What is the most reliable group 31, deep cycle marine battery?

Dr Gil

Adventurist
Size to fit in 96 Land Cruiser (Aux battery spot)
Sizing to fit is secondary importance.
Cost is way down the list of priority.
I don't need any starting or cold cranking capacity.
I have a Blue Sea ACR.
This is strictly to run my fridge (on 24 hours), inverter, aux 12v plugs, Andersons and USB's.
I can shore charge on a daily basis and have solar panel when I'm out overlanding.
 
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I have been researching Lithium options and a group 31 size one smokes any AGM in every level other than price. Capacity, weight, run down to 20% without damaging, accepts 97% of input charge energy and keeps the voltage at a consistent level through out discharge. Also on average 2500-3000 charge cycles.

Definitely the future of aux batteries. Downside, $1000 price tag.
 
I have been researching Lithium options and a group 31 size one smokes any AGM in every level other than price. Capacity, weight, run down to 20% without damaging, accepts 97% of input charge energy and keeps the voltage at a consistent level through out discharge. Also on average 2500-3000 charge cycles.

Definitely the future of aux batteries. Downside, $1000 price tag.

Ouch!! Price still down the list of priorities, BUT... Can't justify that price for my frequency and type of usage.
 
My concern with lithium is how it does in the cold. Ever have your phone fully charged and then when it gets cold overnight it’s dead? Then plug it in and it’s instantly full once you’ve warmed it up? Also they don’t handle heat well so can’t put them under the hood.
 
I run the VMax Tank AGM 125ah, minimum self discharge while in storage mode, withstand cold weather doesn't loose charge, I like the 8 yr warranty too as along as I do not run it below 50% which I haven't.
I have this one in my current & will be buying another for the new trailer.
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My concern with lithium is how it does in the cold. Ever have your phone fully charged and then when it gets cold overnight it’s dead? Then plug it in and it’s instantly full once you’ve warmed it up? Also they don’t handle heat well so can’t put them under the hood.

I think the cold/warm phone level issue is likely a software issue with the phone. No battery is going to be dead to fully charged just by changing it's temp. Lithium for a house battery is the correct usage versus an under hood starting battery. Those I would use AGM for.

Hopefully as technology improves, the prices will come down. Similar to how solar panels have dropped in price.
 
I've had good luck with the X2Power from Battery Plus. Now that I've seen that VMax that might be my next trailer battery.
 
I've had good luck with the X2Power from Battery Plus. Now that I've seen that VMax that might be my next trailer battery.
I run the X2Power AGM dual purpose in Ol' Heavy my truck, powers my Engel & winch as well as a starter battery.
 
I think the cold/warm phone level issue is likely a software issue with the phone. No battery is going to be dead to fully charged just by changing it's temp. Lithium for a house battery is the correct usage versus an under hood starting battery. Those I would use AGM for.

Hopefully as technology improves, the prices will come down. Similar to how solar panels have dropped in price.
Then why are the lithium batteries on drones etc doing the same thing? Then even more interesting why are the lithium battery companies like relion and dragonfly actively seeking self warming circuitry for their batteries? We know for a fact that heat is an issue with them. They can’t be mounted under the hood without causing charging issues.
 
Then why are the lithium batteries on drones etc doing the same thing? Then even more interesting why are the lithium battery companies like relion and dragonfly actively seeking self warming circuitry for their batteries? We know for a fact that heat is an issue with them. They can’t be mounted under the hood without causing charging issues.

Good points :coffee
 
Then why are the lithium batteries on drones etc doing the same thing? Then even more interesting why are the lithium battery companies like relion and dragonfly actively seeking self warming circuitry for their batteries? We know for a fact that heat is an issue with them. They can’t be mounted under the hood without causing charging issues.

Interesting, I haven't been up on drone stuff so had not heard of these issues with them. Like all things, I am sure as technology advances, these issues and prices will be solved. That said, I am likely going to have AGM batteries as house and starting batteries when I get things built out. Cost to benefit ratio. If we were going to live full time for months, the expense might be justified but not for the 6-12 weekend type trips we are likely to have time for.
 
opening a can of worms . . . .

