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

[OceanSeaSpray]

Originally Posted by SV THIRD DAY

We just need a little tweaking of that comment in my opinion.
...
...if your plain wet lead charging system has the ability to set the charging parameters (Voltage) then besides the real risk of overheating and burning up an alternator by keeping it at full output for too long, you can successfully charge your LiFePO4 bank with more standard charge devices.

A further tweak to that would be saying "until something fails" and "as long as you live on board and cycle the system" and also to some extent "as long as you don't care too much about life expectancy".

Several of the charging sources mentioned clearly don't implement charge termination, so the whole thing relies on a balance of charging and consumption in order not to overcharge - which doesn't actually have a lot to do with voltage alone, but also how long you keep at it for.

A guy here, who had done more or less this, later saw his alternator fail. 30 minutes after leaving his berth under power, he noticed a funny smell coming from down-below and the cabin was filled with a less-than-breathable mist. Voltage was at 17.5V with the engine back to idle just before he killed it and he found his cells swollen out of shape and so bloody hot he feared they were going to set the locker on fire or plainly burst into flames and he put a call out for assistance. They took hours to cool off enough to be touched. A little longer and things could have been a whole lot more interesting.

This is also what "your plain wet lead charging system" has the ability to do, hence - just for the benefit of any newcomers really - no drop-in replacement even with voltage tweaks.

[SV THIRD DAY]

Originally Posted by OceanSeaSpray

A further tweak to that would be saying "until something fails" and "as long as you live on board and cycle the system" and also to some extent "as long as you don't care too much about life expectancy".

Several of the charging sources mentioned clearly don't implement charge termination, so the whole thing relies on a balance of charging and consumption in order not to overcharge - which doesn't actually have a lot to do with voltage alone, but also how long you keep at it for.

A guy here, who had done more or less this, later saw his alternator fail. 30 minutes after leaving his berth under power, he noticed a funny smell coming from down-below and the cabin was filled with a less-than-breathable mist. Voltage was at 17.5V with the engine back to idle just before he killed it and he found his cells swollen out of shape and so bloody hot he feared they were going to set the locker on fire or plainly burst into flames and he put a call out for assistance. They took hours to cool off enough to be touched. A little longer and things could have been a whole lot more interesting.

This is also what "your plain wet lead charging system" has the ability to do, hence - just for the benefit of any newcomers really - no drop-in replacement even with voltage tweaks.

The post wasn't about alarms...it was about Charging and the wrong implication that along with installing a new LiFePO4 battery bank you would also have to swap out all of your current charging control devices, which is totally not true as long as your current charge device has the ability to set the charge voltage. It's a common Myth.

Overcharging...regulator failures...Hello....McFly....
Why wouldn't you put a cheap and easy Voltage Alarm on your $1700 400AH LeFePO4 bank for the love of Pete? Who was advocating the straw man you burned alive in a LeFePO4 overcharge fire?

Question:
If you charge device is putting out 13.7V and your battery bank is at 13.7v, how many Amps will flow into the battery....answer...you can't overcharge, at least that's how it's been working on my boat now for about 6 months.

[OceanSeaSpray]

"The post wasn't about alarms". Indeed, it wasn't: it would have mentioned "human-powered battery protection systems".

Considering that a full LiFePO4 cell really sits at about 13.35-13.38V, what do you think you are doing holding it all day at 13.7V? And what do you think it actually does to it? And why do you think there is no current flowing into it any more? Ahem indeed.

[SV THIRD DAY]

Originally Posted by OceanSeaSpray

"The post wasn't about alarms". Indeed, it wasn't: it would have mentioned "human-powered battery protection systems".

Considering that a full LiFePO4 cell really sits at about 13.35-13.38V, what do you think you are doing holding it all day at 13.7V? And what do you think it actually does to it? And why do you think there is no current flowing into it any more? Ahem indeed.

It's good to see ADD/ADHD isn't just in the USA, but also down under also...

It's also part of the problem in a near 300 page thread, you talk about charging, and someone wants to talk alarms. You talk about Charging voltage and someone assumes you would keep the battery at 13.7v all day and not just charger there. Assumptions are bad and we have seen a string of them here. Charge at 13.7V...who said anything about leaving the battery bank there all day like we were talking Lead Acid with a float charge? What next...equalizing LiFePO4...or using leaches....

[OceanSeaSpray]

Originally Posted by SV THIRD DAY

It's good to see ADD/ADHD isn't just in the USA, but also down under also...

It's also part of the problem in a near 300 page thread, you talk about charging, and someone wants to talk alarms.

Oh really??

Originally Posted by SV THIRD DAY

The post wasn't about alarms...
...
Why wouldn't you put a cheap and easy Voltage Alarm on your $1700 400AH LeFePO4 bank for the love of Pete?

I can only find one guy starting to talk about alarms here. ADHD maybe, yes.

Originally Posted by SV THIRD DAY

You talk about Charging voltage and someone assumes you would keep the battery at 13.7v all day and not just charger there. Assumptions are bad and we have seen a string of them here. Charge at 13.7V...who said anything about leaving the battery bank there all day like we were talking Lead Acid with a float charge? What next...equalizing LiFePO4...or using leaches....

Is it a case of "when you are wrong, just expand to confuse the matter"? Oh, but wait a minute, just before we had the same ADHD guy saying:

Originally Posted by SV THIRD DAY

Question:
If you charge device is putting out 13.7V and your battery bank is at 13.7v, how many Amps will flow into the battery....answer...you can't overcharge, at least that's how it's been working on my boat now for about 6 months.

The issue with ADHD is that it makes discussions quite worthless. And the problem with guys who "just dropped them in" is that they always get quite upset (wonder why??) when you quote an instance where it went quite wrong (which couldn't possibly happen to them), and they need to justify what they did so much that they are always on the front line trying to enrol followers.

