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 > New 2 stage PD lithium Converter charger yet?

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time2roll

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Posted: 06/15/22 08:10pm Link  |  Quote  |  Print  |  Notify Moderator

As I understand it LFP will have a reduced life when held above resting voltage (about 13.4v) for extended periods. The higher the voltage the greater the issue. There is very little additional energy above 13.4 volts to be gained anyway from holding above resting. Maybe 1%

The higher voltages are just for charging. Need zero absorption if going to 14.4-14.6 volts. Charging to 13.8 is common and may need a couple hours absorption. But again no harm to get to only 97%. If that last 3% matters so much the purchased battery should have been larger.

This is all nominal. The real issues actually happen at the cell level. Charging to 14.6 volts will inevitably charge one or more cells over the maximum. The battery makers tolerate this as part of the warranty but it still shortens the life. At the top of charge the cells gain voltage exponentially so it may not seem much at the battery level but individual cells can spike up very fast if not perfectly balanced. Very few battery will hold perfect balance and most are good but not perfect even when assembled.

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3 tons

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Posted: 06/15/22 08:13pm Link  |  Quote  |  Print  |  Notify Moderator

Per BFL, “Perhaps there should be a new set of voltages for LFP for what to use while actively camping and what to use when the rig is not being used?”

Unlike conventional FLA batts, there is no real need to keep a LFP on a charger when the rig is not in use - isolation, or charge controller disconnect does the trick…

When charging, LFP’s are quite forgiving, as anything from the higher 13’teens to say the mid-14’teens will get the job done…When a full 100% SOC cell-balancing is desired, a charging source that’ll ‘post-charge’ passively transition to a max of 13.6v (or less), as does the Boondocker-Li and PD-Li will extend LFP battery life…

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StirCrazy

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Posted: 06/16/22 06:36am Link  |  Quote  |  Print  |  Notify Moderator

otrfun wrote:

Good question. Depends on what you want from your lifepo4. Maximum usability? Maximum cycle life? Or, something in the middle?
14.6v nets you maximum ah's and minimal charge times at the expense of cycle life.
You can charge a 12v lifepo4 with any voltage between say, ~13.15v and 14.6v with varying degrees of usability and cycle life. 14.6v nets you maximum ah's and minimal charge times at the expense of cycle life. ~13.15v nets you maximum cycle life with reduced ah availability and increased charge times.

There is no one charge profile that provides both max usability and max cycle life. It's either one or the other, or a little of both.

Pick your poison.


Im not sure the way this part is worded is the best. and it could be leading to a lot of the confusion.

I think it would be better to say "advertised cycle life" instead of "at the expence of cycle life" some one like BF13 or PT might interpret that as by charging to 14.6V we are only going to get 1800 cycles now.

the max figures are what the cycles are based off so 14.6 charge 100 to 0 discharge, but yes like you say if you don't need all of your battery bank operating between say 80 and 20% would normaly take a 3000 cycle battery up to the 5000 cycle range and using less than 50% so 30 to 80 could take you up to 7000 cycles. so there is a big trade off, but generaly to get more life you have to spend more on batteries to let you use that smaller amount of capacity.

Im trying to figure out how to set up my peramiters on my solar charger to stop charging at 90% right now, but I have 10x my daily use capacity so using 90% as my celing should gain me a tone of life that I probably won't live long enough to see anyways haha


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otrfun

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Posted: 06/16/22 08:37am Link  |  Quote  |  Print  |  Notify Moderator

StirCrazy wrote:

otrfun wrote:

Good question. Depends on what you want from your lifepo4. Maximum usability? Maximum cycle life? Or, something in the middle?
14.6v nets you maximum ah's and minimal charge times at the expense of cycle life.
You can charge a 12v lifepo4 with any voltage between say, ~13.15v and 14.6v with varying degrees of usability and cycle life. 14.6v nets you maximum ah's and minimal charge times at the expense of cycle life. ~13.15v nets you maximum cycle life with reduced ah availability and increased charge times.

There is no one charge profile that provides both max usability and max cycle life. It's either one or the other, or a little of both.

Pick your poison.
Im not sure the way this part is worded is the best. and it could be leading to a lot of the confusion.

