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Old 12-01-2013, 12:48   #1021

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

Dave-
"What Li Technology was in the Boeing" Dunno. My point being that even with a company like Boeing, who hopefully have some grasp of engineering issues, they've adopted some kind of lithium technology. And still had some kind of problem. Perhaps simply from a loose battery strap, perhaps from the lithium choice itself.
If it takes this long for anyone (besides the patent holders) to figure out which technology, what charging...Hey, I only want to be a customer. When I go to the fish store, I just want to see fresh fish, not do biology research projects to figure out which is dinner.

Maybe we need Consumer Reports to partner with Practical Sailor, and do some real long term testing, with and without anything beyond "use 'em, till they burst into flames or die". (Could be fun.<G>)
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Old 12-01-2013, 13:30   #1022
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:
Originally Posted by deckofficer View Post
Once balanced, these cells exceed their rating.
This may well be due to the fact that cell capacity is measured at the "standard discharge" rate of 0.5C---which you have been well under---and the Peukert exponent is not a perfect 1, but actually something like 1.05.

So you'd expect to see more capacity at lower discharge rates.
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Old 12-01-2013, 13:38   #1023
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by diugo View Post
This may well be due to the fact that cell capacity is measured at the "standard discharge" rate of 0.5C---which you have been well under---and the Peukert exponent is not a perfect 1, but actually something like 1.05.

So you'd expect to see more capacity at lower discharge rates.
Your right Doug, and I knew that. A lot are based on the 20 hour rate to produce good numbers, some on a 10 hour rate. My load at only 30 watts was like a 40 hour rate, so I expected more then 1280 w-hr, but like I said 1350 w-hr and cell voltage was 3.26 volts. You have to admit, that is pretty good.

With that said, I'm never going back to lead acid for any cycling type of duty.
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Old 12-01-2013, 14:39   #1024
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Bob,
I'm glad to see your and Main Sail's tests, as I didn't go that far with mine.
Your last statement is what I've been telling people for several months.
I never thought batteries could be THIS GOOD, but experience has shown me otherwise.
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Old 12-01-2013, 14:58   #1025
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by senormechanico View Post
Bob,
I'm glad to see your and Main Sail's tests, as I didn't go that far with mine.
Your last statement is what I've been telling people for several months.
I never thought batteries could be THIS GOOD, but experience has shown me otherwise.
The reason I'm going through all of this is ........

My cells were 2 1/2 years old before I got them, so had some balance issues.

I want to run without a BMS.

I also want to charge at 0.5C for just a 2 hour time frame.

So I figure I need to start with good balance and I'm getting there.

After all this, I don't think I will need to re-balance for 2 years.
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Old 12-01-2013, 16:53   #1026
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Anyone know how a lithium batt fire could be put out on a boat? I read it took 40 mins to extingush on the 787.
To answer my own question. I couldn't find the MSDS on the Balquon site, but here's the Firing Fighting section from a different LiFePO battery company
Quote:
Section 5 Fire-fighting Measures
Extinguish with water, dry powder extinguishers, sands, earth. Combustion products and decomposed products by contact of water or air with internal substance include: carbon monoxide, carbon dioxide, hydrogen fluoride, phosphorus fluoride.
Quote:
Section 9 Toxicological Information
LiFePO4 is not hazardous when used properly.
Hydrogen fluoride:Extremely toxic. May be fatal if inhaled or ingested. Readily absorbed through the skin - skin contact may be fatal. Possible mutagen. LCLo: 50 ppm/30m (human beings),LC50, 1276 ppm/1h ,rats
Looks like the fire fighting is pretty standard. It is just the Hydrogen Fluoride that will do you in.
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Old 12-01-2013, 18:09   #1027
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

The manufacturer of the Dreamliner battery is Yuasa, which touts lithium cobalt oxide as its cathode material of choice in its LVP 10 and 65 aviation batteries. This gives these batteries unusually high energy density---and more instability---than lithium iron phosphate. In simple terms, the oxygen atoms are bound more tightly to iron than they are to cobalt.
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Old 12-01-2013, 18:26   #1028
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

On topic, since we bought our boat we have looked at safety in a big way installing stand-alone smoke detectors in each cabin and passageway.

We have two diesel fired heaters tucked away in cupboards so whacked two in there. the batteries are under the bunk so have put one in there, any early warning even if muffled is an advantage. They cost $8:00 each, i'm seriously looking at moving the new battery installation in a locker at the mast base running the power back into the cabin via heavy cables.
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Old 12-01-2013, 20:26   #1029
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Quote:
Originally Posted by hellosailor
Dave-
"What Li Technology was in the Boeing" Dunno. My point being that even with a company like Boeing, who hopefully have some grasp of engineering issues, they've adopted some kind of lithium technology. And still had some kind of problem. Perhaps simply from a loose battery strap, perhaps from the lithium choice itself.
If it takes this long for anyone (besides the patent holders) to figure out which technology, what charging...Hey, I only want to be a customer. When I go to the fish store, I just want to see fresh fish, not do biology research projects to figure out which is dinner.

