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

[exMaggieDrum]

Originally Posted by Highland Fling

OOOOPS you are talking too much sense here. You are trying to change opinions with facts......that just confuses and upsets some people and causes deeper entrenchment in their beliefs and the results are not nice to see or read.

As I am seeing 0.001V of a difference in cell voltages in my three seperate batteries.......using cheap and chearful RC/ cell monitors, producing results which had me thinking this cannot be right. That was until I pulled out my FLUKE DVM which displays to three decimal places at low voltages and confirmed that these <$10.00 monitors were accurate.

Well this after a year has me thinking - I have FOUR BMS/ 200A relay units and TWELVE Cell Boards....(and some spares) PLUS I know from experience that my Delco Remy 10SI alternator is a solid as a rock and is incapable of generating an HVC voltage..........

Since I have no idea of the MTBF of these 'BMS and associated components' and since i am monitoring individual cell voltages and it would be very easy to set up some HVC alarms with parts I have already.

Maybe I really should go total KISS and remove the BMS's and the Cell Boards as they could quite easily be the weak link in the chain, doubly so as I never expect to see an HVC or LVC and have triple redundancy having three seperate 200AH batteries as my house bank..........NOT that I see even if all three went offline simultaneously this being a critical situation.

I see few 'real' differences between LA and LIFePO4, in a how should we look after them way.....

LA has generated a nice wee idustry in LA Battry 'things' POWERFUL WHITE alternators (why would you ever want to insulate the case of your alternator and make heat dissipation more difficult).....three stage external alternator control......you want to run your main engine for long enough for the third stage of the charging profile to kick in do you? Battery monitors that tell lies lies and more lies BUT look good and convince people that they are maintaining their LA batteries 'properly'.

I think I know how to take care of my batteries since my Gel Cells were dumped at 14 years old ONLY because while the F/F was happy (well the batteries were able to handle the loads) the minute I tried to move over to electric cooking, the Gel Cells were not up to supporting these loads.

While I am not suggesting LIFePO4 is a drop in replacement for LA the changes needed are minimal for a KISS system........the more complexity you add the more things you have to go wrong and cause issues.......which is why having some experience now I think one should monitor cell and battery voltages as a minimum, a HVC/LVC alarm yes too, is a nice to have thing......but how often are you going to test it? and a BMS with Cell Modiules is also nice to have BUT NOT neccessary IF you look after your batteries properly........

Probably for the masses who seem to have constant battery issues (certainly here in SXM) a BMS is eseential.

Just my views of course but feedback based on having installed a LIFePO4 house bank myself and using them in a cruising liveaboard situation .

Excellent to get your experiences on this thread. We've heard them a couple of times now. Thank you. What would you suggest for the masses of cruisers who do not liveaboard (can't believe not every one does not but go figure), who would not be there to hear an alarm as their battery gets stuffed with excess electrons from the shore power charger or solar panels they neglected to turn off before leaving the boat for a few days, weeks, months? Perhaps they deserve what they get? My KISS principle in working on other people's boats is to help make it KISS for them, i.e. harder for them to screw up with common mistakes or oversights. I even want to do that for myself.

I admit I am put off by the extra gear and complexity as suggested by many here. I love simplicity. I am not enamored with complexity nor do I view my boat as a floating laboratory. I am still trying to understand it all and make my own decisions on it. I will have to live with them. I will also have a back up plan if I find myself with a failed BMS should I choose to have one. I do that, within reason, for every critical system on my boat. You are entitled to you opinions of course but it's not needed nor helpful to hold it against the rest of us for our discussions on this. Your own experiences are very valuable to hear.

I for one managed to keep a bank of AGM batteries healthy for over ten years with many years on the docks and an equal number off shore and at anchor. I am OK with a little overkill for a new technology for a critical system that is relatively unproven for the "masses". I am not familiar with what SXM is though.

[exMaggieDrum]

Originally Posted by OceanSeaSpray

Got much better things to do than arguing with opinionated ignorance...

Is that necessary or helpful?

[Highland Fling]

Originally Posted by exMaggieDrum

Excellent to get your experiences on this thread. We've heard them a couple of times now. Thank you. What would you suggest for the masses of cruisers who do not liveaboard (can't believe not every one does not but go figure), who would not be there to hear an alarm as their battery gets stuffed with excess electrons from the shore power charger or solar panels they neglected to turn off before leaving the boat for a few days, weeks, months? Perhaps they deserve what they get? My KISS principle in working on other people's boats is to help make it KISS for them, i.e. harder for them to screw up with common mistakes or oversights. I even want to do that for myself.

