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

[T1 Terry]

Originally Posted by TassieBloke

+ 1 to Downunder & Marqus

I am a newbie to anything Li in a boat, so I am watching this thread very closely. The main point that is coming across loud & clear is the absolute sensitivity of Li to overcharging, and the necessary charging controllers to ensure this.

Like most here i guess, I am a firm believer in redundancy, and therein lies the conundrum. What happens when I am offshore and the electronics go pear shaped, and then my 20yr 120amp alternator run off my 30yr old diesel donk is cooking my battery bank?

Bloke

I guess if the regulator on your 20yr old alternator powered by your 30yr old diesel failed, and the cell logger failed at the same time so you didn't get an over voltage warning and you didn't notice all the lights were really bright and the volt meter way past where it should be and the smoke was coming ot of the instruments then I guess you would eventually damage the Li batteries. Remember 4 volts per cell is 16v so if the cells were balanced and the system got over 16v without you noticing....... what do you think would happen to your flooded wet cell lead acid batteries at over 16V?

I am not an early adopter, more a 2nd or 3rd gen adopter waiting that little bit longer to get the major bugs sorted. I know I will change my house bank over from Floodies to Li, but this charging controller issue has balked me. I do not want to cook my $5000 battery bank, so i guess i need to carry even more spares on board...or am i missing something here?

There are those that make the pioneering moves, the early adopters, they form a tight group and help each other, then those that wait till a few others have proved it works, the followers, there may be a few early adopters willing to still help, and then those that waited till the everyone else has them and wonder why people only want to point them to thread links for yrs ago and don't want to help out with one on one guidance. Who knows what the earlier adopters will have by then, maybe you should wait to see how that goes too......

T1 Terry

[Whimsical]

Terry
The main worry i have is with the alternators. I have seen them go seriously over voltage when the reg fails so i was thinking of a field disconnect if that happened either triggered by the cellog or just a simple analogue circuit at the alternator. But then that woud only occur when the motors were running so i would be there to hear the alarm and turn off the alternator so not a biggie i guess. I have a good collection of mosfets and i like to tinker so we will see what happens
As i have 960W of solar and am budgeting for use of about half that the batts should spend a lot of thier life floating so i do like to keep the terminal voltage as low as possible and am not worried if they stay a little undercharged as info i have read suggests this may be conducive to an even longer life. I have never seen a switch mode supply fail to give an over voltage so thats easy.
As to the dc dc convertor. Not sure if they can be bought but i have modded several smps's before to different voltage and curent o/ps so i don't think that would be a problem although your idea is even simpler so i may steal it. Efficiency doesn't matter as its only an annual tune up i would think. I think with your idea of an inverter and a plug pack this would be an easy way for non electrical types to balance things out if needed, far less fiddly than using loads to drop a high cell, just put it on and come back later to move it to the next low cell.

Downunder
Thanks for the compliments but still a fair way to go

Mike

[Whimsical]

Tassiebloke
I think the car and bike guys were the early adopters. They have sorted most of the problems and put the research into the public realm. Us boaties are the second wave

[TassieBloke]

Originally Posted by T1 Terry

There are those that make the pioneering moves, the early adopters, they form a tight group and help each other, then those that wait till a few others have proved it works, the followers, there may be a few early adopters willing to still help, and then those that waited till the everyone else has them and wonder why people only want to point them to thread links for yrs ago and don't want to help out with one on one guidance. Who knows what the earlier adopters will have by then, maybe you should wait to see how that goes too......

T1 Terry

Geeze mate, what got up your trousers? Maybe I should have written I am not an early adopter of things I do not fully understand. That make you happy?

There are many here (self included) who appreciate the info that you and others are sharing on this topic, I am sure. I would hazard a guess that there are also many that are not fully conversant with the electrical system on their boat, and are thus hesitant to plunge fully into something that they are not confident enough to repair or jury rig when out at sea. There is a vast difference to being days or weeks from shore, compared to being on the highways where help is usually but a phone call away, or hitchhiking back to the nearest town.

Anyway, all the best with your build.

Bloke

[T1 Terry]

Originally Posted by TassieBloke

Geeze mate, what got up your trousers? Maybe I should have written I am not an early adopter of things I do not fully understand. That make you happy?

