AGM batteries?

No price movement means they get cheaper.
I remember buying car and truck batteries for $40-something not farther than decade ago.
Now finding one cheaper than $100 takes lot of skills.
Even I am not buying those things, I got one of those cigarette pack-sized battery as gift. It saved my phone camera couple of times and lately I hooked it up to my Honda 3000 starter.
It turned the engine just fine.
I am not easy to impress, but this time I truly am.

I am starting my 8th year with a set of Lifeline AGM batteries. Of course I have had to do no maintenance. I do open the battery compartment every year or two just to check and make sure all looks OK

HMS Beagle wrote:


It isn't clear than lithium batteries will get a lot cheaper with time - they've been out there for a number of years without much price movement. More likely is a better chemistry will be introduced, such as carbon air or aluminum air.

I wonder where supercapacitors will go. Graphene supercapacitors seem to hold a lot of promise. Perhaps hybrid systems that could include a battery for sustained energy and SC for high load short durations.

cewillis wrote:

Depth of discharge was explicitly including in my calculation by using available AH instead of rated AH.
Agree about the price being better in the future.

You included depth of discharge but not expected number of cycles for each type. Including that will make the lithiums seem cheap.

It isn't clear than lithium batteries will get a lot cheaper with time - they've been out there for a number of years without much price movement. More likely is a better chemistry will be introduced, such as carbon air or aluminum air.

cewillis wrote:

DWeikert wrote:

The only other thing your missing is the practical depth of discharge (DOD) for an AGM battery is 50%. For Lithium-iron-phosphate, it's 80% DOD. Thus, to get the same usable energy the AGM needs roughly double the Ah rating of the lithium.
lithium-ion vs agm

That said, I just installed 2 new GRP-31 AGM's in my camper. I'm thinking by the time these need replaced the lithium price point will be much more attractive.

Depth of discharge was explicitly including in my calculation by using available AH instead of rated AH.
Agree about the price being better in the future.

My bad. I see now you did say "available".

(in the voice of Emily Litella) Never mind.

DWeikert wrote:

The only other thing your missing is the practical depth of discharge (DOD) for an AGM battery is 50%. For Lithium-iron-phosphate, it's 80% DOD. Thus, to get the same usable energy the AGM needs roughly double the Ah rating of the lithium.
lithium-ion vs agm

That said, I just installed 2 new GRP-31 AGM's in my camper. I'm thinking by the time these need replaced the lithium price point will be much more attractive.

Depth of discharge was explicitly including in my calculation by using available AH instead of rated AH.
Agree about the price being better in the future.

cewillis wrote:

work2much wrote:
My cost per 100Ah battery delivered with bus bars is $ 550. Fo me at least this takes AGM and wet cell batteries out of the game for what I was looking for.

Sounds like good work on your part, and I'm certainly not going to argue the value of lithium batteries -- at some point.
But just for reference, in my case -- 4 x 140AH@12v for less than $1000.
Let's say that's 280AH available for $1000.
That's $3.57/AH. Your's -- $550/100 = $5.5/AH
Unless I'm missing something.
Cost comparison only -- I bet mine weigh a good deal more at 375 lbs.

The only other thing your missing is the practical depth of discharge (DOD) for an AGM battery is 50%. For Lithium-iron-phosphate, it's 80% DOD. Thus, to get the same usable energy the AGM needs roughly double the Ah rating of the lithium.
lithium-ion vs agm

That said, I just installed 2 new GRP-31 AGM's in my camper. I'm thinking by the time these need replaced the lithium price point will be much more attractive.

nightshift wrote:
Has anyone installed these carbon foam units in their rig? Expensive but if you can discharge them 80% as claimed, that's impressive.

I know many people who have these in boats. They cost more (somewhere between good AGM and lithium). They have two advantages: you can discharge them more deeply without as much affect on life, and they tolerate a partial state of charge much better than AGM. Maybe one more advantage is that as they are lead acid chemistry, they are a true drop in replacement for AGM. There have been ongoing production issues with them, limiting supply. They are available in only one size.

Many lithium batteries are marketed as drop in replacement for lead acid, but the pundits in the yachting industry dispute that this can be true. You need to be able to reprogram the charging voltages, float points, include balancers and/or disconnects in order to have a long lived and safe installation. If you just drop them into a lead acid setup and ignore, you probably will not get the lab tested life, and may ruin them in short order.

cewillis wrote:

work2much wrote:
My cost per 100Ah battery delivered with bus bars is $ 550. Fo me at least this takes AGM and wet cell batteries out of the game for what I was looking for.

Sounds like good work on your part, and I'm certainly not going to argue the value of lithium batteries -- at some point.
But just for reference, in my case -- 4 x 140AH@12v for less than $1000.
Let's say that's 280AH available for $1000.
That's $3.57/AH. Your's -- $550/100 = $5.5/AH
Unless I'm missing something.
Cost comparison only -- I bet mine weigh a good deal more at 375 lbs.

It was the size and weight that takes them out of the game. Our bank weighs 200 pounds less and stores about 40% more capacity. Going with AGM to 500Ah usable is more weight and space than I would care to haul around.

The batteries are more expensive upfront but over time they will cost less with far more cycles available .

But even more than the benefit of lower overtime cost is how much faster these batteries can be charged. They bulk at a high rate straight to the top. This is huge when traveling in the winter with short days and more cloudy skies.

In addition their ability to run endlessly day after day with any SOC above 20%. You could run for a month while never getting to 100% SOC without degradation. Combined with a large Ah reserve this allows for multiple cloudy days where output exceeds input.

I understand that this system isn't for everyone, especially those who don't camp months at a time in their camper. If we were building this for 2-3 week vacations a couple times a year like we used to do I would throw a couple lifelines in there with a couple panels and be done with it.

Has anyone installed these carbon foam units in their rig? Expensive but if you can discharge them 80% as claimed, that's impressive.