Comparing system prices with various battery types

[SternWake]

I was taught that the thinner the plates in a FLA battery the faster it can discharge or charge, (more surface area in contact with the acid). You say it takes 3 hours to charge a deep cycle battery, I don't think it takes that long for a starter battery.

True that Lead acid starter batteries have less resistance than marine or deep cycle.

Top quality AGM batteries have less resistance than either, and still take 3.5 hours minimum to achieve 100% from 80% with these. No matter if starting, marine, or deep cycle.

The difference would be more measurable when the batteries are depleted to 50%, not in the 80 to 100% range.

Blars, at what point does acceptance begin tapering with Lifepo4.

Lets use the 100AH as the example. Lead acid would begin slowing at a c/5 charge rate at ~ 80% state of charge and require that 3.5 hours to reach 100% when held at absorption voltage.

At what percentage does the lifepo4 slow acceptance?

 

[RVTravel]

Are they speaking Greek?

 

[blars]

You don't have to connect the cells together? Bracket the cells so they don't swell? LiFePo needs a battery management circuit to prevent over discharge or over charge, unless one is an expert and willing to do that manually.

The 4 LiFePO4 cells are connected in series. The two 12v AGMs are connected in parallel. The two 6v LFA are connected in series. 3 vs 2 vs 1 wires, but not different in kind.
My LiFePO4 cells are strapped together to hold them in place. Lead-Acid needs a battery management circuit to prevent over discharge or over charge or habitual under charge, unless one is an expert and willing to do that manually.

blars, I your comparison do you have any Li battery protection in your circuit or do you manually monitor during usage to prevent problems? Also do you balance your cells from time to time?

I manually monitor during usage mostly because I find that interesting, not that they need it often. T should check the cell balance more often, but I have never balanced after install.

 

[blars]

I don't understand what you mean by "won't exceed the 8A of the AGM"

Standby on the linked Powerwerks LVD is 4mA.

The AGMs I was comparing with were 160Ah at the 20 hour rate. If you discharge faster than 8A, you'll get fewer amp-hours out at lower voltage and still have to put the full amount of power back in. I did not factor that in to this comparison, only mentioned it.

It was not clear to me what Powerwerks meant by standby. I was guessing it was "low voltage, no power passed", so only when your battery is below threshold.

 

[highdesertranger]

we need pics of these Li battery systems. highdesertranger

 

[blars]

Blars, at what point does acceptance begin tapering with Lifepo4.

At what percentage does the lifepo4 slow acceptance?

Recommended charging is constant current until the set voltage is reached, then constant voltage until the current tapers off to C/50 or so. 14.0v is good for C/2 or so, 13.8v might be better for C/20. That's to around 95% of rated capacity. The current tapers off pretty fast, depending on the voltage. No need to float.

 

[blars]

Are they speaking Greek?

It's the RV-Electrical dialect of techno-nerdspeak.

 

[DannyB1954]

Are they speaking Greek?

Yep. Someone said I can speak every language except Greek. The other guy said, let's hear you say something in Spanish. He replied that is Greek to me. I thought I had a grasp on what a "C" rating was. Then someone said they could charge at 5c. That would be 500% of the amp hour capacity? Yikes.

I think I will stay with lead acid for a while. Tomorrow is battery delivery day for my local WM. Last week they didn't get any maxx 29DC with the 2 year replacement warranty. Maybe this week I will get lucky.