New PowerMax Lithium Series Converter/Chargers

[Browneye]

From the resource doc...

Constant current aka bulk
During this phase the charger controls the charge current by controlling the charge
voltage.
Current flow is a product of voltage differential.
In other words there needs to be a difference in voltage between the battery and
the charger to make current flow.
As the battery fills up its voltage increases.
The charger increases the charge voltage to maintain the prescribed current flow.

Constant voltage aka absorption
When the charger no longer has to adjust its voltage down from the configured
charge voltage to maintain the the prescribed current flow, the charger is in the
absorption phase.
During the absorption phase the charge current decreases as the battery voltage
approaches the charge voltage.
The absorption phase ends when the charge termination criteria is reached.

Got it...no sense wire. Like what I saw my bench power supply do when top-charging. CC and CV are like interconnected.

And yeah, I wouldn't' want my BMS controlling charging parameters.

So if 3.45 per cell - 13.8 for 4 - is the 100% full charge level, why is it acceptable to charge them at 3.65/14.6 without overcharging them?
Is this to get the voltage differential to keep current flowing? And then they settle back to 3.45V when charging is terminated?

When I set the powermax to 14.4 or 14.6 (can't remember) I did have one cell hit the top - BMS said it was 'over voltage' and the grayed-out 'balancing' text became visible. So the BMS stopped charging that one cell and let the others catch up? And that one time does register in the history on the bms app.

 

[John Frum]

And yeah, I wouldn't' want my BMS controlling charging parameters.

Good to hear.

So if 3.45 per cell - 13.8 for 4 - is the 100% full charge level, why is it acceptable to charge them at 3.65/14.6 without overcharging them?

Any voltage equal to or greater than ~3.45 volts per cell will fully charge a cell.
3.65 just does it faster.
You stay in CC longer and CV shorter at 3.65 volts per cell.
With the commodity big blue cells that we all know and love its not practical to charge a multi-cell battery to 14.6 volts because one or more cells can exceed 3.65 volts and trip the bms.

Is this to get the voltage differential to keep current flowing?

Yes.

And then they settle back to 3.45V when charging is terminated?

Yes.

When I set the powermax to 14.4 or 14.6 (can't remember) I did have one cell hit the top - BMS said it was 'over voltage' and the grayed-out 'balancing' text became visible. So the BMS stopped charging that one cell and let the others catch up? And that one time does register in the history on the bms app.

The BMS stopped all cells from charging.
The fet conrolled current path goes through all the cells.

I'm going to suggest one more time to set your powermax to 13.4 or 13.45 volts fixed voltage so that you have a safe setup.
Even if you forget to turn off the generator no harm will come to your battery you will just waste some fuel.

 

[time2roll]

I'm going to suggest one more time to set your powermax to 13.4 or 13.45 volts fixed voltage

Seems low. 3.4 to 3.45 vpc?

 

[John Frum]

For even the best quality big blue cells that we get here my ideal charge profile would be...
3.55 per cell at .2c(56 amps) to a tail current of .05c(14 amps) with an optional float of less than or equal to 3.35 volts.
For the discharge...
Don't discharge at greater than ~140 amps and stop discharging when the weakest cell drops away from the pack.
Which is typically ~3.0-3.1 volts per cell.

 

[Browneye]

Got it. Will write down hard numbers - I need to set everything there.
3.55 x4 = 14.2V. Shut down at 14A tail. Otherwise charge at 3.4 x 4 = 13.6 Any floating chargers set to 13.4, like Orion or SCC. Right?

I think I'll print this out in big numbers and paste it in the battery compartment as bible.

The powermax is currently set to 13.5V - I think I will leave it there. I got good charging current - about 30A when the pack was showing 13.0 volts after turning off the test load. If the pack is way down it will likely charge at the full 50 A or close. I checked at lunch today, charging amps finally got to zero - all the cells were sitting at 3.37 +/- 6 milliamps.

My OK bms is 120A, so I don't have to worry about discharge max current. Plus I don't have anything that draws that much. However I am already thinking of upgrading the inverter from 600W to 1000W. Here we go again...

That Mean Well charger is in my cart...have to think hard on that one. Who's gonna push me over?

 

[John Frum]

3.55 x4 = 14.2V. Shut down at 14A tail. Otherwise charge at 3.4 x 4 = 13.6

If your charger has reasonable charge termination I suggest you use it.
Reasonable is configurable tail current or configurable absorption timer or sense leads.