Maybe we need Consumer Reports to partner with Practical Sailor, and do some real long term testing, with and without anything beyond "use 'em, till they burst into flames or die". (Could be fun.<G>)
If you read the report it was more to do about containing a fire that may have started elsewhere that comes in contact with lithium batteries.

Large prismatic LiFeP04 technologies we are dealing with here are a very stable form, we trade some ultimate capacity for that benefit. Outside of that Li is common technology, widely adopted, in everything from cordless tools to iPhones

But as far as boat owners ate concerned, its not so much the technology as it is adapting what we used to do with LA to the newer technology and building up some knowledge of operating procedures.

To use your analogy, we arnt doing biology reports in the fish shop, merely attending a cookery class to learn to cook a fish we haven't eaten before. ( which my local fish shop hosts every Wednesday night by the way )

The fact is hello sailor once you seen these batteries in action , you realise that Lead Acid is like a steam engine. You'd never go back. at today's pricing, they are now approaching good quality AGMs. ( which is a battery variety in my opinion has no advantage being on a boat anyway )
Dave
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Old 12-01-2013, 20:50   #1030
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by deckofficer View Post
So I figure I need to start with good balance and I'm getting there.

After all this, I don't think I will need to re-balance for 2 years.

I concur, Bob. My bottom-balanced bank started off this chilly morning with all cells at 3.088V. After several hours of solar charging, they're now at 3.2500.002. And they didn't even catch fire!

I'll charge them some more on Sunday then let them sit for a few days while I await the bolts and straps to arrive. If all goes well, they should start earning their keep by week's end.
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Old 13-01-2013, 04:26   #1031
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

I've been offline for 4 weeks in the Eastern San Blas...so a couple of general comments on all the posts for that time to catch up....

I've been using 48 100Ah cells connected 12P/4S making a 1200Ah house bank for about 6 months now. Several posts on my install are way back in this thread. The batteries have been great so far, some issues with the BMS, but mostly resolved now after a replacement part.

Initial Balance/Charging
--------------------------

Unless you have perfectly capacity matched cells (unlikely), its impossible to have a bank where cells remain at the same voltage at both top and bottom of charge. For balancing on initial installation, I believe a marine installation must be top balanced. That means all cells are equalized at full charge since that's a condition we see in marine every time we plug in at a marina, or have bright sunny days with solar. We should not see below 20% SOC normally...and if we do under normal operation...more battery capacity is probably needed.

Many of the EV guys bottom balance, but that's because their requirements are relatively high discharge rates and an occasional need to go below 10% SOC in order to get home.

As already mentioned, the only way to do this is to initially balance by paralleling all the cells for a few hours and then either charge them with low voltage power supply to 3.6V or connect in series and tinker with each cell until they match at 14.4V or 3.6V for each cell. I found a 100 foot piece of 16-14 gauge wire (poor mans resistor) worked well with an isolated 6V golf cart battery to top off an individual cell. The same wire can be used to short a cell and remove charge.

My personal opinion is you should limit the initial balance charge to a maximum of 3.6V per cell and to allow for some possible cell imbalance during operation, only charge to 14V or 3.5V per cell. I'd prefer even lower, 13.8V, but my charging systems are not adjustable enough. There is some evidence that suggests cycle life is extended by avoiding the extreme ends of the charging curve by keeping the cell voltage within the range of say 3.0-3.5V. It's possible that the Winston/Thundersky chemistry is more tolerant of higher voltages based on their specs, but I'm not convinced yet.

Even with the bank perfectly top balanced at 3.6V, the voltage of the cells do not track together above 3.35V even though they all reach 3.6V at the same time. For example, I've seen the cells range from 3.45 to 3.5V during charge, but lining up exactly at 3.6V at the end.

One question I have is if anyone using them has found a need to rebalance after some period of time? I don't have enough cycles on my bank since I replaced a bad cell monitoring board that was drawing down one cell more than the others.

Bank Disconnect/Separate Charge and Discharge Paths
-----------------------------------------------------------

I'm in the camp that believes you should have some sort of cell based monitoring system to disconnect the bank if any cell reaches too low or too high a voltage. I'm using >3.6V and <2.8V now as limits.

The problem for many is inverter/chargers which don't support different paths for charging and inverting. Also, if you want to use the Junsi Celllog 8 as a basic monitor, it only has one connection for a disconnect.

To solve this problem, I leave my starting batteries, a pair of AGM's connected in parallel to my Li house bank. It's not elegant, but it works. Should the Li bank disconnect, the AGM's are still connected. While the Li are discharging, it's basically a "float" voltage for the AGMs at around 13.2V, and during charge I normally only get to 13.6-13.8 before I turn off the genset and this does not seem to overcharge the AGM. The cost is the trickle charge to the AGM's at under 1 amp, about 10-15 Ah per day.

Eventually I plan to hook a solenoid up to the engine switch such that the parallel connection is only made underway, since at anchor, I'm not as concerned about a sudden disconnect. Not sure how to do that for a sailboat.