I would start by figuring out what kind of charging system you have, and what you are willing to spring for. I went with a good old Marine Deep Cycle FLA (Duracell). I got it on sale at Batteries Plus so I ended up with 105AH for about $100. Now with an FLA you will lose cycles if you take it down below 50%, but you can still hammer it down to 80% DOD for 2-400 cycles. In actual use, I almost never get below 50%, so it will probably be many, many years before I get 3-400 nights camping out of that truck. i.e., unless you're full timing, the number of cycles is probably not a real concern.

My bigger concern is not the battery, but how to get the charge back in it when I have used it. A good charging system, well matched to the battery, will keep the battery happy and extend your usable capacity. A little solar goes a long way in reducing the depth of discharge you see, and a good onboard charging system (my old Toyota is crying out for a Redarc or CTEK), will drastically shorten the run times required to put amps back in with the motor.

If you get the charging system right, you may be just as happy with a $100 battery as a $400 battery. If you don't get the charging system right, then that $400 battery may not last any longer than that $100 battery. A prime example for me is the Odyssey. No doubt they are one of the finest lead acid batteries out there, but to get that performance out of them, they want to be charged at 14.7v. (source https://www.odysseybattery.com/documents/US-ODY-TM-002_1214.pdf) If you lower that to 14.2v (which Odyssey describes as the typical automotive charge voltage), you reduce the life of the battery at 80% DOD from 400 cycles to 150. i.e its starts to perform just like (or even worse than) my $100 FLA.

My Landcruiser charges at about 13.3 and lower. That would be awful for an Odyssey. Without help for the charging system, it doesn't matter what I buy. With some help on the charging system, I can get by with almost anything. If it weren't for some parking deck issues, I could have everything I want with a roof mounted panel. Likewise, in my situation, I would be much better off with a CTEK D250 ($239 at Amazon) and a $100 Group 31 FLA, than I would be dropping a $400 high end AGM in without any other changes to make it work. My charging system just won't take advantage of it. As things stand, I am probably going to cannibalize a Redarc 1225 from an unsuspecting Turtleback.

Of course once you have invested in a better charging system, you may start wanting (as opposed to needing) a better battery to take full advantage of it. One of the most attractive features to me of Lithiums and premium AGMs like Odyssey and Lifeline is that they recharge very quickly. (Fast charge on a typical FLA is about 0.2C, Odyssey advertises up to 3.1C, Lifeline advertises 2.5C). A fast recharge is more important to me that overall storage capacity. All AGM's will give you faster charge than FLA, spill resistance, better shelf life, lower internal resistance etc... They really do have a lot of advantages. So I may face new temptations soon . . . .
 
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opening a can of worms . . . .

I would start by figuring out what kind of charging system you have, and what you are willing to spring for. I went with a good old Marine Deep Cycle FLA (Duracell). I got it on sale at Batteries Plus so I ended up with 105AH for about $100. Now with an FLA you will lose cycles if you take it down below 50%, but you can still hammer it down to 80% DOD for 2-400 cycles. In actual use, I almost never get below 50%, so it will probably be many, many years before I get 3-400 nights camping out of that truck. i.e., unless you're full timing, the number of cycles is probably not a real concern.

My bigger concern is not the battery, but how to get the charge back in it when I have used it. A good charging system, well matched to the battery, will keep the battery happy and extend your usable capacity. A little solar goes a long way in reducing the depth of discharge you see, and a good onboard charging system (my old Toyota is crying out for a Redarc or CTEK), will drastically shorten the run times required to put amps back in with the motor. I posted what kind of charging system I have. I have a Blue Sea ACR. I have shore charging every night, and solar when don't have shore charging.

