Lithium Iron Phosphate Batteries

[ghaynes755]

Here's some information on long term lithium storage. For the LiPo batteries I use for UAV use I always draw the battery down to 40% charge before any long term (more than a month) storage.

This is from the Elite Power Systems website. http://www.elitepowersolutions.com/faq.html

How should Li-ion Batteries be stored ?
Our batteries have characteristics of very low self-leakage rate, ~ 3% per month, which allows batteries to be stored over extended period of time. Batteries are to be charged to 40-60% full and disconnect all loads before long term storage. Batteries must be stored in cool temperature environment. Avoid batteries being exposed to summer heat. Users are recommended to check cell voltages periodically, e.g. every 2 weeks, to ensure proper voltage level. If cell voltage drops close to 3.0V or under 3.0V, battery needs to be recharged.

[field & stream]

Excuse me for being slow-wittted here, but I don't get the meaning of this: "Our [lithium] batteries have characteristics of very low self-leakage rate, ~ 3% per month"

3% of what? Of the fully charged voltage? Of some other number?

For example: if it is the fully charged voltage, then if the battery starts the month at a nominal 13v losing 3% the first month would be 12.6v remaining, and after two months only 12.2 volts would be remaining. That does not seem like very low self leakage.
For comparison, what is the leakage rate for AGM's and lead acid?

[lewster]

Originally Posted by field & stream

Excuse me for being slow-wittted here, but I don't get the meaning of this: "Our [lithium] batteries have characteristics of very low self-leakage rate, ~ 3% per month"

3% of what? Of the fully charged voltage? Of some other number?

For example: if it is the fully charged voltage, then if the battery starts the month at a nominal 13v losing 3% the first month would be 12.6v remaining, and after two months only 12.2 volts would be remaining. That does not seem like very low self leakage.
For comparison, what is the leakage rate for AGM's and lead acid?

The lithium cells we are working with have a far lower 'leakage rate' (also more commonly known as the self discharge rate) than 3%. Also, they should be fully charged before isolated storage ( this is easily dine in the coach/trailer by using the disconnect switch that is part of the BMS, or battery monitor system) In a 1 year shelf test, they showed the same voltage as when the test began. That is pretty good for long term storage.

Also, as I stated before, lithiums do not show 'voltage sag', or the slow, gradual drop in measurable voltage over time like lead based batteries do. they maintain there output voltage of 12.8 VDC almost until they are totally discharged, and then the voltage drops off a cliff. This is a situation that you never want to be in, as the battery will likely be ruined from this excessive discharge. The BMS we use is designed to cut off the battery from the loads at 80% depth of discharge to avoid any potential damage.

Lifelines use a 2% self discharge rate for the purpose of programming the sophisticated Blue Sky solar chargers that we use. The last time that I moved my storage facility, I discovered a pair of GPL-6CT 300 amp/hour Lifeline batteries in the back of the storage bay that I had completely forgotten about. It was at least 7 months from the time that I received them!

Since Lifeline ships all of their batteries with a full charge, I expected to see either a very low voltage, or almost no voltage at all. Much to my surprise, The measured 6.51 and 6.53 VDC (remember these are 6VDC golf cart batteries). In effect, they lost nothing during the 7 months of forgotten storage!

amaeir7771,

The cell balancers are electronic boards that read the voltage of each 3.2 VDC 'pack' and assure that all of the cells in that group receive the same amount of charge, as individual lithium cells can accept charge at slightly differing rates. Each 12.8VDC complete lithium battery that we use has 4 of these cell balancers in use. It is these electronic boards that dictate that the lithiums not be placed in outside storage, or any place of high moisture.

[field & stream]

Lewster -- thanks, again! You are the best, a real asset to this community.

[lewster]

My pleasure............ Always!


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[kry226]

Originally Posted by lewster

I always disable the TV's charge line when placing Lifelines in my installations, per direction from Lifeline as the constant alternator output will overcharge AGMs

How do you do this? Just cut the line (where?), or possibly install an inline switch?

Don't think I'd ever want a permanent disconnection as there's always a chance one may need some charging from the TV.

ETA: Or is this only with a solar installation?

[Tincampers]

Originally Posted by kry226

How do you do this? Just cut the line (where?), or possibly install an inline switch?

Don't think I'd ever want a permanent disconnection as there's always a chance one may need some charging from the TV.

ETA: Or is this only with a solar installation?

There should be a separate fuse in your TV fuse block. But having a switch in the cab sure would be handy.

[switz]

With all the trailer rewiring we did, we put a TV battery disconnect switch along side the main battery disconnect switch behind the sofa. Thus the 7 pin plug on the truck is always hot in case I tow a different trailer. If ever needed, I can turn the switch on to allow the truck charge to enter the trailer to the battery.

