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

[caipirinha]

Hi, thanks for the advice, a few points if I may

Originally Posted by ebaugh

1) Of the three I like CALB

Q1 : Any particular reason ? Personnally I was leaning towards Winston, mostly due to their claimed wider temperature range (up to 80°C vs. 55°C for CALB). That being said, the various posts seem to indicate that CALB claims are more serious than Winston's...
I am concerned by resistance to "high" temperatures (40-50°C likely in hot climates for my battery location), and in view of your recent capacity test maybe a higher temperature rating would have helped ?

Other questions :
a) battery monitoring system : my house bank being 24V I will have 8 cells in series (each cell being possibly twin smaller ones in parallel). I plan to have a CellLog8 to monitor voltage at cell level and have LV disconnect (maybe) or alarm.
- Can this remain connected full time ? (it seems a minor modification & firmware upgrade will make it draw the same current from all 8 cells)
- to have cell-level HV alarm, does one still have to set up a second CellLog8 ?
b) solar panels :
- the last thing I want is to fry my future LFP bank by a bad MPPT regulator, but seller's info is not always clear as to their suitability for various types of batteries. Cheap option EV-Power | MPPT Solar Regulator 12/24 V, Tracer 30 A, Input 150V (TR-3215RN) says "Support for LiFePO4 and LiFeYPO4 batteries was tested successfully" but also "Sealed, Gel and Flooded battery option". More expensive could be BlueSolar MPPT 12/24-40 or Régulateur solaire 50A 12/24V BlueSolar MPPT 75/50 Victron Régulateur Solaire MPPT (toutes marques) , noting that usually Victron equipment can be configured but nowhere does it explicitly say suitable for LFP...
- by the way I was planning on 6x12V80W panels (2S3P), can I just connect all 3 sets at the MPPT regulator entry or should I have one MPPT regulator for each set of panels (2S to get 24V)

[goboatingnow]

Originally Posted by Singleprop

Thanks for that, my eye-balling or ball-parking was a bit off.

I assume that the data is based on the battery bank being kept "topped up" - could be a once a month top up or as required, its not clear how they keep the 100% charge for many years...

If my memory serves me correct - keeping a LiFePo4 at 100% charge is not optimal - thats why they are delivered at approximately 50% charge. As per some estimates: 40-90% charge seems to be better for longevity - and cycling the bank also seems to increase the service life.

So the 6 years @ 100% charge is actually not applicable to our use and is way off compared to our continuous cycling of the house bank.

Correct , optimum storage is at around 50-60% SOC. Li shouldn't be subjected to long term float charges. , when the battery is charged disconnect the charging sources.

I currently have a GSM based tracker under development , it has lithium power sources , but that power source is essentially backed up by 12v supply on a nearly permanent basis. This is not dissimilar to a boats battery

Several factors shorten life

(A) mini cycles. Where the battery is subject to light discharge followed by immediate recharge , very common on shore
Power connected or solar boats. Also where load sharing is going on , can lead to a lot of mini cycles.

(B) 100% charge maintained for too long , evidence shows plating of the anodes can occur.

(c) ambient temp cycling.

Such shortening can in fact be quite dramatic resulting in quite large loss of capacity. In my case I don't care because I only need 10 minutes power support . So I can still operate with a battery with reduced capacity.

Li works best in they charge-use-recharge modes , like drills etc where on charging the battery is in the dril until dead.

Lots more data to be collected , life cycle data is still quite sketchy on Li.

Dave

[caipirinha]

Hi,

Originally Posted by goboatingnow

Li works best in they charge-use-recharge modes , like drills etc where on charging the battery is in the dril until dead.

Dave

Would that make a strong argument for twin house banks, one in use (loaded but not charged), one being charged until full then left disconnected, switching from one to other when bank 1 nearing 20-30% SOC ?

[goboatingnow]

Originally Posted by caipirinha

Hi,

Would that make a strong argument for twin house banks, one in use (loaded but not charged), one being charged until full then left disconnected, switching from one to other when bank 1 nearing 20-30% SOC ?

Yes indeed, it would. Not to mention providing a reserve. Could even be asymmetric in size too. Bit more expensive

Dave

[Lagoon4us]

I think that would be a goer, the solar does a good job of alternate charging by availible light.
Anything on a boat is about management the ones who seek a set and forget system are dreaming it doesn't happen with any system on a boat.
It would be very much cheaper to add 4 more cells and a changeover switch and gives a degree of redundancy which i like.
Cheers

[Lagoon4us]

Originally Posted by caipirinha

Hi, thanks for the advice, a few points if I may


Q1 : Any particular reason ? Personnally I was leaning towards Winston, mostly due to their claimed wider temperature range (up to 80°C vs. 55°C for CALB). That being said, the various posts seem to indicate that CALB claims are more serious than Winston's...
I am concerned by resistance to "high" temperatures (40-50°C likely in hot climates for my battery location), and in view of your recent capacity test maybe a higher temperature rating would have helped ?

