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Hkalan · 08-05-2014, 18:21

Hello,

Any Charge controller you use for LifePO4 should be set to have a single stage charge... NOT the 3 stage charging used on a standard Lead Acid Battery. A constant "Float Charge" is how I have set my MorningStar TS-60. Only reason I have the MPPT controller, is that I can network the controller and monitor on my computer at the saloon desk... nothing to do with it's MPPT function... "monitoring" is the key word!!!

I went to the CALB head office a few weeks ago in my search for cells (I live in Hong Kong). I was talking with one of their German engineers there. He was a down to earth guy, and made a statement that stuck in my heard... "LifePO4 first takes all the "AMP's" you throw at her, then the cells top off with "Volt's", thus a BMS is a necessity. LifePO4 is happy with enough in her belly to stay comfortable, you don't need to treat them like every day should be a Christmas feast, and be stuffed constantly". This is coming from an engineer that designs LifePO4 cells that are used in 747, and AirBus air planes across the globe... who am I to say he is wrong !!!!

1 - If you have a Solar MPPT or PWM solar charge controller set for a constant charge... Thats what you need.
2 - If you have the cell/bank BMS set for your cells... perfect

If you want to add wind for charging, you have several variables you need to consider. That is a completely different can of worms for a different thread !

Alan

steelwrk1 · 08-05-2014, 19:15

Quote:

Originally Posted by Hkalan

Hello Hkalan,

Any Charge controller you use for LifePO4 should be set to have a single stage charge... NOT the 3 stage charging used on a standard Lead Acid Battery. A constant "Float Charge" is how I have set my MorningStar TS-60. Only reason I have the MPPT controller, is that I can network the controller and monitor on my computer at the saloon desk... nothing to do with it's MPPT function... "monitoring" is the key word!!!

I went to the CALB head office a few weeks ago in my search for cells (I live in Hong Kong). I was talking with one of their German engineers there. He was a down to earth guy, and made a statement that stuck in my heard... "LifePO4 first takes all the "AMP's" you throw at her, then the cells top off with "Volt's", thus a BMS is a necessity. LifePO4 is happy with enough in her belly to stay comfortable, you don't need to treat them like every day should be a Christmas feast, and be stuffed constantly". This is coming from an engineer that designs LifePO4 cells that are used in 747, and AirBus air planes across the globe... who am I to say he is wrong !!!!

1 - If you have a Solar MPPT or PWM solar charge controller set for a constant charge... Thats what you need.
2 - If you have the cell/bank BMS set for your cells... perfect

If you want to add wind for charging, you have several variables you need to consider. That is a completely different can of worms for a different thread !

Alan

Hello Alan,

No wind for me .

I have a BMS set for high level and low level cut off. It also powers a display where I can monitor the banks condition at all times

I have been following your posts with great interest. It is exciting for us to read one of us is actually visiting the LiFeP04 manufacturing facilities in China.

I have 84 only 60 amp used GBS LiFeP04 batteries that are wired to give me 1260 amps at 12 volts and it is my house bank.

I have been searching the web for someone with exactly your Morningstar MPPT-60 charging LiFeP04 house batteries.

There is lots of good info here but no-one with your/my specific Morningstar MPPT-60 charging LiFeP04.

When you connect your PC up to your MPPT-60 there are a lot of parameters to set.

I have ordered and have recieved my complete solar package to be installed as life permits asap in the next couple of months.

MY QUESTION TO YOU is ......would you be so kind as to tell me exactly what settings you set or are going to set your MPPT-60 to in the custom profile.There are a lot of possible settings and I would appreciate your experience.

I would / will benifit from your knowledge and could tweek for my exact batteries later.

I will have 3 seperate sets of solar ( different shading) panels feeding 3 different Morningstarr MPPT-60 and they will feed my house bank.
2 x 250watt =set A .......2 x250 watt =set B......3 x 220 watt = set C .................. total 1660 watts.

I am challenged electrically, but will have this info to give to my electronic man and its always nice to have the benifit of others help and first hand " Been there done that " experiance.

My boat is presently on the hard and going in the water next Wednesday, then all the various projects will commence with the solar panel installation to follow ...hopefully mid June.

IF you were to ask me this question next year I would have the answer for you....now I could use the specific advice , help and guidence from what you have and will learn..

Thank you for your time,

Pete

PS nothing in this life is free so some day some how I will owe you...and I pay my debts.

Maine Sail · 09-05-2014, 07:08

Finally getting around to doing some more testing of MPPT vs. PWM on LFP batteries.

It was stated by some that MPPT does not work well on LFP? I had never found this to be true.

Day 1 testing (with this particular set up) showed a 12.89% increase for MPPT over PWM. Course I was getting it set up yesterday and did not even fire it up until about 1:40 PM..

This morning I just checked at 9:30AM and the MPPT controller is handily beating PWM again, but it is early.

So far I am testing a Genasun GV-10 MPPT and a Morningstar PS-15 PWM..

I am doing "print screens" every so often because I am having trouble with the exported data files. Bogart has been helpful but I am using a Beta version so no guarantees. Easiest to just capture a "print screen" shot... The 400Ah LFP bank was drawn to -304Ah's or about 75% DOD before the controllers were let loose....

All wires are same gauge and carefully measured for exact lengths to be as fair and equal as possible. There is some slight voltage drop in the wiring but no different than I see on most marine installations.

Ah's returned are being measured by a Bogart Engineering Pentametric System fed to a laptop via a USB interface. Each panel gets its own shunt.

The panels are identical, Kyocera 140W, and are placed right outside my garage, in an area where both panels are treated equally to avaible light. I monitored them for a few days at different times for shading. Panels have been kept flat, like they would be on a boat.

I also have a Rogue MPPT 3048 and a MidNite KID to test, if I can get to it before I stick my LFP bank back into the boat.

It is still early to fully analyze but it is lining up with what I have seen on our own boat with LFP, and that is about a 10-15% gain for MPPT with LFP.... While not huge it is a gain that can be worthwhile when you run out of real estate. The real reason I use MPPT on LFP is for the programability of the MPPT controllers over a typical PWM...

Test Bench: The Victron BMV is used to measure the capacity of the LFP bank and the Pentametric is tracking solar performance.

L to R: LFP Bank, Fluke DVM for measuring LFP terminal voltage directly, LFP capacity test station with Victron BMV-602 and inverter load for taking capacity out of the bank, Pro Star 15 PWM controller (gray), Genasun GV-10 (black), Rogue MPT-3048 (off white), MidNite KID (on top of Rogue), Pentametric Monitoring System and shunts, laptop.

Solar Panels: Two Kyocera KD140SX-UPU

Hope to have more data in a week or so...

**noelex 77** · 09-05-2014, 08:32

Thanks for doing the testing. I know this sort of data must be a lot of work and its great that you share this with the forum

T1 Terry · 25-05-2014, 11:48

Hmmm.....Caravaners Forum • View topic - MPPT vs PWM "real world" test This lot of testing cam up with a different result if you read the actual figures, but naturally there is spin on the results if they didn't fall into line with what was expected.
I have never argued that MPPT wouldn't give a better esult than PWM if there was a mismatch between panel Vmp and battery charging requirements, but proper matching of the Vmp to LFP charging requirements puts the MPPT controller in a different light so to speak.

I guess there will always be those who have purchased an MPPT controller that will bend over backwards to try and prove they made a good investment. In reality, your would be far better off investing the money in solar panels with a Vmp that matches the battery charging requirements rather than an expensive controller to try and make the poorly matched Vmp better suit the lower voltage charging requirements of LFP batteries.

T1 Terry