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

[T1 Terry]

I have around 4 1/2yr experience with a lot of systems that run 24/7 as remote house power set up in R/V's and a few houses that are off grid. In all that time and with well over 100 systems I have never seen an LiFeP04 prismatic cell go dead short circuit. The cylindrical cells do so don't confuse information about one type of cell with the other. Cell voltage monitoring is the only way you will detect a problem before it becomes a serious problem, 8 cells in parallel is seen as one cell when voltage monitoring. A problem with a cell connection will show up as high voltage when charging yet low voltage under load on that cell group. The touch test will tell you real quick just where the problem is because that joint/bolt will be hot to the touch. You could monitor the temp of every connection but a properly cleaned and Alminox protected connection will not give you problems for yrs if you do regular touch tests and bolt tightening checks. The temp sensor/balance boards will cause more problems than they prevent with crushing out resulting in a loose connection so I can't see the value in fitting them in the first place.
As far as Sinopoly and Winston cells, from experience you won't go wrong with either as long as you make sure they aren't old stock that has been sitting on a shelf for 5 yrs. Personally I think the LYP cells are the best there is for house battery use and these are Winston brand, the Sinopoly and Thundersky are LFP, still good quality but I just have a preference for the LYP chemistry as it is more forgiving in low temps and accidental minor over voltage charging.
CALB make excellent electric vehicles cells as they handle high discharge currents with a reduced level of voltage sag, not something experienced with house batteries so of no real value. They do this by reducing the thickness of the active material on the plates, like the difference between lead acid start batteries and deep cycle batteries, reducing the material thickness will result in a shorter cycle life, just one of the trade off for high current low sag discharge capabilities.
Lead acid start batteries connected to Li batteries for charging via the alternator? Makes a high cell disconnect easier as the lead acid battery is somewhere for the alternator to dump its load while it reduces its field current, but you do need to either drop the alternator voltage to around 14v or limit the current as the Li batteries are greedy buggers and they will take all the current they can get resulting in stuffed alternator belts, lead acid batteries failing because of extreme discharging over a long period and the cables/connections get real hot causing problems of their own.
After you have relied on Li batteries for a long time you forget the short comings of lead acid batteries and wonder what has gone wrong when they take so long to recharge yet go flat far too quickly.
As far as engine starting from a deeply discharged Li battery, I've more than once dragged the motorhome batteries below 0% SOC yet they still started the engine when the lead acid wouldn't, even deeply discharged there is still a lot of energy available.


T1 Terry

[T1 Terry]

Originally Posted by exMaggieDrum

I'll ask simply and point blank: Is there any direct knowledge by anyone that Balqon Corp is still in business? Their website does not give a phone number nor an email address, only a contact form. I sent them the contact form and I have not received a reply two weeks later.

I would contact Winston/Thundersky direct and ask them if they still have a distributor in the USA. Balqon was bailed out once by Winston and made the US distributor but it certainly looks like they have not survived in a difficult market place. We have 2 distributors in Aust and they seem to be getting on ok so I can't understand why there isn't sufficient sales in the US to support a distributor

T1 Terry

[OceanSeaSpray]

Originally Posted by exMaggieDrum

Would this imply the need for a temp sensor for each cell, e.g. 16 for a 4p4s configuration? Is there any other way to monitor the temp differences between cells otherwise?

No. What I like to do is slip a sensor between each pair of cells, in one of the vertical grooves of the casings. This allows monitoring a 4S pack with two sensors only, a 2P4S with 4 sensors etc. I don't measure electrode temperature (and I don't care) and this way I get any temperature rise in any of those two cells.

Since they essentially stay extremely close to ambient temperature at all times, any difference anywhere in the readings is of interest. Sensor break or short-circuit is easy to detect and wouldn't compromise reliability.

The other benefit I see is that the sensors are fully isolated electrically and completely surrounded by non-conductive materials. The sensor cables go back to the BMS from there.

[senormechanico]

Originally Posted by 44'cruisingcat

When did you install them, and what's your useage? ie, do you live aboard full-time etc.?

