My Battery Decision

[Dbrote]

Well, here’s my story. We bought a used 2016 2400R in late summer 2017. Who knows what the group 27 flooded batteries had been through. On our way to the Canadian Rockies in late summer of 2019 I noticed the 2 Group 27s were not holding a charge very well and we were going to do quite a bit of boondocking on this trip. I stoped at the last auto shop in the US in Idaho on the way into Canada. They only had regular group 27 marine starter batteries. I bought 2 for $99.00 each. My DW and I installed them on our first night in Canada. They have worked ok for a year and 1/2.
Well, I tested them this week and they are shot. Partially my fault. Never check water levels.
So now I spend hours researching what to replace them with. Lithium is obviously best but since I’m a numbers guy (semi retired CPA) I’m doing the math. All up to go to lithium it looks like $1,800 to $2,200 or so. I’ve got the money, but that’s not the point.
I just bought 2 Duracell AGM group 31 Deep Cycle for $500.00. Yes, they fit the stairwell compartment, barely. For those batteries to move the rig would have to turn upside down! Batteries at that point would not be on my mind.
I will probably be able to get at least three years on these batteries I’m guessing. We don’t use an inverter and everything is LED.
Who here thinks like me that in three years the lithium upgrade will be at least $500.00 cheaper anyway. Maybe then.
Or we can just spend $500.00 every three or four years for new AGMs.
I would love to hear thoughts on this.

[TomAR]

LiFePO's will cost closer to $3K: two batteries, Li-Charger/Converter, Li-BIM, Victron BVM-712.
$3000 over 10 yrs = $300 per year. Peace of mind = priceless!!!

[NMWildcat]

Two Interstate marine deep cell SRM 27 flooded batteries for a total of $250 at the most. 5 year average life span even though I abuse them when we boondock. And we usually boondock for weeks at a time.
$50 a year. Easy and they work.
I doubt lithium will ever be as cheap as flooded before the next generation of energy storage makes them obsolete

[Dbrote]

Well...Five years with deep cycle regular flooded is pretty, pretty, pretty good. Good value for you.

[Mikegjax]

Originally Posted by Dbrote

Well...Five years with deep cycle regular flooded is pretty, pretty, pretty good. Good value for you.

I got 4.5 years out of mine.

[Ejs4029]

I'm still using my Interstate SRM 24 Battery and it will be six years old in June

[richp]

Five years out of my Trojans and 600 watts of solar, and still going strong.

At my age (74) and with my use pattern, I'll never get my money back out of a switch to lithium.

And I do wonder whether prospective buyers, on resale, would appreciate the upgrade enough to let me recover the investment...

Rich Phillips

[wharfrat48]

Should be able to get more than 3 yrs out of your AGMs. My 6V flooded deep cycles last about 5 - 7 yrs before needing replacement. We boondock almost exclusively. I have done the math for my situation and moving to lithium would not be cost effective for me. That's not to say they are not the right move for someone else, just not for me.

[FFred]

Marine deep cycle & start are to be avoided as they are not real deep cycle batts. There made for the outboard fish folks to use a trolling motor and still have enough ooomp to start the outboard.

I would install a SOC (state of charge) meter and be cautious about deep discharging .
This should solve the number of seasons you get from a batt-set.

Series 31 AGM should go at least 5 years if brought up to 100% charge after a deep discharge.

[eric1514]

Originally Posted by Dbrote

...
I will probably be able to get at least three years on these batteries I’m guessing. We don’t use an inverter and everything is LED.
Who here thinks like me that in three years the lithium upgrade will be at least $500.00 cheaper anyway. Maybe then.
Or we can just spend $500.00 every three or four years for new AGMs.
I would love to hear thoughts on this.

Why are you only getting 3 years out of your batteries? Take care of them. You should get 5-7 by doing nothing more than not discharging them too deeply and fully charging them back up before you store them.

[PhilFromMaine]

Originally Posted by eric1514

Why are you only getting 3 years out of your batteries? Take care of them. You should get 5-7 by doing nothing more than not discharging them too deeply and fully charging them back up before you store them.

.......and there lies the rub. Who does that?

The thing people are missing about LIFEPO4 (lithium) batteries are that they will last as long as 10 years with normal care and some abuse. After that, they are on average good to 80 percent. So a 200AH LIFEPO4 battery will still be producing 160 AH.

LIFEPO4 charge really fast and at a high rate which for mine are up to 100 amps. The Battery Institute wrote that LIFEPO4 batteries should out live the user and last a life time if treated really well.
https://batteryuniversity.com/learn/...ased_batteries

[eric1514]

Originally Posted by PhilFromMaine

.......and there lies the rub. Who does that?

The thing people are missing about LIFEPO4 (lithium) batteries are that they will last as long as 10 years with normal care and some abuse. After that, they are on average good to 80 percent. So a 200AH LIFEPO4 battery will still be producing 160 AH.

LIFEPO4 charge really fast and at a high rate which for mine are up to 100 amps. The Battery Institute wrote that LIFEPO4 batteries should out live the user and last a life time if treated really well.
https://batteryuniversity.com/learn/...ased_batteries

I do that. I'm my lead-acid battery's BMS. I do agree, however, most folks won't and some even buy batteries every year.