LiFePo4 vs Lead Acid...Some points of interest.

Why do you think the graph must be at the maximum charge rate? It is an example charging curve, not necessarily the fastest you can charge at.

As they clearly state, the maximum charge rate for their lithium batteries is 1C. Are you disputing that? Otherwise this is a silly discussion over semantics.

FWC wrote:

BFL13 wrote:
There are two straight lines--the constant current in Bulk at .25C in the one graph and the constant current in Bulk at .4C in the second graph. One takes four hours and the other takes one hour. How can that be?

If C is 100,

25a x 4h = 100AH and they haven't even started the Absorption stage yet.

40a x 1h = 40AH and then the 15 minute? Absorption stage gets the batt full to 100AH?

I am having some difficulty accepting that this is a sincere question, when the answer is right there in the paragraph you quoted from:

Powersonic wrote:
Stage 1 battery charging is typically done at 30%-100% (0.3C to 1.0C) current of the capacity rating of the battery. Stage 1 of
the SLA chart above takes four hours to complete. The Stage 1 of a lithium battery can take as little as one hour to complete,
making a lithium battery available for use four times faster than SLA.

You can charge their lithium batteries at 1C, which is four times fast than 0.25C for lead acid.

I already said that way back. You are ignoring my question about the Stage 1s in the two graphs. What is your comment wrt : (where C =100AH)

.25C x 4 hr =100 AH and the batt is not full yet so how can it be at C?
.4C x 1hr = 40AH nowhere near C.

.4C where C is 100 would take 2.5 hrs with no tapering amps

So either my calculator is broken or this is all more sales BS as you call it, or I have missed how they are doing this comparison.

BFL13 wrote:
There are two straight lines--the constant current in Bulk at .25C in the one graph and the constant current in Bulk at .4C in the second graph. One takes four hours and the other takes one hour. How can that be?

If C is 100,

25a x 4h = 100AH and they haven't even started the Absorption stage yet.

40a x 1h = 40AH and then the 15 minute? Absorption stage gets the batt full to 100AH?

I am having some difficulty accepting that this is a sincere question, when the answer is right there in the paragraph you quoted from:

Powersonic wrote:
Stage 1 battery charging is typically done at 30%-100% (0.3C to 1.0C) current of the capacity rating of the battery. Stage 1 of
the SLA chart above takes four hours to complete. The Stage 1 of a lithium battery can take as little as one hour to complete,
making a lithium battery available for use four times faster than SLA.

You can charge their lithium batteries at 1C, which is four times fast than 0.25C for lead acid.

Gee, when a flashlight battery is almost exhausted its blub isn't bright like it was when the battery was new. Wow.

“Can anybody please explain? What am I missing?”

Well, as a male I can’t experience pregnancy, yet after some considerable time at observation :) I can understand what it means - it’s in this light that ‘substantial’ means ‘more’...

3 tons

Freep wrote:
Yeah I'm so happy with LFP and solar that I'm seriously considering getting rid of the generator and replacing that space with eight of those Winston cells for 1400 ah(or 16.8 Kilowatts).

Next RV for me might come with a broken generator so I can cry about the repairs to get a good price. Then just rip it out for space to put a monster battery.

Freep wrote:
I went from FLA to AGM to LFP. I'll never go back.

I've been away from this site for a while and came back to let everyone here know about some new Winston cells that are going for cheap. I'm not sure where to post about it or what the forum rules are so it would be nice if a mod gave me a little direction on that.

Here is a thread on building an LFP:

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/30223204

Post a link with your thoughts on the product for discussion.

"Though my system is a bit smaller than your’s (@200a/h LFP, 440w solar), the charge recovery advantage is substantial,"

Solar charging rate goes up till noon then back down in a bell curve. 440W of solar can do about 30 amps at high noon, pick 20 amps average for a mid-morning to mid afternoon time? Hard to pick a charge rate with solar.

Say there is 200AH of SLA and 200AH of LFP getting 20 amps for however long so they are getting the same amount of sunshine at whatever rate for the comparison. Say both are down to 30% SOC (60AH) at the start.

Allow that the LFP does constant 20 amps to about 97% SOC, but the SLA tapers in the Absorption stage at a lower SOC. We know that 20 amps is a 10% charging rate on 200AH and that Bulk will go to 90% SOC (180AH) with the SLA before amps taper. (At a higher charging rate, Bulk would end at a lower SOC, making the LFP look better, but this is with the 440w and the 200AH.)

So 30-90 SOC = 180-60 =120AH at 20 amps = 6 hrs. So equal charging time for the first 6 hrs and now both batts are at 90% SOC (20AH left to go)

The "substantial recovery advantage" is all in the time it takes to do that last 20AH if you choose to go that high in SOC.

That would depend on your definition of "substantial".

3 tons wrote:

Though my system is a bit smaller than your’s (@200a/h LFP, 440w solar), the charge recovery advantage is substantial, and peak harvest times are considerably exploited - this attribute is pretty much a ‘settled science’ (per the principle of Occam’s razor...) and likely why NASA chose a Lithium variant for Mars Opportunity Rover’s energy reservoir...JMO

3 tons, in HarvestVille Central (e.g. the high NV Desert)

Yeah I'm so happy with LFP and solar that I'm seriously considering getting rid of the generator and replacing that space with eight of those Winston cells for 1400 ah(or 16.8 Kilowatts). Two big problems with that, justifying it with my wife and timing. It's the wrong time of year for a big project like that. If this were the end of fall, I'd probably pull the trigger.

“I have a 12v 271 ah pack that I built for my truck camper and it's usually fully charged by the time lunch is finished, when there is full sun. It takes all day on a cloudy day. This is with 600 watts of solar panels.“

Though my system is a bit smaller than your’s (@200a/h LFP, 440w solar), the charge recovery advantage is substantial, and peak harvest times are considerably exploited - this attribute is pretty much a ‘settled science’ (per the principle of Occam’s razor...) and likely why NASA chose a Lithium variant for Mars Opportunity Rover’s energy reservoir...JMO

3 tons, in HarvestVille Central (e.g. the high NV Desert)