LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[OceanSeaSpray]

Originally Posted by Maine Sail

If you stick around .3C the taper is pretty quick, hours and hours faster than LA...... I have also noted that the rate at which you discharged the battery has some effect on how the battery performs during charging. I have not sat down to analyze it yet but at frac C discharge rates the battery voltage seems to rebound a bit easier than the same charge rate after a higher discharge rate......

The current taper seems quick regardless of current. I have charged at 1C as well as 0.03C and everywhere in the middle. Once the absorption voltage is reached, it seems to be a matter of about 35 minutes at the most... but this is absorbing at 14.0V.

I quickly pulled the pin on charging at lower voltages. I have had the feeling that if the voltage is low, reaching the same SOC also requires tapering down to a lower current, and this takes significantly longer.
At this point, the process starts heading back to where we were with LAs.

I toyed with the idea of using lower absorption voltages for low-current sources, like solar, while keeping the alternator setpoint higher. In the end it made no sense at all, because I want efficient solar charging and maximum cycling capacity when energy is not so plentiful - like in winter - and it would cripple the system. If I get a sunny day, I really want the system to make good use of it.
In summer, the control strategy hugely extends the cycles before occasionally fully recharging and the battery doesn't actually see the absorption voltage very often at all.

The other consideration was that a decent absorption voltage from time to time should assist with overcoming memory effects from repeated partial cycles and 14.0V might hardly be enough for that anyway.

The absorption voltage just needs to be below the threshold where it starts causing apparent balance issues, and this naturally keeps the cells out of the high stress zone. I just can't see any point whatsoever in trying to limit lower on a well-designed system. I have absorbed at 14.2V, but with a fair current and the bank getting close to the top, it sometimes caused momentary uneven cell voltage readings. I could have reprogrammed the BMS to allow them, but there didn't seem to be much upside and I operate a system that is quite conservative with good performance throughout and everything happening very gently.

[ColdEH]

Originally Posted by OceanSeaSpray

The current taper seems quick regardless of current. I have charged at 1C as well as 0.03C and everywhere in the middle. Once the absorption voltage is reached, it seems to be a matter of about 35 minutes at the most... but this is absorbing at 14.0V.

I quickly pulled the pin on charging at lower voltages. I have had the feeling that if the voltage is low, reaching the same SOC also requires tapering down to a lower current, and this takes significantly longer.
At this point, the process starts heading back to where we were with LAs.

I toyed with the idea of using lower absorption voltages for low-current sources, like solar, while keeping the alternator setpoint higher. In the end it made no sense at all, because I want efficient solar charging and maximum cycling capacity when energy is not so plentiful - like in winter - and it would cripple the system. If I get a sunny day, I really want the system to make good use of it.
In summer, the control strategy hugely extends the cycles before occasionally fully recharging and the battery doesn't actually see the absorption voltage very often at all.

The other consideration was that a decent absorption voltage from time to time should assist with overcoming memory effects from repeated partial cycles and 14.0V might hardly be enough for that anyway.

The absorption voltage just needs to be below the threshold where it starts causing apparent balance issues, and this naturally keeps the cells out of the high stress zone. I just can't see any point whatsoever in trying to limit lower on a well-designed system. I have absorbed at 14.2V, but with a fair current and the bank getting close to the top, it sometimes caused momentary uneven cell voltage readings. I could have reprogrammed the BMS to allow them, but there didn't seem to be much upside and I operate a system that is quite conservative with good performance throughout and everything happening very gently.

I charge to 14.0 to 14.1volts and my batteries are taking 200amps at that point. No heat and just a little out of balance at that end at around 12mv difference between the cells. That settles back to 13.3 volts and 5mv drift between cells after an hour of shutting off the charge source. Seems to work just fine so far I hope for many years of use .

Regards

You can see my setup on my youtube site on the link below

[JBPohle]

Can't wait to see the link....



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[ColdEH]

Sorry I thought the link would show up at the bottom of my post , maybe not if I post from my phone .

