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Billylll
USA
8035 Posts |
 Posted - Jul 29 2010 : 21:17:25
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To think we used to debate AGM vs. flooded battery systems and cost vs. reward!
Has anyone looked at the Lithium LFP Genasun systems? Extremely light weight, puts out constant current/voltage until it discharges to 10%, they can be cycled 3,000 times and they only need 14.2 volts no 3 stage chargers. The hook money and the LFP is more than just the battery bank you need a control and monitoring system.
Right now the big issue other than cost is the manufacture warranty only 2 years for the Genasun system.
Still I am fascinated with the safety over Litium I's and the specifications. Having large enough alternators to recharge them is another issue. Hypothetically if you have a 360AH system (actually 2 180AH systems they can be totally recharged in less than an hour from almost stone dead.
Bill |
WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
Edited by - Billylll on Jul 29 2010 22:39:43 |
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Capt. Bill1
USA
5602 Posts |
Posted - Jul 29 2010 : 22:38:01
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Yes they are very interesting. And the coming thing I would think. But as you noted, the cost is out of reach of the average user for now.
So it's back to AGMs vs. flooded. :-) |
The two most common elements on Earth are oxygen and stupidity.
Creationism is to science what storks are to obstetrics.
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stmbtwle
8740 Posts |
Posted - Jul 30 2010 : 06:53:06
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| Yes lithium batteries are very impressive. They seem to be the battery of choice for the new electric and hybrid vehicles, so I think when the production ramps up the prices will come down. No idea how long it'll take though. |
Willie... She's a tired old gal but she's paid for! (several times over) |
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Billylll
USA
8035 Posts |
Posted - Jul 30 2010 : 19:24:43
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quote:
Originally posted by stmbtwle
Yes lithium batteries are very impressive. They seem to be the battery of choice for the new electric and hybrid vehicles, so I think when the production ramps up the prices will come down. No idea how long it'll take though.
While Lithium "I" are great performers they can be very dangerous compared to the new P version.
LI's if overheated can cause firworks the LPF's are safe. There is also -0- gassing with the newer series. Because the recharge rate is so efficient you can use a smaller AH battery bank depending on the application. I think these battery systems are a real break through for many industries not just marine applications.
Bill |
WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
Edited by - Billylll on Jul 30 2010 19:25:36 |
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solar
Virgin Islands (United Kingdom)
655 Posts |
Posted - Jul 30 2010 : 20:20:53
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The perfect energy transfer of electric current happens with matched resistance or impedance of the load. Since the internal resistance of a Lithium battery has very low internal resistance a short circuit of the battery could produce a very high amperage into the load. In the case of an accidental short, like a tool across the terminals can cause an explosion of the battery.
As previously indicated these are expensive, For a group 24 they are about $800 or more.
This is why these batteries can only be shipped with a plastic caps on the terminals. They make perfect starter batteries if you need a high rpm to start a diesel engine. |
SOLAR |
Edited by - solar on Jul 30 2010 20:29:40 |
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stmbtwle
8740 Posts |
Posted - Jul 30 2010 : 21:24:29
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| ANY battery is stored energy, just like a cup of gasoline. Mishandled and it's going to be trouble. period. |
Willie... She's a tired old gal but she's paid for! (several times over) |
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Billylll
USA
8035 Posts |
Posted - Jul 31 2010 : 00:15:41
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Thats the beauty of these batteries the Lithium P's vs. I's they are extremely safe other than an unfused dead short. Also interesting is they do not drop voltage like a conventional battery as they discharge. They hold 14.2 volts until they reach 10% or their total discharge. There are negatives fairly complex charge monitoring and control for each cell of the battery and to make the most efficient use you need a charger that can output up to 500 amps at 14.2 volts into a 360AH battery bank. However you could recharge a fully discharged 360AH battery system in less than an hour if you have the charge capability. These systems with multiple Victron inverters are able to run marine AC units as an example. No voltage sag means the current draw does not increase as the battery system discharges. Conventional battieries when running high current loads drop voltage which in turn increases current, not the case with the Lithium LFP system.
The price has to come down but these really look like the future for diesel electric boats and electric autos.
Bill |
WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
Edited by - Billylll on Jul 31 2010 14:08:47 |
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stmbtwle
8740 Posts |
Posted - Jul 31 2010 : 10:54:10
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| BillyIII if they can make that work at an affordable price it'll be VERY interesting..... |
Willie... She's a tired old gal but she's paid for! (several times over) |
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Billylll
USA
8035 Posts |
Posted - Jul 31 2010 : 14:06:45
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The reason they can take a high charge is there is no accept and float charging curve needed. Just give it in the case of a 12VDC boat 14.2 volts at as much current as you can throw at it and your recharged in a very short period of time. The last 15% of any standard flooded or AGM battery's charge takes the longest. This is eliminated with LFP's. So in essence you really don't need as large a house bank with LPP systems as you do with a conventional house bank if you can recharge them with enough current. Peukerts exponent is set to "1" with LFP systems.