Any floating chargers set to 13.4, like Orion or SCC. Right?

By "floating charger" I think you mean a fixed voltage cc/cv source without charge termination logic, confirm?

I got good charging current - about 30A when the pack was showing 13.0 volts after turning off the test load.

If the pack is down to 13.0 volts you should get the full constant current from the powermax.
If the powermax is rated for 50 expect 45 amps tops.
The fact that you are only getting 30 amps is surprising.
What awg is the wire between the charger and the battery?
How long is the round trip length of the circuit?
I suspect excessive voltage drop.

That Mean Well charger is in my cart...have to think hard on that one. Who's gonna push me over?

Don't get the meanwell.
The powermax is good enough for you use case.
If you didn't already have the powermax I would advise to go with the Meanwell.
Even better... buy an inverter/charger and sell the powermax.
An inverter/charger also includes a built in automatic transfer switch.

 

[sshibly]

MPP solar stuff on watts247 is good value, I concur with Joey,
3k watt pure sine inverter alone from meanwell/samlex will cost nearly $1k

for $600 you get an all in one = 3k solar, 3 inverter, 60A a/c charger, and might even bring hair back to my head.

but like most of us, you have some major pieces already, tweak em a little and you are good to go.

 

[Browneye]

If your charger has reasonable charge termination I suggest you use it.
Reasonable is configurable tail current or configurable absorption timer or sense leads.

By "floating charger" I think you mean a fixed voltage cc/cv source without charge termination logic, confirm?

If the pack is down to 13.0 volts you should get the full constant current from the powermax.
If the powermax is rated for 50 expect 45 amps tops.
The fact that you are only getting 30 amps is surprising.
What awg is the wire between the charger and the battery?
How long is the round trip length of the circuit?
I suspect excessive voltage drop.

Don't get the meanwell.
The powermax is good enough for you use case.
If you didn't already have the powermax I would advise to go with the Meanwell.
Even better... buy an inverter/charger and sell the powermax.
An inverter/charger also includes a built in automatic transfer switch.

So far in testing the powermax in fixed voltage slowly brings the SOC up to the set voltage. It quits sending current when the battery reaches full charge - it just takes a long time because it tapers current. Which is fine. When the pack is down on volts it pulls full current. AFAIK it does not terminate charge current at any point, but will equalize to zero output. If you add a load it adds current to supply it.

Yes, a floating charger like solar or orion - set charge voltage and let it go.
I got a RS485 cable today so I can set the Tracer mppt SCC - I have two of them. I'll set them for lithium profile and go thru the charge voltages.
I have a surface pro to download the software to. You can't select their lithium profile without the PC/USB cable connector and the configuration software for them.

When the pack was discharged to 13.0 volts, it pulled 30a from the fixed charger powermax set to 13.5 volts.
If I set the fixed voltage at 14.0 or 14.2 it will pull the full 55A (53-54 measured on the bms).
There has to be enough voltage drop from charge setting to battery voltage to push full amps. Seems powermax has a very non-aggressive charge profile, and then never terminates charging.

If anything I'm over-wired. The charger sits a foot away from the lithium pack on 4g wire, 70A anl fuse. The lithium pack is 5' away from the main circuit branch on 2g wire, 150A class t fuse at the battery. There's a 12V house circuit breaker row there with a foot of 6g connecting, then another 6g wire that goes out to another row of circuit breakers for 12v house loads. The inverter used to connect there, but I got worried about that 6g connection, so I ran it's own 4g wire direct to it. Frame ground is a foot away on 4g. It has it's own 80A anl fuse. Everything has fuses.

All ground wires are short except for the lifepo pack, it has it's own 4' 2g lead to the frame with a smart shunt as the battery terminal, and the charger body ground has it's own 8g to the frame ground. I ran that ground wire and THEN read you can connect it to the main ground wire. Oh well, we're well grounded and fused. LOL

Both SCC's are on their own fuses, connecting to a positive bus where the inverter lives. 2' of 8g wire for the 30A, and then it goes 3' on 6G wire to the mains where it connects to the lifepo's 2g positive cable. So SCC's are 3' of 6G then 4' of 2g to the battery. No voltage drop there. Both SCC's have their own circuit breakers appropriate to their charging output current - 15A on the 10A mppt and 40A on the 30A mppt. Both EPever mppt charge controllers.

