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

[s/v Thea]

I guess that would depend on how charger is built. All I know is that as soon as solar/alternator goes into float the pack starts discharging and charging source reports 0 amps charging. Might behave differently if no load but I always have at least an amp or two load.

After four years pack seems fine, I've never done a capacity test, I do take that pack as low as 20% on occasion so all I can say for certain is I haven't lost 20% capacity yet.


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[transmitterdan]

If the pack is truly discharging then the charger is not in "float". It's setpoint must be less than the resting voltage of the pack. That is what Li needs according to the research. But most LA chargers don't do that. They typically float at more than 1 V above the resting voltage. If you do that with Li bad things will happen.

[s/v Thea]

It's a three stage charger, bulk and absorption are above resting voltage, so if it's not in float what is it in??? If you set float below resting voltage, for my chargers anyway, they are effectively turned off.



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[ColdEH]

I set up my system very simply , I only have one charge source for my 600 AH pack, a Echo Tec alternator coupled to a 3 cyl yanmar . I have a simple set point on the alternator of 13.85 volts and it shuts off at that point. I only charge while Im aboard and attending to it. Alternator puts a minimum of 200 Amps into the back so at the most I would run it for two hours.

Regards

[Dod42]

Silly question , but do LifePo4 cells have to be mounted vertically or can they be used lying down? Where I want to fit mine I have a height limit but would be fine if I can mount them lying flat and stack 4 high. They look sealed any issues with this?

[Rimica]

I install 260 amp cells in my boat and when I asked the Balqon people about it they said that they need to be upright. I therefore lifted my aft cabin bed by 3 inches to fit them. It was easy to do.

[hellosailor]

AFAIK most manufacturers say "any direction except upside down" but you'd have to check for your specific battery. The internal construction and support make the difference.

[KASHMIR]

Originally Posted by Dod42

Silly question , but do LifePo4 cells have to be mounted vertically or can they be used lying down? Where I want to fit mine I have a height limit but would be fine if I can mount them lying flat and stack 4 high. They look sealed any issues with this?

The manufacturers recommendation is that the prismatic cells should not be mounted on the size, the terminals and vent should be no more than 45deg from upright.

[senormechanico]

Terminals on top is ok
Terminals on the side with prismatic cells on edge ok.
Laying flat, NOT OK.

[KASHMIR]

It must vary between manufacturers, because have told me OK to 45deg only.


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[Dod42]

Ok jury is in. I sent an email to winston about the 400ah cells I was looking at and the answer came back as NO then cannot be run lying down. The terminals must be at the top. Oh well time to find a different location


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[offpist]

Sometimes you have to be creative.
I made a custom battery box under the bed. ¨

[Hawkeeye2]

Originally Posted by transmitterdan

If the pack is truly discharging then the charger is not in "float". It's setpoint must be less than the resting voltage of the pack. That is what Li needs according to the research. But most LA chargers don't do that. They typically float at more than 1 V above the resting voltage. If you do that with Li bad things will happen.

Would 5-10A continuous discharge (or less) be enough to keep the solar or wind generator charger in absorption mode (out of float mode)?

[darylat8750]

Here is a twist on the "drop in replacement" LiFe that I hadn't seen before. All our discussion has been about 4 cells in series for a "12 volt" system. Balqon is marketing a "drop in" with 5 cells for a voltage range 12.5 to 16.
http://www.balqon.com/store-2/#!/ESS...egory=12286436

With the usual concern about business practices and whether they will be able to honor warranty claims: Does this make sense as a way to charge with currently installed charging equipment? Might this 5 cell string make a "drop in replacement" a possibility? Does a 5 cell make any sense for a home built system?

[Dod42]

Originally Posted by darylat8750

Here is a twist on the "drop in replacement" LiFe that I hadn't seen before. All our discussion has been about 4 cells in series for a "12 volt" system. Balqon is marketing a "drop in" with 5 cells for a voltage range 12.5 to 16.
Balqon Electric Vehicle Manufacturer

With the usual concern about business practices and whether they will be able to honor warranty claims: Does this make sense as a way to charge with currently installed charging equipment? Might this 5 cell string make a "drop in replacement" a possibility? Does a 5 cell make any sense for a home built system?

I'm confused. The link you supplied shows "Battery bank with 4 cells" not 5 am I missing something?