I'm very interested to read about people's long term experiences with LiFEPO4.

It's been at least 5 years if I remember correctly.
We don't live aboard, but we keep the fridge running all the time and have lots of toys on the boat, including ElectroScan Sanitation system, HAM radio, radar, autopilot long distance wifi, computer etc. When we want hot water we turn on the inverter, and the engine never needs to be used for electricity. The battery is full almost every day, and it sure is nice to not have to worry about battery state of charge.
We run them daily to about 55-60%.

The only time shore power is connected is in the dead of winter.

The boat gets liveaboard use in the summertime for about a month and a half.

[exMaggieDrum]

Originally Posted by T1 Terry

I have around 4 1/2yr experience with a lot of systems that run 24/7 as remote house power set up in R/V's and a few houses that are off grid. In all that time and with well over 100 systems I have never seen an LiFeP04 prismatic cell go dead short circuit. The cylindrical cells do so don't confuse information about one type of cell with the other. Cell voltage monitoring is the only way you will detect a problem before it becomes a serious problem, 8 cells in parallel is seen as one cell when voltage monitoring. A problem with a cell connection will show up as high voltage when charging yet low voltage under load on that cell group. The touch test will tell you real quick just where the problem is because that joint/bolt will be hot to the touch. You could monitor the temp of every connection but a properly cleaned and Alminox protected connection will not give you problems for yrs if you do regular touch tests and bolt tightening checks. The temp sensor/balance boards will cause more problems than they prevent with crushing out resulting in a loose connection so I can't see the value in fitting them in the first place.
As far as Sinopoly and Winston cells, from experience you won't go wrong with either as long as you make sure they aren't old stock that has been sitting on a shelf for 5 yrs. Personally I think the LYP cells are the best there is for house battery use and these are Winston brand, the Sinopoly and Thundersky are LFP, still good quality but I just have a preference for the LYP chemistry as it is more forgiving in low temps and accidental minor over voltage charging.
CALB make excellent electric vehicles cells as they handle high discharge currents with a reduced level of voltage sag, not something experienced with house batteries so of no real value. They do this by reducing the thickness of the active material on the plates, like the difference between lead acid start batteries and deep cycle batteries, reducing the material thickness will result in a shorter cycle life, just one of the trade off for high current low sag discharge capabilities.
Lead acid start batteries connected to Li batteries for charging via the alternator? Makes a high cell disconnect easier as the lead acid battery is somewhere for the alternator to dump its load while it reduces its field current, but you do need to either drop the alternator voltage to around 14v or limit the current as the Li batteries are greedy buggers and they will take all the current they can get resulting in stuffed alternator belts, lead acid batteries failing because of extreme discharging over a long period and the cables/connections get real hot causing problems of their own.
After you have relied on Li batteries for a long time you forget the short comings of lead acid batteries and wonder what has gone wrong when they take so long to recharge yet go flat far too quickly.
As far as engine starting from a deeply discharged Li battery, I've more than once dragged the motorhome batteries below 0% SOC yet they still started the engine when the lead acid wouldn't, even deeply discharged there is still a lot of energy available.
T1 Terry

Thanks Terry. Good info. Very helpful. Regarding your suggestion to contact Winston, I did and they said I should order batteries direct from them, i.e. no US distributor. I will follow up and see what the logistics might be but that would add a big level of difficulty and cost. Others have warned not to do that. The Winston LYPs sound good and based on what I have seen I am leaning towards them.

[exMaggieDrum]

Originally Posted by OceanSeaSpray

No. What I like to do is slip a sensor between each pair of cells, in one of the vertical grooves of the casings. This allows monitoring a 4S pack with two sensors only, a 2P4S with 4 sensors etc. I don't measure electrode temperature (and I don't care) and this way I get any temperature rise in any of those two cells.

Since they essentially stay extremely close to ambient temperature at all times, any difference anywhere in the readings is of interest. Sensor break or short-circuit is easy to detect and wouldn't compromise reliability.

