Lithium Batteries (for the rest of us)

[Thumbs Up]

LI (lithium) FE (iron) PO4 (phosphate)

The thread: Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks
has over 2500 posts

For those of us that need to replace our battery banks in the near future, these batteries seem like the way to go, it seems like we are right on the verge of creating practical guidelines of how to purchase and install this technology in our boats.

I am starting this thread with the hope that what you are discussing in the related 2500 posts can be summarized for the rest of us.

I am seeing that I can buy 100ah 3.2 volt cells for $130. each Sinopoly 100 Amp Hour Lithium Battery

For the purpose of this discussion, Lets say that I took four of these, hooked them together and installed them in place of my old battery bank. I am using typical charging systems for a boat designed to maintain a lead acid battery bank. Would it work? and what are the issues?

The more technical aspects of this subject could go in the other thread but could you guys keep us posted as to what the current consensus is regarding these installations and what the issues are?

I understand the basic advantages of these batteries, but would somebody please do a brief outline for us (without getting to technical, please)

If you need to debate the technical issues, it should be done on the other thread except for the basics of the disagreement so that we can keep this discussion shorter and more navigable (for the rest of us)

[Badsanta]

Great link. Thanks

[ebaugh]

The simple answer to your question is "make sure you never overcharge or over discharge any individual cell" and you are good to go....the biggest problem that crops up in a retrofit is some equipment designed for standard batteries won't stop charging soon enough and can shorten the lifespan of LFP cells.

A more detailed summary of my installation, my general opinions and some links to additional reading I found helpful is documented here:

http://marazuladventures.files.wordp...batteries8.pdf

My only other comment is 100Ah bank capacity is probably too small to bother with LFP. I probably would not consider anything less than 300-400 Ah worth the effort for a house bank.

[Thumbs Up]

That is a great article, Bob! I haven't been through all the links yet but I have a better understanding already. Now I realize also that my so called bank of 4 100 amp cells of 3 volts each is only 100 amp total at 12 volts which is only a fourth of my current capacity. Though with these batteries you will only need 1/2 to 2/3 of what you needed before because you will have up to twice the useable capacity.

[familycruisers]

100ah of storage means 80 ah of usable storage so opposed to 50 ah.

[Zil]

just want to give this thread a bump.

[manitu]

The other lithium chemistries has some uses too..

LiCo (lithium cobalt)3,6v nominal. This is the portable pc cells (16650 cells) 16x650mm in size. Same as the tezla uses. These are what I use on my electric bike, cause they are CHEAP.
These are old hat , and individual cells with less than 2600mAh has some issues with igniting or rupturing if charged hard.

LiPo (lithium polymer) 3,7v nominal. this is the square soft packs wich is used in RC cars. They come in a range of charge/decharge ratings up to 60C, wich means you can charge and drain the useful capasity in ONE MINUTE! This makes for incredible light buffer batteries for the windlass and other heavy power-users.

edit: Balancing the cells: this is what I use to check/balance my lithium batteries: http://www.hobbyking.com/hobbyking/s...arehouse_.html

.manitu

[Zil]

LiCo has history of igniting during normal use as well.

[EddieS]

Thank you Thumbs up!
This is just what I need too.
Thanks
Ed

[Cotemar]

Why not just go with these 12 volt Lifepo4 batteries?
Balqon - Advanced Transportation Solution

[Hyprdrv]

It think this thread is an excellent idea but needs to be kept to facts as well as maybe installation parameters. Maybe list the Facts in the first posting here and then modify it as we develop the list over time.
For instance:
GENERAL
LiFePo4 batteries are the most safe of the Lithium's that we know of at this time.
Advantage over LP: Lithium=80% usable energy over LP=50%
Life expectancy: Still out. Estimated 10 years or more.
Weight savings: 60%
Space savings: Depending on size 30%
Charging
Do not over charge or undercharge these batteries or damage will occur.
Charge to 90% and do not Discharge below 10%
Anyway if we can keep the theory to the other string (even refer to it) and the results to this string we could get some progress on the actual install and use.
BMS FACTS
To be a Subject.
And so on..

By the way I will be using 48 LiFePo4's for my propulsion pack down the road. I'm also looking at a distributorship of LiPo's located in Virginia.

Steve in Solomons MD

[goboatingnow]

Originally Posted by Zil

LiCo has history of igniting during normal use as well.