If you get the charging system right, you may be just as happy with a $100 battery as a $400 battery. If you don't get the charging system right, then that $400 battery may not last any longer than that $100 battery. A prime example for me is the Odyssey. No doubt they are one of the finest lead acid batteries out there, but to get that performance out of them, they want to be charged at 14.7v. (source https://www.odysseybattery.com/documents/US-ODY-TM-002_1214.pdf) If you lower that to 14.2v (which Odyssey describes as the typical automotive charge voltage), you reduce the life of the battery at 80% DOD from 400 cycles to 150. i.e its starts to perform just like (or even worse than) my $100 FLA. My charging system works just fine for what it's supposed to do. The House battery is used only for starting and stock items, no aftermarket electronics are connected to the House battery.

My Landcruiser charges at about 13.3 and lower. That would be awful for an Odyssey. Without help for the charging system, it doesn't matter what I buy. With some help on the charging system, I can get by with almost anything. If it weren't for some parking deck issues, I could have everything I want with a roof mounted panel. Likewise, in my situation, I would be much better off with a CTEK D250 ($239 at Amazon) and a $100 Group 31 FLA, than I would be dropping a $400 high end AGM in without any other changes to make it work. My charging system just won't take advantage of it. As things stand, I am probably going to cannibalize a Redarc 1225 from an unsuspecting Turtleback.

Of course once you have invested in a better charging system, you may start wanting (as opposed to needing) a better battery to take full advantage of it. One of the most attractive features to me of Lithiums and premium AGMs like Odyssey and Lifeline is that they recharge very quickly. (Fast charge on a typical FLA is about 0.2C, Odyssey advertises up to 3.1C, Lifeline advertises 2.5C). A fast recharge is more important to me that overall storage capacity. All AGM's will give you faster charge than FLA, spill resistance, better shelf life, lower internal resistance etc... They really do have a lot of advantages. So I may face new temptations soon . . . .
 

Hi Doc,

If you are shore charging every night, almost any quality deep cycle battery Group 31 will do what you need. If you have enough solar, then you should have even more run time between shore charging. If you're just stationary for a day or two between long drives, then you may not even need that. I've been running that way for years, and always scraped by. I added a portable solar panel last October, and have been very impressed with how much better things work with a little contribution from it. It sounds like you're in pretty good shape for what you want to do.

As to charging system, the Blue Sea ACR is definitely part of it, but I was referring to whether you were using the factory alternator, or a DC-DC setup like a Redarc or CTEK, or have one of the "shotkey diode" style mods that raise the factory voltage. Our old Landcruisers (mine is a 1990 FJ62) charge at very low voltages and often have difficulty keeping an aux battery topped up. I also have a Blue Sea ACR. It's rock solid and works perfectly to combine and separate the batteries, but it doesn't make the Toyota alternator charge at the voltage my aux battery wants to see. Sometimes at a stop light, the voltage will drop low enough that the Blue Sea disconnects. I feel that on our Toyotas, this is a higher (and less expensive) priority than a high-end aux battery.

I am also one of the barbarians that will happily hammer my aux battery down to 20% charge if I need to. This means I can get 80 amps out of that FLA in the engine bay. Sure it won't last as long, but I only run the fridge when camping, so on cycles, it may still last 5-6 years, and I only have about $100 bucks in it. If I had a $400 battery I would be more reluctant to go below 50%, I would only get 50 usable amps, and I would probably still wonder about replacing it after 5-6 years.

If I had $400 to spend on electrical for the Cruiser, I would buy a CTEK D250, a good Flooded Lead Acid Battery, and assorted cables, terminals, etc.... If I had $500, I would buy the CTEK and as good an AGM as I could swing. The Redarc is supposed to be great as well, but its $410 for 25 amps instead of $239 for 20 amps. If you have more batteries, or high-end batteries that will take a higher charge rate, then the 40 or 50 amp Redarcs start to be a real temptation. I would love to have a Lifeline or Odyssey and a Redarc 1250, but I can't justify the $$$ for the way I use it. Don't get the 40-50 amp Redarcs and the single FLA battery. The charge rate is too high.
 
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