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Old 04-05-2010, 08:12   #316
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Originally Posted by LiFeTech Energy View Post
Perhaps we should separate boats into two categories-
1) those boats using LiFePO4 batteries for house power (since this will be of interest to most boat owners) and
2) boats which use LiFePO4 batteries for electric propulsion (either pure electric or hybrid).
Agreed, good idea. Of the boats I listed, only the Zogo is electric (sometimes) propulsion. It has the new Steyr motors parallel hybrid drive, where the electric motor/generator is for slow speeds (7kts top, 5kts cruising) and the diesel engages directly through the motor to the shaft for higher speeds.

I think Steyr may have missed the (sail)boat marketing-wise by not making the generator/motor capable of charging under sail. That would be a nice option for cruisers.
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Old 15-05-2010, 04:07   #317
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Originally Posted by hellosailor View Post
"12V cranking batteries are simply made up of 4 LiFePO4 cells in series to provide the nominal 12V."
Just what voltages are you working with? I'm seeing nominal voltages reported as a maximum 3.8V charging voltage, 2v maximum discharge state, and 3.2V as a normal "fully charged and rested" voltage, comparable to the 2.2V for a wet lead cell.
So, a 4-lifepo4-cell "12v" battery would actually be...a native (3.2x4=) 12.8 volts if a matched charging source was being used? As opposed to 12.6-12.7 for typical lead acid batteries?
Happily charging to a full charge state on the usual 13.8-14.4V auto/marine alternator then, without any extra consideration for the slight voltage difference, and the LiFePo4 cells are quite happy to function in that range?

By the way, how do they take to prolonged non-use, i.e. storage discharge damage? Can they be left on a shelf for six months (unlike wet like) without capacity loss?

And, if one cell DOES develop a defect...without a BMS to prevent that one cell from overcharging and overheating, just how is (pardon the phrase) fire control accomplished in this situation?
The nominal voltage of a LiFePO4 cell is accepted as being 3.2 - 3.3V. Four cells in series are used to make a 12V battery (actually 12.8-13.2V).

Most alternators designed to charge lead acid batteries have an end of charge voltage (as determined by the regulator) of 14.4V. LiFePO4 requires 14.4V since 3.65 is the end of charge/fully charged voltage per cell. There may be slight variation to this with different manufacturers. By charging via a regular alternator designed for lead acid batteries means you will never over charge a LiFePO4 battery. It will never actually reach full capacity unless the alternator regulator can be adjusted to 14.6V.
This is why when using a solar regulator designed for lead acid batteries, if charging parameters can be altered it is best to change the regulator end of charge voltage from 14.4V to 14.6V so as to fully charge the battery.

Most lead acid battery manufacturers will void warranty if their battery has been left sitting on the shelf without a charge for 6 months or more. LiFePO4 batteries have far superior self discharge characteristics and is yet another area where they far outperform their lead acid battery counterparts.
A typical LiFePO4 cells if fully charged and then left resting for a long period of time will still retain more than 80% capacity after 2 years.
Below you can see the self discharge curve of a BMI/LiFeTech LiFePO4 cell.

If overcharged a LiFePO4 cell or battery will fail without catching on fire as will most likely happen with the more hazardous lithium chemistries.
There are many design features built into the higher quality LiFePO4 batteries which the average battery user would not even realize. For example in the photo of the BMI LiFePO4 battery shown earlier in this thread, the battery case is not made from your regular ABS plastic as are lead acid/AGM batteries. The plastic used in the manufacture of BMI batteries is made from a special plastic which is manufactured by DuPont and is called Xytel. This plastic is chosen for its flame retardant properties. Since these batteries are designed for the electric vehicle market if an electric car powered by these batteries was to be involved in a crash resulting in fire, the battery casing actually will help to retard and extinguish any flames rather than promote further fire.
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File Type: xls self discharge (1).xls (16.5 KB, 68 views)
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Old 16-05-2010, 18:03   #318
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A flame retardant case, nice bonus.

"change the regulator end of charge voltage from 14.4V to 14.6V so as to fully charge the battery." So that means in typical operation (off a simple regulator) the batteries are really being used at only some 80% of their potential capacity, and users would effectively gain 25% more capacity by using a 14.6V regulator setting? (Kludging in a diode with a 0.2V drop in the voltage sense lead would do that trick for a simple 3-wire integral alternator, assuming you could source a 0.2v drop diode. IIRC 0.3V is the lowest standard drop? which might push the batteries too far?)
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Old 18-05-2010, 06:40   #319
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Originally Posted by hellosailor View Post
A flame retardant case, nice bonus.

