MPPT Charge Controller for LifePO4 Batteries

[senormechanico]

It's not optimum for a boat, but an MPPT/inverter under each panel is the heart of the Enphase system.

Enphase Energy

[dennisail]

There is a prob with the manual I linked. The one I linked that has a lithium setting is the 50A version which was in the wrong section at outback marine.

This is for the 15A.

http://www.victronenergy.com/upload/...R_DE_ES_SE.pdf

Here is the USB data protocol.

http://www.victronenergy.com/upload/...t_Protocol.pdf

Unfortunately it looks like you cant make the necessary adjustments

[familycruisers]

Thought I'd throw my experience in the hat.

Midnite Classic 150
200AH CALIB Lifepo4
2-255w SolarWorld. (40voc ran in series)
Custom program
Absorb 14.4
Float 14.2

It charges then ramps down, then trickles and load shares. I don't believe in mini cycles. I'm @ 13.3 resting every night.
It runs refrigeration, tablet, laptop, cell phones,tv, bluray, all ships systems are led.
Incredibly impressed.

[dennisail]

Do you have any sort of BMS or are you just relying on the controller?

The controllers I am looking at have the same absorption as yours of 14.4, but float of 13.8. This might be satisfactory if temp comp can be disabled.

[familycruisers]

That controller basically is a bms. It logs just about everything. I monitor individual cell voltage manually. Use to do it a lot. Especially when figuring out charge voltages. Now, not so much. Maybe tomorrow since you brought it up. They've just been so consistent.

[dennisail]

Yeah. I would run individual cell voltage displays too. For under $2 why not. Self powered to as low as 2.7V. So if it turns off you know you are in trouble.

Mini DC 0 32V LED Panel Voltage Meter 3 Digital Display Voltmeter Motorcycle | eBay

Seems a BMS is not really required if you set it up correctly, IE make sure no charge devices can exceed the max voltage, plus use a low voltage disconnect relay, and periodically check cell balance.

[campr]

Originally Posted by noelex 77

The best controllers like the Outback use a fair bit of power to operate their complex tracking circuitry. Using one per each 200w panel is not likely to be the best option.

There are circuit designs that use less power and still track reasonably. Some of these are commercially available such as Genasun.
I think we need some more research on this topic. Will the slightly worse tracking of these simpler controllers, be compensated for by tracking each panel separately? I suspect the results will be similar, but there is little data to go on.

The cost of both approaches is similar. Multiple controllers give redundancy, but you loose some of the reported data and the set up has less adjustable battery parameters.

In addition, I like the fact of having four mppt controllers. If one packs up, there is still 3/4 of the generation capability available.

[Maine Sail]

Originally Posted by familycruisers

Thought I'd throw my experience in the hat.

Midnite Classic 150
200AH CALIB Lifepo4
2-255w SolarWorld. (40voc ran in series)
Custom program
Absorb 14.4
Float 14.2

It charges then ramps down, then trickles and load shares. I don't believe in mini cycles. I'm @ 13.3 resting every night.
It runs refrigeration, tablet, laptop, cell phones,tv, bluray, all ships systems are led.
Incredibly impressed.

I would be very careful with those charge voltages. Alex MeVay of Genasun has done more testing with CALB cells than anyone I know of. Even with their highly sophisticated BMS, which is specifically designed for the CALB cells, and that is used in the Genasun batteries, the highest they go is 14.2V... Alex also has an amazing machine he designed and built that matches cells almost identically so when they build a pack the balance and Ah capacity of each cell is extremely closely matched, far better than you or I could ever do mail ordering cells a few at a time..

There is zero need to push CALB cells above 13.9V - 14.0V.. You will get more Ah than they are rated for by charging to just 13.9V and you will never have to worry about pushing into the knee or having one cell go off before the others, unless you get EXTREMELY out of balance..... At 3.6VPC this is a very, very real possibility...

You could not pay me to design and build a LiFePO4 system with CLAB cells that charge any higher than 14.0V and even then this would be a system with a .5C - .75C charge capability...

Keep in mind that 14.4V is the absolute MAX charging voltage for CALB cells and puts you smack dab at the very edge of the cliff or the danger zone...

While not a direct correlation think of it as charging lead acid batteries to 15.5V, every time you charge them....

Genasun specifically builds their system to work with their in-house matched and perfectly balanced CALB SE cells so they can go to 14.2V/3.55VPC. I would not suggest even 14.2V unless using a factory built Genasun battery...

Jack Rickard and other experts STRONGLY advise a max of 14.0V even for the EV guys!!!

I don't know why anyone would want to push LiFePO4 cells up to the edge or into the danger zone when it is 150% unnecessary..????

[goboatingnow]

Just a point, power consumption and the quality of mppt tracking are not linked

Dave

[dennisail]

I just heard back from Morningstar. They say its fully adjustable. Still waiting to hear about the victron.

Also, what are the charging parameters for Winston cells? How do they compare to Genasun?

[noelex 77]

Originally Posted by goboatingnow

Just a point, power consumption and the quality of mppt tracking are not linked

Dave

Manufacturers are very reluctant to reveal data about the self consumption of their controllers. In fact the only way seems to be to go out and measure it yourself.
It is particuarly a concern for boat systems as we have much smaller arrays than domestic systems (appart from the lucky cat owners) operating at lower voltages (so we need a "big" controller that will handle large currents).

There have been some promising designs of controllers manly developed for solar car projects that track well for reasonably low power consumption, but these designs are not manufactured commercially.
At the moment we are left with the practicalities of the better controllers extracting more power from the solar array, but with increased self power consumption.

Mounting a controller on each solar panel the self consumption becomes especially important.