Other questions :
a) battery monitoring system : my house bank being 24V I will have 8 cells in series (each cell being possibly twin smaller ones in parallel). I plan to have a CellLog8 to monitor voltage at cell level and have LV disconnect (maybe) or alarm.
- Can this remain connected full time ? (it seems a minor modification & firmware upgrade will make it draw the same current from all 8 cells)
- to have cell-level HV alarm, does one still have to set up a second CellLog8 ?
b) solar panels :
- the last thing I want is to fry my future LFP bank by a bad MPPT regulator, but seller's info is not always clear as to their suitability for various types of batteries. Cheap option EV-Power | MPPT Solar Regulator 12/24 V, Tracer 30 A, Input 150V (TR-3215RN) says "Support for LiFePO4 and LiFeYPO4 batteries was tested successfully" but also "Sealed, Gel and Flooded battery option". More expensive could be BlueSolar MPPT 12/24-40 or Régulateur solaire 50A 12/24V BlueSolar MPPT 75/50 Victron Régulateur Solaire MPPT (toutes marques) , noting that usually Victron equipment can be configured but nowhere does it explicitly say suitable for LFP...
- by the way I was planning on 6x12V80W panels (2S3P), can I just connect all 3 sets at the MPPT regulator entry or should I have one MPPT regulator for each set of panels (2S to get 24V)

Try GSL Electronics : Homepage Ours works beautifully and they back up with warranty.

[ebaugh]

Originally Posted by caipirinha

Hi, thanks for the advice, a few points if I may

Q1 : Any particular reason ? Personnally I was leaning towards Winston, mostly due to their claimed wider temperature range (up to 80°C vs. 55°C for CALB). That being said, the various posts seem to indicate that CALB claims are more serious than Winston's...
I am concerned by resistance to "high" temperatures (40-50°C likely in hot climates for my battery location), and in view of your recent capacity test maybe a higher temperature rating would have helped ?

Other questions :
a) battery monitoring system : my house bank being 24V I will have 8 cells in series (each cell being possibly twin smaller ones in parallel). I plan to have a CellLog8 to monitor voltage at cell level and have LV disconnect (maybe) or alarm.

It's a weak preference given the choices you mentioned. Based in part on Jack Rickard's writings, in part due to the turmoil and long term unknowns of the Thundersky breakup.

You are correct to worry about temperature, but I'm not sure if there is a "real" difference or a marketing one.

I believe the CellLog will work for both high, low and cell differential at the same time. However it can only operate one dry contact. So if you want separate solenoids, say one for a charge path and one for a load path to the batteries, it will require multiple CellLogs. Or if you want a remote alarm, that's another CellLog. You've found the 8 cell issue and fix for the CellLog. If you implement that, I don't see any reason it can't stay connected.

I'm not the right person to suggest solar regulators since I've only read the specs, never implemented one. But a runaway failure of the MPPT controller should be detected by your battery monitoring or management system and steps taken to isolate the bank. This system could be a HV alarm at something like 28-28.4V, and you flip a battery switch. But that does assume you will be there to hear it.

[T1 Terry]

Originally Posted by ebaugh

I fully agree with you. But time and effort is an issue, so there are some limits to what I can do.

Yesterday, I validated the test setup. I verified the time base for the CellPro software is using the PC clock for a time base, so that part is accurate. I added a 50A, 50mV shunt to the test rig to verify the current flow. I recharged the cells and it took 79 Ah to go from 0-100% on the weakest cell of 4 in my test pack at 30A. Then I individually recharged all the cells using CC-CV terminating at 3.6V and 2A. That's full.

I am planning to run the discharge test again today. This time to 2.5V on the low cell. In my view, that is 100-0%. Then I will immediately continue the test individually with the 3 remaining cells. This will give me 3 more numbers, one for each cell. Ideally, I would pull more cells, but by the time I get these back installed, I've reached my limit of interest at 30-40 hours invested. 4 of 48 is almost 10%, I have no reason to suspect substantially different results from the other cells.

I heard back from the USA importer of the cells. He indicated their capacity ratings are based on 4.0V to 2.5V, but suggested that range was not recommended. He thought the 2.85-3.6V range might represent about a 5Ah difference. Finally, he suggested that GBS has recently added about 10Ah of capacity to their 100Ah cells to insure the capacity is present at recommended ranges. Oh...and the new cells are on the shelf ready to ship.....

