Auxiliary Battery in RAMBOX

Torq · Post by **Torq** » Mon Jul 15, 2019 1:04 am

I think I've settled on mounting an auxiliary battery and switches for lights and camping stuff in the RAMBOX. I'm using a National Luna battery isolator so non-matching batteries should be ok. I'm having a hard time with research on a small car battery that will fit in the RAMBOX. I think deep cycle would be ideal. Anyone have any ideas on a battery that would fit comfortably in there?

Probably doesn't change anything, but I have the RAMBOX divider kit and I'm probably going to mount the solenoid or switch panel to one of the dividers.

Jack187 · Post by **Jack187** » Mon Jul 15, 2019 5:46 pm

Considering something similar. I'd be interested in how it turns out. Good luck!

Oilbrnr · Post by **Oilbrnr** » Mon Jul 15, 2019 5:53 pm

Pretty sure that you're committed to a wet lead acid given that the Luna is just a smart(er) direct connection relay. There are a variety of AGMs that would probably fit, but they require a different charging profile than what your going to get from the engine system. RedArc DC-DC would allow you to do that though.

Torq · Post by **Torq** » Fri Jul 19, 2019 7:39 pm

Oilbrnr wrote: ↑
Mon Jul 15, 2019 5:53 pm
Pretty sure that you're committed to a wet lead acid given that the Luna is just a smart(er) direct connection relay. There are a variety of AGMs that would probably fit, but they require a different charging profile than what your going to get from the engine system. RedArc DC-DC would allow you to do that though.

What about the charging profile from the RAM alternator is no good? I'm a EE by profession, but batteries are not my forte. Across the National Luna solenoid, I thought the secondary battery got a similar charge current at 0.7V lower (from the diode drop). I don't know enough about AGM batteries to understand why they care about that. I'm not stuck on AGM I guess; the auxiliary will take just as much of a beating in the RAMBOX as the stock battery will in the engine compartment.

Oilbrnr · Post by **Oilbrnr** » Fri Jul 19, 2019 10:53 pm

I pretty sure that AGM's require a higher finishing voltage at a much lower current than wet lead acid. I know that it was enough to stop me when I investigated to know that RedArc was the proper solution vs. NL or IBS which is what I have in my Lexus. It has a charging profile for AGM.

Advantage of AGM is that they come in a bigger variety of shapes, and you can mount them in any direction.

Colibri · Post by **Colibri** » Sun Jul 21, 2019 11:29 pm

I can’t speak to all brands of agm batteries, but I’ve installed a ton of odyssey’s in my vehicles and customers over the years and never seen any troubles with them. I know some people on this forum have had poor results when running multiple battery setups with agm’s though, so maybe they can chime in. But never had an issue in my 09. in the last ten years I’ve only had 2 batteries in it, and the first one lasted about 7 years. And even the most basic stone age truck I have (an old m35a2) has been using dual odyssey’s for years without issue.

Also, the alternator on our trucks is dumb, it’s the ecu that regulates voltage in the system.

Reloaderguy · Post by **Reloaderguy** » Mon Jul 22, 2019 12:21 am

I've been running a Yellow top off of a Blue Sea ML-ACR for two years now.

Oilbrnr · Post by **Oilbrnr** » Mon Jul 22, 2019 2:11 pm

Found this in a quick search, but it goes along with what I've read prior when researching:

As with all gelled and sealed units, AGM batteries are sensitive to overcharging. A charge to 2.40V/cell (and higher) is fine; however, the float charge should be reduced to between 2.25 and 2.30V/cell (summer temperatures may require lower voltages). Automotive charging systems for flooded lead acid often have a fixed float voltage setting of 14.40V (2.40V/cell); a direct replacement with a sealed unit could overcharge the battery on a long drive. (See BU-403: Charging Lead Acid.)

My point, while maybe moot to this discussion, is mixing battery types and age with a direct (relay) link between them and using the charge profile of the OEM truck system. When you spend a couple hundred bucks on a dedicated second battery for other uses as the OP noted, you don't want to shorten the life of either it nor your starting battery. Hence my suggestion of the RedArc solution vs. IBS, Luna or Blue Sea which are all direct connect rather than a voltage compensating approach.

Whatever floats your lead acid.

Torq · Post by **Torq** » Wed Jul 24, 2019 11:18 pm

If a lead acid battery can survive in the engine compartment, it'll do fine in the RAMbox. I'll look for something that's the right size and go with it. Too late for me to switch to RedArc system now. I need to finish the installation and test phase of this build in the next few weeks.

Torq · Post by **Torq** » Sat Sep 14, 2019 8:19 pm

Well, I was wrong. That battery is toast. I wonder if an Optima yellow top will fit in there.

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Post by **DamageWagon** » Wed Sep 18, 2019 8:32 pm

I tried to think of a nice way to say it. Optimas are never the right choice. Odyssey or Deka. If you’re in Portland there’s a Deka facility in the north side by Danner Boots.

Torq · Post by **Torq** » Wed Sep 18, 2019 9:37 pm

DamageWagon wrote:I tried to think of a nice way to say it. Optimas are never the right choice. Odyssey or Deka. If you’re in Portland there’s a Deka facility in the north side by Danner Boots.

I had Odysseys in my Land Cruiser. Was pretty happy with them and they come in a smaller size. They're definitely on the list.

Why the aversion to Optima?

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Post by **DamageWagon** » Wed Sep 18, 2019 9:43 pm

I have gone through a lot of Optimas. They die quickly and pretty easily. We had them in emergency vehicles and the rate they would go out was not coincidental. 4 batteries in one vehicle would go out in somewhere between 2 months and a year. Had a few go out on me in different vehicles. Had one bulge and boil it’s internals with no warning. They’re cheap batteries made in Mexico with low quality that sells because of their name.

KevinABQ · Post by **KevinABQ** » Thu Sep 19, 2019 11:59 am

So once upon a time they were good?

Post by **DamageWagon** » Thu Sep 19, 2019 1:54 pm

KevinABQ wrote:So once upon a time they were good?

Once upon a time.

Mule007 · Post by **Mule007** » Thu Sep 19, 2019 2:32 pm

IMO the Interstate Megatron 2 with 850 CCA has also proven very reliable with a good warranty

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