New batteries

[MrNoodly]

I knew my eight-year-old Concord Sun-Xtender AGM batteries were approaching the end of their usefulness. They had been taking a lot longer to reach float and they were reading around 12.5V before sunrise instead of their usual 12.7V. The shorter days of winter are approaching, making getting through the days more challenging. Then, when I woke up in the middle of the night a few days ago, the voltmeter read 12.1V, with the fridge cycled on. Not good, even though it returned to 12.5 when the fridge cycled off. Time for new batteries.

I briefly considered LiFePo like all the cool kids but, besides the higher price, there would be the hassle of reprogramming my solar controller. So I'd go the easy way and get AGMs again. Sun-Xtenders like mine are about $340 each. Mmmmmm, seven-hundred bucks would be a tough bullet to bite right now. So I decided to go with a couple of Universal brand at half the price. If I get only half the life out of them, I'll still break even. I'll report on any problems.

<a href="https://imgbb.com/"><img src="https://i.ibb.co/sgBJ7GP/ub1.jpg" alt="ub1" border="0" /></a>

 

[MrNoodly]

Got the new batteries installed, and if one night means anything (yeah, right) things are excellent. The batts held 13.0V most of the night, dropping to 12.9V toward dawn.

 

[user 423]

Were the Concord batteries kept in good shape by your original solar setup?

Or did you upgrade at some point?

 

[MrNoodly]

Everything was original until the new batteries.  A 270W panel, Morningstar controller, and the two 104AH Sun-Xtender batteries.

 

[tripper]

I would still recommend one of the now inexpensive drop in LiFePO4 batteries. Even with your controller not optimized for lithium they would still last far longer than the lead acids, and perform a lot better, smaller voltage sag and higher baseline resting voltage which means you items will take less amps to run. Plus thousands of cycles of use.

 

[wayne49]

Too late.

 

[Calaverasgrande]

Lifepo battery market seems to be getting competitive. I wrote them off and was going to get AGM, but Renogy had a sale a month ago on their bluetooth Lifepo 100AH batteries. Ended up saving several hundred on 2. So far they are working out great.
I was annoyed having to use an app to know status. But now I like that I can see so many details of the battery bank, each battery, or even cells in each battery. Not like I'm going to crack them open though!
I've also seen quite a few others for cheaper than Renogy and other well known brands. Haven't seen any such deals on BB lifepo. though.

 

[PlethoraOfGuns]

A 100ah LiFePo4 battery will cost the same as 200ah of AGM now and have the same useable battery capacity. Yes you need to deal with special chargers and protection stuff but you'll have a battery bank you shouldn't need to touch or maintain for many years. Plus it should last you 4x longer than lead acid. Do the math and LiFePo4 is a lot cheaper in the long run. I'm glad I switched. Got tired of dealing with wet cells all these years.

 

[Calaverasgrande]

the clincher for me was outgassing. Lifepo4 do not outgas. Every other kind does, or has potential to.
Since my battery bank is under my bed. And will probably expand to 400AH or more by next year, no-outgassing was a huge selling point!

 

[user 423]

A 100ah LiFePo4 battery will cost the same as 200ah of AGM now and have the same useable battery capacity.

A quick check shows a Renogy 100ah LiFePo4 costs $765.  Two Universal AGMs are $360.

Renogy seems to have a decent quality rating on the stuff they sell. 

Is it possible to buy a quality 100ah lithium for around $360?

 

[MrNoodly]

Do the math and LiFePo4 is a lot cheaper in the long run.

I did the math on the state of my bank account in the short run. Batteries I can't afford at the moment are useless.

 

[MrNoodly]

...but you'll have a battery bank you shouldn't need to touch or maintain for many years...

I didn't have to touch or maintain my AGM batteries for eight years.

 

[Freelander]

One thing you might think about with LiFePo4 batteries is, if you charge them with the alternator on your van/Bus, if you have very many you run the risk of burning up your alternator. I have 3 BB batteries and install a BIM (Battery Insolation Module) to protect the alternator. The BB batteries will take a 50 amp a piece and my alternator is only 145 amp. Also the BIM will allow for 2 way charging. the alternator will charge the LiFePo4 batteries and the solar/shore power will change the stating battery.

 

[Spaceman Spiff]

 . . . Do the math and LiFePo4 is a lot cheaper in the long run . . . 

My GC2s (208 Ah, $186) cost me $0.071 per cycle (so far, still going strong in year 8).  At $700 per 100 Ah, lithium batteries would have to go 27 years to match that cost.  I don't think so.

the clincher for me was outgassing. Lifepo4 do not outgas. Every other kind does, or has potential to.
Since my battery bank is under my bed. And will probably expand to 400AH or more by next year, no-outgassing was a huge selling point!

I have started my eighth year with my flooded lead acid batteries.  It took me 5 charge cycles to figure out how to charge them without outgassing.  They reside under my bed too.

And yes, Li-ion batteries (of which LiFePO4 is one type) do outgas under the right conditions.

 

[ldsreliance]

Is it possible to buy a quality 100ah lithium for around $360?

No.  At that price point you are buying a low quality BMS and Grade B cells.  And that may be fine for you.  And it will perform about the same as a Grade A battery for a while.  But it will not last as long over time and those cells will drift further apart and the performance will drop.

 

[ldsreliance]

And yes, Li-ion batteries (of which LiFePO4 is one type) do outgas under the right conditions.

What conditions would those be? The only way that an LFP battery can "outgas" is if the cells are punctured. And you have much bigger problems than "outgassing" at that point.

If a Lithium Ion cell is severely overcharged it can emit gas. But that is what the BMS is for and almost none of the commercially available lithium deep cycle batteries are Lithium Ion (at least not the chemistry we normally refer to as Lithium Ion).

 

[Camper]

I just bought a new 100AH Lithium from Amazon for $399, I'll let you know how long it lasts.

 

[user 423]

^
What kind of bank did it replace?

 

[wayne49]

Battery chemistry appears to have become a religious issue.

Repent ye Lead Acid heathens!

 

[Spaceman Spiff]

What conditions would those be?  The only way that an LFP battery can "outgas" is if the cells are punctured.  And you have much bigger problems than "outgassing" at that point.

If a Lithium Ion cell is severely overcharged it can emit gas.  But that is what the BMS is for and almost none of the commercially available lithium deep cycle batteries are Lithium Ion (at least not the chemistry we normally refer to as Lithium Ion).

Lithium-Ion refers to a class of battery chemistries that utilize lithium for ion exchange: LCO, LMO, LFP, NMC, NCA, LTO.  LiFePO4 is currently the most stable.

Lithium starts to outgas at 60ºC (140ºF).  A vehicle sitting in the Arizona sun in July can exceed 60ºC.  A black dashboard in the sun has been measured at 90ºC.
Overcharging or cell imbalance can also raise a cell temperature to over 60ºC.
Outgassing will bulge and eventually rupture the cell.

A corollary to Murphy's Law states: "All fail-safe systems fail, usually at the most inopportune time."