I would diagram it but not sure I could even make sense of it. Maybe a pencil drawing. LOL

Low inverter voltage:
I'll put a watt-meter or DMM on the inverter output and compare to the outlets that are plugged into it. I'm only getting 98-99 volts on the inverter outlets.

I just did a voltage drop calc on the lifepo pack to main switch and ground at 13.4 volts, 50A, 5' one way:
Voltage drop: 0.19
Voltage drop percentage: 1.41%
Voltage at the end: 13.21

And then from the inverter to the main house switch where the lifepo back connects. it's another 4' one way of 4awg from the dropped 13.21V end of the lifepo cable:
Voltage drop: 0.19
Voltage drop percentage: 1.41%
Voltage at the end: 13.02

I should be getting over 13V at the invert, so I'll check that out and see if it's reading lower by the time the current gets to it.

I'm not seeing a lot of voltage drop other than the inverter outlets. They are on 14G extension cords, total length about 8' from the inverter.
That calc on 115V, 8' of 14G at 4 amps:
Voltage drop: 0.17
Voltage drop percentage: 0.15%
Voltage at the end: 114.83
That's only .17 of a volt drop.

Nothing is calculating a big voltage drop for the wire size or length.

 

[Browneye]

I could sell the xantrex 600 SW PROWatt and the Powermax 55lkl and get a 1000w inverter charger. More $$ and more re-wiring. They need 2g to the mains, and a 30A AC input circuit, so I can't just plug one in with a standard 110plug. I do have 2g already run for the lifepo, so it could go next to the battery. I would just have to re-route the inverter outlet connecting wires.

Getting wire routed through the coach is a challenge - double floor, aluminum sheeting, welded battery box, compartments for plus side and the frame ground. It's a little convoluted, but has to all fit in the coach. AFAIK all of the wire is solid and up to current carrying, and everything is fused.

The transfer switch currently switches genset or shorepower. Evidently you can cut an inverter in there somewhere and have it feed all the 120 panel. That's over my pay grade and would need an even bigger inverter.

I was going to try the powermax for awhile. If it acts up or doesn't do what I want it to do I can replace it. I have yet to try the 2-stage charging profile, but my guess is with its default 14.6/13.6 charge values, it will switch from bulk to float way too early, then float the pack to 13.6 'till it reaches full charge. I imagine it to be even slower than the fixed-volt setting.

It's all kind of wonky really. I'm starting to understand the value of the 'set-it-and-forget-it' approach and just let it go. Take the human interaction out of the equation. Ala Joey the wizzard.

 

[John Frum]

So far in testing the powermax in fixed voltage slowly brings the SOC up to the set voltage. It quits sending current when the battery reaches full charge - it just takes a long time because it tapers current. Which is fine. When the pack is down on volts it pulls full current. AFAIK it does not terminate charge current at any point, but will equalize to zero output. If you add a load it adds current to supply it.

Correct a powermax converter in fixed-voltage mode won't terminate charge.
If it were configured in 3 stage mode it will terminate charge.
It terminated charge by dropping its voltage to float level.
Since the battery voltage will be higher than float voltage the battery will service the load.
As the battery gets drawn down to float level the powermax will start servicing more and more of the load.

Yes, a floating charger like solar or orion - set charge voltage and let it go.

This is a charger https://www.victronenergy.com/dc-dc-converters/orion-tr-smart-non-isolated
This is not a charger https://www.victronenergy.com/dc-dc-converters/orion-24-12-5-10

When the pack was discharged to 13.0 volts, it pulled 30a from the fixed charger powermax set to 13.5 volts.
If I set the fixed voltage at 14.0 or 14.2 it will pull the full 55A (53-54 measured on the bms).
There has to be enough voltage drop from charge setting to battery voltage to push full amps. Seems powermax has a very non-aggressive charge profile, and then never terminates charging.

This has nothing to do with the powermax charge profile.
You are using in fixed voltage mode so there is no charge profile.

Do you have an IR thermometer?
If yes, checking every connection point under load may be educational.

 

[John Frum]

I was going to try the powermax for awhile.

I think that is a good idea.

It's all kind of wonky really.

Never has a sentence conveyed less meaning.

I'm starting to understand the value of the 'set-it-and-forget-it' approach and just let it go.