I admit I am put off by the extra gear and complexity as suggested by many here. I love simplicity. I am not enamored with complexity nor do I view my boat as a floating laboratory. I am still trying to understand it all and make my own decisions on it. I will have to live with them. I will also have a back up plan if I find myself with a failed BMS should I choose to have one. I do that, within reason, for every critical system on my boat. You are entitled to you opinions of course but it's not needed nor helpful to hold it against the rest of us for our discussions on this. Your own experiences are very valuable to hear.

I for one managed to keep a bank of AGM batteries healthy for over ten years with many years on the docks and an equal number off shore and at anchor. I am OK with a little overkill for a new technology for a critical system that is relatively unproven for the "masses". I am not familiar with what SXM is though.

OOOOPS SXM is the airport code for Sint Maarten / St Martin

Sorry BUT your question is surely not applicable to ONLY LIFePO4 batteries

[Highland Fling]

99% of my last reply has gone into a black hole somewhere.......I might re write it sorry folks

[exMaggieDrum]

Originally Posted by mcarling

If you want a basic introduction to LiFePO4 electrochemistry, I suggest starting with this lecture by Prof. Jay Whitacre:
http://media2.ev-tv.me/chargecar.mov

Thanks for the video link. Excellent for me. I managed to get a chemistry degree in my early years but haven't worked or taught in the field (other than high school tutoring) and it was great as a background on LiFePO4. May be it's my ignorance but I couldn't see what might be controversial about this basic lecture. It even helped give me more insight on basic battery chemistry and practicalities of other types of battery chemistries, such as LA.

[exMaggieDrum]

Originally Posted by Highland Fling

OOOOPS SXM is the airport code for Sint Maarten / St Martin

Sorry BUT your question is surely not applicable to ONLY LIFePO4 batteries

You are right - it was not applicable to ONLY LiFePO4 systems. A general thing I do. Wish I were at SXM area right now.

[exMaggieDrum]

Originally Posted by Jd1

I really don't understand why more people don't use a small 'oh crap' type lead battery on the charge bus to avoid any spikes. Put some diodes in front of it to isolate it from the lithium batteries and adjust for voltage differences and Bob is your uncle.
Even a small motorcycle battery will absorb any spike that should ever show.
I would suggest a super capacitor but it would probably be more expensive than a motorcycle battery.
While I am at it, may I suggest that more people isolate their different charge sources in case of voltage regulator failure? Put a diode or FET isolator on every charge device so that a failure in one doesn't blow the others. Hopefully the battery bank is protected already by an overvoltage relay and of course you do (don't you?) have a separate charge and load bus so a failed voltage regulator will not blow up your entire electrical system .....

I suppose, if you could handle the expense and additional complexity, you could put individual contactors on each charge source but that wouldn't fix the spikes if they are instantaneous. I hate to put energy robbing diodes on anything where the main purpose of the circuit is to move energy from a source to a use or a store. Every thing is a trade-off.

[mcarling]

Another possible approach (as an alternative to separate charge and load buses) would be to have two parallel battery banks, each of which (separately) is disconnected from the bus manually or automatically. Thus if a fault takes one battery bank offline, the other battery bank can still absorb any plausible voltage spike. The difficulty is that a HVE or LVE that takes one battery offline would probably also take the other battery offline. As another poster previously suggested, a small sacrificial battery (small 12V LiFePO4 motorcycle batteries can be had for $100) could be installed without any sort of automated disconnect, to act as a capacitor.

[Highland Fling]

Originally Posted by mcarling

Another possible approach (as an alternative to separate charge and load buses) would be to have two parallel battery banks, each of which (separately) is disconnected from the bus manually or automatically. Thus if a fault takes one battery bank offline, the other battery bank can still absorb any plausible voltage spike. The difficulty is that a HVE or LVE that takes one battery offline would probably also take the other battery offline. As another poster previously suggested, a small sacrificial battery (small 12V LiFePO4 motorcycle batteries can be had for $100) could be installed without any sort of automated disconnect, to act as a capacitor.

I have (in circuit) (fouth one as a spare) three 200AH LIFePO4 batteries with individual BMS's with a 200A cut off relay, with manual override - Triple redundancy AND a 8D AGM as the engine start all fed via a diode block from the alternator.....The solar only goes direct to the LIFePO4 batteries and is set well below any voltage that could harm the LIFePO4 batteries and below the HVC of the BMS.