"change the regulator end of charge voltage from 14.4V to 14.6V so as to fully charge the battery." So that means in typical operation (off a simple regulator) the batteries are really being used at only some 80% of their potential capacity, and users would effectively gain 25% more capacity by using a 14.6V regulator setting? (Kludging in a diode with a 0.2V drop in the voltage sense lead would do that trick for a simple 3-wire integral alternator, assuming you could source a 0.2v drop diode. IIRC 0.3V is the lowest standard drop? which might push the batteries too far?)
Yes, that is correct hellosailer. If you only charge to 14.4 volts you are charging to somewhat less than 100% capacity. There is certainly no risk of over charging the battery at that level.
It is best to check the maximum permitted voltage permitted since it will vary slightly between manufacturers.

Yes the old BMI HPS series batteries came in the plastic DuPont flame retardant battery case. The case of the new LiFeTech factory packs is all aluminium.
However both series share in common gold plated battery terminals for complete corrosion resistance in a salt/sea water environment.
The batteries have been tested as part of QC in a salt spray chamber.
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Old 18-05-2010, 08:52   #320
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A conductive aluminum case, in a salt water atmosphere which is kinda infamous for corroding aluminum?
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Old 18-05-2010, 17:15   #321
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The aluminium case is completely electrically isolated from all live electrical components within the battery. It is only used as a high strength battery container.
The reason these batteries use the aluminium case is purely from a strength point of view since these batteries are designed for application in electric vehicles and are made strong enough so that several batteries can be stacked directly on top of each other and secured in place so as to make the total battery bank as compact as possible.
Of course the plastic case version is also available if preferred.
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Old 28-05-2010, 04:36   #322
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Great info Lifetech!!

Do you happen to have a list of the cell manufacturers that you know are using Phostech powder? Thundersky, Sky Energy,...others? I hear that Valence is doing something a bit different (Li-Mn?) as is Corvus (Lithium NMC?), what are their respective advantages/disadvantages vs. LiFePO4?

From the marine safety perspective, I never considered the early Li-Co systems a good idea when they showed up on boats. Now I've been convinced that LiFePO4 is good and am recommending it, but would like to know more about the alternatives touted by Valence/Corvus/others.

Info greatly appreciated!
None of the Chinese LiFePO4 battery manufacturers use Phostech powder. The Chinese manufacturers such as Sky Energy and Thundersky use a low grade LiFePO4 powder in their batteries which has been copied (to varying degrees of success) from the original LiFePO4 battery as invented by the University of Texas / Phostech Hydro - Quebec.
It is no different to any other product which was invented in the USA or Europe or some other western country then simply copied in China cheaply with no respect or recognition for the actual inventor / patent holder.
A bit like the choice in buying a genuine pair of Nike running shoes compared with a cheap copy from a factory in China which were pirated with a Nike label or a Rolex watch compared with a copy made to look like the original in China.
People can form their own views about originals and copies and their quality of manufacture and how they perform.

The handful of companies which use genuine Phostech product in some or all of their LiFePO4 batteries include LiFeTech Energy, PHET and SAFT amongst a few others.
These companies generally make specialised batteries which serve a particular market segment. For example PHET has the market in LiFePO4 batteries used for electric wheel chairs and mobility scooters while SAFT is the major battery manufacturer of lithium batteries to the military.

Valence is "doing something different" as a way to try to get around the patent issues since they are being sued by Phostech.
A123 Systems is also in the next round of law suits brought about by Phostech for patent infringement.
Phostech is taking legal action against the US companies who manufacture good quality batteries who are major competetors with Phostech.
It is virtually impossible to sue a Chinese company. They don't recognise patents and simply do as they like. In any case the Chinese companies don't have the technology as yet to make a good quality, high power LiFePO4 battery which is why Phostech is not so concerned about them and is focussed on the US manufacturers.

I have not heard of Corvus. I will check out their website and let you know what I think of their product.

You can read about the latest in the battle between Phostech and A123 Systems here- Second Amended Complaint Filed in UT v. A123 Lithium Battery Case - Philip Brooks' Patent Infringement Updates
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Old 28-05-2010, 05:03   #323
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I have not heard of Corvus. I will check out their website and let you know what I think of their product.
Corvus batteries are not LiFePO4. They use lithium NMC (nickel manganese cobalt).
These cells are a low discharge rate cell. From the manufacturer's data sheet they can provide 7C discharge but only for 10 seconds. They don't say what the continuous rating is. Perhaps I just can't see it? From the data sheet I am quite surprised at how poor the discharge curve is even at very low C rates as low as 0.3C. The cell voltage drop considerably as the cell discharges and in fact the discharge curve characteristic for lead acid batteries looks to be better than that of the Corvus battery. The curves are here-
http://corvus-energy.com/pdf/corvus_energy_at6200x.pdf
Also the maximum charge rate is only 2C while for LiFePO4 is can be as high as 5C.
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Old 05-06-2010, 04:57   #324
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Oops...I think I was supposed to put this reply in this thread instead of the other one. So here it is again:

Sorry to say that I'm not yet allowed to discuss very much with this particular project, or even the name of the boat. Hopefully they will let me soon. They don't want the competition to know their exact set-up. DEFINITELY no photos allowed.