Good to hear.

Do you have the 55 amps version of this https://powermaxconverters.com/product/pm3-lithium-series/ ?
If yes the charging algorithms are described here.

https://powermaxconverters.com/wp-content/uploads/2021/11/PM3-LKL-Manual.docx

Who knows they might even be moderately accurate descriptions of reality this time.

Off topic a bit but I must say I find it pretty cheesy that they publish in Microsoft format.
I feel dirty for having opened that link.

 

[triplethreat]

I think that is a good idea.

Never has a sentence conveyed less meaning.

Good to hear.

Do you have the 55 amps version of this https://powermaxconverters.com/product/pm3-lithium-series/ ?
If yes the charging algorithms are described here.

https://powermaxconverters.com/wp-content/uploads/2021/11/PM3-LKL-Manual.docx

Who knows they might even be moderately accurate descriptions of reality this time.

Off topic a bit but I must say I find it pretty cheesy that they publish in Microsoft format.
I feel dirty for having opened that link.

I've been following this conversation/thread as I am in the process of building my first every LFP battery. I will likely try my existing WFCO OEM converter/charger (9855) that is strictly a FLA), but I also would like to know what my best options are for the replacement of that unit if it doesn't work out. I still don't understand why the PowerMax user manual still shows both the two stage and the three stage graph at 14.3V in the boost mode...THEN...in the description part of the process, talks about 14.6V in boost. The 14.3V in two stage mode would be the one most likely for me to use, but I also understand that the "stage" charging voltage is not adjustable.....so my question to Powermax is........which one is it..14.3 or 14.6. I am not going to buy one right away, but I do want the voltage output issue made clear before I would even think about buying one.

The WFCO that I have, at least in theory would be great....14.4, then down to 13.6, then the 13.2.....but I have read that they really don't work as described, as it takes a voltage level to drop down in the 11.xx volts in order for it to go into Bulk charging again. I'm not far enough along on my battery build to be able to test anything yet, so I'm just watching this thread with interest as it may be able to help be in the future. Thanks to all those that have contributed so far......and Browneye...I look forward to the Two Stage Testing with your Powermax.

 

[John Frum]

I will likely try my existing WFCO OEM converter/charger (9855) that is strictly a FLA), but I also would like to know what my best options are for the replacement of that unit if it doesn't work out.

An inverter/charger is your best option.
They just don't make discrete chargers with the same level of configuration granularity.
Basically discrete ac2dc chargers don't get any RnD because the inverter/charger has eaten their lunch.
The value proposition of an inverter/charger with built in automatic transfer switch is killing discrete ac2dc chargers, transfer switches and inverters.
There is also a class of product called an all_in_one that has all the features of an inverter/charger plus a solar charge controller.
Once Victron, Samlex makes a decent but affordable all_in_one for the North American market it will very likely supplant the inverter/charger.

 

[triplethreat]

An inverter/charger is your best option.
They just don't make discrete chargers with the same level of configuration granularity.
Basically discrete ac2dc chargers don't get any RnD because the inverter/charger has eaten their lunch.
The value proposition of an inverter/charger with built in automatic transfer switch is killing discrete ac2dc chargers, transfer switches and inverters.
There is also a class of product called an all_in_one that has all the features of an inverter/charger plus a solar charge controller.
Once Victron, Samlex makes a decent but affordable all_in_one for the North American market it will very likely supplant the inverter/charger.

Thank you for the reply. I didn't mention this in my previous post, but I do not have any solar or need for an inverter. I have zero interest in doing anything solar and without a need for an inverter, that is why I'm leaning toward just a converter/Charger......just maybe not the one that came in the trailer (FLA with no adjustments for LFP batteries). I guess I should clarify my usage too.....5th Wheel camper/Toy Hauler that will be getting a 12V compressor style 18 cu. ft. refrigerator. I almost never boondock, so I'm on shore power at most campgrounds and I have 50A shore power at my house where I store the camper.

 

[time2roll]

The WFCO that I have, at least in theory would be great....14.4, then down to 13.6, then the 13.2.....but I have read that they really don't work as described, as it takes a voltage level to drop down in the 11.xx volts in order for it to go into Bulk charging again.