No it hasn't, it has to be provoked, usually through mis-understanding.

Dave

[ebaugh]

Originally Posted by Cotemar

Why not just go with these 12 volt Lifepo4 batteries?
Balqon - Advanced Transportation Solution

Inside of the case are 4 individual cells that need to be monitored for maximum life. Wiring 2 in parallel to increase the Ah capacity gives you 8 cells to monitor vs 4 if you wire regular cells 2P, then 4S. It's a great starter battery, assuming the alternator won't overcharge it, but not too usable for a house bank.

[neelie]

Only thing I would add is that with LFP, it is essential to monitor individual cell voltages and to protect individual cells from over charge and/or discharge.

There are many ways to do this:-

Manual :- standing over the cells with a volt meter and watching each cell like a hawk as you charge, discharge and balance the cells. With experience you can probably sort out some sort of usage and charge regime which is "safe-ish". Its risky, and you have no warranty for the cells. And there is probably no one in their right mind who would ever dream of suggesting this as being viable.

Semi Auto : Using Cell Loggers to monitor the cells with alarms and also possibly to drive a battery disconnect relay. Less risky, But again, no warranty from the battery manufacturer. There are a few who do suggest that this a viable solution to managing a battery. If cells need balancing, this will have to be done manually.

Auto: Get a BMS and wire it up with a loud alarm and a battery disconnect relay. Usually battery manufacturers say they will honor the warranty if you have an approved BMS installed. This is the most risk averse solution and most will balance cells as well.

Further complications: Protecting your alternator and charger - there needs to be a strategy to gracefully shutdown the alternator and charger before disconnecting the battery.

The jury is of course still out as to whether cells used in a house bank drift out of balance often enough to need an automatic cell balancing system.

[Maine Sail]

Originally Posted by familycruisers

100ah of storage means 80 ah of usable storage so opposed to 50 ah.

A more fair comparison would be the real usable capacity of LA batteries is about 30-35% or 50% SOC to 80-85% SOC due to acceptance current limiting.

Unless you are at a dock every day when you can "full charge" your LA batts then you're likely not starting out at 100% SOC where you would have 50% usable capacity.

On day two away from the dock your real usable capacity becomes about 30-35% because charging beyond 80-85% SOC becomes a time consuming waste of fuel.

With LiFePO4 you can charge right back to about 99% before the batteries begin "limiting" current or you've achieved a charging voltage that just won't push any more current into the bank. With LA batts this limiting can start as low as 70% SOC and as high as 90% for some AGM's. The last few % take hours and hours and hours....


I think it is important to ask a few questions before installing LiFePO4:

1- How am I going to charge the bank? Can my battery charger be custom programmed (most can not)?

2- How am I going to charge my bank via alternator? Do I have an external regulator that allows for full customization of the charging voltages?

3- Are my solar and wind controllers able to be fully customized for charging LiFePO4?

4- How do I plan to terminate charging when the bank is full?

5- Can I live without an alt sensed tachometer when the alternator charges the bank to full then cuts the field?

6- Can my alternator and belt system handle the massive current suck from LiFePO4, most can not?

7- What will I use to keep my alternator from melting down? Do I have temp sensing of the alternator?

8- Do my solar, wind, battery chargers or alt regulators have the ability to 100% disable temperature compensated charging (especially if "ambient sensed")?

9- How will I initially balance my pack? Do I have a bench top power supply to do so?

10- How will I keep my cells balanced?

11- What BMS system will I employ (it's looking like a BMS will be a "minimum" requirement)?

12- How will I terminate the alt regulator when the bank is full or an high voltage event (HVE) occurs? Regulator power feed cut, field cut etc. Balmar recommends a B+/power cut for the regulator power wire.

13- How will I terminate the solar or wind controllers in a HVE? Can my controller be "open circuited" without harm?

14- How will I terminate a shore charger in an HVE? What relay will I use?

15- What will I use for bank over current protection?

16- If a charge management device was used previously to keep "two banks" charged how will I now charge the second bank?

17- How will I "band" the cells.

18- How will I monitor cell level voltage?

19- How will I keep track or % of charge or "capacity"?

20- How am I protected against a low voltage event (LVE) situation? What relay/contactor am I using to disconnect the loads?

21- Will I employ a dual bus system, as in a charging bus and load bus??




There are many more that perhaps others will add, gotta run...