We had rewired the truck much earlier with a direct to the battery #10 wire with an inline auto-reset 30 amp circuit breaker that goes directly to the proper 7 pin plug terminal replacing the #14 wire from the factory.

We also had to put a second #10 wire with 30 amp auto-reset breaker to go to the Tuson DirecLink NE trailer brake controller and then continued with #10 wire from it to the proper location on the 7 pin plug at the rear of the truck. This was necessary for the Titan BrakeRite II SD hydraulic disc brake pump and control head that resides in the original factory battery box.

[lewster]

Originally Posted by kry226

How do you do this? Just cut the line (where?), or possibly install an inline switch?

Don't think I'd ever want a permanent disconnection as there's always a chance one may need some charging from the TV.

ETA: Or is this only with a solar installation?

2 ways. The easiest is to just remove the fuse in the TV for the charge line. The second is as Switz described above. #2 is a bit more involved, but great if you tow other trailers that need the charge line to be active.



Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[kry226]

Thanks for the info, gents. Much obliged.

But again, we're only doing this when solar is installed, yes? Otherwise there seems to be little chance of overcharging with only the TV power.

[lewster]

Nope,

If you install Lifeline AGM batteries, the TV charge line needs to be disabled. I can't address other AGMs or liquid cells as I don't install them. Same with lithiums, but they need more sophisticated charging and would gave solar and inverter/chargers anyway.


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[rodsterinfl]

On the smart website I see a five year warranty and around $1200 for a battery. I pay $200 for two- two year Johnson controls 184 amp hour batts (total) that last usually around 3 years. Not counting having to change out chargers and controllers and adding monitors that same money provides 12 years of full replacement, 92 amp (50%) and 18 years of personally realized life each 2-3 years starting fresh with lead acid. I like AGM too but cost/life difference is important.

[guskmg]

One lithium fact that AM Solar shared with me was the long range cost of lithium battery replacement. Good news, a replacement cell is only $175 dollars, bearing in mind that it has to be brought into balance with the remaining cells before installation. That changes the long run cost considerably for the better.
Now, if you are younger than me, lifetime lithium costs in addition to future price reductions could make them the cheapest of all types of batteries. It may become more practical to keep your batteries when you trade or sell your Airstream. Also, future batteries may be made of aluminum and/or other material. Aluminum is being tested as I write. There will be all kinds of future cost reductions. Think ball point pens again.
guskmg

Lew, thanks for all your info on this subject. I can't think of a more exiting project as upgrading our Airstreams to your standards.

[ghaynes755]

Replacing a single cell is an interesting topic. Would like to see some more data on doing that in the configurations that we use. Besides the balance of voltage there are likely other factors that would affect how well it would play with the other older cells. Discharge rates, internal resistance, whether you are monitoring each pack with its own BMS (Battery Management Sensor) or monitoring a pack of cells with a single sensor to name a few.

Still lots to learn about these. So far I really like the setup that Marvin Braun from PrecisionRV did in my 2015 Classic. With full sun it looks like I can run the AC for about 4 hours if required solely from the lithiums (400ah). Throw a single Honda 2000 into the mix and it would nearly double the time.

[grizbear]

I brought up lithiums a while back and was blasted now it is a topic growing much more popular funny how things change here. Rand

[lewster]

You were just ahead if your time!!!


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[Aviator]

One concern I have with the Lithium Ion is thermal runaway. The Boeing 787-8 initial woes come to mind as a big example.

I have been reading about Aluminum Ion which has similar and possibly superior capabilities to the Lithium, but is not yet commercially viable.

[lewster]

Lithium ion commonly refers to the formulation using cobalt. They did have thermal and other incendiary problems and gave lithiums in general a bad name. This is why we can't shop the (yet).

The formulation we use is lithium iron phosphate (LiFePO4). They are referred to as lithium phosphate batteries, or dimply 'LiPo'. Different chemistry and different characteristics.


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[Aviator]

Thanks, Lew. That definitely makes a huge difference and raises the confidence factor.

[lewster]

[QUOTE=lewster;1632963]Lithium ion commonly refers to the formulation using cobalt. They did have thermal and other incendiary problems and gave lithiums in general a bad name. This is why we can't shop the (yet).

The formulation we use is lithium iron phosphate (LiFePO4). They are referred to as lithium phosphate batteries, or dimply 'LiPo'. Different chemistry and different characteristics.


Sorry about the spelling! The phone likes to do it's own thing sometimes and if I don't proof read the message, this is what you get!! The message should have read:

Lithium ion commonly refers to the formulation using cobalt. They did have thermal and other incendiary problems and gave lithiums in general a bad name. This is why we can't ship them (yet).

The formulation we use is lithium iron phosphate (LiFePO4). They are referred to as lithium phosphate batteries, or simply 'LiPo'. Different chemistry and different characteristics.

Hope it makes more sense now!