LFP battery chatter ( AKA LiFePo4, Lithium Iron Phosphate )

[northerner]

I am following your conversation with great interest, having just looked first at AHI, then AGM, and finally FLA as a newbie. I did not spend time on LFP, because an article I read made the case that LFP are not well suited for off-grid applications without an integrated battery monitoring system at the individual battery level - since if one battery in a series string goes to too high a voltage, it can be destroyed. Something like that.

Balqon claims on their site that their LFP Energy Storage Systems include a built in BMS that monitors cell temperatures and controls voltages. They also claim they work seamlessly with most leading solar inverters and charge controllers. They do stipulate that maximum charge voltage is not to exceed 28.8 volts.

[Living Large]

Balqon claims on their site that their LFP Energy Storage Systems include a built in BMS that monitors cell temperatures and controls voltages. They also claim they work seamlessly with most leading solar inverters and charge controllers. They do stipulate that maximum charge voltage is not to exceed 28.8 volts.

There you go - where there is a need, there is innovation.

I'd be very interested in literature they have that specifies which inverters and charge controllers and/or manufacturers they are compatible with. I browsed their site quickly, I'll have to look further when I have a chance.

[Sunking]

Balqon claims on their site that their LFP Energy Storage Systems include a built in BMS that monitors cell temperatures and controls voltages. They also claim they work seamlessly with most leading solar inverters and charge controllers. They do stipulate that maximum charge voltage is not to exceed 28.8 volts.

None of that is unique to Balqon. Just about every LFP distributor packages their batteries with a BMS that is compatible with most controllers you can limit voltage to 14.6 volts for 12 volt, 29.2 for 24 volt, and 58.4 volts at 48 volt battery.

What is unique about Balqon is they are going bankrupt. Don't believe me? Fine, go look for yourself just Google the search term "balqon bankruptcy" and see what you get.

For LFP it does not take elaborate Active BMS that monitors everything and shuffles power around from one cell to the next. That is only required for EV's where you want to optimize range to squeeze every AH into each cell you possible can. That is not required for solar as you only design to discharge around 30 to 35% a day. That extra AH does not buy you anything, only shortens cycle life. All solar requires is a simple Passive BMS circuit board that Bleeds the Cell or in practice shunts current around a fully charged cell. Basically it switches on when when the cell reaches a predetermined voltage of around 3.6 volts, then diverts charge current around the cell to charge lower state of charged cells.

LFP does not require cell temperature monitoring of any kind because they do not go into thermal runaway. Even if they could on a solar system you cannot and will not charge or discharge at high enough rates to cause them to Thermal Runaway. All you need is a simple device to prevent overcharging and LFP is pretty forgiving with respect to over charging as you can go as high as 4 volts per cell without damage. Th eonly thing they are sensitive to like any lithium chemistry is is over discharge and a simple Low Voltage Disconnect protects you from that problem.

I have a 48 volt GBS 100 AH system in my golf cart. It cost me roughly $2900 and came with BMS and LVD. I do not use the LVD device because my motor controller has it built into its firmware to operate the traction battery solenoid. I charge them with a standard 48 volt golf cart charger set up for float voltage set to 90% SOC of 3.55 volts or 56.8 volts. But the good news is with solar, you don't have to be dead nuts on because solar is not a stiff source and will never reach 100% SOC which is a good thing because you double the life cycles only going to 89 to 90% SOC.

So the only thing you really have to worry about if using solar to charge lithium is over discharging, and an occasional balancing of the batteries. All that takes is a Low Voltage Disconnect device which hopefully never gets activated, and a good 12,24, 48 volt ac powered battery charger to balance cells once in a while by using the BMS bypass boards you get with your cells. You simple leave it on at at a low charge rate until all the BMS boards turn on indication 100% SOC. Piece of cake.

[northerner]

None of that is unique to Balqon. Just about every LFP distributor packages their batteries with a BMS that is compatible with most controllers you can limit voltage to 14.6 volts for 12 volt, 29.2 for 24 volt, and 58.4 volts at 48 volt battery.

What is unique about Balqon is they are going bankrupt. Don't believe me? Fine, go look for yourself just Google the search term "balqon bankruptcy" and see what you get.