Multiple MPPT trackers and voltage converters (one for each panel) feeding a single central battery management controller seems to hold the best solution. By removing, unnessasary multiple battery management modules power consumption (and cost) would be reduced and any (slight) battery management conflict issues are eliminated. Unfortunatly systems like this are not produced.

[familycruisers]

Howdy Maine,
Was under the impression the CALIB cells voltage range per spec sheet was 2.5-3.65. The first cell hits 3.63 while the others are at 3.59 till 3.6, I also terminate absorb after ten minutes. One more thing . I capped my controller output @ 30 amps . Fractional C charge. Highly fractional C usage.
I have never seen these cells out of balance save the one cell that was out from the others. I monitored it and over the course of the cruise down the east coast, it balanced perfectly with the rest. Now the only difference is if its putting a good amount of current in the first cell reads higher.
Really respect your opinions though so anything I'm missing Lmk .
BTW sir, your rewire Universal Diesel article was superb! Thank you.

One more thing, I did drop the Absorb down to 14.3 at one point. I forgot I did that. Probably to do what you suggest and stay away from the knee with the first cell always reading high.

[Maine Sail]

Originally Posted by familycruisers

Howdy Maine,
Was under the impression the CALIB cells voltage range per spec sheet was 2.5-3.65. The first cell hits 3.63 while the others are at 3.59 till 3.6, I also terminate absorb after ten minutes. One more thing . I capped my controller output @ 30 amps . Fractional C charge. Highly fractional C usage. Really respect your opinions though so anything I'm missing Lmk . BTW sir, your rewire Universal Diesel article was superb! Thank you.

Do yourself a favor and please ignore the Chinese spec sheets and follow what guys like Jack Rickard, companies like Genasun, Clean Power Auto, Charlie J, T1 Terry already know... You DO NOT need to charge beyond 14.0V to get the capacity out of your bank. We know pushing into the knees is where damage can occur, we know you don't need to push into that range to get all the capacity so why risk it!

Winston says max voltage is 4.0VPC but my cells hit the upper knee well below 3.8VPC. I have a 400 Ah 4S pack and at 13.8V charging I get 425 Ah out of the bank.. Why charge higher and create unneeded risk.

The only time I push to 3.8VPC is if I am doing a parallel top balance. BTW even Winston says not to push to 4.0V, even during balancing, yet the crappy Chinese manual leads one to believe this is safe.. D'oh...

The Chinese spec sheets on these cells can be very dangerous and misleading if they are taken at blind trust.. Unless you are top balancing the cells keep the voltage to a safe range. Charge to a max of 13.8V to 14.0V especially with no BMS....

The higher you push voltage the less room for error or imbalance you will have.. This only leads to more chance of creating a big fat hole in your pocket where your wallet used to be. This is not Vegas and you don't need to gamble with these cells. Just change & reduce your voltages.. Your cells are already drifting in this upper range by 4 hundredths / 0.04V.

My bank now has in excess of 250 cycles, most to 80% DOD. It also has six 100% DOD capacity tests. They are still in balance to a max spread of approx 6 thousandths of a volt or 0.006V.. Other than one top balancing and two capacity tests, to determine capacity beyond 13.8V, the bank has never been charged beyond 14.0V. It has never been balanced except for once 250+ cycles ago.

My solar is set for 13.7V. My alt reg s set for 13.9V bulk then it drops to 13.8V. Shore charger is set for 13.8V. I charge to below 10A of acceptance then charging is terminated/dropped to 13.1V..

[NahanniV]

Aren't those maximum voltage specs for charging at .5C rates where the internal resistance of the cell needs to be factored into the charged voltage.

I.E. for a 400AH Cell .0008ohm * 200A = .16V

[OceanPlanet]

Originally Posted by Maine Sail

Do yourself a favor and please ignore the Chinese spec sheets and follow what guys like Jack Rickard, companies like Genasun, Clean Power Auto, Charlie J, T1 Terry already know... You DO NOT need to charge beyond 14.0V to get the capacity out of your bank. We know pushing into the knees is where damage can occur, we know you don't need to push into that range to get all the capacity so why risk it!

Winston says max voltage is 4.0VPC but my cells hit the upper knee well below 3.8VPC. I have a 400 Ah 4S pack and at 13.8V charging I get 425 Ah out of the bank.. Why charge higher and create unneeded risk.

The only time I push to 3.8VPC is if I am doing a parallel top balance. BTW even Winston says not to push to 4.0V, even during balancing, yet the crappy Chinese manual leads one to believe this is safe.. D'oh...

The Chinese spec sheets on these cells can be very dangerous and misleading if they are taken at blind trust.. Unless you are top balancing the cells keep the voltage to a safe range. Charge to a max of 13.8V to 14.0V especially with no BMS....

The higher you push voltage the less room for error or imbalance you will have.. This only leads to more chance of creating a big fat hole in your pocket where your wallet used to be. This is not Vegas and you don't need to gamble with these cells. Just change & reduce your voltages.. Your cells are already drifting in this upper range by 4 hundredths / 0.04V.

My bank now has in excess of 250 cycles, most to 80% DOD. It also has six 100% DOD capacity tests. They are still in balance to a max spread of approx 6 thousandths of a volt or 0.006V.. Other than one top balancing and two capacity tests, to determine capacity beyond 13.8V, the bank has never been charged beyond 14.0V. It has never been balanced except for once 250+ cycles ago.

My solar is set for 13.7V. My alt reg s set for 13.9V bulk then it drops to 13.8V. Shore charger is set for 13.8V. I charge to below 10A of acceptance then charging is terminated/dropped to 13.1V..

AMEN...