Bill |
WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
Edited by - Billylll on Jul 31 2010 14:08:04 |
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solar
Virgin Islands (United Kingdom)
655 Posts |
Posted - Jul 31 2010 : 14:28:11
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| Bill, maybe you should give us the formulas for Peukert's Law for those who are not familiar with his theory. |
SOLAR |
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Billylll
USA
8035 Posts |
Posted - Jul 31 2010 : 15:30:15
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The Peukert Effect
As you can see below, the Peukert equation in its simplest form consists of several factors.
Peukerts Equation: I n x T = Cmax
where
•I is the current (usually measured in amperes)
•T is time (usually measured in hours)
•n is the Peukert number / exponent
•Cmax is the storage capacity of the battery measured in amp-hours at 1 ampere draw. Usually, the C/100 capacity comes close to this. Adding 10% to the 20-hour rating (also known as C/20) usually comes close also.
For a more accurate calculation, you need to modify the equation to account for the fact that most battery capacities are measured using higher currents than the 1 ampere draw that Peukert used. The folk at Smartgauge.co.uk have a good and comprehensive explanation on their site, with lots of examples. Thus, the equation would have to be re-written as (I x Hact / Cact)n x T = Hact, where Hact is the actual hour rating (i.e. over how many hours the battery was drawn down) and Cact is the available battery capacity (in amp-hours) at that draw. Most batteries' storage capacity is published assuming a constant 20-hour draw, i.e. with Hact being 20. Assuming 20-hour ratings, the equation would thus simplify down to (I x 20 / C20)n x T = 20
Either way, the available current is dependent on the rate of discharge and the Peukert exponent for the battery. The closer the exponent is to 1 (one), the less the available capacity of a battery will be affected by fast discharges. Peukerts numbers are derived empirically and are usually available from manufacturers. They range from about 2 for some flooded batteries down to 1.05 for some AGM cells. The average peukerts exponent is 1.2 though the exact number depends on the battery construction and chemistry.
The following example shows the dramatic impact of the Peukerts exponent on the available capacity of a 120Ah battery, depending on the ampere draw. As you can see, the lower the Peukerts Exponent, the lesser the effect on available capacity. Note the dramatic difference in Available Capacity between the average flooded cell (n = 1.20) and a deep cycle AGM (n = 1.08) with high-current applications.
When the time comes to charge a battery, the Peukerts effect also comes into play. The capacity of a battery to absorb a charge during the bulk phase is also dependent on it's Peukerts number. This is one of the reasons why AGM cells can be bulk charged at much higher rates than either Gel or Flooded cells. |
WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
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Billylll
USA
8035 Posts |
Posted - Jul 31 2010 : 15:31:32
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Some more about (CEF)
Conversion Efficiency
The conversion efficiency denotes how well a battery converts an electrical charge into chemical energy and back again. The higher this factor, the less energy is converted into heat and the faster a battery can be charged without overheating (all other things being equal). The lower the internal resistance of a battery, the better its conversion efficiency.
One of the main reasons why lead-acid batteries dominate the energy storage markets is that the conversion efficiency of lead-acid cells at 85%-95% is much higher than Nickel-Cadmium (a.k.a. NiCad) at 65%, Alkaline (a.k.a. NiFe) at 60%, or other inexpensive battery technologies.
Battery Life
Battery manufacturers define the end-of-life of a battery when it can no longer hold a proper charge (for example, a cell has shorted) or when the available battery capacity is 80% or less than what the battery was rated for. The life of Lead Acid batteries is usually limited by several factors:
•Cycle Life is a measure of how many charge and discharge cycles a battery can take before its lead-plate grids/plates are expected to collapse and short out. The greater the average depth-of-discharge, the shorter the cycle life.
•Age also affects batteries as the chemistry inside them attacks the lead plates. The healthier the "living conditions" of the batteries, the longer they will serve you. Lead-Acid batteries like to be kept at a full charge in a cool place. Only buy recently manufactured batteries, so learn to decipher the date code stamped on every battery... (inquire w/manufacturer). The longer the battery has sat in a store, the less time it will serve you! Since lead-acid batteries will not freeze if fully charged, you can store them in the cold during winter to maximize their life.
•Construction has a big role in battery life too, some designs are better at preserving batteries than others and the suitability of a design for a given application plays a role also. For example, flooded lead-acid cells will typically fare worse than their VRLA cousins in operations that involve a lot of jerky motion - the immobilized plates in VRLA cells will be stressed less than suspended plates in cheap flooded cells.
•Plate Thickness helps - the thicker the plates, the more abuse, charge and discharge cycles they can take. Thicker plates will also survive any equalization treatments for sulphation better. The heavier the battery for a given group size, the thicker the plates are, so you can use weight as one guide to buying lead-acid batteries.
