MPPT Charge Controller for LifePO4 Batteries

[downunder]

Originally Posted by s/v Holiday

You could get a soft starter for the elec motor.

Yes. That is standard fare if one goes with one of Brownies units.

[s/v Holiday]

HI Noelex,

My feelings exactly. Can't have too much solar.

Thanks for the info on the charge controllers. Looks like Outback makes some nice inverters as well and the whole system can be integrated into a remote control head that also includes a amp meter counter. Pretty slick.

CJ

[ardoin]

Anyone have recommendations for an MPPT controller for those of use that have only a few hundred watts of solar and LiFEPO banks?

[T1 Terry]

Originally Posted by ardoin

Anyone have recommendations for an MPPT controller for those of use that have only a few hundred watts of solar and LiFEPO banks?

Why do you want to use an MPPT controller if you only have a few hundred watts of solar? Is there a big voltage mismatch, like 24v panels and a 12v system? If not, save the $$ and get a PWM controller, one with battery voltage sensing wires but it can be a single stage charging regime, Li don't need multi stage charging and it can be harmful to cycle life in some cases as the absorption stage can not be controller.
i have a 3kw system using a single PWM controller for both the solar and mains/alternator charging and the reduced cost allowed for the purchase of more solar and battery capacity. It doesn't take much more solar capacity to gain a better result than an MPPT controller can give, even more so with Li batteries.

T1 Terry

[Jimbo485]

Terry has got it right. Listen to him.

[noelex 77]

Money spent on more panels is always going to return more, but this is not always feasible on a boat.

Unfortunately there are few controllers designed for lithium. The Genasun range is worth looking at:
Genasun MPPT Solar Charge Controllers | Get more power + reliability
Some of their litium models have a sligher higher charging voltages than I would prefer to see, but they will make a custom model.

Many controllers designed for lead acid are adjustable enough to to be programmed with a suitable algorithm for lithium, but it tends to be only the expensive models.

I disagree with Terry about relative improvement of MPPT technology with lithium. The lower charging voltages used for lithium should give a greater gain for the MPPT voltage conversion than is seen with lead acid.

[ardoin]

Terry,
the question was, which controller to use. I have looked at the all of them and the all have Flooded, AGM, and GEL presets. I know that none of these are what I need for LiFePO. So my question is what MPPT or other controller is recommended for LiFePO house bank. The previous discussion on this thread was more about how big someones bank was, and an outback is way to big and not IP65 or higher rated.
The morningstar PWM chargers i have seen as well as most other brands have presets for FLOAT, AGM, and GEL and nothing for LI except Genasun and I am not a big fan of Genasun.
So I'm looking for more options that will allow be to use 300W of solar to help keep my LiFePO banks alive.
Oh, more solar is not an option, the space is limited
Thanks

[noelex 77]

You need a fully adjustable charge controller. These allow you to set any voltage cut off you want and disable the float and equalisation stages. So a controller designed for lead acid can be adjusted for an algorithm suitable for lithium.
Unfortunatly controllers with this level of adjustability tend to be the more expensive models.

For around 300w the Rogue would be my choice, but they have been promising a new model for a while now.
Rogue Power Technologies - MPT-3024 MPPT Charge Controller

Once you get above 300w the Outback and Midnite controllers are the best option.

The Plasmatronics range are also worth looking at, but they are not MPPT so there is a small reduction in the AHrs collected.

[ardoin]

Thanks Noelex

[OceanPlanet]

"The morningstar PWM chargers i have seen as well as most other brands have presets for FLOAT, AGM, and GEL and nothing for LI except Genasun and I am not a big fan of Genasun."

Hi Ardoin,
What don't you like about the Genasun MPPT controllers? Just asking...

[ardoin]

OP,
My objection is that these must be programmed at the factory. My batts are in the V and the charger would be in the aft. I am looking at these, but everything is on hold as i broke by arm on the ice last week.

[SV THIRD DAY]

Originally Posted by s/v Holiday

I would rather error on the side of too much solar while I am still working and can afford it.

Amen....
I can't remember sitting through a cockpit cocktail hour and hearing the phrase:

"I have too much solar"

[OceanPlanet]

Originally Posted by ardoin

OP,
My objection is that these must be programmed at the factory. My batts are in the V and the charger would be in the aft. I am looking at these, but everything is on hold as i broke by arm on the ice last week.

Yikes, best wishes healing up. The boat will wait.

Just back in the door from nighttime mountain biking with a bunch of hotshots on icy snowmobile trails (studded knobby tires) I THOUGHT I was going to break an arm, about 20 times. Happy to still be alive.

[dennisail]

I have been looking at controllers to charge a proposed lithium bank. Seems the good MPPT controllers are very expensive, huge, heavy and possibly not all that much better than PWM (well not as good as spending that extra money on one more panel).

Here is a $41 adjustable 30A PWM controller which is small and light. So you could easily buy 2 or 3 to power your panels, and having multiple controllers has its benefits anyway. The fact you can adjust it should mean it will work fine with lithium. It has a separate temp sensor which you could easily rig up to a variable resistor to disable it.

http://www.ebay.com.au/itm/30A-LCD-S...0769c3e&_uhb=1

I see a many cheap supposed MPPT controllers but I am not convinced they will work as desired.

Thoughts?

[dennisail]

Also, is a panel with a max power output of 12V and max panel voltage of 15V to low? The other option is max power output of 18V and max voltage of 22V. What will work better?