Just go to youtube and search for
S/V Salserenity

Let me know how you make out

Regards


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[JBPohle]

Thank you I found the you tube link. I like the cabinet work to hide the anti siphon... nicely done.


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[ColdEH]

Originally Posted by JBPohle

Thank you I found the you tube link. I like the cabinet work to hide the anti siphon... nicely done.


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Thanks , it was tough trying to match the cabinetry of the Bristol. The little vent is for the heating system . Got more videos coming .

Regards

[evm1024]

I went ahead and set my bench supply up to charge to 14.0 volts and hooked it up the the house bank which was likely sitting at 80% or 90%. As you may recall I had thought that my bank was at 100% charge after charging without an absorption phase.

Initial charge current was around 30 amps and tapered down to 20 amps pretty quickly.

If they were at 80% SOC then it would take 7 hours to get to 100% at 20 amps. BUT of course we know that the charge would taper further. (700*.2/20=7)

So I decided to leave them overnight. I actually came back to the boat after 36 hours and the supply was sitting at 14.0 volts at just a few 100 mA.

After resting for 24 hours the bank was at 13.42 volts and each cell was at 3.363, 3.349, 3.349, 3.358.

the maximum delta between cells was 14 mV the min being 0 mV. 14 mV, 9mV, 5mV.

I think I will pull 10% off the cells and let them rest then see if the cell voltages converge.

I'm not sure that I have the energy or time to take 10% per day till flat. I may opt to do a full capacity test to see the baseline capacity. Time will tell.

--Ethan

PS of course I don't want to leave them at 100%

[SV THIRD DAY]

I've been using these Liyuan batteries now for two years and just now landed my hands on some literature...ha ha ha.

So here is the link to the Liyuan LY-400 3.2v cells literature as an FYI.
Now remember this is right out of China and I have absolutely NO relationship with Lithium Ion Storage except that I'm a happy customer and have several cruiser friends with these that are happy.

Link to Download PDF Spec Sheet

[exMaggieDrum]

Originally Posted by SV THIRD DAY

I've been using these Liyuan batteries now for two years and just now landed my hands on some literature...ha ha ha.

So here is the link to the Liyuan LY-400 3.2v cells literature as an FYI.
Now remember this is right out of China and I have absolutely NO relationship with Lithium Ion Storage except that I'm a happy customer and have several cruiser friends with these that are happy.

Link to Download PDF Spec Sheet

Another link to the company website: LIYUAN BATTERY CO.,LTD_Mobile power supply

[SVFairIsle]

Thanks to all the contributors on this topic. I have been following for over a year, and am thinking about taking the LFP leap (spurred on by the fact that when I returned to my boat, I had six dead LA's this spring, all less than 2.0v, and they were on smart charger) I have gutted my Whitby 42 ketch to totally re-configure entire set-up. Most everything is purchased. I have an Ample Marine Generator w/150 Amp Alternator, programmable Xantrex 3000w Inverter/150 Amp Charger, Village Marine 200GPD Watermaker, and planned 600w solar. Originally, the inverter was purchased to run 5000BTU Aft cabin A/C and 110v refrigeration. Have since gone to 12 volt refrigeration.

After being on four charters to BVI's and Belize, my wife does not think we can go without the A/C for sleeping in the Caribbean, especially in the aft cabin. I estimated my daily usage at 75Ah refrigeration, 50Ah Misc, and 50Ah for water every second or third day. Initially, hoping for 100Ah/day from solar to handle majority of load, then using genset to top off nightly for hot water and charging a 300Ah LFP bank. Now the 200Ah of nightly A/C has made things different. Is it naive to think a 540Ah bank can be kept in the 20-80% range (324Ah delta) using 600w solar with 2 hours of daily charging from 150A single cylinder genset. Are these assumed efficiencies off target?

I guess I am asking is this a naive mindset and approach, and the appropriate usage for a LFP bank. Without the A/C could probably get by with 200-300 Ah bank. Also, after reading some posts, am wondering about average 1200w daily off of a 600w solar array.

