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Lifepo4 battery

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podwerkz View Drop Down
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Post Options Post Options   Quote podwerkz Quote  Post ReplyReply Direct Link To This Post Topic: Lifepo4 battery
    Posted: 11 Nov 2019 at 5:16pm
Originally posted by TheBum

...accurate predictions of remaining charge from a monitoring perspective are almost impossible.

Not impossible. Look at any smartphone or laptop, it shows a pretty accurate indication of charge remaining, and that battery is a lithium battery with a flat voltage discharge curve.

The technology is just different, that's all. You can buy li-compatible coulomb counters or li-compatible amp counters (battery monitors) that will keep track of the energy stored and energy used.
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Post Options Post Options   Quote TheBum Quote  Post ReplyReply Direct Link To This Post Posted: 11 Nov 2019 at 6:33pm
Originally posted by Olddawgsrule


Originally posted by TheBum

One thing you need to be aware of, if you aren't already: LiFePO4 batteries have a very flat voltage curve. While that's nice while there's still charge in the battery, you have little to no warning when it runs out of juice and, consequently, accurate predictions of remaining charge from a monitoring perspective are almost impossible.

Okay, I'll bite... It's still a wattage thing..??!!??


No, it's an energy thing, as in amp-hours.
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Post Options Post Options   Quote GlueGuy Quote  Post ReplyReply Direct Link To This Post Posted: 11 Nov 2019 at 7:11pm
I prefer watt hours. Easier to deal with parallel and/or serial batteries.
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Post Options Post Options   Quote DavMar Quote  Post ReplyReply Direct Link To This Post Posted: 11 Nov 2019 at 7:12pm
Originally posted by Olddawgsrule

Every battery has a limit to cycles before they break down. How you cycle effects the life of the battery. My old LA solar battery bank was purchased new. 2 year limited warranty, said they would last 5-7yrs (lucky if I get 10yrs) and they lasted 17yrs. Cycling is key to longevity. Same for the Lithium battery.

I passed this along for anyone researching or looking for a Lifepo4 and wishes to save $$, here's a way.


Any tip you can pass on to save money on batteries be them LA or Lithium I'm sure is much appreciated by all on this forum. It also reads to me as you did your homework on manufacture spec's and vendor to buy from in China. Your more then right allot of the Lithium and Glass Mat batteries we buy sadly do come from overseas.

I can more then see the advantage of Lithium batteries if you have the money to spend on them I say I go for it, especially if you do allot of boon-docking. Yet, here is my counter argument to you of Lead Acid verses Lithium. Other then weight savings, no argument there your win hands down. Your said from two lead acid batteries you got 17 years use out of them, which is exceptional. Though even at ten years life span if you divided the cost for Lithium per year and then Lead Acid you tell me which is more economical to use not factoring in the few pound of weight savings? Not to be crass but please do convince me and everyone else here that it makes economical sense to trash our Lead Acid for Lithium batteries.

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Post Options Post Options   Quote crazycoyote Quote  Post ReplyReply Direct Link To This Post Posted: 11 Nov 2019 at 11:07pm
very interesting info, but I'll stick to my 2 Golf Cart 6v batterys, as Costco is the next town down, if I need to replace them.
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Post Options Post Options   Quote Olddawgsrule Quote  Post ReplyReply Direct Link To This Post Posted: 12 Nov 2019 at 8:21am
Originally posted by DavMar

Yet, here is my counter argument to you of Lead Acid verses Lithium. Other then weight savings, no argument there your win hands down. Your said from two lead acid batteries you got 17 years use out of them, which is exceptional. Though even at ten years life span if you divided the cost for Lithium per year and then Lead Acid you tell me which is more economical to use not factoring in the few pound of weight savings? Not to be crass but please do convince me and everyone else here that it makes economical sense to trash our Lead Acid for Lithium batteries.


