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Old 13-04-2015, 18:41   #1
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Solar Charging LiFePo4 battery??? HELP

I obviously don't know as much about this as I thought I did and I need some help.

Solar Panels - We have 450 Watts consisting of 3 x 150 watts 18 Volt solar panels mounted flat on an arch. They are connected in parallel via 8/2 cable. This cable leads to the SCC.

Battery - I have installed a single LiFePo4 battery consisting of four cells of 3.2V500AH to make up one battery with PCM that allows 50A charging and 100A with 250/5 discharge. The package is all in a steel case and has two terminals that I have hooked up my distribution to. When we first installed the battery the meter read 13.5 V and it hasn't been back up there since after the first night providing power. I measured it at the terminals with my multi and the meter also read 13.5 V.

Controller - Is a BlueSky Engergy 3024i with IPN Proremote to give me battery condition and allow changing the parameters for charging, etc. It is MPPT and will handle 40 A at 12 volts. It is connected via the shunt to the battery terminals.

Engine - The Volvo MD30A engine starts with its own SLA battery with its own alternator charging it and the only time I combine the two is to turn the switch to all and let the LiFePo4 battery charge the house bank for a few minutes, if its low and then turn it back to #1 and start the engine.
It has a separate 120 A alternator with Balmar MC 614 regulator that charges the house bank on a separate circuit. This seems to work fine with the charging voltages set for LiFePo4. The 3024i will put a 2 amp charge to the starter battery on float & absorption stages.

Problem - The boat can sit at anchor and with the set up we have it charges with the first light of day. I may use up to 130 AH over night depending on what happens for entertainment the night before. Usually around -60 AH overnight. The remote meter shows 100% battery and -00 AH usually before noon to two in the after noon. A week or two of this repeating and the meter voltage starts to drop. I think I have enough solar power to do it properly.
I know I am in trouble when it starts to go down around 13.1V which it has been doing the last few nights. It worked its way to 12.8V which wouldn't be bad with the Old AGMs I had but not for this battery. I woke this morning and the PCM had everything shut off.
I started the engine and it shot up to 96 A and has worked its way down to 50 A an hour later.
This happens also when I have 13.2V on the meter and 100% battery and -00 AH and I decide to move the boat and the amps from my engine alternator may roll in for over three hours of traveling.
I must not have the right settings on my MPPT charge controller or I have the wrong controller.
Any suggestions? Sorry for the long description but I could use some help. The boat is currently in Langkawi, Malaysia with lots of sun most of the time.
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Old 13-04-2015, 21:47   #2
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Re: Solar Charging LiFePo4 battery??? HELP

Single 200 aH lifepo4 bank with Bluesky 2512 iX for several years.
Fridge on 24/7/365.
Settings on Bluesky, 13.8 bulk. 13.4 float.
Never a problem, and it is also the start battery.
Lots of stuff on boat, ElectroScan, HAM, Spectra, radar autopilot, freezer etc.
320 watts of solar, all in parallel.
Oh, and when we need hot water (in the summer) for showers, we use the inverter to run the 1kw hot water tank element for about 20 minutes.
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Old 13-04-2015, 22:09   #3
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Re: Solar Charging LiFePo4 battery??? HELP

Steve:
Many thanks for your response. I am not sure how to set the bulk charge as I have asked Blue Sky and they didn't help. I will put the maximum voltage at 13.8 V and see if that helps. I will also change the float to 13.4 V and see what happens with that.
I have been running the engine now for almost four hours and it is still chucking in 49A.
I have similar loads as you but watch movies at night through a 9 - 16V converter to 12.1V and plug in directly.
I cannot use the house bank for my windlass or starter as I believe they have given me the wrong PCM. Long story.

Cliff
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Old 13-04-2015, 22:28   #4
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Re: Solar Charging LiFePo4 battery??? HELP

LiFePO4 Batteries - Thoughts & Musings Photo Gallery by Compass Marine How To at pbase.com
I suggest you read this article. Especially the part about NO FLOAT.
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Old 14-04-2015, 00:15   #5
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Re: Solar Charging LiFePo4 battery??? HELP

DeepFrz:
Thanks for the link. A lot of information that I believe I can use or test out to see how it helps or not.
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Old 14-04-2015, 09:00   #6
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Re: Solar Charging LiFePo4 battery??? HELP

The BlueSky controller comes with fixed voltage setting (at least it did when I purchased mine).
With the IPN Pro Remote display, you can program all kinds of settings any time you want. I recommend it.
Sorry I forgot to mention that.
Re the no float part, that's ok if you don't have any loads present, but in both my home and the boat, there are 24/7 loads.
I've programmed the float on the boat system so the input aH roughly equals load aH.
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Old 15-04-2015, 18:16   #7
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Re: Solar Charging LiFePo4 battery??? HELP

Steve:
Yes, I have that capability but BlueSky doesn't call it bulk charge, they call it Maximum Battery voltage setting. So far, I have brought that down to 14.1V. I have brought the Acceptance Charge to 13.8V. I have brought the Float Charge to 13.5V because I would like to see the battery up to where it was when I first hooked it up. I might have to set this higher to achieve that.
The time on the Acceptance Charge is one other setting and I have it at 5.0 hours but have no idea if that is good or not. I hope it doesn't check the voltage after that much time.
The T-comp slope is at default because I don't know how it works. The Float Current is set for 2.0A/100AH so that is set at 10A at the 13.5V if the power is there I guess.
Naturally the cloud cover the last few days has been about 50% or raining. I don't think that this should interfere with the actual workings of the SCC that much.
Two other things, the Charge Efficiency is set to Auto and is reading 91% at this time. Self discharge is set to 1%/Month at this time as well.
I did change my Balmar MC614 setting to HAL and limited the High Voltage to its minimum of 14.6V. It is the closest to LiFePo4 settings I could find.
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Old 16-04-2015, 09:24   #8
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Re: Solar Charging LiFePo4 battery??? HELP

For Lithium, the T-Comp Slope should be at zero.
It's Temperature Compensation Slope which adjusts the voltage up or down from the other settings, i.e. higher voltage when battery temp drops.
You don't want that with Lithiums.
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Old 16-04-2015, 19:28   #9
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Re: Solar Charging LiFePo4 battery??? HELP

Steve:
Thanks again. I have changed the T=Slope to 0.0 mV/C/C from 5.0 mV/C/C. What ever that means. It doesn't sound like a lot. Any other ideas would also be appreciated. I have plenty of sun today and it is going to be hot. Haven't noticed much change in charging and also got up late. Will continue to monitor it all.
Cliff
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