LiFePO4 Batteries - Okay Tear Me Apart ;-)

[gael]

Originally Posted by rebel heart

So 2-3 years later, any updates from the people who are using the li batteries?

since 2010 I'm living on Camao with my wife and our 2y old daugther.
this is a 45ft aluminium sailboat.
We have 2 packs of 130Ah ,8series to get28V, from CALB.
All regulation come from Genasun.
I have also gold plated all connection, screws ect.. (this cost peanut)

So on board we have a100L/H watermaker from desslator
3PCs, MAC and Ipad
One fridge. All ligths with leds
2KW windlass

Since 3 years we have no major issues with this technologies.
Over the 16 cells, one is a bit weak ie it get its max voltage before the others.

Average we can stand mooring for 3daysbefore cranking the engine, fitted with a dedicated 28V 80A alternator
Outside we have a single 130W solar panel.

So far so good.

I'm thinking now to remove all propane intallation ( 80Kgs) on move to full electrical galley. Will be an other story.

Cheers
Gael

[witzgall]

HI all,

If you remember, we have a 400ah lifepo4 house bank. two of the eight cells bulged a bit, most likely from a bad cable going from from one set of four to the other (they are in a 2s4p configuration). I think those two cells were damaged somewhat, but to what extent, I do not know.

What I would like to ask other lifepo4 users is what kind of voltages they are seeing at perhaps a 10a load, with no charging sources. I am now seeing a low voltage from 12.6 - 12.4 under a 5-10a load, and then 12.8-13.1 when the load is less than 2a. They are also reading 13.7+ volts earlier than I think they should when charging under solar/wind.

I have yet to draw them down less than 70% since these lower voltages started happening. Or am I remembering things wrong, and these are ok?

I wired up a cellog 8, but I don't trust it, and getting individual cell voltages means emptying out the quarter berth each time, which is full of stuff (full-time live aboard - garage).

Anyways, I would love to here some thoughts.

Chris

[senormechanico]

Our LifePo4 200aH 12 volt bank (4 200 ah cells in series) sits at 13.2. until we put a huge load on them.
When Janet makes a smoothie, the sinewave inverter powering the Vitamix draws about 125 amps.
This runs for nearly a minute and the battery voltage goes down to about 12.6 or so.
When she's done with the Vitamix, the voltage returns to 13.2 and stays there for normal loads like the fridge , furnace, watermaker and lighting.
After making hot water with the inverter (20 minutes @ 100+ amp load) the battery bank is down to 12.3 volts while still under load.
Steve

[McG]

I charge my 12V 800A bank up to 14.3V with a 100Amp charger when the solar cannot keep up. It quickly drops back to 13.2V for an hour or two after a good charge and then it will go down to 13.0V. This is with a load of 60W 12V compressor fridge/freezer and a laptop (90W). This equates to roughly 10A load.
When the fridge switches on, the volts drop to 12.9 and goes back to 13 when it stops. This goes on for about 24hours. Then it will sit at 12.9V with the same load for approx another 48hours. Then it will drop start fluctuating between 12.9 and 12.8 for a few hours and steady out on 12.8 for a day or 2. This is happening with the solar constantly connected. I am getting between 0.2Kw and 0.8Kw per day charge currently (winter). In summer the solar is so much that it pushes the battery bank to 14.3 volts by mid day.

When I switch the diesel heater on, the voltage will drop by 0.2 for startup and then it will draw 0.1V while running. I take the batteries down to approx 12.5V before charging. It lasts 7 to 10 days on full charge depending on the sunshine. When using the inverter to run the hairdryer(1200W) the volts will drop 0.3 and return when done.

I do have a cell equaliser on the system that automatically balances the individual cells when the bank is close to full.

Although I can draw the bank much lower, all my 12V appliances run on 12.2 or higher. I also found that the battery starts dropping faster when going below 12.4 so I tend to keep it above this. The BMS was expensive but it gives you such a carefree run and you only need to buy it once.

Now it is someone else's turn to write an essay. Hope you're still awake after reading through it.

[Maine Sail]

Originally Posted by witzgall

HI all,

If you remember, we have a 400ah lifepo4 house bank. two of the eight cells bulged a bit, most likely from a bad cable going from from one set of four to the other (they are in a 2s4p configuration). I think those two cells were damaged somewhat, but to what extent, I do not know.

What I would like to ask other lifepo4 users is what kind of voltages they are seeing at perhaps a 10a load, with no charging sources. I am now seeing a low voltage from 12.6 - 12.4 under a 5-10a load, and then 12.8-13.1 when the load is less than 2a. They are also reading 13.7+ volts earlier than I think they should when charging under solar/wind.

I have yet to draw them down less than 70% since these lower voltages started happening. Or am I remembering things wrong, and these are ok?

I wired up a cellog 8, but I don't trust it, and getting individual cell voltages means emptying out the quarter berth each time, which is full of stuff (full-time live aboard - garage).

