AGM 31 Deep Cycle Battery

Looking into replacing my existing battery with a AGM 31 Deep Cycle battery to power my Dometic CFX 50 quarte fridge and auxiliary LED lights. I don’t want to deal with the dual batteries, prefer to just use one giant one. The group 31 batteries I’m looking at are the North Star or Full throttle.

My concerns with getting the group 31 battery is the weight, at 77lbs I’m nervous the fender well will begin to crack or break.

Is there a battery bracket that can hold that size battery and distribute the weight somehow?

The other option is to go with a group 34 Odyssey Extreme and sacrifice some amps hours for weight.

Your advice will be greatly appreciated

 

I’ve been running a group 31 with a slee mount for about a year, haven’t had any problems with it

 

The group 31 Northstar is only 7 more lbs than the group 27F. I run the NorthStar 27F.

By the way Full River - Full Throttle batteries are made in China. NorthStar is made in the USA.

 

I think I’m going with Northstar, I here a lot of good reviews. I’m also going to get the slee battery tray

 

Look at the Northstar, or X2 Power, 27F. Fits better, is lighter, don’t have to extend any wires, cheaper and 195 reserve capacity. Should do all you need.

 

I have an unused slee battery tray I'll sell you. I never used it and went with a pelfrybuilt one. New slee tray sell for $110 plus shipping, I'll sell you it for cheaper, PM me. And I'm in SD too.

 

NorthStar and X2 Power are the same thing. The X2 Power says NorthStar right on the side. Benifit for X2 Power is you can pick them up locally at a Batteries + Bulbs store if you need it ASAP like I did.

 

That’s why I said “Northstar, or X2 Power”. Not everybody has a Bateries + near them so I was giving more options by adding Northstar. I can get a Northstar closer to me but Batteries +’s X2 Power has 12 month longer warranty.

 

Has anyone used a Northstar 27F or equivalent (single batter) to powar a ARB or Dometic fridge/freezer? Would like to get your thoughts. I’m still debating whether to get the AGM 31 or 27

 

Was just clarifying, I definitely appreciated being able to pick up a NorthStar "2X Power" locally in a pinch! Batteries plus was also offering 10% off if purchased online and picked up in-store plus a $30 mail in rebate making it cheaper than ordering a NorthStar online.

 

To stay on topic here;
I’ve read a lot of your threads and you seem to be very 12V knowledgeable. Do you agree a 27F is a better bang for your buck for the OP’s situation?
He didn’t say he’d be off grid for days on end without starting his vehicle.

I did a dual battery set-up on my FZJ80 and honestly, it was overkill. I contemplated a 31M on my Taco but an X2/Northstar 27F seemed to be plenty for camping and off roading running my fridge/LED light bars/LED rope lights/etc.
(I’ve actually done just fine with a normal 27F but wanted the extra coverage the AGM offers with the 195RC)

 

Btw, code CDP13175 gets you 20% off so that’s $72 savings then $30 mail in rebate for a $102 saving until March. Damn good savings!

 

The 195min RC rating is assuming a 25A discharge rate, which is relatively extreme for the use case. Looking at the power demands of the fridge, it looks like it pulls 7.8A DC. Meaning if the fridge compressor was to run non-stop, it is only pulling 31% of the discharge rating. In other words, 25A/7.8A = 3.2. 3.2 x 195min = 624min, or about 10.4 hours of continuous compressor run time to drop the voltage to 10.5v. Fridge compressors cycle, meaning they do not continuously run. A quick google search says 50% duty cycle is common, meaning the compressor is only running half the time to keep the contents cool, so that 10.4 hours of power draw, should actually last 20.8 hours. There is a slight overhead of increased power draw from compressor startup, so the number is not perfectly scaleable to 2x. But good for a general approximation. Of course duty cycle is going to be partially determined by temperatures of the environment, but fortunately it tends to be cooler at night reducing the duty cycle load.

With the above paper napkin math it seems the fridge would very easily be able run off the 27F Northstar overnight with plenty of power to spare. Going multiple days of not starting the truck would be very risky and would likely lead to a failure to start. Stepping up to a type 31 battery would push RC from 195 to 220, or a difference of 25 min RC. 3.2 x 25min = 80min additional runtime, and at 50% duty cycle, that is good for roughly 160min more, or about an additional 2.6 hours.

So to break it down you are looking very roughly fridge run time of:
Group 27F 20.8hrs
Group 31 23.4hrs

Stepping up to a Group 31 buys more capacity, but ultimately the truck only gets 2.6 hours more fridge run time, meaning you still cannot go multiple nights without starting the truck to charge the battery, so the functionality is only very slightly increased. If that is worth it or not is up to the OP.

And there is the added Taco lean.

 

so..."X2 power" from batteries plus is mfd. by northstar... hmmm?
sounds good - i have a batteries plus somewhat close by in the event of needing to return for warranty which is important...
northstar/X2 power vs. odyssey...thoughts?

 

Excellent response, as always!

They’re both damn good batteries. In my opinion, the top 2 but YMMV. I compare all batteries to Odyssey but some say they may have become just a smidge lower quality than they used to be (unlike Optima that has turned to garbage). Look at this screenshot then take another $30 off for the rebate, another $14 off for trading in a core and it’s ~$282 for the 27F X2 Power. Pretty impossible to beat at this price.

 

@crashnburn80 Good info, and I'll add to that.

Batteries aren't all the same. People call them starter batteries or trolling motor batteries for a reason. That's because plate configurations and chemistry of the batteries allow for different dischare rates. A cranking batteries' plate configuration inside the cells are designed to allow high current short bursts, where a battery for a trolling motor is better for steady draw, or lower amp draw over a longer time.

Charging a battery too fast can damage it. Discharging a battery starting battery past 80% of it's capacity can permanently damage it. Discharging a SLA or a Deep Cycle battery past 50% of it's capacity can permanently damage it.

So in a cranking battery typically reserve capacity is a factor, where as most use the terms AH (Amp hours) as a measure in other batteries, such as deep cycle.

There are some batteries which can deeply discharge to 20% and not damage it.

So to add to Crash's math, if you factor in the full capacity of the battery and say it's good for 23.4 hours of runtime.
Starter battery @ 80%: ~5 hours safe
SLA / Deep Cycle @ 50%: ~12 hours
Super deep discharge @ 20%: ~19 hours

The main reason for a second battery is to put in a VSR, a cutoff, or a DC-DC charger with logic so you can disconnect the aux battery from the truck starting battery to protect it from accidentially killing it. In addition, my CTEK DC-DC charge not only charges, it charges at 14.6v (which most car alternators can't do), provides a 5 step charge process, has a MPPT solar charge controller built in, and has logic to disconnect the aux battery in case of voltage too low state.

Welcome to battery rabbit holes. We haven't even talked about solar yet

 

Geez where are you looking??

 

Been there, done that. They call the X2 Power a “Deep Cycle, Dual Purpose (Starting/Cycling), Starting“ battery. It’s either a lie, which I doubt, or a new style configuration.

 

There’s no way you can get that for $109. That’s a $400 battery. If it WILL let you buy it for that then order 10 of them and make a small fortune.

Can you post a direct link to that so I can buy some????

 

Ok I’m about to pull the trigger with the X2Power 27F AGM battery
Reserve Capacity 195 min
Capacity-20hr rate 92Ah

Battery + Bulbs has killer deal %20 Off plus $30 rebate.

Just want to get peoples opinion if this is the right battery for my needs to power auxiliary LED lights and Dometic 50 fridge?