New 2 stage PD lithium Converter charger yet?

Keeping Lithium batteries at a constant 100% SOC isn't recommended by most manufacturers.

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.

yes they have a whole line of two stage chargers for Li out now.

Steve

Even 13.6 continuous is a bit high. I would stick with what you have.
Also charging the lithium at the absolute max 14.6 volts is overrated and unnecessary.
The 13.2 - 13.6 - 14.4 profile is better. Especially with minimal use due to solar.

When the need arises for occasional battery top-off (primarily just for cell re-balancing…) I opt for either the Charge Wizard (above about 95% SOC, actively monitored via Victron BMV 712), or when off-grid, a programmable 2 stage BlueSky solar charge controller set respectfully at 14.4 & 13.6 volts…I see no real need to swap out the PD…

3 tons

time2roll wrote:
Even 13.6 continuous is a bit high. I would stick with what you have.
Also charging the lithium at the absolute max 14.6 volts is overrated and unnecessary.
The 13.2 - 13.6 - 14.4 profile is better. Especially with minimal use due to solar.

Agree.

Unless your 3-stage (13.2v/13.6v/14.4v) lead-cell converter has a lead-cell/AGM equalization mode that goes above 14.6v, there is zero need to upgrade to a so-called "lithium" approved converter/charger.

The so-called equalization mode on many of the Progressive Dynamic units simply reverts to 14.4v bulk mode for about 15 min. every 21 hours, if the battery remains fully charged. Absolutely safe for a 12v lifepo4 battery.

If you leave a 3-stage (13.2v/13.6v/14.4v) lead-cell converter connected to a fully charged 12v lifepo4, it will eventually drop to 13.6v, then 13.2v. Lifepo4 batteries don't like sitting around at a high SOC (13.6v - 14.6v/99 - 100% SOC) for long periods of time, so dropping to 13.2v is good for a 12v lifepo4. 13.2v equates to roughly 70% SOC. The closer you can long-term float at 30-50% SOC the better. Long-term float at 30-50% SOC (13.0v - 13.15v) results in absolute maximum cycle life from a lifepo4.

Most 2-stage lithium converter/chargers will continue to float at 13.6v (99-100% SOC) indefinitely. Although long-term float at 13.6v for long periods of time won't damage a 12v lifepo4 per se, it will reduce the cycle life of the battery a nominal amount (vs. 13.2v).

IMO, the best all-around 3-stage lithium converter/charger would have a 14.6v bulk charge (maximum charge current, minimal charge time, slightly reduced cycle life), a 13.6v absorption, and a 13.1v long-term float (for maximum cycle life).

For those who have a preference for absolute maximum cycle life, a user selectable switch to limit bulk charging to 13.6v, then a 13.1v long-term float, would be ideal.

It is my understanding that PD entered into a "Partnership" with Battle Born Batteries.. You should be able to get the PD LiFePO4 converter from BB.

Battle Born (among other LFP makers) has also influenced PowerMax in their design of a charger. See BB's comments here (scroll down)

The PowerMax has a big advantage over the PD in that you can also choose to manually adjust the charging voltages to your own idea of what your LFP needs, to do what you want. (Some like to use lower charging voltages than the fixed 2-stage ones) Price is probably better too.

https://powermaxconverters.com/product/pm3-lithium-series/

BTW I really hate the way BB uses "Absorption" for the 13.6 stage and "Floating" for 13.2v. In real life, the Absorption Stage is when amps are tapering following the Bulk Stage, but the charger's voltage remains at its Vabs setting of 14.x.

It seems to be a losing battle with these companies to get them to use proper language for charging profiles. :(

On voltage choice, we know that with FLA./AGM the standard 13.6v works when on shore power and you are using 12v things while camping. 13.2v is only for "storage" when not camping.

I am unclear what goes on with LFPs for that, where many say 13.6 is too high with LFP for "Float", but is it too high for while camping using 12v things? 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? The PowerMax can deal with whatever is chosen of course, having the adjustable voltage option to it.

Using a conventional PD 9245 (with Charge Wizard dongle) I haven’t really seen LFP charging as problematic, mainly because there’s little need on a routine basis to fully charge to 100% SOC, except for an occasional cell re-balancing, which (via PD, or programmable 2 stage solar controller…) I might preform say every few weeks or so - otherwise, 85-90’ish % SOC has worked well, and extends battery life…

Thus (per this example…), except when allowing for periods of camper non-use (e.g. battery isolated and in hibernation at roughly 50% SOC…), how often might this ‘charging to a full 100% SOC’ task even occur (??), and when it does, simply pick a time when the last few SOC% can be briefly monitored, then (post cell balancing activity…) just discontinue the charging…

3 tons

BFL13 wrote:
. . . I am unclear what goes on with LFPs for that, where many say 13.6 is too high with LFP for "Float", but is it too high for while camping using 12v things? 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? . . .

Good question. Depends on what you want from your lifepo4. Maximum usability? Maximum cycle life? Or, something in the middle?

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.

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.