Anyways, I would love to here some thoughts.

Chris

Chris,

In my experience with a 400Ah LiFePO4 pack this is absolutely not normal behavior.. IIRC your bank was over charged due to a solar regulator going into temp compensating. When the temps dropped it drove the battery voltage up and high enough to bulge your cells. Did I remember this correctly?

I can give you some numbers from just today.

A few hours at a 18-20A +/- load (Espar, 12V refrigeration, cabin lights, VHF, stereo & subwoofer with a 400Ah Winston bank. Battery voltage after approx 3 +/- hours was still 13.3V+.

When I kicked on my shop vac, via inverter, and drew 85A the voltage dipped to about 12.8V but then rebounded to 13.3V when turned off and only under the 18-20A load....

We have not yet seen our bank dip below 13.2V under our normal house loads which are between 5A and 20A. When not using the Espar we are normally under 10A and the voltage will hoover at 13.4+ for many hours before dipping into the 13.3 range.

Where are you "sensing" this voltage? Is it a direct voltage sense connection direct to the bank with their own dedicated + & - wires..? No other loads on it other than the voltmeter???

If it is my guess is you damaged a couple of cells. You might try a capacity test...

My Cell Log 8 compares pretty darn close to my Fluke, close enough that I trust it for "at a glance" cell voltages... Our cells have not budged balance wise and are still spot on...

[witzgall]

Yes, it was the alternator going into temp compensation + a bad cable. I am sure that two were damaged, I am just trying to figure out just how bad it is. I think I just need to disconnect the solar/wind and drop them down, and see what happens. We are full-time live aboards, so of course this is hard for me to do!

I could re-configure the pack as a 200ah pack, or if I can find a replacement cell, I have one spare, so I could swap two out. I may write the mfgr. and see if I can still get this form factor, as they have a different shape now.

ugh.

Chris

Originally Posted by Maine Sail

Chris,

In my experience with a 400Ah LiFePO4 pack this is absolutely not normal behavior.. IIRC your bank was over charged due to a solar regulator going into temp compensating. When the temps dropped it drove the battery voltage up and high enough to bulge your cells. Did I remember this correctly?

I can give you some numbers from just today.

A few hours at a 18-20A +/- load (Espar, 12V refrigeration, cabin lights, VHF, stereo & subwoofer with a 400Ah Winston bank. Battery voltage after approx 3 +/- hours was still 13.3V+.

When I kicked on my shop vac, via inverter, and drew 85A the voltage dipped to about 12.8V but then rebounded to 13.3V when turned off and only under the 18-20A load....

We have not yet seen our bank dip below 13.2V under our normal house loads which are between 5A and 20A. When not using the Espar we are normally under 10A and the voltage will hoover at 13.4+ for many hours before dipping into the 13.3 range.

Where are you "sensing" this voltage? Is it a direct voltage sense connection direct to the bank with their own dedicated + & - wires..? No other loads on it other than the voltmeter???

If it is my guess is you damaged a couple of cells. You might try a capacity test...

My Cell Log 8 compares pretty darn close to my Fluke, close enough that I trust it for "at a glance" cell voltages... Our cells have not budged balance wise and are still spot on...

[Zil]

I have used lifepo. I have not bulged any cells. My reading convinces me that when the cells bulge, they have been damaged and will fail.

[McG]

Howdy all you sailors, I'd like to submit 4 quick questions if I may. This may serve as a comparison to see if your bank is within performance spec?
1.To what voltage do you charge your Lifepo4 bank?
2.To what voltage do you draw your Lifepo4 bank before charging?
3. How long does it last after a full charge?
4. What is your average daily load?

[McG]

Originally Posted by gael

since 2010 I'm living on Camao with my wife and our 2y old daugther.
this is a 45ft aluminium sailboat.
We have 2 packs of 130Ah ,8series to get28V, from CALB.
All regulation come from Genasun.
I have also gold plated all connection, screws ect.. (this cost peanut)

So on board we have a100L/H watermaker from desslator
3PCs, MAC and Ipad
One fridge. All ligths with leds
2KW windlass

Since 3 years we have no major issues with this technologies.
Over the 16 cells, one is a bit weak ie it get its max voltage before the others.

Average we can stand mooring for 3daysbefore cranking the engine, fitted with a dedicated 28V 80A alternator
Outside we have a single 130W solar panel.

So far so good.

I'm thinking now to remove all propane intallation ( 80Kgs) on move to full electrical galley. Will be an other story.

Cheers
Gael

Howdy Gael, it is a good alternative if you don't want to fork out the dollar for LIFEPO4. However, lifepo4 has 80% useful energy before hurting the bank whereas LA in all variations has a 50% useability before damage occurs. In plain Greek it means I have 600+ useable amps in my 800Ah lifepo4 pack whereas an 800Ah LA pack only has 400 useable amps.