There are many here (self included) who appreciate the info that you and others are sharing on this topic, I am sure. I would hazard a guess that there are also many that are not fully conversant with the electrical system on their boat, and are thus hesitant to plunge fully into something that they are not confident enough to repair or jury rig when out at sea. There is a vast difference to being days or weeks from shore, compared to being on the highways where help is usually but a phone call away, or hitchhiking back to the nearest town.

Anyway, all the best with your build.

Bloke

Sorry, shouldn't have gone off at you like that. The battles I've had with know it all armchair engineers on a number of Aust RV forums has made me a little gun shy.
These batteries have been around for about 10yrs, the first were NASA type stuff, then the petroleum industry paid to have the technology stalled and it wasn't till the Chinese with their total disregard for patents started developing them that these prismatic cells have made an appearance at a price the average person can afford.
A few very early adopters in the EV field decided they could simply apply lead acid charging logic to these Li cells resulting in disaster and the Li cells getting a bad name. Now the mention of lithium has people comparing them to model plane batteries and the problems the very early use EV people had.
So when you started with the negatives I bit, please accept my apologies.

T1 Terry

[goboatingnow]

Agree Terry. The Chinese prismatic cells changed the game. Heres hoping Winston doesn't go out of business.

Li has been around now for some time and now dominates small device battery tech. There a whole slew of chips to deal with charging and balancing ( which make good reading ). LiFePo4 is one of the Li technologies that offers the possibility of large banks as the runaway problem seems to be cured ( I'm not about to test my thunderskys though)

My experience is that they are easier to use then LAs. By that I mean in a typical Boat type installation not EVs. it's easier to get the capacity from them. Easier to charge and more tolerant of poor recharge regimes. The key factor is the removal of the need to go to 100% SOC to maintain health as is the case in LAs.

Dave

[T1 Terry]

I don't think Winston Chung is as silly as the people at Sinopoly, fancy paying that much money without making sure you were actually buying a company, not just a name. Winston Chung always owned the rights to the yttrium technology, it was never part of thundersky to start with, I guess they still have a lot of business learning to do in China.

T1 Terry

[TassieBloke]

No harm done Terry. I was typing on my ipad which is a royal pain, and I tend to get a little cryptic.

Cutting edge technology around here is the argument between Rocna and Manson anchors

goboatingnow: Overall, I would agree with the statement that Li seems to be easier and more cost effective longterm in a boat house bank, all things considered. I have no doubt that when my current LA house bank is kaput, that Li will be installed. I am considering a whole bunch of modifications to my propulsion system which looks like it will involve a 18-25kW motor at 144V, so I need to sort all that out before sizing and replacing the house bank.

Anyway, thanks again to you all for the informative discussion.

Bloke

[Marqus]

Originally Posted by goboatingnow

The key factor is the removal of the need to go to 100% SOC to maintain health as is the case in LAs.

Dave

That reminds me of the two main factors attracting me to LifePO batteries:

1) As Dave stated above: "Removal of the need to go to 100% SOC to maintain health".

2) Charge acceptance: I can use high capacity charging sources for much shorter periods. When charging Lead-Acid, your alternator output can drop appreciably before you get close to 90% SOC, substantially extending the charging duration. I hope I can charge LifePO at high output (eg. full 80A) until 90% SOC (or more), then stop.

If anyone with experience/expertise feels either of these aims is misguided, I would appreciate your reply to alert me to any misconceptions.

[witzgall]

Terry;

I have Hipower LIFEPO4 cells installed on our boat, I put them in a few weeks ago., There are a few more folks here that will be putting them on their boats as well, as they bought some that I had but did not need.

Here is the specs for some of them, and the ones I have:

http://www.evsource.com/datasheets/B...wer%20cell.pdf

I am interested to hear what you think about the voltages we should be using for these cells. I personally installed eight cells, in a 2p4s configuration. I have four charging sources onboard, wind (AIR-x), solar (morningstar 15MPPT) Charger (truepower 20a) and a Balmar alt with external reg.

Electric1, who got me started on these, stated that I could use the LA settings on these charging sources, essentially leaving things as-is, and do fine. The Alt regulator is configurable - right now it puts out 14.8v when doing bulk charging. I actually contacted Balmar for advice, they were useless, and actually quite negative about helping in any way with regard to LIFEPO4.

I am glad you are using the cell log - I have been looking at those ever since I built a 24v LIFEPO4 Torqueedo motor battery, but never tied them. I wil place my order now.