As I am landlocked here in Oklahoma, I do not have much assistance or expertise in this geographic area. And this being a $3K-$4k purchase, just wanted some of your feedback. I plan on 12 180Ah Calb, 3P4S.

Thanks, Pat

[SV THIRD DAY]

I'm my 9yrs of cruising and living aboard there is a phrase I have never heard out at anchor...

"I have too much solar...."

Oh sure, the Marina Queen Cruisers that go from shore power to shore power could get by with a 100W solar panel and 200AH battery bank. But for those that plan to really live at anchor, you will not regret putting on the most solar that will fit on your boat.

If not, you will just have to live with running your generator daily...which isn't the end of the world IF you planned on it that way.

A LiFePO4 battery bank will help you get the most out of the power you have available...but it's won't help make a boat that is under powered (or under battery sized) better.

Our family of 4 have now been living full time on a mooring ball with a 400AH LiFePO4 battery bank, solar from 420W to 1300W and as I type this I'm running my trusty Honda 2000 generator up on deck...why...because it is foggy...

[nixsee]

Anyone know anything about CleanPowerAuto (maker of the popular House Power BMS) possibly stopping operation? Their website (https://minibms.mybigcommerce.com/) has been showing a maintenance message for well over a month now.

On a related note, one of my cell boards for my HPBMS doesn't seem to work properly. When all cells are above 3.55V(as verified by my multimeter and Junsi CellLog), 3 of the boards are shunting but the 4th only does so intermittently. It therefore attains a higher voltage/SOC. I generally keep below this voltage anyway, but it is a nuisance when I'm trying to periodically top off the batteries.

Also, the shunting and HVC levels seem to trip about 20mV too high (3.57 and 3.62) indicating a calibration issue. Anyone else have any similar experiences?

Otherwise it has been working nicely.

[s/v Thea]

Try going here?

http://cleanpowerauto.com/store/


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[nixsee]

Originally Posted by nixsee

Anyone know anything about CleanPowerAuto (maker of the popular House Power BMS) possibly stopping operation? Their website (https://minibms.mybigcommerce.com/) has been showing a maintenance message for well over a month now.

On a related note, one of my cell boards for my HPBMS doesn't seem to work properly. When all cells are above 3.55V(as verified by my multimeter and Junsi CellLog), 3 of the boards are shunting but the 4th only does so intermittently. It therefore attains a higher voltage/SOC. I generally keep below this voltage anyway, but it is a nuisance when I'm trying to periodically top off the batteries.

Also, the shunting and HVC levels seem to trip about 20mV too high (3.57 and 3.62) indicating a calibration issue. Anyone else have any similar experiences?

Otherwise it has been working nicely.

My mistake. I had the site bookmarked. Looks like they partnered with Lithionics to build some new stuff, but still cater to the hobbyist (our) market.

Anyway, my questions regarding voltage discrepancies still stand... Any one experience any of this?

[agk]

Hello everyone,
I am a newbie here, so please bear with me. I have spent quite some time now reading this thread, but still not clear on several things. I am bought on lithium and ready to order stuff. I live full time aboard my 36 ft catamaran in Panama. I have 520 W or solar. During the night my system consumes about 60 Ah. I think, I will be happy with a 200 Ah battery pack. I don't think I need a BMS. I think, I will use these mini led digital voltmeters on each cell to monitor them.
So I am ready to make a purchase and found a good deal on CALB 100 Ah cells. I am thinking to buy 8 and connect them in 2 parallel strips.
Another option - to go with 4x260 Ah cells from Voltronix. Which is preferable? I am afraid I am missing some problems having multiple batteries connected in parallel: like what happens if one cell fails? The voltage on that battery will fall and become a short for another battery, connected in parallel?
Similar question: is it a bad idea to connect cells in parallel pairs and then connect four pairs in sequence? Again, if one cell in a pair will fail, will it kill the one it is paired with?
On another hand, having multiple small cells vs 4 big ones looks attractive to me as being easier manageable.
Maybe I am missing something else?
Please advise...