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Old 16-01-2013, 21:48   #1126
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by ebaugh View Post
Everyone is making a case for a minimal BMS or cell voltage monitor I think? Even if cells are matched at installation, there is no reason to believe they will age exactly the same. And it doesn't matter...so long as none are driven to extremes?
The life of a battery is measured in its capacity, "dead" is when they have only 80% of original capacity available, since typically they have steep decline after they reach this point.
The best system is one which controls/monitors the CURRENT going into and outof a pack, and only uses the "middle" 80%. Thus voltage is useless as the cells should always stay at 3v when in the "middle".
So a 400ah pack will discharge max 320ah, and charge back in 320ah.
So a cell should never drop to 2.8v after only 320ah is discharged, otherwise the pack itself is probably dead. It should not hit 3.8v when putting back in 320ah. Thus there is no reason to monitor cell voltage in normal circumstances. The pack should live its life just fine until it dies, and for this you only need to measure the full pack voltage.

Now with a 12v pack, the cost to monitor each cell (4 of them) isn't a big deal, there are things that can happen, connections get loose, one cell might be next to a heat source (engine) and die much faster than the rest.
So if any cell hits 2.8v OR 3.8v, something went wrong.
But "balancing" them is not needed in normal circumstances.

JackB
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Old 16-01-2013, 23:48   #1127
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by ebaugh View Post
Everyone is making a case for a minimal BMS or cell voltage monitor I think? Even if cells are matched at installation, there is no reason to believe they will age exactly the same. And it doesn't matter...so long as none are driven to extremes?
It seems that no one really knows yet. Our guesses/intuition/theories cover a rather broad range.
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Old 17-01-2013, 00:25   #1128
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Ok, so today the latest's fire which resulted in the Grounding Of the Boeing Dream Liner.

The fire on-board is LI-technology.....BUT mind you it's not the same LI being discussed here.

BUT

ARGUABLY Boeing engineers are State of the ART...especially in their-own technology.

Not to mention the buyers for the same technology.

So how do we apply it across our current use of our technology???

Will your Yacht Policy stand behind a failure when you make a claim??

If Boeing can't get their system ready for an already launched READY FOR PRIME TIME....

How can we expect a Manufacture with no claims to responsibility to get us ready for prime time???


Early adopters need not worry as you are not covered by insurance, so self-insurance is the game...hope ya got deep pockets.

I stand by my post from over a year ago, as well as the post a few days ago.

Lloyd
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Old 17-01-2013, 02:29   #1129
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

EV-Power | Lithium Battery 12V/90Ah (WB-LP12V90AH)

Don't see the difference between buying 5 of these at 12 volt as against 20 at 3.6 volt and linking.

My policy doesn't blacklist any form of battery.

My installation will be very well engineered.
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Old 17-01-2013, 02:38   #1130
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by Lagoon4us View Post
EV-Power | Lithium Battery 12V/90Ah (WB-LP12V90AH)

Don't see the difference between buying 5 of these at 12 volt as against 20 at 3.6 volt and linking.

My policy doesn't blacklist any form of battery.

My installation will be very well engineered.
So to you I ask will it be insured???

HOW WILL YOU KNOW???

TODAY'S INSURANCE BUSINESS IS THE BUSINESS OF DENYING CLAIMS AFTER RECEIPT OF PREMIUM.

lloyd
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Old 17-01-2013, 02:56   #1131
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by FlyingCloud1937 View Post
Ok, so today the latest's fire which resulted in the Grounding Of the Boeing Dream Liner.

The fire on-board is LI-technology.....BUT mind you it's not the same LI being discussed here.

BUT

ARGUABLY Boeing engineers are State of the ART...especially in their-own technology.

Not to mention the buyers for the same technology.

So how do we apply it across our current use of our technology???

...

If Boeing can't get their system ready for an already launched READY FOR PRIME TIME....

How can we expect a Manufacture with no claims to responsibility to get us ready for prime time???
Boeing are required by a heavy regulatory burden to choose not only specific technologies but specific components years before first flight. Once certified, the cost of switching from LiCoO2 to LiFePO4 involves very high certification costs. Now, due to the fires, it looks like Boeing will have to bear the recertification costs and probably switch to LiFePO4.
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Old 17-01-2013, 02:58   #1132
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by FlyingCloud1937 View Post
So to you I ask will it be insured???

HOW WILL YOU KNOW???

TODAY'S INSURANCE BUSINESS IS THE BUSINESS OF DENYING CLAIMS AFTER RECEIPT OF PREMIUM.

lloyd
If i shared your attitude i would stay home in a bubble, our boat is insured we buy quality equipment, we maintain our boat impeccably.

We are not lessening our boats viability by purchasing a different type technology of battery.
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Old 17-01-2013, 03:11   #1133
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Insurance is a tax on people who cannot do math. The premiums paid have to cover the claims paid out + the operational overhead + taxes + profits. It should be obvious that insurance companies collect more than double (sometimes three or four times) in premiums than they pay out in claims.

There are exactly three circumstances it might make sense to buy insurance:
1. The magnitude of a potential loss (relative to net worth and income) is so large it would ruin one's life. For example, one who is retired with little or no income and owns only a boat would be ruined by loss of the boat.
2. Insurance is required by law and the penalties for non-compliance are more severe than the expected losses of paying for insurance.
3. One has private information not available to the insurance companies that shows the real risk is much higher than the insurance companies would think. Formally, this is called "moral hazard". Hypothetically, if an insurance company thinks a boat is safe but the owner knows that it's being eaten by an unknown-to-science species of marine termites then insurance would be a good deal for the owner and a bad deal for the insurance company.

