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-   -   LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks (https://www.cruisersforum.com/forums/f166/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069.html)

hellosailor 08-02-2013 08:44

Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks
 
Just as a reference point, how far do the cells in a typical 12v wet acid battery vary as they go out of balance?

On vibration specs, I don't think "vibration" really applies to the pounding that a battery would see on a boat slamming around at sea. The repeated impacts would be more like hitting potholes in a truck, fairly large sudden high-g events, occurring way less frequently than something like the vibration from engines or other sources. Given all the talk about how the mebranes in Li-Anything cells can be punctured by crystal growth, I would think "high g" impact events might be a different area of concern.
I'm thinking of a short trip on a highly overpowered RIB slamming across chop, where my kidneys definitely weren't calling it "vibration". And my knees agreed.

witzgall 08-02-2013 09:10

Bulging cells
 
Hi all,

I have a situation I would like to discuss.

We have a 400ah "Hipower" bank on Alchemy. It is comprised of eight, 200ah cells in a 2p4s configuration. Physically, they are grouped into two banks, 4 cells each connected with metal interconnects (6v), with a heavy cable in-between each to form 12v. The cable is only about 18 inches, it is done this way to fit into our existing battery boxes, which previously held 4 t-105 wet cells (two in each box).

Alchemy was on the hard for about 8 months, after some summer storm damaged forced us to pause cruising. We had spent the previous 6 months cruising down to the Bahamas and back, and they performed very well.

I kept them at about 50% for much of the refit period, and only started to charge them with a 120w solar once we were getting ready to go back into the water. By the time we splashed her, the bank was about fully charged, and it was cold.

I ran the engine for about an hour, and towards the end, I noticed that the Link10 voltage, which is usually a bit higher reading then actual battery voltage owning to where it reads in our wiring, was at 14.7 with the engine running. It did not click that this was something really bad right away, so the engine ran for about an hour, and then again for 1/2 a hour moving the boat from the yard to a nearby slip.

At this point, I inspected the batteries. They lie on their sides, so I could only see the top cells in each box. The aft cells, third in series, were at 3.9 volts! Worse, there was bulging in those two cells.

Furthermore, when I pulled the cells out, one of the lugs of the heavy cable came off. This cable was re-used from the original LA install, and it looked like the end, with very nice heat shrink, was never crimped properly!

I figured out where the high voltage came from. We have a Balmar 612 regulator. I had set the bulk to 14.1, float to 13.4, but I failed to change the compensation limit, and yes, I had a temp sensor installed. IT was set to 14.8! So it was cold, and volted compensated the charge up to 14.6-7 ish. It was left-over from the LA install, and I figured it could not hurt. Woa, I was wrong!

I have pulled all the cells out, removed the temp sensor for the batteries (and kept the one on the alternator). I am now charging each cell-pair with a 6a 3.6v charger to top balance. I had drained to top cell with a long 16ga wire.

The bulging seems to be about 2mm on either side on the two parallel cells.

I have an uninstalled mini-bms house bank system, that I may install, but only to balance and buzz, not to disconnect or do anything active (yet). Once the cells are all top balanced, I will put them in, draw them down, and then charge back up.

So, what do I have, are they damaged too far? I will install the bms, but can turn it on or off with a switch. Should I re-order the parallel groups?

Looking for comments.

Chris

electric1 08-02-2013 09:29

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

Originally Posted by goboatingnow (Post 1151255)

SO if the BMS shunts the charge current, how do you protect the BMS from excessive shunt current, It has no control over the charger, nor has it any idea of the potentially greatest charge current that could be applied. Surely you could just fry the bypass device

ie I set my set point on my charger a little to high, so there is stiull serious current flowing at the BMS setpoint, it detects imbalance, and "lots of magic smoke escapes", or a fuse goes, but the balancing has failed. It all seems a little haphazard
Dave

This is precisely why there is no good BMS which does just balancing. There were some early on, all of them failed, went up in smoke. No one does it anymore.
Proper BMS must have HVC/LVC functions first and foremost. It must be able to shut off charging when any cell reports HVC and must be able to shut off load when first cell reports LVC. If you don't have these 2 functions, then you don't have a BMS.