Rest assured however that my comments weren't ever intended for your own benefit (!) and I somehow fully expected you to get upset when I wrote how someone had recently toasted a set of cells to a crisp.

[SV THIRD DAY]

Originally Posted by OceanSeaSpray

Oh really??

I can only find one guy starting to talk about alarms here. ADHD maybe, yes.


Is it a case of "when you are wrong, just expand to confuse the matter"? Oh, but wait a minute, just before we had the same ADHD guy saying:



The issue with ADHD is that it makes discussions quite worthless. And the problem with guys who "just dropped them in" is that they always get quite upset (wonder why??) when you quote an instance where it went quite wrong (which couldn't possibly happen to them), and they need to justify what they did so much that they are always on the front line trying to enrol followers.

Rest assured however that my comments weren't ever intended for your own benefit (!) and I somehow fully expected you to get upset when I wrote how someone had recently toasted a set of cells to a crisp.

You just gotta love a guy who puts post out of order to make a flat out LIE of a point....ha ha ah ....classic. You put my post about the alarm conveniently out of order to totally change the context, come on amigo...when you have to stoop to that level you are on your last leg and it shows.

Me....I'll just go back to watching my LeFePO4 bank perform like a champ, while you want to play internet chat room games.

[OceanSeaSpray]

Originally Posted by SV THIRD DAY

You just gotta love a guy who puts post out of order to make a flat out LIE of a point....ha ha ah ....classic. You put my post about the alarm conveniently out of order to totally change the context, come on amigo...when you have to stoop to that level you are on your last leg and it shows.

Me....I'll just go back to watching my LeFePO4 bank perform like a champ, while you want to play internet chat room games.

Haha... the disturbing thing here is that the only thing "out of order" would be in your head my friend, and it is quite plain to anyone who cares looking one page back! I quoted you twice, between two posts in sequence, no tricks (I even explicitly clarified precedence by saying "just before"), and yet doesn't it look silly??

There is nothing easier than making a LFP bank "perform like champ": just charge/balance the cells and drop it in. We all know that, heaps have done it. You really don't need to congratulate yourself here! The one that was cooked had also been performing "like a champ", rest assured of that!

Unbelievable.

[SV THIRD DAY]

What was your point again.....

[bill good]

I recall a professor in the USA producing a report that indicated even a static voltage would cause reaction within the cell indicating the need to remove the voltage unless being charged. However the paper did not have photos for all the voltage range & I assumed it was the top end. So the advice seems to disconnect the charging when it is finished.

Bill

[roetter]

Originally Posted by ganryu

Dear all, I just registered since I was looking at the Lifepo market in the US.

Apprently, few manufacturers offer an integrated solution with BMS + Cells + Controller.
....
I do not know if I can post the link, but since it's not available in the US:

EZA ® - Integrated Lithium system Powered System for motorhomes, caravans, boats, houses,...

You can clearly see the different features and would be promising.

....

I would not trust that. They are unable to use proper units on their web site. Shows lack of understanding of the whole thing.

Two cases here:
Home page - it should read
->Recharging speed. A recharging speed unmatched before, Up to 130A.
NOT 130 Amp/h
Learn More page - It should read
->Extremely fast charging 15 Minutes 25Ah charge.
NOT 15 minutes 25A charge

I stopped reading after that. Too dangerous those guys.

[transmitterdan]

It's pretty simple really. Li wants the charge voltage to be "removed" once the bank is full. This means that when the bank is "full" the charger has to change its voltage setpoint to be less than the resting voltage of a fully charged Li bank. But that isn't how boaters want their charger to work. They want to save the battery capacity for when they don't have a charging source. So they want to keep the charger above the resting voltage of the battery. For LA this is fine because the float voltage is above the resting voltage. Also, there is no way to make an alternator do this except by totally removing the field voltage. It will not regulate to a setpoint below the battery resting voltage no matter how hard you try.

So we can't just use existing charge sources and change the voltage setpoints. That is too simplistic a design if you want maximum life from the battery bank.

[s/v Thea]

Originally Posted by transmitterdan

So we can't just use existing charge sources and change the voltage setpoints. That is too simplistic a design if you want maximum life from the battery bank.

I don't agree. I have a 800ah Winston pack that is 4 years old now. Resting voltage is about 13.3-13.4.

I have a blue sky solar controller set to float of 13.3. What that means is in morning it starts charging, if pack gets full, switches to float and unless I'm using a lot of power won't charge again for that day. >90% of my charging is from solar.

I have an Ample power smart regulator, set to gel charging, has a float set to 13.2 or something like that. Main problem I have with that is that it switches to float too soon, so I've added a toggle switch that will holds regulator at absorption voltage (about 14v). This requires me to manually switch off, as I don't normally motor too long it's not a problem. If I wanted to get fancy I could add a voltage relay for <$100 to automatically switch off.

I have set charge point on my prosine inverter charger but never use it. If you're plugged in all the time why spend money on Li?

Doug


Sent from my iPad using Cruisers Sailing Forum

[transmitterdan]

If you manually control charge cutoff from the alternator that's fine. But most boaters won't do it.

There is a lot of data that says floating Li packs continuously reduces the life and/or capacity making the economic benefits less attractive. Let us know how it works for you.

[s/v Thea]

If you are saying floating at <= resting voltage will damage pack that doesn't make any sense at all. If that we're true connecting cells in parallel would damage each other.




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[transmitterdan]

It's very hard to "float" Li because of the flat discharge curve. According to all I have read it isn't possible to float at less than resting voltage. The resting voltage will always be a tiny bit less that the charger voltage. Let us know how your bank capacity is holding up after 4 years. That kind of real world data is very helpful.