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Old 08-02-2013, 12:42   #2011
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by hellosailor View Post
Durundal, I'm not confusing vibration types. I'm suggesting that the only unusual movement on a boat is not vibration of either kind, but is shock. And that both share the common attribute of being motions, as opposed to fixed-installations. The speed (rate) and range of the motions in the environment may vary, but it still comes down to whether the batteries have been installed on inertial dampers or acceleration couches. Oh, wait, you don't have those on this planet yet, do you? <G>
True, it is all a bit of semantics, with the definitions I'm familiar with if you were experiencing true "shock" events as we worry about them in aerospace (moving platforms, not fixed installations) you would be hurting a lot more than just your knees... man rated rockets do have significant shock isolation mounts to protect the astronauts from the various shock events that are encountered during launch (imagine sitting in a chair that is hitting your entire back like what happens with that splitting maul example, that would sure sting!). Random vibe still is shaking them up plenty but it is for relatively long durations (not microseconds) and can be handled by harnesses and muscles keeping you steady. I believe that for the timescales of a RIB slamming into a wave you would be better covered by a random vibration qualification test rather than a number of shock tests, particularly as the waves will be impacted from any number of directions over a period of seconds for each hit.
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Old 08-02-2013, 15:38   #2012
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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There is supposed to be a reply to Terry's question about the vibration datasheet but it needed moderator approval somehow? It had a reference link to a nasa page, does any link require a mod approval?
No, only links affecting National Security.

Joke.

That was just cos you were a newb at the time, and caught in our spam trap. You should be OK now
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Old 08-02-2013, 16:50   #2013
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Thanks for the info on vibration v shock effects, this is something way outside my zone of knowledge, thats why I put up the info supplied and didn't attempt to put any value to it.

With the bulging cell, the bulge does sound very small, but this is the reason for recommending the cell packs are strapped with rigid end plate. the effect of cell bulging is it allows the anode and cathode to move away from each other, there is only a tiny amount of electrolyte in each cell pack, if you add volume to the inside area of the pouch there is not enough electrolyte to fill the space, it stops conducting and capacity is lost. Press them back together and most of the capacity returns. you need to get the rigid plastic case warm enough to reform it's shape, sitting in the direct sun will usually achieve this.
A couple of aluminium plates and a couple of G clamps will do the trick.

T1 Terry
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Old 08-02-2013, 17:12   #2014
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

I don't plan on bulging my cells, but rather safe than sorry.

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Old 08-02-2013, 17:13   #2015
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Aha! Youtube has found me (admittedly in German) a video of someone opening up one of the Thundersky/Winston 12V packs, it looks to just be 4 of the cells in a plastic case, with the end straps and copper links pre-installed. It looks like the outer case can also be opened up pretty easily to get at them if you ever needed/wanted to.



<iframe width="560" height="315" src="http://www.youtube.com/embed/pV9g8lf0lf4?rel=0" frameborder="0" allowfullscreen></iframe>

Any chance someone on here can translate what he's saying?
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Old 08-02-2013, 19:33   #2016
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

A member on our Austraila RV lithium forum has done the same. If you wanted a basic looking battery you could buy 4 of these, empty the cells out and connect them in parallel to make a 3 v cell with 4 times the capacity, then link the 4 cell boxes together to create a 12v battery. They come in 40Ah, 60Ah and 90Ah. Not sure what the gain would be besides looks. You could also just use a 4 cell 12v battery, pop the top off and wire a cell logger to the 4 cells, that is what the member on our Aussie forum has done. I'm guessing it might be a good thing for an electric outboard battery.

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Old 08-02-2013, 22:21   #2017
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Have results for cell and pack voltage at different DOD.

Started with a charged 100 a-hr 12 volt pack that was off the charger for 36 hours.

Starting voltage 14.38 volts, 3.59 volts all cells

As much as I would have liked to give voltages in nice increments of 10%, I missed the capacity at the amp draw I was using.

Big charge knee

0% DOD 14.4 volts, all cells 3.59

8% DOD 13.3 volts, all cells 3.32

17% DOD 13.26 volts, 3.32, 3.31, 3.32, 3.31

34% DOD 13.15 volts, 3.28, 3.29, 3.28, 3.29

51% DOD 13.1 volts, 3.27, 3.28, 3.27, 3.28

68% DOD 12.9 volts, 3.21, 3.23, 3.21, 3.23

85% DOD 12.7 volts, 3.17, 3.16, 3.15, 3.17

100% DOD 11.13 volts, 2.97, 2.66, 2.66, 2.83

Sharp fully discharged knee
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Old 09-02-2013, 03:36   #2018
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Battery Date February 13,2013


not your fathers Oldsmobile, I mean battery



Abstract

In the development of energy storage devices, simultaneously achieving high power and large energy capacity at fast rate is still a great challenge. In this paper, the synergistic effect of structure and doping in the graphene is demonstrated for high-performance lithium storage with ulftra-fast and long-cycling capabilities. By an in situ constructing strategy, hierarchically porous structure, highly conductive network, and heteroatoms doping are ideally combined in one graphene electrode. Compared to pristine graphene, it is found that the degree of improvement with both structure and doping effects is much larger than the sum of that with only structure effect or doping effect. Benefitting from the synergistic effect of structure and doping, the novel electrodes can deliver a high power density of 116 kW kg-1 while the energy density remains as high as 322 Wh kg-1 at 80 A g-1 (only 10 s to full charge), which provides an electrochemical storage level with the power density of a supercapacitor and the energy density of a battery, bridging the gap between them. Furthermore, the optimized electrodes exhibit long-cycling capability with nearly no capacity loss for 3000 cycles and wide-temperature features with high capacities ranging from -20 oC to 55 oC.
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Old 09-02-2013, 03:51   #2019
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