Balancing is a 3rd function, and its optional in some systems, or very weak in other systems. In our HousePower BMS system balancing is limited to only 0.6A on average ( peak at 0.75A ) after which it will shut itself off via PTC fuse, preventing overload and overheating.

This is why BMS cannot do initial balance in reasonable time, it does not have enough shunting capacity. Since initial balance is only needed one time when bank is constructed, it does not make sense to build a BMS with huge shunting capacity. So, BMS has a small shunting capacity, designed to keep the pack balanced over years of daily use. But initial balancing still needs to be done with other tools, such as single cell charger. Initial balance depends on quality controls at the cell maker/vendor. Some make sure they ship cells at well matched SOC, in which case initial balance is not required, or very little is needed. Some vendors ship cells from different batches, different manufacturing dates, different SOC, etc. These require a lot of initial balance. Its like a box of chocolates, you never know what you going to get.

ebaugh 08-02-2013 09:44

Quote:

Originally Posted by witzgall (Post 1151432)
Hi all,
So, what do I have, are they damaged too far? I will install the bms, but can turn it on or off with a switch. Should I re-order the parallel groups?

Looking for comments.

Chris

I don't have any experience with overcharged cells, but there is a picture in a Thundersky manual of a device that compresses bulging cells flat again. If you used a couple of pieces of plywood at each end of the bulged cells and tightened them in a vice for a few hours it would perform the same function.

Hopefully you will find the cells recover. If not, and the others test OK, I'd be inclined to replace only the bad cells. You could pretty much use anyone's cell at the same capacity rating.

I would hook up the House BMS to a disconnect solenoid to prevent future occurrences. The alarm won't save you if the next failure is your solar controller and you are away.

electric1 08-02-2013 09:45

Re: Bulging cells
 
Quote:

Originally Posted by witzgall (Post 1151432)

I have pulled all the cells out, removed the temp sensor for the batteries (and kept the one on the alternator). I am now charging each cell-pair with a 6a 3.6v charger to top balance. I had drained to top cell with a long 16ga wire.

The bulging seems to be about 2mm on either side on the two parallel cells.


Chris

Chris,

I bet that poor connection resulted in voltage drop and produced extra heat, which was absorbed by the terminal and the guts of the cell. This caused a small amount of electrolyte to vaporize into gas and bulge the cell a little. I have seen this happen a couple of times.

If the bulge is so small, then the cell is not ruined, but its likely lost a bit of capacity and has a bit higher internal resistance now. It will still work perfectly fine as long as reduced capacity does not cripple your needs.

Once you balance them and put them back in use, try to run them down until first cell reports LVC, it will likely be the bulged cell. If amount of AH taken out by that time is not too bad, then you can live with it. If not, then cell must be replaced.

electric1 08-02-2013 09:50

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

Originally Posted by ebaugh (Post 1151464)
I don't have any experience with overcharged cells, but there is a picture in a Thundersky manual of a device that compresses bulging cells flat again. If you used a couple of pieces of plywood at each end of the bulged cells and tightened them in a vice for a few hours it would perform the same function.

Its my understanding that this process does not recover any capacity and does not make much improvement in cell's life. Vaporized electrolyte cannot be pressed back into useful form. Perhaps all it does is make the cell physically able to fit back into the box, if its still usable at that point.

If its just 2 mm bulge on a 200AH cell, I think the damage is minimal.

durundal 08-02-2013 11:54

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

Originally Posted by T1 Terry (Post 1151053)
From the Winston test information that i have on hand:
Vibration test
Vibrate direction: rack vibration
Vibration frequency: 10^55Hz
Maximum acceleration: 30m/S2
Vibration duration: 2hrs
Discharge: discharge the cell with 1/3 3C (A) current until the voltage reach 2.5V
there should not be significant discharge current transformation, abnormal voltage, case distortion or electrolyte leakage.

It's a bit chinglish but maybe it means some thing to some body

T1 Terry

Those numbers are describing vibe parameters, in units that are pretty standard. Placed on a random vibe table you would experience accelerations of up to 3G (30m/s^2) at frequencies from 10-55 Hz.

