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Old 05-02-2013, 01:03   #1906
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All the wires on LFP banks are undersized and will vaporize on a dead short that does not involve the usually distant main fuse. What would 100C or 20,000A do to your battery mains?

LA systems don't compare. Nor does domestic (home) wiring practice as the fault current is limited by the transformer out on the pole.

What should be done is not entirely clear. But little sense wires are not the problem. One can use fiberglass cloth sleeves for abrasion and thermal protection of the sense wires.
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Old 05-02-2013, 01:14   #1907
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

here is som info from Victron, on LFB banks.

http://www.victronenergy.com/upload/...0%20-%20EN.pdf
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Old 05-02-2013, 01:25   #1908
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by mbianka View Post
A question d0 Lith Ion's charge faster than LA?
Yes. They have high acceptance all the way up to 100% SOC.

And 1C charging currents are nothing extreme. They just take it.
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Old 05-02-2013, 02:13   #1909
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Balancing cells with a hobby charger.

I am just in the process of ordering (hopefully) my lithium start/anchor winch battery.
I am not sure why I am bothering when the old Gel cells lasted 15 years in the role, but I would like to get some experience with these larger cells.

There is a lot a debate about balancing. I think its going to necessary, perhaps every 6 months or so. We shall see.

Thinking about making this easier I wonder if my hobby charger could do this automatically.
It runs from 12v it will boost voltage so can charge a higher voltage than its input. It will even put back energy into the input battery when it is discharging.
My thinking is that it could be powered from the house bank and equalise the lithium start bank (or vice versa for most people).
The charge and discharge current is limited to 6A (although you can buy bigger models).
It will plug directly into the plug from the cell logger.
Its not clear what the differential balance current is. If the cells were reasonably out of balance you may have to charge or discharge a single cell, but for the most part it could be hooked up and left to automatically balance the bank.
The voltages and charge profile are completely adjustable and the voltage control is very tight.
It will charge from 1 o 19 cells of any battery chemistry.

These are available quite cheaply (although mine is an expensive model). They would provide near atomic balancing whenever the cell logger indicated it was necessary (just plug it in) without the worry of BMS failure that is perminantly connected to the batteries.

Thoughts anyone?
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Old 05-02-2013, 04:30   #1910
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Balancing cells with a hobby charger.

Thinking about making this easier I wonder if my hobby charger could do this automatically.

My thinking is that it could be powered from the house bank and equalise the lithium start bank (or vice versa for most people).

The charge and discharge current is limited to 6A (although you can buy bigger models).
It will plug directly into the plug from the cell logger.

The voltages and charge profile are completely adjustable and the voltage control is very tight.

Thoughts anyone?
So, basically you want to use an advanced hobby charger in a manner resembling echo chargers, only not permanently. Can't see why it would not work.

Just a couple of remarks.
Voltage control is tight in some models, others are less than perfect.
Plugging directly into the logger plug (aka balancing plug) is OK, but its limitations should be observed, as contacts are designed for less than 3A current. I know that it can take more and hobbyists are pushing it way higher, but it is just that - pushing it.
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Old 05-02-2013, 04:42   #1911
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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So, basically you want to use an advanced hobby charger in a manner resembling echo chargers, only not permanently. Can't see why it would not work.

Just a couple of remarks.
Voltage control is tight in some models, others are less than perfect.
Plugging directly into the logger plug (aka balancing plug) is OK, but its limitations should be observed, as contacts are designed for less than 3A current. I know that it can take more and hobbyists are pushing it way higher, but it is just that - pushing it.
Thanks for the comments.


Ev power have now said they cannot deliver to Greece.
Despite assuring me in a email that this was OK and even providing a delivery cost.
Apparently the classification of the batteries as dangerous goods is the problem.

EV-Power | Your Complete Power Solutions

Does anyone know of another supplier in the EU?
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Old 05-02-2013, 05:21   #1912
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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here is som info from Victron, on LFB banks.

http://www.victronenergy.com/upload/...0%20-%20EN.pdf
I saw this quite some time ago, I don't understand why such a big company would risk destroying their reputation by publishing such nonsense in the first few lines.
Why a Battery Management System (BMS) is needed:
1. A LFP cell will be destroyed immediately if the voltage over the cell falls to less than 2,5V.
2. A LFP cell will be destroyed immediately if the voltage over the cell increases to more than 4,2V.