I think it would be better to say "advertised cycle life" instead of "at the expence of cycle life" some one like BF13 or PT might interpret that as by charging to 14.6V we are only going to get 1800 cycles now.

the max figures are what the cycles are based off so 14.6 charge 100 to 0 discharge, but yes like you say if you don't need all of your battery bank operating between say 80 and 20% would normaly take a 3000 cycle battery up to the 5000 cycle range and using less than 50% so 30 to 80 could take you up to 7000 cycles. so there is a big trade off, but generaly to get more life you have to spend more on batteries to let you use that smaller amount of capacity.

Im trying to figure out how to set up my peramiters on my solar charger to stop charging at 90% right now, but I have 10x my daily use capacity so using 90% as my celing should gain me a tone of life that I probably won't live long enough to see anyways haha
I stand by my comment: "14.6v nets you maximum ah's and minimal charge times at the expense of cycle life". I'm not claiming it's a large, or a small amount, I'm simply claiming that there is a drop in cycle life, which is a true and correct statement.

I purposely worded it this way because the amount of cycle drop cannot be quantified unless you're comparing cycle life at 14.6v vs. cycle life at a specific, lower charge voltage, which I did not do.

If BFL13 or PT (or anyone else) want to assume I meant a large, small, or specific drop in cycle life, that's their right to do so. However, I only claimed there was a drop---nothing more, nothing less.

On the flipside, I very much agree with your comment, " . . . using 90% as my celing should gain me a tone of life that I probably won't live long enough to see anyways haha". Most of this debate about the best charge profile, voltage, converter, or charger for a lifepo4 is probably a moot point for the vast majority of lifepo4 users. Even the use of a single-stage 14.6v lithium converter/charger, which is probably the worst charging device you can use to charge a lifepo4, will probably still net the average lifepo4 owner 10 years of use before capacity drops below 80%.

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Posted: 06/16/22 09:02am Link  |  Quote  |  Print  |  Notify Moderator

Another factor (though widely overlooked…) that impacts longevity is determined during the manufacturing process via final testing, and suggest the cost difference between say a BattleBorn or an Aims (grade ‘A’ cells), versus the bargain brands - note that ‘non’ grade ‘A’ cells will generally* lack a QR code designation…

*except where a A cell is re-inventoried as a B cell

(Video clip at bottom):

https://www.seplos.com/news/cheap-battery-part-1-grade-a-vs-grade-b-what-is-the-grade-b-lithium-ion-battery-cells-69852.html

Summary:

https://www.lithiumstoragebattery.com/news-grade-a-and-grade-b-for-lithium-ion-battery.html

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Posted: 06/16/22 10:08am Link  |  Quote  |  Print  |  Notify Moderator

SFVdave wrote:

When I installed lithium batteries 18 months ago I also changed out my converter charger. I didn't want it constantly charging 14.4 volts. so I returned it and have been using my original PD converter charger and just hit the charge wizard to get it fully charged. With 300 watts of roof top solar and an MTTP controller, it stay fully charged shile camping. But I heard that PD was going to produce a 2 stage one that drops to 13.6 after fully charging the batteries. Wondered if they came out with it? Can't find it on their site if they did. they have changed the num,bers around with upgrades so I may have missed it.


"Compatible" for a converter is not just an LFP problem. EG Trojan wants 14.8v but many converters only do 14.4.

Above all, converter makers want to satisfy the majority who want automatic, don't have to think about it, equipment.

But all of a sudden with LFPs out, converter makers feel the need to be compatible with them. First they went to 14.6 instead of 14.4 (and said not to go over that with temp comp so turn off your temp comp--first problem with staying automatic--you have to do something!)

Then they had to allow for not staying at 14.6 for too long (where too long is not clearly defined--somewhere between 20 minutes and two weeks maybe.) Same as for battery boiling with FLA staying at 14.x So back to the 2-stage idea to drop to what they used to call "Normal"--13.6v. Why 13.6?

13.6 was chosen way back as "normal" even though it can lead to battery boiling if left on too long with FLAs. On shore power you need the converter to run the 12v things (but you can do that at 12.6 so why 13.6?) Why 12 things? Because you have a 12v battery for when not on shore power. FLAs need 13.x to stay charged. The converter has a loaded voltage below 13.6 at times depending on what is running, so 13.6 keeps it above 13 anyway.