At work the environment is determined as a function of the booster and location relative to it, and the number of joints between the booster and your item of interest, but that is on a case by case basis as every gram matters. The unit under test would then be placed on the shaker table and the responses measured against the structural limits. There is a graphic of a typical vibe curve as a spec here: FEMCI Book - Creating a Random Vibration Component Test Specification, with what looks like an example of actual data from which that curve was derived. The text Terry has makes it sound like they are just plugging in a flat line curve to the shaker table and not actually measuring the responses in situ (this is expensive and usually requires a good finite element model to exist to compare predictions against results), just looking at the effect after the test was done.

Presumably for the marine universe someone went out in a storm with some data loggers and made a bounding case of vibrations that can be expected to be seen and units can just be tested against that standard.

Andy

durundal 08-02-2013 12:06

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

Originally Posted by hellosailor (Post 1151411)
On vibration specs, I don't think "vibration" really applies to the pounding that a battery would see on a boat slamming around at sea. The repeated impacts would be more like hitting potholes in a truck, fairly large sudden high-g events, occurring way less frequently than something like the vibration from engines or other sources. Given all the talk about how the mebranes in Li-Anything cells can be punctured by crystal growth, I would think "high g" impact events might be a different area of concern.
I'm thinking of a short trip on a highly overpowered RIB slamming across chop, where my kidneys definitely weren't calling it "vibration". And my knees agreed.

I think you're confusing random vibration (many frequencies all at the same time, what you get with most of real life in shaking situations) with sinusiodal vibration (things ringing at specific frequencies, which is relatively uncommon). Random vibe can encompass everything from what your butt feels driving down a smooth interstate to what the space shuttle SRBs feel when they light off, it all depends on the spectrum and values that are specified. Shock values are another (related) regime, where they are extremely high G (thousands) but for very short durations (milliseconds), and are actually relatively unlikely to occur in the marine environment. Typical shock causing events are pyros firing or burst vents blowing, or what you feel when you have your hand on a splitting maul handle when someone hits the maul with a hammer to split a tough piece of wood. Vibe can kill any structure, shock is mostly an issue for very rigid, brittle structures.

durundal 08-02-2013 12:10

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

hellosailor 08-02-2013 12:14

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

durundal 08-02-2013 12:42

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

Originally Posted by hellosailor (Post 1151597)
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.

SaucySailoress 08-02-2013 15:38

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

Originally Posted by durundal (Post 1151592)
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 :)

T1 Terry 08-02-2013 16:50

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

deckofficer 08-02-2013 17:12

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.

https://www.cruisersforum.com/attachm...13ba43b71b.jpg

durundal 08-02-2013 17:13

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.

How do you open these Thundersky 12V 90Ah LiFeYPo4 - YouTube

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

Any chance someone on here can translate what he's saying?

T1 Terry 08-02-2013 19:33

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.

T1 Terry

deckofficer 08-02-2013 22:21

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

FlyingCloud1937 09-02-2013 03:36

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.

Ram 09-02-2013 03:51

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 ~

Lagoon4us 09-02-2013 03:58

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

Originally Posted by Ram (Post 1152100)
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.

FlyingCloud1937 09-02-2013 04:10

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

Originally Posted by Ram (Post 1152100)
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

mrm 09-02-2013 04:41

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

Originally Posted by Ram (Post 1152100)
... 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?

T1 Terry 09-02-2013 06:07

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

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

CharlieJ 09-02-2013 06:56

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."



deckofficer 09-02-2013 09:51

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.

deckofficer 09-02-2013 10:27

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

(4) of these 700 a-hr cells will run $1848, they were $3080 3 months ago, and from other suppliers over $4000.

NahanniV 09-02-2013 11:27

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

Originally Posted by deckofficer (Post 1152363)
Ram,

(4) of these 700 a-hr cells will run $1848, they were $3080 3 months ago, and from other suppliers over $4000.

To be fair, you must remember to let people know that the prices you are quoting are for used cells that are up to 3 years old !

deckofficer 09-02-2013 12:20

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

Originally Posted by NahanniV (Post 1152430)
To be fair, you must remember to let people know that the prices you are quoting are for used cells that are up to 3 years old !