The lifepo4 stores around 70% of its power in the 11.8V to 13.2V range whereas the LA stores more evenly from 0 to 12.7V Therefore, a big chunk of the 50% useable power is unusable unless you have appliances that run on less than 12V or you have a Boost Power Supply.

A Lifepo4 Winston bank can be recharged from 200 to 800 amps in as little as 4 hours without hurting the pack. That is if you have a big enough charger. You'll send your LA pack to Mars at that charging rate...

I thought I'd throw this bit in just to paint a very basic picture on the main differences between the 2 technologies for those interested. Figures may vary depending on brands. Now I'm outta here ...

[ebaugh]

Originally Posted by McG

Howdy all you sailors, I'd like to submit 4 quick questions if I may. This may serve as a comparison to see if your bank is within performance spec?
1.To what voltage do you charge your Lifepo4 bank?
2.To what voltage do you draw your Lifepo4 bank before charging?
3. How long does it last after a full charge?
4. What is your average daily load?

1. Normally I don't charge to a specific point, just add more energy when the genset is running.

But when underway (power boat), I limit charge to 3.3V per cell or 13.2V. I've run a couple of tests to "full" charge following a couple of days at sea, full charge being 3.6V per cell or 14.4V at about 50A charge, then stop charging. After a long run I've never been able to add more than 100Ah on a 1200Ah bank. This exercise was to determine SOC for a float of 13.2V. And the answer is north of 90% SOC.

For routine charging, I never go past 13.8V. Any voltage over 3.4V per cell or 13.6V, if held long enough, will overcharge and damage the battery. I don't have them, but I would be very conservative with solar or wind chargers.

2. No specific point, 12.5V is the lowest Ive ever seen the bank.

3. I have not tested "capacity" yet. I do need to do that at some point.

4. We use 400-500Ah a day at anchor.

[goboatingnow]

We use 400-500Ah a day at anchor.

wow!

Dave

[McG]

Originally Posted by ebaugh

4. We use 400-500Ah a day at anchor.

Wow again!! That means without charging you will flatten your 1200Ah bank in 3 days??!!
That is a lot of power draw.

[ebaugh]

Originally Posted by McG

Wow again!! That means without charging you will flatten your 1200Ah bank in 3 days??!!
That is a lot of power draw.

It's mostly refrigeration, 4 units. With the ice maker and watermaker off, I can probably get it down to 250Ah. But since our only charging source is the genset, and we have an electric galley, it's not hard to keep them charged.

[poiu]

Just as a comparison, I also have 4 units. A 3 cu ft fridge another at 4 cu ft, each on BD35 keel cooled units. They consume 25A @ 24v. I also use about 50A/day @ 24v for a 9cu ft fridge and an 8 cu ft freezer. Working on an old Glacier Bay compressor system. So 75A total or 150A/day if it were at 12v. Modern equipment is hugely more efficient than old stuff. I suspect efficient equipment is the issue.

My home fridge/freezers use a fraction of the power that the equipment from the mid 1980s. I have changed it twice in that time solely on efficiency grounds where the new equipment was completely paid for in savings in power.

[ebaugh]

Originally Posted by poiu

Just as a comparison, I also have 4 units. A 3 cu ft fridge another at 4 cu ft, each on BD35 keel cooled units. They consume 25A @ 24v. I also use about 50A/day @ 24v for a 9cu ft fridge and an 8 cu ft freezer. Working on an old Glacier Bay compressor system. So 75A total or 150A/day if it were at 12v. Modern equipment is hugely more efficient than old stuff. I suspect efficient equipment is the issue.

My home fridge/freezers use a fraction of the power that the equipment from the mid 1980s. I have changed it twice in that time solely on efficiency grounds where the new equipment was completely paid for in savings in power.

I struggle with the solution vs. the costs on refrigeration. We have two 5 cu ft fridges, one 5 cu ft chest freezer and a Uline ice maker. Except for the ice maker, the others are $200 US free standing appliances. All run on 110-120VAC off the inverter. The solution to get efficient involves 1) insulation, 2) efficient compressor/heat transfer and finally 3) good solar and 4) a propane galley. None of which are present. We asked a couple of refrigeration guys about converting the exiting fridges to BD35 or 50 units in St Martin, but their thoughts without better insulated "boxes", the differences would be be minimal.

We had 18-24 months of cruising left before we plugged in for awhile, so the cost to make us efficient at anchor was not recoverable short term. I did add an active ventilation system for the fridges to give them a fighting chance in the tropics. But the rest was sidelined.

The batteries were a separate decision, comparing FLA to LFP, given the abuse we knew we would give them. So we used the 2 sets of FLA we would have needed to justify the LFP on the hope that the cycle life would make the numbers work.

I will be able to make more comments on that shortly, but so far it looks pretty good.....