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

[deckofficer]

You did very well for 2010, they were higher then, and my quote was late 2011, so yes, your price beat anything I got in 2010. I use the batteries for EVs, but will for the future boat also.

[sytaniwha]

Following on from Bob's comment, I figured that the price I got was directly competitive with AGM prices.

Apart from the claimed greater cycle life (we'll find out whether that's true in a few years), the other thing to remember is that they allow a greater depth of discharge per cycle compared to lead acid. So in your capacity sizing calculations, in lead-acid you typically should assume a useful DOD of about 30% (cycling from about 50% absolute DOD to 80%). With LiFePO4 cells, because you can easily get more charge into them, and take more out at the bottom end, you can do the same calculation with a swing between about 95% and 25%, or 70% DOD.

That means that you need less battery capacity to provide the same usable capacity as lead-acid. To be conservative, I used a factor of 2, meaning that my 400 Ahr battery would give me a usable capacity equivalent to an 800Ahr lead pack.

That seems to be absolutely true in real life (and maybe a little conservative).

It greatly changes the cost equation.

Cheers,
Paul.

[downunder]

Originally Posted by sytaniwha

Following on from Bob's comment, I figured that the price I got was directly competitive with AGM prices.

Apart from the claimed greater cycle life (we'll find out whether that's true in a few years), the other thing to remember is that they allow a greater depth of discharge per cycle compared to lead acid. So in your capacity sizing calculations, in lead-acid you typically should assume a useful DOD of about 30% (cycling from about 50% absolute DOD to 80%). With LiFePO4 cells, because you can easily get more charge into them, and take more out at the bottom end, you can do the same calculation with a swing between about 95% and 25%, or 70% DOD.

That means that you need less battery capacity to provide the same usable capacity as lead-acid. To be conservative, I used a factor of 2, meaning that my 400 Ahr battery would give me a usable capacity equivalent to an 800Ahr lead pack.

That seems to be absolutely true in real life (and maybe a little conservative).

It greatly changes the cost equation.

Cheers,
Paul.

With prices now directly competetive with AGM looks like very little reason not to move to LiFeO4 now.

[Surf City]

I'm waiting on a quote from Lithium Storage for 600 ah. Looking at three batteries of 200 ah each. Let you know when the quote arrives.

Wil
s/v Full Monty | Keep up with us as we sail the world and its many remote places.

[Hoohaa]

Just on a different tack, I currently have two batteries in my boat and am about to add a 3rd. I already have a good battery for this but have been cautioned against adding to my existing battery because it is not the same type of battery as the existing, that is the new battery is led acid and the existing batteries that I want it to run in parallel with is a Life battery.
Is it a real problem to do this or should I only join the same type of batteries?
This is a pic of my existing setup.

Attachment 39525

[sytaniwha]

Hoohaa,

It's off topic for the thread, but you certainly should not parallel different types of batteries, even different types of lead-acid batteries.

In your photo, it looks like the top battery is Lifeline brand, which almost certainly makes it an AGM lead-acid battery (Absorbed Glass Mat). If that is true, it's a sealed lead acid chemistry, so it supposedly does not need (and has no way to add) water topped up during it's life.

The bottom battery is clearly different (size, maybe brand, maybe type). It's hard to tell in the photo, but it may not be an AGM lead-acid - it looks like there is some type of vent on each cell, but hard to tell if you can gain access by unscrewing the cap (in which case it's a normal "flooded" lead acid battery), or not (in which case it probably is AGM lead acid and the caps are just non-access pressure release valves).

One odd thing is that looking at the wiring it appears as if these batteries are connected in series, which would give you 24V (assuming that they're 12V batteries, which it looks like they are).

Regardless of whether they are in series or parallel, your current setup isn't ideal. To get the best life and performance from batteries, you should really have only batteries of the same type, capacity, and age connected together. If you don't (as in your case), at some point you will almost certainly damage one (or more) of the batteries.

Regarding your new battery: if it also an AGM lead-acid battery, then connecting it to your existing batteries would work (if they are indeed both AGM), but would produce less-than-optimum performance, as I suggest above for your current setup.

If the new one is a "flooded" lead acid, or a Gel lead acid, then it shouldn't be connected at all (they all require slightly different charging regimes, and you will definitely compromise something if you connect them together).

I'd suggest that if you want more capacity, you look at replacing your entire battery bank with new batteries of the same type, size, and manufacturer. It would at least then start you on the right path, and could save you money in the long run by extending the life expectancy.

Unfortunately boat batteries are not the "set & forget" that we'd all like. If you want to get the best out of them, you really need to make sure they're matched, and then charged and discharged correctly. Hence all the "discussions" in this thread.

It's really hard to tell from the photo exactly what the total story is, so be wary of just taking my advice wholesale (or any other website's). It'd probably be worth paying a local boat electrician $50 to come have a quick look & consult.

I hope this helps.

Cheers,
Paul.

