AGM batteries?

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.

Not imperative but highly desirable. Why would you not want them?

At about half the weight $550 is a lot more palatable. If the lithium supply stabilizes or increases the prices will continue to drop like any other product. Who do we need to bomb?

As usual HMS, you are right on target.

The other obvious LFP advantage, especially for a TC is size and weight. I am building a 600Ah (480 usable) bank that will weight 175 pounds. That is not much more than one pair of AGM batteries. To achieve the same usable Amp Hours I would need 8 6v AGM batteries weighing in at 520 pounds. Not practical for most TC applications.

As far as cost. "drop in" units are fairly pricey. About $900-1000 dollars per 100Ah. You can build a far less expensive high quality LFP bank though if you are willing to buy individual cells, build and balance the bank yourself. 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.

Flooded cells are cheap and can be abused some without much damage, require periodic maintenance.

AGM are more expensive but must be fully recharged periodically, no maintenance.

Lithium cost more initially and must be charged with proper equipment, but are the cheapest in amp -hrs delivered over their life. They are also tolerant of operating for long periods at a partial state of charge, which lead acids are not.

In the example given above, discharging the AGMs to 50%, 1000 cycles will give you 100,000 AH by end of life, or $0.0065/AH delivered. The lithiums discharged to 80% for 2500 cycles will give you 400,000 AH by end of life, or $0.0045/AH delivered. In practice you would replace a 200 AH lead acid battery with a 120 AH lithium making the initial cost difference less, while keeping the life cycle cost advantage.

work2much wrote:

rjxj wrote:

joe&julie81 wrote:
What do agm' s vent, what gas? They will be stored in an inside compartment. And yes we may use big draw items, hair dryers etc. Don't know yet how deep the compartment will be.

They dont vent unless you over charge them. They then release pressure through a vent valve and are destroyed. dont worry about that, just know what the manufacturers voltage limit is. Every GC 2 that I have seen is about 11.5 inches tall and that's one of the issues with GC batteries so some compartments wont hold them. I rebuilt my compartment and made a removable tray that drops down out of the FW.

It isn't that you cant invert from GC2, it's just that the design of the AGM is better for it. I have six GC2 and sometimes invert and pull 90 amps so that's only 15 amps per battery. My coffee maker would pull about 125 amps so I usually use the generator for that. No matter which battery you choose it's one thing to heat up a coffee or some leftovers vs cooking something for 1/2 a hour. If you plan on doing that you will need a big battery bank. Part of your energy use plan may actually be centered around your battery box size or ability to expand it.

People sometimes even use lithium batteries because they are small, lightweight, have more usable amps, and charge quickly. The only problem is that they are expensive.

Rough prices depending on where you shop

Wet deep cycle average cycle life 800 200ah = $ 200 25 cents a cycle
AGM 1000 life cycles 200 ah = $650 65 cents cycle
Lithium 2500 cycles 200 ah = $1800 72 cents per cycle

I don't think you calculated DOD into the above. LFP batteries can be discharged down to 80% or more safely and most manufacturers claim more than 2500 cycles. In your example the LFP bank is significantly larger AH rating than the other 2 which would have roughly 100 Ah usable capacity. A LFP bank of 200Ah would have 160 AH usable minimum.

I just grabbed a couple rough figures from AM solar site. I'm not interested in Lit but always understood it to be cheaper per charge than the others so yes dod has to be figured more closely. My concern with spending that much on batteries would be the possibility of a change of rigs or a change in plans or having it be one of them that only makes it out of the warr period and never realize the advantages of such expensive batteries. Stuff does happen.

Both kinds can work. AGM = more initial cost, less ongoing attention, probably less restrictive charge/discharge profiles, possibly/probably longer life. My first AGM set lasted more than 10 years, and 2 of 4 were still good then.
I wouldn't buy anything but high quality AGM.

rjxj wrote:

joe&julie81 wrote:
What do agm' s vent, what gas? They will be stored in an inside compartment. And yes we may use big draw items, hair dryers etc. Don't know yet how deep the compartment will be.

They dont vent unless you over charge them. They then release pressure through a vent valve and are destroyed. dont worry about that, just know what the manufacturers voltage limit is. Every GC 2 that I have seen is about 11.5 inches tall and that's one of the issues with GC batteries so some compartments wont hold them. I rebuilt my compartment and made a removable tray that drops down out of the FW.

It isn't that you cant invert from GC2, it's just that the design of the AGM is better for it. I have six GC2 and sometimes invert and pull 90 amps so that's only 15 amps per battery. My coffee maker would pull about 125 amps so I usually use the generator for that. No matter which battery you choose it's one thing to heat up a coffee or some leftovers vs cooking something for 1/2 a hour. If you plan on doing that you will need a big battery bank. Part of your energy use plan may actually be centered around your battery box size or ability to expand it.

People sometimes even use lithium batteries because they are small, lightweight, have more usable amps, and charge quickly. The only problem is that they are expensive.

Rough prices depending on where you shop

Wet deep cycle average cycle life 800 200ah = $ 200 25 cents a cycle
AGM 1000 life cycles 200 ah = $650 65 cents cycle
Lithium 2500 cycles 200 ah = $1800 72 cents per cycle

I don't think you calculated DOD into the above. LFP batteries can be discharged down to 80% or more safely and most manufacturers claim more than 2500 cycles. In your example the LFP bank is significantly larger AH rating than the other 2 which would have roughly 100 Ah usable capacity. A LFP bank of 200Ah would have 160 AH usable minimum.

joe&julie81 wrote:
What do agm' s vent, what gas? They will be stored in an inside compartment. And yes we may use big draw items, hair dryers etc. Don't know yet how deep the compartment will be.

They dont vent unless you over charge them. They then release pressure through a vent valve and are destroyed. dont worry about that, just know what the manufacturers voltage limit is. Every GC 2 that I have seen is about 11.5 inches tall and that's one of the issues with GC batteries so some compartments wont hold them. I rebuilt my compartment and made a removable tray that drops down out of the FW.

It isn't that you cant invert from GC2, it's just that the design of the AGM is better for it. I have six GC2 and sometimes invert and pull 90 amps so that's only 15 amps per battery. My coffee maker would pull about 125 amps so I usually use the generator for that. No matter which battery you choose it's one thing to heat up a coffee or some leftovers vs cooking something for 1/2 a hour. If you plan on doing that you will need a big battery bank. Part of your energy use plan may actually be centered around your battery box size or ability to expand it.

People sometimes even use lithium batteries because they are small, lightweight, have more usable amps, and charge quickly. The only problem is that they are expensive.

Rough prices depending on where you shop

Wet deep cycle average cycle life 800 200ah = $ 200 25 cents a cycle
AGM 1000 life cycles 200 ah = $650 65 cents cycle
Lithium 2500 cycles 200 ah = $1800 72 cents per cycle

joe&julie81 wrote:
What do agm' s vent, what gas? They will be stored in an inside compartment. And yes we may use big draw items, hair dryers etc. Don't know yet how deep the compartment will be.

No, AGMs do not vent in normal use. They are valve regulated lead acid batteries(VRLA) with a special construction that holds the acid in glass-mat pads between the plates. They do not spill or leak and can be installed on their side if needed to fit into available space.

All lead-acid batteries emit Hydrogen gas during charging and that is the source of explosions. A valve regulated battery does not allow the H gas to escape in normal use

HTH;
John