My trials with WFCO are that voltage at the converter must sag below about 13.0 volts during initial charging to get the boost mode. No easy feat with 55+ amps feeding a small lead-acid through undersized wire. So far I am staying with the WFCO as virtually all charging is via solar. Even if stuck at 13.6 the LFP will charge way faster than the old lead-acid.

 

[triplethreat]

My trials with WFCO are that voltage at the converter must sag below about 13.0 volts during initial charging to get the boost mode. No easy feat with 55+ amps feeding a small lead-acid through undersized wire. So far I am staying with the WFCO as virtually all charging is via solar. Even if stuck at 13.6 the LFP will charge way faster than the old lead-acid.

Thank you for that info. I have zero solar and no interest in putting any on the camper. I am going to try the OEM converter/charger....I have gotten some very good advice from sunshine-eggo about my build and how to do it and he basically told me to at least try the OEM charger too. I'm the type of person that like to have a Plan B in place though, just in case Plan A doesn't satisfy my expectations. ?

 

[time2roll]

My plan B is a $8 battery voltage based relay to cut power to the WFCO if it goes higher than programmed.

https://www.ebay.com/itm/122112737703

 

[triplethreat]

My plan B is a $8 battery voltage based relay to cut power to the WFCO if it goes higher than programmed.

https://www.ebay.com/itm/122112737703

I'm not concerned about it going too high (14.4 volts in Bulk mode), my concern is that it will likely never get to bulk mode, and mostly just stay in absorption mode (13.6 volts or 3.4 volts per cell).

 

[Browneye]

I think that is a good idea.

Never has a sentence conveyed less meaning.

Good to hear.

Do you have the 55 amps version of this https://powermaxconverters.com/product/pm3-lithium-series/ ?
If yes the charging algorithms are described here.

https://powermaxconverters.com/wp-content/uploads/2021/11/PM3-LKL-Manual.docx

Who knows they might even be moderately accurate descriptions of reality this time.

Off topic a bit but I must say I find it pretty cheesy that they publish in Microsoft format.
I feel dirty for having opened that link.

Correct a powermax converter in fixed-voltage mode won't terminate charge.
If it were configured in 3 stage mode it will terminate charge.
It terminated charge by dropping its voltage to float level.
Since the battery voltage will be higher than float voltage the battery will service the load.
As the battery gets drawn down to float level the powermax will start servicing more and more of the load.

This is a charger https://www.victronenergy.com/dc-dc-converters/orion-tr-smart-non-isolated
This is not a charger https://www.victronenergy.com/dc-dc-converters/orion-24-12-5-10

This has nothing to do with the powermax charge profile.
You are using in fixed voltage mode so there is no charge profile.

Do you have an IR thermometer?
If yes, checking every connection point under load may be educational.

Wonky = confusing. I don't know what I don't know. ?

Yes, the PM3-55LKL. The manual is posted earlier in this thread. The unknown is the length of boost time in the 2-stage mode. I'm going to test that out tonight and see how that works, see how long it charges at the higher voltage and current.

The victron orion is the first one, but it's not a smart one. It has a voltage adjust pot where you set the charge voltage. I have that one set at 13.4 volts. The Orion TR 12/12-18
Funny, for some reason I spaced out between ordering it and receiving it, and thought I was getting the smart one. I downloaded the app, installed it, and it couldn't find the unit when powered up. Definitely a 'duh' moment. LOL It was a tip-off when the single page instruction sheet said to manually adjust the voltage before connecting the output side. Whut???? When all else fails RTFM right????

I understand, no profile with a fixed voltage charging - it's for lack of a better descriptive word.

I do have a IR thermometer - for the blackstone griddle. I'll check it out tonight with another test discharge and recharge. I did notice the pack warmed up quite a bit when I was drawing 50A.

I'm also going to open up the inverter compartment and check all those connections and see if I can figure out why it's putting out low AC. If it's getting 13V and the current it needs, it should be more like 110-115V. The fuse for it is one of those inline wire clamp style for audio systems. It likely has too much resistance. I have an extra Spartan heavy duty ANL fuse block, and I can put proper crimped terminals on the cable and replace it. I was going to do some poking around with a DMM.

I was surprise to see a WORD doc myself. A simple 'save-as' and it could have been a cross-platform PDF. Kinda makes ya wonder dont-it?

 

[John Frum]

The unknown is the length of boost time in the 2-stage mode.

I predict it is ~30 minutes in 2 stage and 3 stage mode.