For LFP it does not take elaborate Active BMS that monitors everything and shuffles power around from one cell to the next. That is only required for EV's where you want to optimize range to squeeze every AH into each cell you possible can. That is not required for solar as you only design to discharge around 30 to 35% a day. That extra AH does not buy you anything, only shortens cycle life. All solar requires is a simple Passive BMS circuit board that Bleeds the Cell or in practice shunts current around a fully charged cell. Basically it switches on when when the cell reaches a predetermined voltage of around 3.6 volts, then diverts charge current around the cell to charge lower state of charged cells.

LFP does not require cell temperature monitoring of any kind because they do not go into thermal runaway. Even if they could on a solar system you cannot and will not charge or discharge at high enough rates to cause them to Thermal Runaway. All you need is a simple device to prevent overcharging and LFP is pretty forgiving with respect to over charging as you can go as high as 4 volts per cell without damage. Th eonly thing they are sensitive to like any lithium chemistry is is over discharge and a simple Low Voltage Disconnect protects you from that problem.

I have a 48 volt GBS 100 AH system in my golf cart. It cost me roughly $2900 and came with BMS and LVD. I do not use the LVD device because my motor controller has it built into its firmware to operate the traction battery solenoid. I charge them with a standard 48 volt golf cart charger set up for float voltage set to 90% SOC of 3.55 volts or 56.8 volts. But the good news is with solar, you don't have to be dead nuts on because solar is not a stiff source and will never reach 100% SOC which is a good thing because you double the life cycles only going to 89 to 90% SOC.

So the only thing you really have to worry about if using solar to charge lithium is over discharging, and an occasional balancing of the batteries. All that takes is a Low Voltage Disconnect device which hopefully never gets activated, and a good 12,24, 48 volt ac powered battery charger to balance cells once in a while by using the BMS bypass boards you get with your cells. You simple leave it on at at a low charge rate until all the BMS boards turn on indication 100% SOC. Piece of cake.

Not sure if that is old news with economic difficulties Balqon has encountered, but I did find this link suggesting that they had a good third quarter of 2014? Perhaps they are making a come back? Check out this link. https://www.einnews.com/pr_news/2379...d-quarter-2014

And thanks for the info about the BMS with LFP cells Sunking! That's the kind of info I was looking for!

[Living Large]

This is a little off topic, but does anyone know of company(ies) other than Balqon that sell LFP "energy systems" - complete packages that include a BMS? Balqon has good looking products, but the company appears to be on life support.

The Balqon 30kwh system is about $15k, which isn't bad compared with the $11K+ I was looking at for a quality 800Ah 48V FLA bank. I'd be nervous sending them a check for $15K+ though.

[SunEagle]

This is a little off topic, but does anyone know of company(ies) other than Balqon that sell LFP "energy systems" - complete packages that include a BMS? Balqon has good looking products, but the company appears to be on life support.

The Balqon 30kwh system is about $15k, which isn't bad compared with the $11K+ I was looking at for a quality 800Ah 48V FLA bank. I'd be nervous sending them a check for $15K+ though.

It would be wise to be as cautious as possible with any new "tech" company unless you have money to burn.

[Sunking]

This is a little off topic, but does anyone know of company(ies) other than Balqon that sell LFP "energy systems" - complete packages that include a BMS? Balqon has good looking products, but the company appears to be on life support.

The Balqon 30kwh system is about $15k, which isn't bad compared with the $11K+ I was looking at for a quality 800Ah 48V FLA bank. I'd be nervous sending them a check for $15K+ though.

Sure, already covered this. Any place that sells LFP batteries for DIY EV's. Google EV batteries

Evolve
EV Source
EV Power
Electric Car Parts
EV West
Elite Power Solution
EV Propulsion

Are just a tip of the iceberg. See any pattern? Don't look for solar battery suppliers. Large format Lithium is an EV product.

[Living Large]

Sure, already covered this. Any place that sells LFP batteries for DIY EV's. Google EV batteries

{snip of list}

Are just a tip of the iceberg. See any pattern? Don't look for solar battery suppliers. Large format Lithium is an EV product.