Please do understand, I'm a longtime LA battery guy. Yet here comes a breakdown. If you want a battery to last, for years, water regularly and cycle carefully.
A standard LA 12v battery (marine). Let's work with a 575 CCA or roughly 90ah. To cycle for endurance it should only be drawn to 75% of SOC. That puts us at only 22.5amps of usable power. A Duracell will cost you $95. You get 10% off for online purchase, now $85.50. What's that break down to? 
 $3.80 a usable amp. 

It is said, AGM's and Gel's can be drawn deeper, yet I 'read' only another 5-8% or so. Kinda matches out in cost per usable amp when you factor the addiditonal costs of these. Only what I read mind you.. I have no first hand knowledge on these.

Now Lithium, I just bought a 60ah for $225 shipped to my door. Lithium is rated differently as in it's rated to cut-off voltage. This gives me 54ah usable and a cost of 
 $4.16 a usable amp  

All in for my dual 6v's Right around $250 (batts, cables, box and trade-ins). I determine my usable at 105ah. Here's the deal on Batteries!
$2.85 a usable amp (No trade factored $50 added to cost)

It's not 2-3X the cost when you look at as 'usable' ah's.. 

Then there's the Battleborn folks. That's 400% higher per usable amp. Now there's your "I can buy several LA's" for the same cost. 



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Post Options Post Options   Quote Olddawgsrule Quote  Post ReplyReply Direct Link To This Post Posted: 12 Nov 2019 at 8:37am
Originally posted by TheBum


No, it's an energy thing, as in amp-hours.

Huh?? Care to elaborate a bit?
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Post Options Post Options   Quote TheBum Quote  Post ReplyReply Direct Link To This Post Posted: 12 Nov 2019 at 2:13pm
Originally posted by Olddawgsrule


Originally posted by TheBum

No, it's an energy thing, as in amp-hours.

Huh?? Care to elaborate a bit?


Power (e.g. wattage) is energy expended per unit time. It's only a rate, not a capacity. The same battery can output 10W or 100W, but the more watts it outputs, the less time it'll take to drain the battery. To look at it another way, a LA battery and a LiFePO4 battery can output the same wattage, but the amount of time it'll take to drain the batteries is dependent on the energy stored in the battery.

LiFePO4 batteries have a higher energy-to-weight ratio than LA batteries do and they can output a large amount of wattage, but they're a bit more finicky on how you charge them, i.e. they're only good for a limited number of charge cycles, so it's a bad idea to trickle charge them: it reduces the service life of the battery because it's essentially cycling continuously.
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Post Options Post Options   Quote GlueGuy Quote  Post ReplyReply Direct Link To This Post Posted: 12 Nov 2019 at 8:00pm
Originally posted by TheBum

 Power (e.g. wattage) is energy expended per unit time. It's only a rate, not a capacity. 
Watts is power. Watt-hours is power over time. If you follow electric vehicles at all, you will see that all the batteries are now rated in KWH (kilowatt-hours).

Interesting side note. The EPA considers 33.5 KWH to be roughly equivalent to 1 gallon of gasoline. That means that an SR+ Tesla Model 3 with a 60 KWH battery has roughly 1-3/4 gallons in the "tank". The amazing thing is that it can go almost 250 miles on that. That is approximately 140 miles per "gallon".
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Post Options Post Options   Quote DavMar Quote  Post ReplyReply Direct Link To This Post Posted: 12 Nov 2019 at 9:06pm
Hmmm.... according to Olddawgsrule breakdown (and thank you for the details) that it looks to me soon in the near future the cost for Lithium will be comparable to Lead Acid per amp hour. Yes, there is no argument about the Lithium out preforming Lead Acid and believe me when the day comes I can replace my Lead Acid batteries for near the price of Lithium it will be bye bye Lead Acid. Though for seasonal campers that camp were there is electric available or just occasional boon-dockers the cost of upgrading to Lithium just don't make sense to me, yet. I hope in the future as Lithium prices drop that does make sense because I would love nothing more then to be done with Lead Acid batteries.
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