•Sulphation is a constant threat to batteries that are not fully re-charged. A layer of lead sulphate can form in these cells and inhibit the electro-chemical reaction that allows you to charge/discharge batteries. Many batteries can be saved from the recycling heap if they are Equalized
In closing, the design life of a battery depends in part on its construction, its type, the thickness of the plates, its charging profiles, etc. All these factors come together to determine just how long your battery may ultimately serve you |
WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
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solar
Virgin Islands (United Kingdom)
655 Posts |
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stmbtwle
8740 Posts |
Posted - Aug 02 2010 : 08:35:57
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| What will be interesting is how well one fares being crumpled up in a rear-end collision... I'm sure we'll find out before long. |
Willie... She's a tired old gal but she's paid for! (several times over) |
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Billylll
USA
8035 Posts |
Posted - Aug 03 2010 : 18:54:49
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LFP's are quite safe compared to standard Lithium batteries. They have a video showing a standard Lithium being shot it explodes as each battery cell heats up, then they shot an LFP nothing happens. The video is on the Genasun website.
Bill |
WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
Edited by - Billylll on Aug 03 2010 18:56:02 |
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V1rowT8
USA
169 Posts |
Posted - Aug 03 2010 : 20:31:03
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Here's a 10 minute video some might find boring, but it's good information regarding the extinguishing of lithium ion battery fires. Although the video is intended as information on fighting in flight fires attributed to lithium ion cells, this scenario could easily develop on our vessels as well.....from any number of L-I powered devices.
http://www.youtube.com/watch?v=vS6KA_Si-m8 |
Edited by - V1rowT8 on Aug 03 2010 20:31:53 |
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stmbtwle
8740 Posts |
Posted - Aug 03 2010 : 20:47:14
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quote:
Originally posted by Billylll
LFP's are quite safe compared to standard Lithium batteries. They have a video showing a standard Lithium being shot it explodes as each battery cell heats up, then they shot an LFP nothing happens. The video is on the Genasun website.
Bill
That might be true simply putting a hole in it; but a collision could very easily create that dead short you mentioned earlier, and all that stored energy is gonna go SOMEWHERE. 100kwh running rampant around the chassis of a wrecked car at 500 volts or so is not gonna be nice. I'm sure there are fuses, but if the battery itself is damaged the fuses may be bypassed. |
Willie... She's a tired old gal but she's paid for! (several times over) |
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Billylll
USA
8035 Posts |
Posted - Aug 04 2010 : 14:49:22
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quote:
Originally posted by V1rowT8
Here's a 10 minute video some might find boring, but it's good information regarding the extinguishing of lithium ion battery fires. Although the video is intended as information on fighting in flight fires attributed to lithium ion cells, this scenario could easily develop on our vessels as well.....from any number of L-I powered devices.
http://www.youtube.com/watch?v=vS6KA_Si-m8
I am not talking about Lithium Ion but Lithium P. totally different animals. |
WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
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stmbtwle
8740 Posts |
Posted - Aug 04 2010 : 16:41:07
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| A dead short is a dead short... even if the battery doesn't explode the potential for fire is still there. As most of us know an ordinary 12v auto battery can create some interesting fireworks when shorted. |
Willie... She's a tired old gal but she's paid for! (several times over) |
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Billylll
USA
8035 Posts |
Posted - Aug 04 2010 : 16:46:01
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| Ever hear of High amperage fuses especially in battery house banks? |
WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
Edited by - Billylll on Aug 04 2010 16:46:33 |
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stmbtwle
8740 Posts |
Posted - Aug 04 2010 : 18:02:48
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Yeah I have. My house fuse is "only" 200 amps. at 12 volts that's 2400 watts, still enough to start a really "nice" fire. I hate to think what my car battery at 300+ volts could do!!!
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Willie... She's a tired old gal but she's paid for! (several times over) |
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Billylll
USA
8035 Posts |
Posted - Aug 04 2010 : 18:07:39
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Willie that is true for any battery system. I'm really talking about this type of battery system in a marine application. Thats why the proper installation which includes wire size, fuses, cable protection, caps on terminals and battery mounting needs to be followed.
Bill |
WirelessOne,
40 Mainship
Sedan Bridge
Little Egg, N.J. |
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stmbtwle
8740 Posts |
Posted - Aug 04 2010 : 18:29:04
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| No arguments there, but a collision tends to violate all the "rules". Suppose you get "torpedoed" in the engine room by some maroon with a jet-ski?? That can defeat all your precautions. |
Willie... She's a tired old gal but she's paid for! (several times over) |
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V1rowT8
USA
169 Posts |
Posted - Aug 04 2010 : 20:36:05
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BillyIII,
Understood. I thought it was good info to share though.
As for the dead shorts eluded to in this thread, the problem with the LI cells is that they keep catching on fire after being extinguished. Good to know from the u-tube link that if a laptop, ect... catches on fire while out on the boat, it's work to completely put out the fire. |
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Lithium LFP battery systems