I've been communicating with another EV user of these cells, he has 60 of them installed in converted Mazda with about 200 cycles now. He has not yet run capacity tests post install, but he did prior to install. His new cells ranged from 98-105 Ah when new. He will eventually run some more testing, but rebalancing a 60 cell series connected bank that is bottom balanced is not a trivial task.

What we really need is testing on some other cells installed for a year or more.

A couple of things to remember. My usage at anchor is higher than most. The cells are constantly either under discharge at an average of 20-25A, or under charge at 150-160A. 24x7. These cells are LiFeMnPO4, a slight variation of straight LiFePO4. I don't know if that's good or bad until we start hearing from CALB, Winston, Sinopoly or Thundersky users. I had not noticed in actual operation any deviation from new. But I did size the bank so that at 70% capacity it would still be fully functional for us.

Final numbers in a day or so....

My 720Ah Winston battery pack is made up from half LFP cells and half LYP cells, so half were 3 yrs old in the packing cases and the other half 3 mths old.
The initial capacity test after 3 mths use came in at around 760Ah when I stopped the discharge, there was still some left but I was concerned about cell damage if I went lower. At 6 mths I did a test down to 2.8v for the lowest cell, 780Ah. All tests since then have stopped at 3v per cell so capacity appears less, but not much. At 12 mths, still 760Ah, 18 mths 740Ah but the loads were higher so the 3v may have come up earlier due to the higher loads. At 2 yrs 740Ah and still the same higher loads.
My measurement is via a 200amp shunt, a Plasmatronics PLS shunt adapter and recorded on a PL20 solar regulator. This unit controls all my charging controls plus I have a safety net system that stops charging for 2 mins if a cell reaches 3.6v. The charge parameters are 14.2v for bulk charge, 13.9v for absorption for 2 hrs and 13.8v float, the system returns to bulk charge every day. The batteries are discharged to 50% SOC (360Ah) over night now the heavier loads are connected, they power a lot of my house, solar recharged with 2.5kW of solar. The highest loads would be around 200 amps but that is only short term generally if a number of induction motors try to start up at the same time (2 solar water circulation pumps and 3 fridge freezer compressors)
The next capacity test is around Dec, every 6 mths, the system started running June 2011, only seems like yesterday sometimes, seems like it was never any different other times.

T1 Terry

[ebaugh]

Originally Posted by T1 Terry

My 720Ah Winston battery pack is made up from half LFP cells and half LYP cells, so half were 3 yrs old in the packing cases and the other half 3 mths old.

The next capacity test is around Dec, every 6 mths, the system started running June 2011, only seems like yesterday sometimes, seems like it was never any different other times.

T1 Terry

Terry,

That is better than I'm seeing. Now is it:

1) The battery/slight chemistry difference between GBS and Thundersky/Winston?
2) Temperature? What part of the "Down Under" are you located in and what is the average ambient temp for your bank?
3) Cycle differences, 50% of my time was doing 2 cycles per day, the other 50% was connected to the grid floating.
4) My testing is fixed at a flat 30A discharge rate, or .33 C or so for my test cells capacity.
5) Something I have not thought of, or a combination of sorts.

I owe some more data on my results. Will get that and some pics posted eventually, hopefully soon!

I have been running some tests on new 100Ah "Hipower" look alike cells, white cases sold under a different brand name. They are testing right at rated capacity new out of the box. But unlike my GBS cells, they are essentially discharged at 3.0V, maybe 1-2% capacity remaining at .3C from 3 to 2.85, and falling like a rock at that point. Probably higher than your discharge testing rate?

Bob

[T1 Terry]

My discharge rate depends what is actually running at the time. There are 2 x 1000w PSW inverters powering 2 x 250 ltr fridge freezers, one 500ltr fridge freezer, the solar hot water controls and circulation pumps and the 5 amp battery charger keep my bus project lights on, a Waeco 60 ltr esky type fridge freezer (beer fridge) back patio led lighting and a 600w 12v heater element in the new hot water tank. That means some of the loads switch in and out and some are near constant.
To do the capacity test I switch the hot water service load off and the big fridge if needed to allow the battery to go into float and the charge into the battery to drop to near nothing. Then I reset 100% SOC, zero the Ah out and disconnect the solar, then turn all the loads I removed back on. When the system voltage drops to 11.8v or a cell below 3v the load is turned off, the 240v stuff switched to mains power. I take the readings in the morning and switch everything back to normal but leave the hot water element off till the battery is again past 100% SOC.
Rough answers
The average temp in winter is 10 degC to 25 degC, summer 15 degC to 45 degC.

I think the bigger battery pack made up from 4 x 90Ah cells paralleled allows the strong cells to carry the weak better, the load is less than 0.3C at the highest average, maybe a short peak over it sometimes though.

