When is a beasty 31M battery worth it?

[ntsaint]

The mixed results on this battery are strange. My current Diehard Group 31 is 2 years old and works like a champ. Can run my ARB fridge on the most aggressive setting for 48 hours and then crank right up...and I also run LED lights quite a bit at camp.

I got it warranty replaced a few years ago because of a loose + post, but original (used for 1 year) was just as strong.

 

[fireball]

I have a fancy expensive dual battery setup like Brian posted above. I don't really recommend it. It's overkill for what we do, i.e. usually run with others and only stay put 1-2 days max at a time.

A big grp31 main battery is a nice upgrade and is much less expensive than the dual battery system. If I did it over again I'd just do that.

FWIW, I have dual Sears DHMP batteries, the main grp31 was replaced after 1 year under warranty because it wouldn't hold a charge. It has been working fine the last 4 months or so, but the truck is also driven semi-regularly now. It used to sit for extended periods, with the monthly trickle charge from an appropriate charger.

 

[OregonLC]

^ Same here. i've given up on the Diehard Platinum 31 and have posted elsewhere my suspicions that our trucks don't get those batteries what they need for charging. i've killed 2 (3 really) through sulfating in my truck and I've not been able to revive them.

Were you using one of the Odyssey recommended chargers?

Been thinking about getting one of these ProMariner chargers, but if it doesn't do any good...

 

[uHu]

That looks like a seriously good charger, probably an overkill, but it's on sale right now, half price. It has the AGM setting, which is crucial for AGM batteries.
But, using an AGM in the truck without increasing the voltage of the alternator is a bit useless, as the battery will never be fully charged except when using the external charger. An agm battery needs around 15 volts to charge fully, and the alternator gives only 14.3 or thereabouts.
But then, having the system voltage increased to 15 volts means that bulbs etc will have a shorter life, (and shine brighter if not LED).

AGM is a good technology, but it has a higher charge voltage while the discharge voltage is the same as on standard batteries, and I've even seen some with a lower discharge voltage. So, with the bigger span between in and out volts, it's not the perfect automotive battery, unless the vehicle is designed for it.

What do people here do to keep the AGMs fully charged?

 

[stinkyfj60]

I ran an AGM in my FJ60 with the stock alternator... and it worked wonderfully, for years. i never had a problem keeping it charged; it stated every time no matter how long it sat or if the temps were 80*F or -30*F it was one of the spiral cell Exides.

i just dropped a 34R DieHard AGM in my 100; we'll see how that turns out

 

[wngrog]

Mine was dead this morning after listening to my Rebels get smoked last night.

My new toy came in handy

 

[Sandroad]

AGM batteries are widely sold and used in the automotive market. For most applications now, that's the technology of choice. The DHP Marine 31 does need a high charging voltage, backed up by some serious amperage to fully charge. The tech sheet from the Odyssey line is pasted below and the 31M-PC2150 is the equivalent battery. The LC charging system may not be able to keep the DHP from sulfating. For me, the jury is still out on that, but it looks like the battery needs 14.7 VDC (for a while) to fully charge and the LC nominally puts out somewhat less than that (like Uhu pointed out).

http://www.odysseybattery.com/documents/US-ODY-TM-002_1214.pdf

 

[Output Shaft]

The Sears AGMs were never designed to be installed inside a broiling hot engine compartment. Doing so is guaranteed to overcharge the battery at those temps and damage it on longer trips.

It's a marine/RV battery. Typically located/installed in much cooler locations.

AGMs don't like the heat.

 

[wngrog]

Any other series 31 size batteries that are more suited for the 100 series alternator and engine compartment? Mine is pretty lame.

 

[Hayes]

I ended up staying with the OEM size 27f, but in an AGM with comparable stats to DHP 31M and a full 3 year warranty.

27F AGM battery option

 

[SmoothLC]

So @Hayes, did you use the stock tray, etc.? That's looking like a more attractive option. Have to sell the Slee tray (not yet installed) when I make the purchase, but . . .

 

[SmoothLC]

195 minute reserve.
Yes, OEM battery tray.

Oops. Just saw you replied to my question in your other thread earlier in the year. How has the tray held up? That would be my only concern.

 

[wngrog]

I have gone to the Duracell Group 31 Deep Cycle AGM. So far, so good.

Is it a gel battery or acid?

 

[Slickspawn]

My favorite battery is the super start from O'Reilly auto. I have this battery in our land cruiser now and think it is stellar.

My daily driver has had an Optima red top since 2007. It's located in the hood (rear engine car) so I attribute the long life to lack of under hood temps and also the CTEK 3300us charger I plug into here and there.

I believe the marine batteries are not as well insulated from heat as the automotive batteries. I work for an OEM and we focus so much on batteries and spend and boat load on battery teardown and analysis. In comparing auto to marine the auto batteries have thicker jackets for heat.

Link to O'Reilly battery:
Super Start Platinum 34RPLT - Battery | O'Reilly Auto Parts

 

[wngrog]

This is the battery tender I use

It has rehabbed quite a few of my vehicle batteries

 

[OregonLC]

I've looked at that one as well. My fear with it is that Odyssey says 40A is required for a group 31 and it's just over 10% of that.

 

[Hayes]

Oops. Just saw you replied to my question in your other thread earlier in the year. How has the tray held up? That would be my only concern.

Tray has held up fine. A few wheeling trips and everything is still solid, no signs of wear or breakage.

 

[sdnative]

The Battery Tender Plus is AGM compatible. Not sure how well it can charge the battery, but I use this one to maintain for sometimes weeks at a time.

022-0157-1

 

[hoser]

I believe the marine batteries are not as well insulated from heat as the automotive batteries. I work for an OEM and we focus so much on batteries and spend and boat load on battery teardown and analysis. In comparing auto to marine the auto batteries have thicker jackets for heat.

Odyssey manufactures the group 31 battery with and w/o an outer metal jacket. The metal jacket is beneficial in high vibration applications and also HIGH HEAT applications.

Odyssey states the operating temperature of their standard Group 31 batteries:
-40°C (-40°F) to 45°C (113°F)

Operating temperature with metal jacket:
-40°C (-40°F) to 80°C (176°F)

So, for those running the DHP batteries, which don't have a metal jacket, it would probably be a good idea to run a thermal barrier.

 

[BoiseFJ]

Not in my opinion, but you know what they say about opinions.

If the oem group 24 goes dead due to music around the campfire, what's to say the group 31 won't?...just a few more sing-along's and it's in the same boat.

Since a stock LX has no room for a second battery, it may be your only choice.

Steve

Actually if you get ahold of Torfab they make a dual battery tray that fits 2 batteries where the stock battery sits, it is pretty slick.