Thanks! You will recall I looked at AHI and then AGM for my 7kwh/day usage, with 4400W of PV and was planning for a high quality 700 to 800Ah @48V FLA battery bank. I only have 2 hours of insolation on average on Dec 21. I ended up thinking I might pay $11K for FLA. The Balqon 30+kwh package looks attractive at $15K if it weren't for the fact their stock is 3 cents per share, after a recent high of around 20 cents per share about 6 months ago, and the 5 year warranty may well be useless.

Anything you can say to sway me one way or the other I would be interested in. If something reliable cost 50% more than FLA, I'd pay that premium unless you can show me why other than cost I'd be making an error.

[Sunking]

I only have 2 hours of insolation on average on Dec 21. I ended up thinking I might pay $11K for FLA. Anything you can say to sway me one way or the other I would be interested in. If something reliable cost 50% more than FLA, I'd pay that premium unless you can show me why other than cost I'd be making an error.

Well with age comes wisdom and experience. Or in other words you screw up enough times you eventually get it right. Once you dip below 3 Sun Hours you cross the line of exceeding FLA C/8 max charge limits. But does that mean you cannot use FLA?

No it does not necessarily mean it rules out FLA. If you have an Off-Grid System, then must have a generator. That gives you the option to use the genny early in the morning for bulk charge, and use less panel wattage for all those months when you get more than 3 Sun Hours. In those cold winter days you do not need much refrigeration an dwinter daily watt hours usage should be much lower than say summer. If you are only looking at 4 to 6 weeks of less than 3 Sun Hours I think economics dictate using 3 Sun hour design, FLA batteries, and use the genny an hour or two each day to provide a full C/8 charge current.

A 7 Kwh/day FLA at 48 volt is a 700 AH battery, and with a 3 Sun Hour day requires a 3500 watt solar panel with a 60 amp controller. That will roughly cost you $11 to $12K I think.

A 7 Kwh/day LFP at 48 volts is a 430 AH battery, and to go down to 2 Sun hours for month requires a 4900 watt solar panel and a 80 amp controller. That will cost you roughly $14 to $15K.

Either way you still need the same size genny. All you got to do is figure out if the added fuel cost is worth it or not as both batteries will last you realistically 5 to 6 years. So how long are you below 3 Sun Hours is the key to answer the question. You gotta answer that without my help.

FWIW I would not buy Balqun. Just too many ifs for my comfort. CALB is best bang for the buck and has a good track record. I cannot answer about Balqun as I or anybody I know has any experience with them. My first choice is GBS followed by Calb. GBS is a little higher in cost, but offers slightly better performance, and a better mechanical package.

Hope that helps.

[Living Large]

LFP battery chatter

Well with age comes wisdom and experience. Or in other words you screw up enough times you eventually get it right. Once you dip below 3 Sun Hours you cross the line of exceeding FLA C/8 max charge limits. But does that mean you cannot use FLA?

No it does not necessarily mean it rules out FLA. If you have an Off-Grid System, then must have a generator. That gives you the option to use the genny early in the morning for bulk charge, and use less panel wattage for all those months when you get more than 3 Sun Hours. In those cold winter days you do not need much refrigeration an dwinter daily watt hours usage should be much lower than say summer. If you are only looking at 4 to 6 weeks of less than 3 Sun Hours I think economics dictate using 3 Sun hour design, FLA batteries, and use the genny an hour or two each day to provide a full C/8 charge current.

A 7 Kwh/day FLA at 48 volt is a 700 AH battery, and with a 3 Sun Hour day requires a 3500 watt solar panel with a 60 amp controller. That will roughly cost you $11 to $12K I think.

A 7 Kwh/day LFP at 48 volts is a 430 AH battery, and to go down to 2 Sun hours for month requires a 4900 watt solar panel and a 80 amp controller. That will cost you roughly $14 to $15K.

Either way you still need the same size genny. All you got to do is figure out if the added fuel cost is worth it or not as both batteries will last you realistically 5 to 6 years. So how long are you below 3 Sun Hours is the key to answer the question. You gotta answer that without my help.