[s/v Holiday]

Just received a quote from Sinopoly for their new SP-LFP200AHA cells at 1.15 per ah. 16 cells for total of 800ah at 12v. They are the new 1/3 smaller and lighter version. Is this a good price?

I am waiting on a shipping quote from China, should be around $350 Sure wish there was a dealer in the states that stocked them.

Now I am looking for a Charge Controller for them. Any suggestions?

CJ

[JoeFish]

I've been reading this thread with a lot of interest over the past couple days and have spent some time looking over some other sites to inform myself a bit more, and I have one remaining question.

It seems in automotive applications there have been some battery fires which on a boat could turn into a real serious problem, especially on a wood one like mine.

Has anyone spoken up about this or is this just not an issue?

Thanks!

J

[hellosailor]

Joe, battery fires with lithium technologies are a real issue. The problems vary with the technology (the chemistry) and the manufacturer. If the manufacturer you choose hasn't had any problems, and you follow proper charging parameters, in theory you have no problem. Regular batteries explode more frequently than people realize, it is just some of the lithium types that apparently prefer to catch fire in very limited circumstances. Usually involving charging, or after impact damage, not just while they're sitting there.

[senormechanico]

IFAIK, the fire problem is with Lithium Ion, not Lithium Phosphate cells.

[goboatingnow]

Originally Posted by JoeFish

I've been reading this thread with a lot of interest over the past couple days and have spent some time looking over some other sites to inform myself a bit more, and I have one remaining question.

It seems in automotive applications there have been some battery fires which on a boat could turn into a real serious problem, especially on a wood one like mine.

Has anyone spoken up about this or is this just not an issue?

Thanks!

J

LIFEPo4 does not suffer the thermal runaway characteristics other Li technology exhibits, equally they have slightly power WH/kg figures as well.

Dave

[hellosailor]

The only memorable kerfuffle about a "lithium" car battery fire recently was the bit about a Chevy Volt that was heavily damaged in crash testing--and had a battery fire something like 3 weeks later, from the steel body panels intruding into the battery. As GM pointed out, with that kind of damage one would hope someone had removed the cracked battery after that length of time, in any normal application.

I'd be more concerned with the discrepancies in BMS "requirements" and the difference between claimed cycles and warranty coverage. So many claims, so many dollars, and so many big corporations with big R&D budgets of their own who have not universally acclaimed lithium in any way. Yet.

[goboatingnow]

Originally Posted by hellosailor

The only memorable kerfuffle about a "lithium" car battery fire recently was the bit about a Chevy Volt that was heavily damaged in crash testing--and had a battery fire something like 3 weeks later, from the steel body panels intruding into the battery. As GM pointed out, with that kind of damage one would hope someone had removed the cracked battery after that length of time, in any normal application.

I'd be more concerned with the discrepancies in BMS "requirements" and the difference between claimed cycles and warranty coverage. So many claims, so many dollars, and so many big corporations with big R&D budgets of their own who have not universally acclaimed lithium in any way. Yet.

Who has not acclaim ed lithium , there everywhere.

Dave

[hellosailor]

Dave, there's more than one Big Brand Name automaker who is, and has been, making "electric" cars that did not and do not use Lithium batteries of any kind.

Toyota Prius, possibly the most widely deployed. NiMh.

Tesla. NiCd.

Everywhere? Not lithium, not yet. The vote is still not in.

[bcn]

Just the opposite:

almost all the car manufacturers are employing LiPO cells,
- Tesla is LiPo
- GM Volt/Opel Ampera LiPO
- Nissan Leafe
- Mitsubishi i MiEV
- Renault
- The hybrid solutions from Mercedes, BMW, AUDI, Porsche
- Future VW plug-in models (->2013) will be LiPO

LiPo = LiFePO4 or similar

There are a lot of Joint Ventures between car manufactures and cell producers (Japanese and Korean mainly in this cases) under way, Bosch, Continental and Johnson Control just to cite a few tier 1 suppliers are working heavily in that field - everybody with lithium chemistry as the main line in this moment. A123 as the US player the same.

Issue is the price: 100€/Kwh is the target but the manufactures are a quite distant from achieving it:
"Der Leiter des Bereiches Lithium-Ionen-Akkus bei Johnson Controls in Hannover, Stefan Suckow, sieht nach Angaben der „Wirtschaftswoche“ einen Preis von 350 Euro frühestens in fünf Jahren."
(The responsible of Johnson Control for LiPO sees a price of 350€ within 5 years as realistic)

This is the main reason too for the slow ramp-up of sales.

The big difference between traction solutions and housebanks has been mentioned several times in this thread:
- stacks with much higher voltages - 400V is not uncommon
- much higher discharge/charge currents
- and for those reasons sophisticated BMS are a must
- cooling systems for the batteries and the power electronics required

With 400V, high energy density and thermal issues you know why crash worthiness and monitoring are considerations with high priority in this applications.

And btw: all a little more advanced Pedelecs (bicycle with e-motor support) are employing LiPo battery packs.

bcn