunch of energy into a dead cold battery doesn't sit well with em.

and I can understand and agree with that, but I expect that out of any starting battery in those conditions, not just AGM. What surprises me is that you don't have this issue with wet cell starting batteries, in fact I would expect them to be worse.

 

[TCDiesel]

At time things don't conform to logic, they conform to experience.

 

[Mingoglia]

After years of refusing to pay the ridiculous $200 price tag, I purchased an Optima battery charger. More often than not Optima batteries can be recovered, if done correctly. There's a whole gray market of used Optima batteries. People have friends who work at the auto stores and give them the turned in batteries to be recovered. I just did one of my own. I spent a half a day with various chargers, even dumping 50 amps into it for long periods of time and couldn't get an Optima to hold more than 2-3 volts. Stuck the thing on my new Optima charger, and it recovered it and it's now like new. If I didn't see it myself I wouldn't believe it. I did this process about 2 months ago and the thing is still at 12.65 volts. I already replaced this battery when I thought it was dead so it's a loose battery with no load on it.

Mike

 

[Shadrach]

Unless it's real cold ( or you have weak batteries ) sitting for a few weeks won't drain the batteries enough to cause problems. I let mine sit for 2-3 weeks when it below freezing with no issues, a few months is a different story, then I use the battery tender.

 

[jacknife]

Get a battery minder or a charger that senses full charge and shuts off. that is what a battery minder does. i have had one hooked up to two deep cycle 6 volt hooked togather to provide 12 volt to 5 th wheel. No problems going on 3 yrs. Living in S Cal might make a difference. When I traded my 06 3500 in 14 it still had the original batteries in it and it would sit up to six wks at a time. I never did have a charger on them. Guess I was just lucky.Never had a set of batteries last that long.

 

[CWade]

My 2014 RAM diesel sometimes sits for a few weeks between drives. I was thinking of using a "trickle" charger on it while it's sitting. I'm guessing that I should simply hook the positive clamp to one of the two batteries and the negative clamp to the opposite battery in order to keep both batteries charged?

These posts are correct about the need to only charge one of the batteries because they are hooked together. Harbor Freight makes a "Float Charge" that is usually on sale for around $6. I own a dozen of them and use them on all my equipment all winter long. My truck usually sits from October until April when camping season begins. The inexpensive float charger does the trick, starts right up. The original Mopar batteries on my old truck lasted a couple months shy of 12 years doing this.

 

[NDanecker]

My 04 was a second vehicle for more than half its life so it sat for 1 or 2 months at a time without being started. Never found the need to boost it or charge the battery. It started every time even in some sub-zero temps. Sold the truck 10 years later with the original batteries that still started the truck in cold temps.