Very strange comment re AGM v Lifepo4

[bds70]

During a conversation today with a major supplier of lifepo4 & AGM Batteries etc. The tech I was talking to stated that for an entirely off grid installation like me in my home on wheels, AGM batteries were better than Lifepo4. I have never heard that before and he states that Lifepo4 require to be charged every 3 months via a 240V lithium charger, and that couldn't be done on an entirely off grid setup.

I think he misunderstands the concept of a 3000W inverter supplying 240V.

But that aside what does anyone else think of the statement?

 

[Bob B]

Sounds like he has some AGM batteries he needs to unload .... I wouldn't buy anything from them.

 

[Hedges]

Of course lithium can be properly charged by an off-grid PV system.

Lithium needs to be kept within temperature range where it can charge without damage.
AGM can be charged well below freezing. Charge voltage needs to be temperature compensated. It is highly freeze resistant when charged, but completely drained it can freeze and burst at not as cold temperatures.

Lithium should give 10 to 15 years of deep cycling.
AGM maybe 2 years. But good for 10 years of mostly 15% cycling (assuming good brand.)

Lithium doesn't care what SoC it is left in, although middle is better for long-term and high temperature.
AGM needs to be fully recharged including absorption. But it can be left for a year with no loads.

Lithium BMS will cause some parasitic drain. Not a problem if left with charger attached and PV panels.

 

[Skypower]

Lifepo4 are usually superior to AGM except below freezing temperatures, or when kept at a high state of charge with little to no cycling like emergency standby or high inrush like starting a large engine ( small bms/battery bank). I’m thinking the guy is getting anxious about the date code on his AGM stock.

 

[sunsurfer]

lead acid is a dead battery chemistry. Its only a matter of time now.

 

[Crowz]

Lifepo4 and hybrid inverters is the ONLY reason I was willing to do solar on the new house after having lead acid batteries on my old house's setup.

Lifepo4 kicks agm butt in my opinion if you can afford them for a normal setup IF cold weather isn't a problem that you can't account for. Cost is better now than when I first learned of them though.

 

[Skypower]

The only way I’d cut the salesman some slack is if someone doesn’t want to make the proper changes for a lead to lithium conversion.

 

[Crowz]

The only way I’d cut the salesman some slack is if someone doesn’t want to make the proper changes for a lead to lithium conversion.

Or if they had a bunch of lead acid batteries and just wanted to replace a bad one or add to what they had. Its hard justifying ditching a functional large battery bank to switch battery types.

 

[Bob B]

In a mobile application ... The weight difference is also a big factor.

 

[Skypower]

When I had my boat I had three 8D Vmax 310 Ah AGM’s on inverter duty. What always struck me was how much power was wasted round trip. At the time they were pretty much the best standby power you could get. They were the heaviest of their class. I’ve got the hernia scars to prove it. Not kidding ?. Found out the new owner killed them by leaving them at a low state of charge for a long time. A lithium battery would have shut down to save itself.

 

[Crowz]

That's one thing I never looked forward to was moving my lead acid batteries. As old as I am now I don't think my back would tolerate it at all.

 

[Skypower]

That's one thing I never looked forward to was moving my lead acid batteries. As old as I am now I don't think my back would tolerate it at all.

Yeah, I’m in the category of “numbered” items picking things up. I work smarter, get someone dumber to pick it up.

 

[Crowz]

Yeah, I’m in the category of “numbered” items picking things up. I work smarter, get someone dumber to pick it up.

Can't. Kids grew up and moved out

 

[Hedges]

LiFePO4 should be the baseline assumption for a mobile system.
Consider cold weather protection, allowed charge rate vs. temperature, inrush/precharge, surge loads vs. BMS specs during selection and sizing.

 

[Skypower]

Can't. Kids grew up and moved out

Want a good laugh. I found an old video. I changed out the boat’s single “house” battery and got smarter, not using my back. I was so tempted to just slide that puppy into the drink but for the lead price, I didn’t. Later, I paid a young guy a cold beer to put it in the harbor cart and then into my suv.

 

[Crowz]

I use an engine hoist aka cherry picker to do all of my heavy moving these days. But considering how much trouble it is to get that thing where ever I need it job wise its a last resort even with it

 

[Skypower]

Two of the three inverter batteries, the one that got me is out of frame and in an awkward position. They weigh 170 pounds each. I don’t miss them at all.

 

[bds70]

Lifepo4 are usually superior to AGM except below freezing temperatures, or when kept at a high state of charge with little to no cycling like emergency standby or high inrush like starting a large engine ( small bms/battery bank). I’m thinking the guy is getting anxious about the date code on his AGM stock.

Yup perhaps and there's no chance of freezing in Queensland, lowest temps here would be maybe 15⁰C and that's bloody cold for us lol.

 

[Hedges]

Engine hoist - Me too, lifting inverters, transformers, tool cabinets.

And dolly & ramps to move them around.

Cheapest and easiest way to keep panels working during a power outage

Yes, this is the correct way to do it. But those inverters start at $3k and go up from there Do you know of any? Would a Ecoflow smart panel work?

diysolarforum.com

Here are 8 of my 24 "new" AGM batteries. These little ones are only 76 pounds each. My others are 120 pounds.

Balancing used AGM

I picked up 24x FullRiver DC250-6 AGM batteries, somewhat used. They had powered a couple Tuk-tuk for tourists. 76 lbs. each, so 1800 lbs. https://fullriverbattery.com/batteries/part-dc250-6/ Most measured 6.26 ~ 6.29V, but a couple were lower, lowest being 6.05V (40% SoC per manual) I set...

diysolarforum.com

All my AGM are used for grid-backup.
They're dumb and simple, don't need to worry about BMS.

 

[Skypower]

Engine hoist - Me too, lifting inverters, transformers, tool cabinets.

And dolly & ramps to move them around.

Cheapest and easiest way to keep panels working during a power outage

Yes, this is the correct way to do it. But those inverters start at $3k and go up from there Do you know of any? Would a Ecoflow smart panel work?

diysolarforum.com

Here are 8 of my 24 "new" AGM batteries. These little ones are only 76 pounds each. My others are 120 pounds.

Balancing used AGM

I picked up 24x FullRiver DC250-6 AGM batteries, somewhat used. They had powered a couple Tuk-tuk for tourists. 76 lbs. each, so 1800 lbs. https://fullriverbattery.com/batteries/part-dc250-6/ Most measured 6.26 ~ 6.29V, but a couple were lower, lowest being 6.05V (40% SoC per manual) I set...

diysolarforum.com

All my AGM are used for grid-backup.
They're dumb and simple, don't need to worry about BMS.

Hard to beat for SHTF backup