The chemical make up might be an advantage, they claim better cycle life but not to 100% DoD, only 1,000 cycles for Winston cells, unknown if that means they can no longer supply the advertised capacity past 1,000 cycles or if they just die, haven't found anyone who would put their hand up to do that test.

One of the big differences is Winston cells along with the old Thundersky LFP cells had a bit more than their advertised capacity if the load was less than 1C, quite a bit more if the load was less than 0.5C, I think that allows for an initial loss of capacity when they first settle in, that seems to level out after a while.

My load continually varies, maybe that gives the cells time to capacity balance a little so no cell suddenly hits the end of capacity, voltage drops like a stone then.

I also condition charged all my cells before hey were ever put under load, it reduces their ability to handle high discharges without dropping voltage a bit, but protects them from further build up on the plate surfaces, only time will tell if that theory is correct though. That was just something I picked up watch the Jay Whitacre video for the god knows how manyeth time, each time the knowledge grows and you get a bit more out of it, one very smart cookie is Jay Whitacre, I doubt anyone knows these cells characteristics better than him.

T1 Terry

[nimblemotors]

It is unfortunate you could not do an initial test, without that data there remains the question of what the initial capacity was. Of course, being sold 100ah you should expect 100ah, and if only 80ah now, I'd see about a warranty replacement, keep these guys honest.
Any data on the kinds of temps they experience?

[Jeff Millar]

Would be very interested in your details, how to buy the same set up and cost, suppliers etc along with your recommendations.
I was looking at one House bank battery around 800 to 1000 ah ( seperate engine start battery ).
Ended up almost buying Odyssey PC - 1800 FC ( agm's ) for 1000 ah +
After many tries to find out the size of the battery charger and the detailed charging procedure to follow to meet Odyssey warrant dictates. I was told that ( 80a x 4 ) 320 amp battery charger would be required. Where would even find a 12v, 320 amp charger. This was information from Odyssey.
Would really like to learn from your experience and do things correctly.
I hope to be a full time live aboard and World Cruising Sailboat. Requesting information for my house bank battery and associated battery charger.

Thank you

Jeff

[ebaugh]

Originally Posted by Jeff Millar

Would be very interested in your details, how to buy the same set up and cost, suppliers etc along with your recommendations.
I was looking at one House bank battery around 800 to 1000 ah ( seperate engine start battery ).
Ended up almost buying Odyssey PC - 1800 FC ( agm's ) for 1000 ah +
After many tries to find out the size of the battery charger and the detailed charging procedure to follow to meet Odyssey warrant dictates. I was told that ( 80a x 4 ) 320 amp battery charger would be required. Where would even find a 12v, 320 amp charger. This was information from Odyssey.
Would really like to learn from your experience and do things correctly.
I hope to be a full time live aboard and World Cruising Sailboat. Requesting information for my house bank battery and associated battery charger.

Thank you

Jeff

There just isn't enough information to answer the question. What are your electrically powered loads? Will you have solar or wind charging? Will you have a generator to power the battery charger? What boat are you putting this on?

I would not worry too much about the battery warranty, collecting anything on failed batteries in a boat is difficult if the supplier is in the same city. Thousands of miles away in another country, forget about it.

If interested in LIthium, start at the beginning of this thread on page 1 and start reading.....Narrow the questions a bit and you will get more usable responses.

[hellosailor]

"Where would even find a 12v, 320 amp charger"
Apparently not at the local WalMart, but considering the high power demands for electric vehicles, and Odyssey's blithe mention of it, they must be available from commercial sources.
It isn't very hard to make a bootstrap array of power transistors, so that even a cheap two buck regulator can then control hundreds or even thousands of watts of charging power, so there's nothing to stop these from being available. Or made up custom. (Yes, I've made and used a 1500 watt power supply, based on a cheap 3-terminal regulator and eight bootstrap power transistors. All inexpensive.)

[Talbot]

Originally Posted by caipirinha

b) solar panels :
- the last thing I want is to fry my future LFP bank by a bad MPPT regulator, but seller's info is not always clear as to their suitability for various types of batteries. Cheap option EV-Power | MPPT Solar Regulator 12/24 V, Tracer 30 A, Input 150V (TR-3215RN) says "Support for LiFePO4 and LiFeYPO4 batteries was tested successfully" but also "Sealed, Gel and Flooded battery option". More expensive could be BlueSolar MPPT 12/24-40 or Régulateur solaire 50A 12/24V BlueSolar MPPT 75/50 Victron Régulateur Solaire MPPT (toutes marques) , noting that usually Victron equipment can be configured but nowhere does it explicitly say suitable for LFP...

I have not YET changed to lithium, but have prepared my boat as best I could. I have a generator and Victron multiplus, which can be customised to enable the correct voltages. I also have 555 watts of solar with an Outback Flex 60 controller, which can also be customised as needed.