Remember, insurance can never be a good deal for both the insurance company and for the owner, unless the owner is vastly more risk-averse than the insurance company (see exception #1 above).
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Old 17-01-2013, 03:14   #1134
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Think this is drifting from the theme, LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks
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Old 17-01-2013, 04:29   #1135
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Quote:
Originally Posted by Lagoon4us View Post
EV-Power | Lithium Battery 12V/90Ah (WB-LP12V90AH)

Don't see the difference between buying 5 of these at 12 volt as against 20 at 3.6 volt and linking.

My policy doesn't blacklist any form of battery.

My installation will be very well engineered.
If the 12V LiFePO4 batteries were "as good" as individual cells, we would probably see EV's being built with them, especially since they run much higher voltages. But Ive not seen anyone using them. Internally there still are 4 individual cells and a problem with one ruins the battery. I think the ability to work with cells is a strength of the whole Li concept.
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Old 17-01-2013, 04:45   #1136
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Bob the point i was trying to make was that here is a commercially available battery that is available on the world market.
If a consumer chooses one of these to fit to his boat his insurance company cannot reasonably deny a future claim if one was made (ie fire etc) if it wasn't common knowledge that the technology was doubtful or unless the insurance company had a proviso in the policy banning such batteries.

My point then was to separate into lower voltage cells makes no difference, it's the same technology in a different configuration.

Are vehicles catching on fire as a result of the technology? Probably pro-rata far less than gas producing LA's. A single spark around a gassed LA = disaster it's a no-brainer.
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Old 17-01-2013, 04:54   #1137
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Seems it is simply too new a concept for Lloyd at present. Thats OK.

The insurance issue he raises is a red herring though.
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Old 17-01-2013, 05:11   #1138
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Quote:
Originally Posted by nimblemotors View Post

The life of a battery is measured in its capacity, "dead" is when they have only 80% of original capacity available, since typically they have steep decline after they reach this point.
The best system is one which controls/monitors the CURRENT going into and outof a pack, and only uses the "middle" 80%. Thus voltage is useless as the cells should always stay at 3v when in the "middle".
So a 400ah pack will discharge max 320ah, and charge back in 320ah.
So a cell should never drop to 2.8v after only 320ah is discharged, otherwise the pack itself is probably dead. It should not hit 3.8v when putting back in 320ah. Thus there is no reason to monitor cell voltage in normal circumstances. The pack should live its life just fine until it dies, and for this you only need to measure the full pack voltage.

Now with a 12v pack, the cost to monitor each cell (4 of them) isn't a big deal, there are things that can happen, connections get loose, one cell might be next to a heat source (engine) and die much faster than the rest.
So if any cell hits 2.8v OR 3.8v, something went wrong.
But "balancing" them is not needed in normal circumstances.

JackB
The 80% original capacity does define cycle life, and life is good in the middle 3V range as you described. And I even agree balancing is not needed in normal operation. But I think it's very possible that eventually, before a pack reaches its cycle limit, there may be a need to rebalance. By monitoring only pack voltage, there is no way to know. The disconnect feature is only to prevent damage in an unusual circumstance, possibly saving the pack. Even a small imbalance can cause the high cell to go over voltage, once this happens, it happens every time the pack is charged. Only cell level monitoring will detect this.

But beyond balance, the disconnect feature is there to protect from an errant charge source of which cruising boats have many, 5 on my boat, and I don't have wind or solar yet. And to protect from accidental total discharge...anyone you know ever done that? I have, but not recently.

Monitoring current is imperative to know SOC since voltage won't work. But no system out there today manages a pack by monitoring current in and out. Im not sure one could even be designed that way. About the best you could get is one that monitors and reports cycle capacity, but it's still going to have to use voltage to define end points. In your example, 320 Ah usable becomes 256 Ah usable, but only voltage can define this, and only then if you routinely use the full capacity of the pack.
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Old 17-01-2013, 05:26   #1139
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Quote:
Originally Posted by Lagoon4us View Post
Bob the point i was trying to make was that here is a commercially available battery that is available on the world market.
If a consumer chooses one of these to fit to his boat his insurance company cannot reasonably deny a future claim if one was made (ie fire etc) if it wasn't common knowledge that the technology was doubtful or unless the insurance company had a proviso in the policy banning such batteries.

My point then was to separate into lower voltage cells makes no difference, it's the same technology in a different configuration.

Are vehicles catching on fire as a result of the technology? Probably pro-rata far less than gas producing LA's. A single spark around a gassed LA = disaster it's a no-brainer.
Whoops! I don't see any insurance issues unless you were grossly negligent, say you left out any kind of OCP for the bank AND that was proven to be the cause of the loss. But Im not a lawyer either.....

Eventually ABYC here and I guess "Lloyd's" for you will define some rules....

There have been a couple of EV's destroyed by fire, but Im not aware of one with LiFePO4 where the battery started the fire. Anyone know of one?
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Old 17-01-2013, 05:31   #1140
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by ebaugh View Post
Whoops! I don't see any insurance issues unless you were grossly negligent, say you left out any kind of OCP for the bank AND that was proven to be the cause of the loss. But Im not a lawyer either.....

Eventually ABYC here and I guess "Lloyd's" for you will define some rules....

There have been a couple of EV's destroyed by fire, but Im not aware of one with LiFePO4 where the battery started the fire. Anyone know of one?
Bob the following post from Flying Cloud aka Lloyd was the pre-cursor to my comment:-

Originally Posted by FlyingCloud1937
So to you I ask will it be insured???

HOW WILL YOU KNOW???

TODAY'S INSURANCE BUSINESS IS THE BUSINESS OF DENYING CLAIMS AFTER RECEIPT OF PREMIUM.

lloyd
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