Safety Issues
--------------

I don't know the battery chemistry in the Boeing case, but I think Cessna also used lithium in a certified design in production. They also had a fire, on the ground in a customer aircraft and subsequently issued an AD directive to remove the Li from all their aircraft.

I doubt that either was lithium ferrous, LiFePO4. But I don't know that. Testing has shown that LiFePO4 is very unlikely to explode into a fire on their own, unlike other Li cells can. Under most any condition. They are undoubtably the safest Li chemistry available today. But they can create quite a bit of heat, especially if overcharged. There is also a tremendous amount of energy potential in a fully charged bank that deserves a lot of respect, just like any other battery. But even more so since it will deliver it almost all at once.

I believe that cell voltage monitoring/disconnect and appropriate bank fusing offers the needed protection to reduce the risk to acceptable levels. Just like we live with propane tanks, fuel tanks .... even fiberglass boats instead of steel, but take steps to mitigate those risks. But this is virgin territory and there is more to learn and probably even safer versions of the batteries themselves as the technology is adopted.

We know they will vent gas if severely overcharged or shorted internally. See the YouTube videos of the Sinopoly testing. This venting is not a likely, but is a possible event. How possible and under what "normal" condition is the first unanswered question since I don't plan on shooting one with a 45 caliber bullet. And second, nowhere can I find documentation of the volume or composition of the gas vented, specifically for a LiFePO4 cell. I'm pretty sure it will vary based on the electrolyte, which may not be the same for every manufacturer. It may turn out some sort of active/passive/contained ventilation to the outside is desirable? I don't know. If anyone has seen data on this vent gas, please post it. I think this area represents the most significant unanswered safety questions.

Bob
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Old 13-01-2013, 10:09   #1032

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

Dave-
"The fact is hello sailor once you seen these batteries in action , you realise that Lead Acid is like a steam engine."
Marvelous way of hitting the nail on the head. Of course you realize the most advanced "engines" on the market today are the military nukes, and what is a nuclear engine? Right, a steam engine! The technology steam engines) was abandoned somewhat prematurely, triple and quad-expansion steam turbines came about as "too little too late" but steam ain't dead yet.<G>

I do feel "there's gotta be a pony in that pile" (pun line of an old joke) and perhaps every mfr is right even though each one contradicts the others. I'd just have more confidence in lithium technologies if the choir wasn't making such a dissonant ruckus instead of singing one song.

The quote about lithium fires makes it sound a bit like Chernobyl: Best way to put it out is to bury it, and we don't keep big bins of sand on boat. Maybe the conventional battery box really should be a "containment vessel" if the consequences of a fire are that nasty.

Oddly enough I'm reading the memoirs of a B29 pilot. He mentions that in the rush to get them into action, the first engines had a number of problems, and one of them could lead to an engine fire in a magnesium engine block, which simply could not be extinguished. Leading to the wing coming off and the aircraft crashing in rapid order.

IIRC the makers of EVs are putting their batteries in "containment vessels" now too, aren't they?

I'm not afraid of the, but hacing blown up small NiCad packs and seeing what that can do, I give all kinds of batteries a bit more respect these days.
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Old 13-01-2013, 14:10   #1033
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Correct my thinking if i'm wrong please as i consider whether to incorporate a high and low voltage disconnect.

Our charge method will be 1) Solar 850watts. 2) Battery Charger powered by genset/shorepower. 3) Alternators on mains.

As far as the Lithiums going into an auto disconnect mode which of the above sources would suffer?

We are able to switch manually to the start batteries to power the house for nav lights etc in a situation like this.

Our start battery bank are lead acids at present.

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Old 13-01-2013, 14:17   #1034
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Correct my thinking if i'm wrong please as i consider whether to incorporate a high and low voltage disconnect.

Our charge method will be 1) Solar 850watts. 2) Battery Charger powered by genset/shorepower. 3) Alternators on mains.

As far as the Lithiums going into an auto disconnect mode which of the above sources would suffer?

We are able to switch manually to the start batteries to power the house for nav lights etc in a situation like this.

Our start battery bank are lead acids at present.
My biggest concern with the setup described would be the possibility of the alternator being directly connected to any electronics without the capacitance of the battery bank. If you have an MPPT for the solar, that should be safe. The battery charger might also fry electronics without a battery connected, but it depends on the charger (some are fine).
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Old 13-01-2013, 14:21   #1035

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

"As far as the Lithiums going into an auto disconnect mode which of the above sources would suffer?"

Is that a trick question? If you are using conventional 3-wire alternators, or a conventional regulator, and the alternator relies on a voltage sense lead which is connected to the batteries, what happens when the batteries disconnect? The sense lead also disconnects?

In which case, the alternator will self-destruct soon afterwards.

What your charger might do, I have no idea, Probably just pout, since they are designed to run disconnected. But alternators? Not unless you're running a "1 wire" configuration, which is common but inefficient.
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