The other benefit I see is that the sensors are fully isolated electrically and completely surrounded by non-conductive materials. The sensor cables go back to the BMS from there.

Thanks for the excellent suggestion/clarification. Makes sense as far as the practical temp measurement and the electrical isolation. I really don't prefer to put sensors in the terminal stack and then tighten it all down.

[mcarling]

Originally Posted by exMaggieDrum

I have room for about 9H x 14W x 23L.

40 CALB CAM72 cells would provide 720AH in a 12V configuration and would easily fit within 12" x 22". The cells are 8.75" high without fasteners, so height might be a problem.

[exMaggieDrum]

Originally Posted by mcarling

40 CALB CAM72 cells would provide 720AH in a 12V configuration and would easily fit within 12" x 22". The cells are 8.75" high without fasteners, so height might be a problem.

I was thinking 16 was a lot of cells. 40? But they would fit if you did the math right.

[mcarling]

Originally Posted by exMaggieDrum

I was thinking 16 was a lot of cells. 40? But they would fit if you did the math right.

I computed the size without the plastic spacers, but you should be fine even with the plastic spacers if the height will not be a problem. I didn't have space for the plastic spacers so wrapped each cell in Tyvek to ensure the cells are electrically isolated from each other. Wrapping them in Tyvek instead of using the plastic spacers that come with the cells also allows for them to be compressed, but eliminated cooling airflow. With the fractional C charging and discharging we have on boats, I don't think either the compression or the cooling airflow are important. Just be conservative with charging voltage and your discharge limit and you should be fine.

In the 10x4 configuration that would fit your space, I would cut copper sheet, three with 2x10 rows of holes and two with 1x10 rows of holes to interconnect the cells. Stacking ordinary connectors would work too.

[mcarling]

BTW, exMaggieDrum, you could fit 4x11 CALB CAM72 cells into your space if you wanted about 800AH rather than about 720AH. I don't think 4x12 would fit, but you can check more precisely than I can.

[44'cruisingcat]

Originally Posted by senormechanico

It's been at least 5 years if I remember correctly.
We don't live aboard, but we keep the fridge running all the time and have lots of toys on the boat, including ElectroScan Sanitation system, HAM radio, radar, autopilot long distance wifi, computer etc. When we want hot water we turn on the inverter, and the engine never needs to be used for electricity. The battery is full almost every day, and it sure is nice to not have to worry about battery state of charge.
We run them daily to about 55-60%.

The only time shore power is connected is in the dead of winter.

The boat gets liveaboard use in the summertime for about a month and a half.

Thanks for the info!

I'd really like to hear about someone who's been using these batteries full-time for 10+ years. Which is a bit of an ask, I know, since they probably haven't been readily available for much longer than that.

[mcarling]

Originally Posted by 44'cruisingcat

I'd really like to hear about someone who's been using these batteries full-time for 10+ years. Which is a bit of an ask, I know, since they probably haven't been readily available for much longer than that.

To the best of my knowledge, commercial availability of LiFePO4 cells began in 2007. Does anyone know of earlier commercial availability?

[Highland Fling]

We have available 800AH. I have 200AH sitting in a 4P not in use/in circuit configuration. 200AH is normally switched out of circuit, so we are using 400AH for everything including cooking induction hob/Microwave/Instant Pot/Rice Cooker. I have 800AH because I could have that very cheaply AND at that stage I still had LA thinking. Now having some sort of experience of LIFePO4 batteries I UNDERSTAND the totally different thinking needed when you move from LA to LIFePO4 batteries. For sure I am a happy bunny LIFePO4 beats Duracell

[senormechanico]

Highland Fling said it.
You literally have to take a leap of faith.

[ColdEH]

I have 600ahs of Sinopoly cells on my boat , been in service for over a year . They are great , no balancing problems at all and have given my nothing but great service. We split our time between the boat and the house so essentially they have seen live aboard service . Pics of my install on my profile page.

Regards