However, I can say the main house bank is a standard Genasun 200Ah x 24V system. The alt. reg. is also Genasun, as is the starting battery charger. While I can't give the whole configuration on this boat, of course I can design/suggest systems for particular applications.

It won't be long before systems like these are well-known, but in order to get these jobs one has to make agreements...;-)

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Old 22-07-2010, 18:20   #325
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Elithion Lithiumate BMS max cell capacity

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I wan't convinced that Elithion's circuitry would hold up on a 700Ah cell.
No. Actually, the Elithion Lithiumate BMS can handle up to 32000 Ah batteries.
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Old 22-07-2010, 18:44   #326
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(Kludging in a diode with a 0.2V drop in the voltage sense lead would do that trick for a simple 3-wire integral alternator
Or a simple potentiometer. Then you can adjust for actual battery terminal voltage and temperture effects which are usually significant. Or an op-amp diode.
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Old 22-07-2010, 18:45   #327
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Lifetech, do you have a direct email?
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Old 31-07-2010, 18:11   #328
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I agree with several others in this thread - Li batteries are great but does one want to be on the bleeding edge? Remember the very high power density and the ability to deliver LOTS of current is hazardous and the auto manufacturers have been working very hard on ensuring safety from this power source.

BTW, I don't have a boat - my recreational vehicle has wheels - but it still needs portable power. Very interesting thread!
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Old 07-08-2010, 02:16   #329
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I agree with several others in this thread - Li batteries are great but does one want to be on the bleeding edge? Remember the very high power density and the ability to deliver LOTS of current is hazardous and the auto manufacturers have been working very hard on ensuring safety from this power source.

BTW, I don't have a boat - my recreational vehicle has wheels - but it still needs portable power. Very interesting thread!
You certainly are right about the ability of some LiFePO4 batteries to supply extremely high discharge currents!

LiFeTech Energy are about to release the world's most powerful dedicated diesel engine starting battery.
We have been testing this battery with some large diesel engines at our head office in Taiwan and I have attached a few photos showing a comparison between the old lead acid batteries and the new lithium battery. In one installation four 12V 100Ah engine cranking batteries were used connected as two in series and two in parallel so as to have a 24V 200Ah cranking battery. These four batteries weigh in total approx. 137kg.
We replace these four heavy batteries with a single 24V 48Ah LiFePO4 battery weighing in at 28kg which does an equal (or better job) and includes an inbuilt battery charger.

This single battery will crank over a 2000kVA (2,680 horsepower) diesel engine up to 30 times per charge.

You can see the size difference in the photos between the new lithium battery and the lead acid batteries we replace.

This battery is aimed primarily for use with the huge backup diesel generators as used in hospitals, data centres, telecommunications providers, etc. and is a good initiative in helping the environment since a relatively small eco-friendly lithium battery replaces four large lead acid batteries and so eliminates the need for a reasonable quantity of corrosive sulphuric acid and toxic heavy metals like lead, cadmium etc. from otherwise being used to manufacture these four batteries. Many of the large corporations and government departments who will be using this battery are environmentally conscious and an eco-friendly battery is an important consideration these days (as far as their policy is concerned) when they choose a battery supplier.

Although this battery is aimed mainly at the stationary diesel engine market the same battery would make an awesome bow thruster motor battery and will provide far greater and more consistent current output during discharge compared to any lead acid battery of similar size.

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Old 29-12-2010, 22:35   #330
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Cycle Performance

If your are still there Lifetech.......... As I belong to many forums, I ran across some disheartening Cycle Life in the "electric boats" group for these technology Lithiums. Some reports of THundersky and others that 3C discharge rates to typical 50-80% DOD reduced the cycle life from expected 2000 - 3000 charge cycles to replacement required around 500 cycles. What level of abuse can LiFePo4 take on charge/discharge rates ? I would expect BME control would protect the batts from serious performance degradation. Any comment would be appreciated or others who have some extended experience over the last few years.

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