Anybody who has used these cells at all knows that is complete nonsense, why do they publish this crap? They have obviously not carried out any testing or they would know this was nonsense.
The rest of the article is reasonably correct, but to claim this sort of thing just to sell one of their BMS units, why?

T1 Terry
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Old 05-02-2013, 06:29   #1913
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Ev power have now said they cannot deliver to Greece.
Despite assuring me in a email that this was OK and even providing a delivery cost.

Does anyone know of another supplier in the EU?
I think I posted that link before: Introduction

As for freight, when I had to ship some boat parts and chemicals from Poland to Spain I used those guys Najtasze usugi kurierskie - tanie przesyki zagraniczne i midzynarodowe. Tani kurier od 12,99z They act as shipping order collectors for two courier companies, at wholesale prices. For international they use UPS. Unfortunately site is in Polish only, but I checked, that a 70kg, 50x70x80cm package to Greece from Poland, insured, cost around 120Euro (depending on insured value). Maybe Google Translate will help you some.
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Old 05-02-2013, 07:02   #1914
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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... I don't understand why such a big company would risk destroying their reputation by publishing such nonsense in the first few lines.
Yes indeed. This LFP market is a mess. The facts are scarce. Manufacturers less than honest with their data sheets. The marketers and hungry. The customers are often in a little over their heads. Breathless fanboys on forums. A perfect storm. It may take a few years for all this to shake out. But now all they are doing is damaging the marketplace for everyone with crap like that.

Reading technical papers from real universities and research labs is the only way I am making any confident progress. And reading CF with my goggles on
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Old 05-02-2013, 09:31   #1915
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Deckofficer:

But won't I need four of the 260 a-hr cells for my 48 volt propulsion bank? That's $3280 right? Still it's more amps and cycles so I will certainly rethink the issue when the AGMS need replacing. Prices should even be cheaper and the track record will be longer by then too. I would hope the cell balancing issues should be pretty much taken care of by then too. I want to be reaching for a beer not my Fluke meter when I drop anchor.
I'm bad, was thinking 12 volt house bank, not 48 volt propulsion bank. Your correct, $3280 (16 cells), but then if your not using an inverter yet, you have killed two birds with one purchase because 48 volt inverters are the way to go. The charger side of the inverter will put a full charge on that big bank in about 4 hours of marina juice. Plus you can run your coffee maker and induction hot plate at the same time on the hook.
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Old 05-02-2013, 10:27   #1916
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Had some time over the weekend to get some work done on my battery pack. I've assembled the battery box and lid for it.

She is compressed with 1/4" aluminum plate which is then drawn together with 5/16" threaded rod and precisely spaced with 1/2" aluminum square tube to fit into the slots on the cells.

I also made some 1" X 1/8" thick OFC copper positive and negative connection posts so I don't have to disrupt the BMS system when connecting or disconnecting the pack...

The lid is made from 3/8" thick light smoke polycarbonate/Makrolon..

The finished dimension of the pack is:

18 7/8" Long
12 7/8" Tall
13" Wide (outside of cap nuts)

Next I will clean up the aluminum parts and send them off to be anodized. Have not yet decided on color..... Red, blue or black..?

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Old 05-02-2013, 10:44   #1917
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Beautiful work
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Old 05-02-2013, 11:16   #1918
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

No chance of cell bulging and no errant wrenches are going to fall on your terminals Maine Sail, great design. I vote blue.
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Old 05-02-2013, 11:22   #1919
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Beautiful engineering. I love the way those square tubes interlock with grooves in cell sides. I'd shorten those red wires though. I vote for blue too.
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Old 05-02-2013, 11:33   #1920
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

I realise this is like telling Michelangelo that the Mona Lisa needs to smile more, for the painting to be a success , but can I suggest some polycarbonate (or other electrically insulating) material along the inside of the aluminium sides at the top.
If the connection posts were to swivel outboard aluminium is a great conductor and the resulting short would be spectacular.

My vote is for red anodising.
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