True, I should have mentioned they are old stock and some had been cycled about 25 times. It has been covered on this thread and Balqon states it for those "clearance" cells. So far, all who have purchased the clearance cells have been pleased with the purchase, and Balqon still has the normal 5 year warranty. For us doing EVs, and have been following the prices for the last couple of years, those prices were too good to pass up.

downunder 09-02-2013 23:50

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

What Lagoon4us is about to do with 400AH LiFeO4 right now would be very similar to what you need/have and might be a template for you. If you are in Greece he is not far away.

Cheers

Pieter Dijkstra 10-02-2013 05:50

Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks
 
Hi Ram, we have just finished a 540 Ah 24V system for Catamaran using European Batteries LFP system, fully integrated with BMS and charge control for any type of charger. We added logics so battery system can be hooked up to all sorts of power supplies, also available if needed in 12V system. found EB LFP cells to be very high quality with extreme low moisture content give great calender life. Sure our system would suit your applications as well.

JayH 10-02-2013 06:44

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

Originally Posted by Pieter Dijkstra (Post 1153093)
Hi Ram, we have just finished a 540 Ah 24V system for Catamaran using European Batteries LFP system, fully integrated with BMS and charge control for any type of charger. We added logics so battery system can be hooked up to all sorts of power supplies, also available if needed in 12V system. found EB LFP cells to be very high quality with extreme low moisture content give great calender life. Sure our system would suit your applications as well.

Contemplating a 24V catamaran install myself. Did you put 8 cells together in the center, or 4 cells on each side? Wondering if there are any electrical considerations for physically separating the bank.

Elithion 10-02-2013 09:06

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

Originally Posted by ebaugh (Post 1151246)
I found this site a great source of information on BMS systems:

Li-Ion BMS - Lithium-Ion Battery Management Systems and large battery packs

It's done by the maker of the Elithion BMS.
But either way, his book and white papers are excellent.

Thanks!

Quote:

Originally Posted by ebaugh (Post 1151246)
I found the BMS product more suited to EVs, but it could probably be adopted for marine.

The Lithiumate Lite BMS is specifically just for EVs: it won't work for marine power back-up applications, but would work for an EV boat (electric motor propulsion).

On the other side, the Lithiumate Pro BMS is versatile, for most applications, and has been used in Marine back-up applications.

Here is a selector of all off-the-shelf Li-ion BMSs, from all manufacturers.

Pieter Dijkstra 10-02-2013 11:30

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

Originally Posted by JayH (Post 1153130)
Contemplating a 24V catamaran install myself. Did you put 8 cells together in the center, or 4 cells on each side? Wondering if there are any electrical considerations for physically separating the bank.

In our setup you basically could do either or. Each string will have own BMS in case you split them to two hulls. I would go then for 2 totally separate systems, also providing you redundance in case one system fails. With our topology reconnecting one string to the 24V bus will not give high equalizing current between both strings as well.

JayH 11-02-2013 07:29

Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks
 
I currently tap my 24V AGM bank to get 12V and use an equalizer to keep the 12 and 24 balanced. I'm thinking the equalizer setup won't work so well with LFP since the voltage curve is so flat. I guess I'll need to add starter batteries, cross chargers, and voltage converters to the budget.

witzgall 11-02-2013 08:57

Installing celllog 8s with BMS in place
 
Hi,

I got the housepower bms installed over the week-end, but only the balancing part, no disconnects wired in yet. My cells, when installed are oriented such that taking voltage readings is only possible on two of the four cell groups. I have a celllog 8s that I would like to use for spot checking voltages. The manual shows the first wire going to the negative terminal of the furthest cell, but then it shows each of the remaining wires going to positive terminal of one cell, and the negative of the next in series?

I would have thought it would be wired up just like the BMS, with negative on C1, then a positive on C1, C2,C4,C4. If so, could I not just tap into the wires coming from the cells to my cell boards (mine are not on the cells, but remote to them in a box with the "Main" board, different then the currently sold housepower bms)?

Chris

NahanniV 11-02-2013 10:22

Re: Installing celllog 8s with BMS in place
 
Quote:

Originally Posted by witzgall (Post 1154118)
Hi,

I got the housepower bms installed over the week-end, but only the balancing part, no disconnects wired in yet. My cells, when installed are oriented such that taking voltage readings is only possible on two of the four cell groups. I have a celllog 8s that I would like to use for spot checking voltages. The manual shows the first wire going to the negative terminal of the furthest cell, but then it shows each of the remaining wires going to positive terminal of one cell, and the negative of the next in series?