But 13.6 has issues for long term on shore power with LFPs too (not battery boiling, but something else). So what to do? You can disconnect the LFP and just run on converter. (Except for the odd time your rig might need the battery to help the converter run the slide out)

So what is the point of getting a 2-stage PD that does 14.6 and 13.6 instead of your 3 stage PD that does 14.4, 13.6, and 13.2? You get 14.6 which could be required. But is it? Not clear you can't get to Full at 14.4 and balance the LFP (needs above 14.2 -how much above?)---Seems to be different stories on that?

The 13.6 you already have, and it could be wrong anyway.

Can you take care of your LFP properly with any "automatic" fire and forget converter? You can't look after AGMs or FLAs properly that way either. The converter is set to "sort of" look after things and your battery dies at some point regardless. Few cared because batteries didn't cost much and they got the automatic hands free choice.

LFPs cost a lot! So now you have to do things yourself if you want them to last and not go broke buying new batteries.

For that you can get the manually adjustable voltage PowerMax converter instead of the fixed voltages of the PD. Or if you hate manual and want automatic, win the Lotto and not care about cost. Easy! [emoticon]


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time2roll

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Posted: 06/16/22 10:59am Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

Or if you hate manual and want automatic, win the Lotto and not care about cost. Easy! [emoticon]
Between the solar and the old PD I believe the OP is in great shape to get very near maximum life from the LFP fully automatic and easy.
That is of course not knowing the solar controller charge settings.

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Posted: 06/16/22 11:16am Link  |  Quote  |  Print  |  Notify Moderator

3 tons wrote:

Another factor (though widely overlooked…) that impacts longevity is determined during the manufacturing process via final testing, and suggest the cost difference between say a BattleBorn or an Aims (grade ‘A’ cells), versus the bargain brands . . .
Agree, cell quality and testing is very important. However, there's another significant issue to consider when comparing a 12v 100ah Battleborn battery to other 12v 100ah lifepo4 batteries on the market.

BB's 12v 100ah lifepo4 battery uses 100+ cylindrical lifepo4 cells in a parallel/series configuration. If a few cells go bad, weak, or unbalanced, there's minimal effect on the battery's total output because each cell is connected in parallel with 25-30 other cells. To my knowledge no other 12v 100ah lifepo4 battery manufacturer configures their battery in this manner. The typical 12v lifepo4 battery (found on Amazon and elsewhere) uses 4 prismatic cells, all wired in series. One bad, weak, or unbalanced prismatic cell in a series configuration has an equal and dramatic impact on the entire battery's output. A lot more eggs in one basket so-to-speak.

Battleborn could have built a much lighter, smaller, and less expensive 12v 100ah battery using prismatic cells, but they chose not to in order to achieve maximum redundancy, reliability, and longevity.

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Posted: 06/16/22 12:22pm Link  |  Quote  |  Print  |  Notify Moderator

I just sent this email to a pal:

“Well, BFL is correct in that it’s a poor strategy to use a ‘set and forget’ charger” -

Further, I agree with most else of what he stated [emoticon]

In my view, a ‘true LFP charger’ might have a smart chip in it that would recognize when cell balancing is complete (holding period, and end of current calls), but seriously, how often does one need to fully charge a LFP, and no need to keep on charger when not in use…

My PD in bulk outputs 14.4v (likely 14.3 at terminals), but I never FULLY charge while not in attendance (at least during the last few % of upper SOC), then, after determining completion of balancing on Victron BMV 712, shutdown the PD (or solar controller) after balancing - BUT, I infrequently do a ‘FULL charge’ because, except for cell balancing (incl, meter re-sync’s), most often there’s no need to do such, thus, during ‘routine charging’ (considering LFP’s greater usable capacity…) I mostly charge to around 85-90’ish % using off-grid solar harvest rather than the PD…

On the other hand, Victron’s BMV SOC meter has a built-in programmable load relay feature that can be configured to a inverted parameter function - by this means, the PD (or whatever…) could be shutdown (and restarted) upon reaching a certain voltage…

Again, based on my own camping style I see little effort and far more convenience (due to usable capacity) to the charging LFP’s than with my former GC2’s - JMHO

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Posted: 06/16/22 01:57pm Link  |  Quote  |  Print  |  Notify Moderator

In regards to the previous, one might also note that BFL’s fairly comprehensive points on ‘set and forget’ style charging would seem to apply to all battery types…

3 tons

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