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

[sparrowhawk1]

Got this one. Because the "plates" run lengthwise. if you stand them up or put them on edge the plates are still in "solution". but if laid on their side the top plates are "dry".

[Moonos]

Originally Posted by sparrowhawk1

Got this one. Because the "plates" run lengthwise. if you stand them up or put them on edge the plates are still in "solution". but if laid on their side the top plates are "dry".

So does that mean that laid on their edge it is not as good as standing up, or is there no difference?

[sparrowhawk1]

As far as I know it doesn't make a difference. all the plates are in the solution an equal amount if rotated in line with the plates.

[Maine Sail]

Originally Posted by Moonos

So does that mean that laid on their edge it is not as good as standing up, or is there no difference?

This is straight from Jack Rickard..

"CELL POSITION

The manufacturer advises us that the ideal mounting of the cells is vertical with the vents pointing UP.

Mounting the cells upside down is absolutely forbidden as this causes electrolytes to pool in the pressure vent, disabling it.

Horizontal mounting is somewhat more controversial. The manufacturer advises this shortens cell life, with mounting on edge preferable to mounting flat side down horizontally."


This is straight out of the CALB manual:

"3.1.1 Each group of battery must be properly fixed to the battery box which shall be placed on battery pole up mode after clamping. Changing the direction of installation is not recommended, pictures are as follows."

[Cotemar]

This talks about the do's and don'ts about cell orientation.

http://www.cruisersforum.com/forums/...ml#post1452743

[svAricia]

Finally got my order from Balqon, originally ordered 12 400ah cells back in December with their shipping promo. They still don't have 400ah cells in stock, been emailing back and forth for few month until just recently I told them I couldn't wait any longer so they upgraded me 700ah cells Good thing I have enough space and 2100ah should be plenty.
Not sure how old the cells are but they all have Balqon logos on them, checked their voltage and it ranges from 3.303 to 3.293

[KTP]

Does anyone on here have a CA180 cell on hand and can measure the height including the strap and bolt? The data sheet says 11 inches but EVTV Motor Verks says 10.7". I have right at 11 inches but not a fraction more.

If I can't go with eight of the CA180 cells and do go with 24 of the CA60 cells, would I still bottom balance all of the cells and then connect them in 3p then in a series string (so 3p8s)? Does the bottom balance method (no BMS) work when you have paralleled cells? I am unsure what happens if you place a lower capacity cell in parallel with higher capacity cells...I guess the group just assumes the lower capacity.

The guy at EVTV seems to be a big fan of bottom balancing and then don't use a BMS, just set your charger/discharge system to stay within 10%/90% of the bank capacity.

I wish AGM was not so heavy...it sure is a lot simpler.

[hellosailor]

One of the failure modes with lithium cells also has to do with punctures of the separator material in each cell. Microcrystals can form in the cells, and if these form against the separator material they can work through it and puncture it.

Think of this as sand and bedsheets. Lay the sheets out horizontally, and the sand is trapped and rubs between them. Hang the sheets vertically, and the pressure is off them, the sand can drop down between them.

I could see this being a problem in the cells, since stacking them horizontally would then put the maximum pressure, the weight of a whole stack in each cell, on anything abrading a separator internally.

I haven't seen any mention of this, but it would be "simple" physics and apply to any similar construction.

Similarly, extra electrolyte might be squeezed out of the layers, to float uselessly on top, unable to circulate in between the layers, the way it could in a vertical orientation.

Or it could just be the manufacturers haven't done any long-term testing in that orientation yet, considering 2000 test cycles can take a few years. So, no testing, no results, and they wouldn't gamble on it.

[deckofficer]

Originally Posted by svAricia

Finally got my order from Balqon, originally ordered 12 400ah cells back in December with their shipping promo. They still don't have 400ah cells in stock, been emailing back and forth for few month until just recently I told them I couldn't wait any longer so they upgraded me 700ah cells Good thing I have enough space and 2100ah should be plenty.
Not sure how old the cells are but they all have Balqon logos on them, checked their voltage and it ranges from 3.303 to 3.293

I've heard this before with Balqon. A very long wait for the 400 ah cells, then Balqon offers to upgrade the order to the 700 ah cells. So if I understand, their price per 400 ah cell is $440 and you got (12) 700 ah cells for around $5280?

What a deal, 27.3 kwhr for $5280. The last house bank you will ever need to buy.

[darylat8750]

[/QUOTE]

On the 700amp cells are the pairs of posts connected inside the battery? If so are the secondary posts only required for high loads? I would have thought that all the negative posts should be bussed together and all the positive posts should be bussed together for balancing.

[Maine Sail]

Originally Posted by KTP

Does anyone on here have a CA180 cell on hand and can measure the height including the strap and bolt? The data sheet says 11 inches but EVTV Motor Verks says 10.7". I have right at 11 inches but not a fraction more.

If I can't go with eight of the CA180 cells and do go with 24 of the CA60 cells, would I still bottom balance all of the cells and then connect them in 3p then in a series string (so 3p8s)? Does the bottom balance method (no BMS) work when you have paralleled cells? I am unsure what happens if you place a lower capacity cell in parallel with higher capacity cells...I guess the group just assumes the lower capacity.

The guy at EVTV seems to be a big fan of bottom balancing and then don't use a BMS, just set your charger/discharge system to stay within 10%/90% of the bank capacity.

I wish AGM was not so heavy...it sure is a lot simpler.

Jack Rickard is doing EV batteries where bottom balance is MUCH more critical. We are doing fractional "C" use... They have huge loads, run the batteries to near empty and then charge with ONE charger.

Top balancing for a boat, with multiple charge sources, is preferred because our greatest risk of cell imbalance comes at the top end of charge, rather than the bottom.

Take your time and read through the threads here and don't just take away what you want to hear, take away what you need to hear....

[svAricia]

Originally Posted by deckofficer

I've heard this before with Balqon. A very long wait for the 400 ah cells, then Balqon offers to upgrade the order to the 700 ah cells. So if I understand, their price per 400 ah cell is $440 and you got (12) 700 ah cells for around $5280?

What a deal, 27.3 kwhr for $5280. The last house bank you will ever need to buy.

Thanks, that is exactly what I paid. I had 800ah of L16s before, they lasted 4 years, so I hope this is the last battery I have to buy. Working on the BMS and control panel now.

[svAricia]

Originally Posted by darylat8750

On the 700amp cells are the pairs of posts connected inside the battery? If so are the secondary posts only required for high loads? I would have thought that all the negative posts should be bussed together and all the positive posts should be bussed together for balancing.[/QUOTE]

You are right, the dual posts are for very high loads, they are connected inside the battery, looking at specs, you can pull as much as 14000 amps.

[deckofficer]

Originally Posted by svAricia

Thanks, that is exactly what I paid. I had 800ah of L16s before, they lasted 4 years, so I hope this is the last battery I have to buy. Working on the BMS and control panel now.

Your in Fat City, going from 400 usable ah to 1680 usable ah.

[KTP]

Originally Posted by Maine Sail

Jack Rickard is doing EV batteries where bottom balance is MUCH more critical. We are doing fractional "C" use... They have huge loads, run the batteries to near empty and then charge with ONE charger.

Top balancing for a boat, with multiple charge sources, is preferred because our greatest risk of cell imbalance comes at the top end of charge, rather than the bottom.

Take your time and read through the threads here and don't just take away what you want to hear, take away what you need to hear....

I have tried to wade through the threads. The thing that is hard for me to understand is why Lifeline or Duracell or Trojan is not offering a drop in 12V or 24V Lithium battery with 3 year warranty. If lead is dead, it would seem they better get on the ball.