What Perkert # are you using on your AH meter (I have a link 10)? I have started with 1.05, but that was just a guessimation,. The internal resistance of these cells are listed as <2 milli ohms, if I read the specs correctly.

Finally, you are writing about charge voltages of 3.45v per cell. Is it safe to use these numbers in conversations, without mentioning the cell manufacturer? Are they all really the same with regards to the charging/discharging voltages?

Chris

[senormechanico]

Chris,

All questions I was going to ask!
I've read every single post on this very useful thread.

200 aH Li batteries have been installed, but not quite hooked up.
I've got a MPPT Bluesky controller with IPN Remote, a 100 A alternator (adjustable voltage single stage) and a 20 amp Xantrex shorepower charger.
I'm installing a mini BMS system with an AC solid state relay for the shore charger.
After reading all the variations on recommended voltage settings, I'm hoping for some guidance as well.

[s/v Jedi]

I wonder if we can find consensus on a summary that will help most readers of this thread. Let's say we have a sailboat with a 1,000Ah LA (incl. gel, AGM) house battery bank. They have just an AC powered battery charger and engine alternator. What are the steps to take, in simple terms? I think we should start with capacity needed to equal the old 1,000Ah bank, what cells are good for that etc.

ciao!
Nick.

[T1 Terry]

Hi Tassie Bloke,
you can use the same Li pack for propulsion and house batteries, that's my plan. A 48v inverter/charger, a 48v to 13.8v DC to DC converter, 4 X 90Ah cells for start battery and 12v appliance capacity storage for want of a better word. The DC to DC keeps the start battery charged and supplies the 12v circuit, if at some stage there is a higher peak demand that comes from the battery and then it's topped up by the DC to DC converter. The 4 X 48v packs can be linked in series to give the 144v required and then in parallel to make a very big house battery that is easy to recharge.

T1 Terry

[T1 Terry]

Originally Posted by witzgall

Terry;

I have Hipower LIFEPO4 cells installed on our boat, I put them in a few weeks ago., There are a few more folks here that will be putting them on their boats as well, as they bought some that I had but did not need.

Here is the specs for some of them, and the ones I have:

http://www.evsource.com/datasheets/B...wer%20cell.pdf

I am interested to hear what you think about the voltages we should be using for these cells. I personally installed eight cells, in a 2p4s configuration. I have four charging sources onboard, wind (AIR-x), solar (morningstar 15MPPT) Charger (truepower 20a) and a Balmar alt with external reg.

Electric1, who got me started on these, stated that I could use the LA settings on these charging sources, essentially leaving things as-is, and do fine. The Alt regulator is configurable - right now it puts out 14.8v when doing bulk charging. I actually contacted Balmar for advice, they were useless, and actually quite negative about helping in any way with regard to LIFEPO4.

I am glad you are using the cell log - I have been looking at those ever since I built a 24v LIFEPO4 Torqueedo motor battery, but never tied them. I wil place my order now.

What Perkert # are you using on your AH meter (I have a link 10)? I have started with 1.05, but that was just a guessimation,. The internal resistance of these cells are listed as <2 milli ohms, if I read the specs correctly.

Finally, you are writing about charge voltages of 3.45v per cell. Is it safe to use these numbers in conversations, without mentioning the cell manufacturer? Are they all really the same with regards to the charging/discharging voltages?

Chris

The cell charging voltages and other info I have posted are generic for all prismatic style LiFeP04 cells. Please don't charge the Li cells to 14.8v, they will bulge and die.
The Puekerts factor for Li at the current draw house systems use is that close to zero it's easier just to use zero and reset the 100% mark once every mth or 2.
As far as the 24v and the cell logger, don't forget about the little link needed to be soldered inside. I'll see if I can find the picture and post it here so you can see what needs to be done.

Sorry if I've missed any bit, I'll be back from Sydney tonight so I'll look back through and try to catch up the bit I didn't cover.
glad people are enjoying this thread, I enjoy trying to help.

T1 Terry

[Surf City]

I'm with Jedi on this one. I'm in the same boat boat but have solar (705 watts)also. Do I keep LA starting batteries or turn all over LI? Changing batteries this spring for our worldly departure in June. I would like to do this right the first time. What do I need?

Thank you

Wil