[Highland Fling]

Originally Posted by exMaggieDrum

You are right - it was not applicable to ONLY LiFePO4 systems. A general thing I do. Wish I were at SXM area right now.

YES then you could have a long hard look at my simple system.

MY FREE FOR NOTHING ADVICE to YOU - IS

Purchase four CALB 180AH or four WTS 200AH LIFePO4 cells and the EV-Power BMS and Cell Boards that fit whatever cells you purchase.

Purchase the cheap and cheerful battery cell monitor.

Adjust your charging souces to suit AND learn on the job, it is so easy really.

Then you can come back and tell everyone here how easy it really was once you 'decided' to actually do this.

[ColdEH]

Originally Posted by Highland Fling

YES then you could have a long hard look at my simple system.

MY FREE FOR NOTHING ADVICE to YOU - IS

Purchase four CALB 180AH or four WTS 200AH LIFePO4 cells and the EV-Power BMS and Cell Boards that fit whatever cells you purchase.

Purchase the cheap and cheerful battery cell monitor.

Adjust your charging souces to suit AND learn on the job, it is so easy really.

Then you can come back and tell everyone here how easy it really was once you 'decided' to actually do this.

Exactly what i did.

Using Maine Sail's tech information as a guidline , it really is that easy .

LiFePO4 Batteries - Thoughts & Musings Photo Gallery by Compass Marine How To at pbase.com


Regards

[SailRedemption]

Originally Posted by typhoon

Exactly what i did.

Using Maine Sail's tech information as a guidline , it really is that easy .

LiFePO4 Batteries - Thoughts & Musings Photo Gallery by Compass Marine How To at pbase.com


Regards

Same here, only thing I have left to do is hook up the alternator and external regulator and adjust the settings on my Victron Phoenix 20a charger and I'm done with the bank.

It was daunting at first but once you get everything it sorta falls into place. Hardest part is starting to make a plan and diagram for your system.

See more @ redemptiverepair.com

[mcarling]

Originally Posted by OceanSeaSpray

Oh well, I have now learned about the unique mcarling one-way redox shuttle reaction that stuffs the electrolyte at 4.3V with no come-back, that Tesla uses LiCoO2 chemistry (wrong) and that mcarling's iGadgets are LiCoO2 powered too, which is unfortunate because everyone else's use lithium polymer.

I was going to let this go, but I don't want other people to be misled. LiFePO4 and LiCoO2 refer to the cathode material; Lithium-polymer does not. Among battery researchers, Lithium-polymer refers to the use of a polymeric electrolyte. Among peddlers of Lithium batteries, Lithium-polymer usually refers to the plastic material used to make the case; it is more-or-less synonymous with prismatic (modulo prismatic cells with aluminium cases like the CALB CAM72 cells I'm using). In either case, the term Lithium-polymer does not indicate anything about the cathode material. Tesla use LiCoO2 cells which are not Lithium-polymer in any sense (they are cylindrical cells, with a non-polymeric electrolyte) and laptops and phones generally use cells with LiCoO2 cathodes and polymeric cases, which people who know about batteries call LiCoO2 (or Lithium-Cobalt when speaking casually) and peddlers call Lithium-polymer.

[tsmwebb]

Originally Posted by mcarling

Tesla use LiCoO2 cells...

I thought they were using LiNiCoAl02 in 18650 size cells (eg. Panasonic NCR18650A), no?

[mcarling]

Originally Posted by tsmwebb

I thought they were using LiNiCoAl02 in 18650 size cells (eg. Panasonic NCR18650A), no?

That's a variant of LiCoO2 with traces of Nickel and Aluminium. There are similarly variants of LiFePO4 with traces of Manganese, Yttrium, etc. Battery design involves many compromises among charging and discharge rates, cycle life, operating temperatures, etc. The idea is to move somewhat along the curves of compromise. Adding traces of various metals to the cathode, changing the mix of compounds in the electrolyte, and varying the thickness of the active layers of the cathode and anode are the main ways in which battery designers choose among these compromises for both LiFePO4 and LiCoO2 chemistries. All the variants of LiFePO4 batteries behave essentially like LiFePO4 batteries, though adding traces of some metal might for example allow it to operate at lower temperatures at the expense of some other parameter. Same for LiCoO2 and all its variants.