With over 2000 posts, trying to sift through it all this seems imposable-can anyone tell me is it time for the average Sailor with only Basic knowledge to go with these new Batteries? My bank is in need of replacement now, and wonder if this makes since, I need about 800am/hrs and will have solar to charge along with a high amp alternator- And if so what to buy and where ~
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Old 09-02-2013, 03:58   #2020
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by Ram View Post
With over 2000 posts, trying to sift through it all this seems imposable-can anyone tell me is it time for the average Sailor with only Basic knowledge to go with these new Batteries? My bank is in need of replacement now, and wonder if this makes since, I need about 800am/hrs and will have solar to charge along with a high amp alternator- And if so what to buy and where ~
Ram mine are ordered along with Junsie's, a basic BMS, cutouts for supply and charge, i'm only starting off with charging from a dedicated 240volt Lithium charger and the Solar with a MPPT controller built for Lithium, i'm keeping the start system seperate enabling a back up either way.

Coming from Czechkslovakia tax free as boat is classed 'in transit'.

I think to have multiple charging sources initially confuses, i want to learn as i go.
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Old 09-02-2013, 04:10   #2021
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by Ram View Post
With over 2000 posts, trying to sift through it all this seems imposable-can anyone tell me is it time for the average Sailor with only Basic knowledge to go with these new Batteries? My bank is in need of replacement now, and wonder if this makes since, I need about 800am/hrs and will have solar to charge along with a high amp alternator- And if so what to buy and where ~
Yes you can do it today, if you don't mind doing manual BMS.

I know, I'm, going to get clobbered by the fanboys.

But that doesn't mean that I don't think that the technology can be had, by those willing to manage.

If there is a reason, then it is self-fulfilling.

Waiting can also be very productive, Lithium-Ion Batteries Were A Bust, But Advanced Lead-Acid Batteries Are Booming - Seeking Alpha

No, I won't sell anyone her a FLAB, AGM, Gell, or Lith...what-ever.

I'm just pointing, you go ahead and make the call.

Lloyd
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Old 09-02-2013, 04:41   #2022
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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... can anyone tell me is it time for the average Sailor with only Basic knowledge to go with these new Batteries?
'Basic knowledge' is such a broad possibility, that it is really difficult to answer your question. However, since:

Quote:
My bank is in need of replacement now, and wonder if this makes since, I need about 800am/hrs and will have solar to charge along with a high amp alternator- And if so what to buy and where ~
I propose, that you make a preliminary design for your system and post it here for discussion. This will serve two purposes, first it will tell us what your 'basic' knowledge/understanding really is, and second it will give a starting point for comments and refinement (if necessary).

Since this thread is quite long already, maybe starting a new specific one, like 'LiFePO4 bank design for Ram' is an option?

Before you start designing, write down your functional and safety requirements list, as a starting point.

Think of two main use cases:

- what is required when I am on board? (minimalist system? is just a loud alarm sufficient? (i.e. brain does the rest))

- what protection/automation features are required when there is nobody on board?
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Old 09-02-2013, 06:07   #2023
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Think of two main use cases:

- what is required when I am on board? (minimalist system? is just a loud alarm sufficient? (i.e. brain does the rest))

- what protection/automation features are required when there is nobody on board?
a very sensible approach mrm, it's the whole thing in a nutshell really. About the only things I'd add are:
If you have the $$ Gensun I think have a ready to go system
If you want to do it at a better price, you need to do a lot of the hands on stuff, that includes reading and learning.

T1 Terry
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Old 09-02-2013, 06:56   #2024
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Flying Cloud-In the give and take of over 2,000 posts and >95k views, there has been an incredible amount of information, education and support provided on LFP technology as it is deployed as house banks on vessels. You have some differing opinions from those who are the early adapters. Fair enough. However, your continuing use of "fan boy" to describe the early adapters and those who are actually advancing the state of the art is disturbing and offensive in a forum of this stature. Make your technical, rational, gut feel points and let the forum members weigh in. Please leave the name calling outside.

Quoting Theodore Roosevelt: "It is not the critic who counts: not the man who points out how the strong man stumbles or where the doer of deeds could have done better."


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Old 09-02-2013, 09:51   #2025
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Ram,

If 800 a-hr of lead is doing the job for you, then 700 a-hr of LiFePO4 would be over kill, but Balqon still as the 700 a-hr cells on sale. Balqon - Advanced Transportation Solution

If LiFePO4 cells were rated as a LA by the 20 hour rate, then the 700 a-hr would be around 1000 a-hr. My small 100 a-hr cells when discharged at a 20 hour rate give about 150 a-hr. Since recommended DOD is 50% for lead and 80% for LiFePO4, below is usable a-hrs.

800 a-hr lead, 400 usable a-hr at low discharge rate

700 a-hr LiFePO4, 800 usable a-hr at low discharge rate.

Unlike LA, these cell's rating are very conservative. At 40 hour discharge rate, my little 100 a-hr cells dole out 165 a-hr.
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