I would have thought it would be wired up just like the BMS, with negative on C1, then a positive on C1, C2,C4,C4. If so, could I not just tap into the wires coming from the cells to my cell boards (mine are not on the cells, but remote to them in a box with the "Main" board, different then the currently sold housepower bms)?

Chris

Sharing the cell connections between the CellLog and the BMS balance boards might cause some measurement errors, most likely when the balance boards are bleeding current from a high cell. The resistance of the wires and connections will alter the voltage reading. Not necessarily a problem, but something to be aware of.

As far as where to connect the CellLog wires, either the positive or negative post will do; If the two posts are well connected by a heavy bus bar there should only be a few mV difference even under a heavy load.

So, if it makes your life easier go ahead and "tap into the wires" to the BMS cell boards, but be aware they may cause some slight errors on the CellLog.

Maine Sail 13-02-2013 11:32

Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks
 
Blue anodized wins....:D

https://www.pbase.com/mainecruising/image/148769974.jpg

https://www.pbase.com/mainecruising/image/148769974

Expenses so far:

4 - 400Ah Winston Cells = $1032.00
Shipping Cells = $250.00
Tyco EV200 Contactor = $79.00
House Power BMS Board = $75.00 (Clean Power Auto LLC.)
Cell Modules = $54.00 (Clean Power Auto LLC.)
Aluminum for end plates/compression = $64.00
3/8" Polycarbonate = $27.00
Anodizing Aluminum = $60.00 (minimum charge)
Nuts, Bolts, Threaded Rod, Washers etc. = $12.80
Solar and Alt HVC relays = $8.60 (Cole Herse 70A)
Bus Bar = $4.80 (Blue Sea)
Switches, Alarm Buzzer etc. $44.00
Terminals = $9.50
Total Materials = $1720.70


Compare that to a bank like this:
https://www.pbase.com/mainecruising/image/143816742.jpg

4 - 100Ah Odyssey PCM2150's for a 400Ah AGM bank = $1509.60
(note I am not even including the hold downs in that price just the batteries)


"Claimed Cycles"
(disclaimer: I don't believe either of these "lab" derived claims and do believe they will both be lower in real world use.)

Odyssey Cycles at 80% DOD = 400 Cycles
Winston LiFePO4 at 80% DOD = 2000 Cycles

$$ Per Cycle Odyssey = $3.77 per cycle

$$ Per Cycle LiFePO4 = $0.86 per cycle


deckofficer 13-02-2013 11:51

Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks
 
The blue was my choice, sets off the yellow of the cells. As to cycle life, with how conservative the LiFePO4 are rated as to a-hr, my money is on at least 2000 cycles before losing 20% capacity.

I've run my cells at the 20 hour rate that LAs are rated at, and I saw 50% more than what the LiFePO4 claims for a-hr. My bet is cycle life is also on the conservative side, but time will tell.

electric1 13-02-2013 13:03

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

Originally Posted by deckofficer (Post 1157044)

I've run my cells at the 20 hour rate that LAs are rated at, and I saw 50% more than what the LiFePO4 claims for a-hr.

Does your meter have Peukert setting or efficiency setting? I think your meter is misleading you. LFP cells do not give more than their actual capacity, regardless of C rate, they just have almost no Puekert effect, so their useful capacity is the same regardless of C rate ( within certain practical limits ).

Its common for Chinese cells to have actual capacity 2%-5% more than rated capacity, but not beyond that.

deckofficer 13-02-2013 13:14

Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks
 
No meter other than amp meter to confirm a 5 amp load. 100 a-hr pack ran 30 hours with that 5 amp load. When I pulled 3.7 amps, managed 165 a-hr before 100% DOD. Ask other owners of these cells, when compared to LA for their capacity, they are rated very conservative. I think even at a 4 hour rate (pulling 100 amps from a 400 a-hr pack) some owners have reported 25% more than the rating. Try that will LA, a 4 hour rate for discharge, those 220 a-hr golf cart batteries might give 150 a-hr.


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