FWIW I would not buy Balqun. Just too many ifs for my comfort. CALB is best bang for the buck and has a good track record. I cannot answer about Balqun as I or anybody I know has any experience with them. My first choice is GBS followed by Calb. GBS is a little higher in cost, but offers slightly better performance, and a better mechanical package.

Hope that helps.

I appreciate very much appreciate these further thoughts on that system, including alternatives and suppliers.

Just curious and this is probably a silly question - what explains going from a 700Ah FLA to 430Ah LFP? Is this assuming close to a 80% DOD for the LFP? Looking at the curves, I was thinking of not going much beyond 60% so to not reduce the cycles. Does it make more sense to take advantage of the larger % of capacity, buy a smaller bank, and take the hit on lifetime cycles? I was originally planning for 2 days of autonomy and a 50% DOD with the 700-800Ah FLA.

[Mike90250]

I only have 2 hours of insolation on average on Dec 21.

You need to incorporate a generator into your system for use for at least 3 months of the year. You don't have to use it, but you need one there, in case you cannot reduce loads any further, and risk damaging the batteries from low charge state.

To try to increase your solar to cover this shortfall, will be very expensive.

You can consider micro hydro, if you have water and elevation change at your site, Even a 200w micro-hydro will give you over 24 hours, 4,800 watt hours. Or wind, if you have to tie your hat on every time you go outside.

But it's not going to easily happen with solar only.

[Sunking]

I appreciate very much appreciate these further thoughts on that system, including alternatives and suppliers.

My pleasure and glad to help.

Just curious and this is probably a silly question - what explains going from a 700Ah FLA to 430Ah LFP?

Not silly at all. For FLA you design for 5 day reserve capacity with roughly 3 days usable down tho the 50/60% DOD. With lithium we can do that with 3 day capacity to be apples to apples. So lets say you want 1 Kwh per day using a 48 volt battery system.

To do that with FLA requires [5 days x 1 Kwh] / 48 volts = 104 AH, or 100 AH is close enough.
For LFP requires requires [3 days x 1 Kwh] / 48 volts = 62.5 AH or call it 60 AH.

I need to add a caveat here. FLA is significantly effected by Peukert Law and this example assumes no more than C/20 discharge rate over a 24 hour period. Usually no problem. LFP is not effected by Peukert Law to any extent so it can be ignored. Where this example falls apart is if you have an application that requires a continuous high discharge current all at one time. For example lets say after dark at 10:00pm you run a irrigation pump for 2 hours at 500 watts. That turns your 100 AH FLA into a 50 AH battery and would be fully discharged in 1 day of use. It would require a 200 AH FLA to equal a 60 AH LFP.

[northerner]

FWIW I would not buy Balqun. Just too many ifs for my comfort. CALB is best bang for the buck and has a good track record. I cannot answer about Balqun as I or anybody I know has any experience with them. My first choice is GBS followed by Calb. GBS is a little higher in cost, but offers slightly better performance, and a better mechanical package.

Hope that helps.

I don't know much about Balqon either, but a quick search with others that had dealings with them, show that they have good customer support. Their batteries are from Winston, which is a large company in China that has been designing and producing LFP batteries for years. Any feedback on Winston batteries?

The one significant advantage I see with Balqon is that they are producing battery packages, that are ready to go for off grid storage systems, with built in BMS, and for a reasonable cost. I don't see other companies doing this???

[Sunking]

Any feedback on Winston batteries?

Winston aka as the Yellow LFP is a spin-off from bankrupt Thundersky. Thundersky split between three companies Sinoploy the black LFP and Winston the Yellow LFP battery, Balqon the other Yellow battery. Calb is the Gray LFP and GBS is the blue LFP battery. I do know a few EV folks that use Black LFP batteries and no real complaints. Take away here is all of the Chi-Com primatice large format batteries are copies of the original Thundersky batteries. Balqon schtick is the very large format cells of 200 AH plus intened for large EV's

The one significant advantage I see with Balqon is that they are producing battery packages, that are ready to go for off grid storage systems, with built in BMS, and for a reasonable cost. I don't see other companies doing this???

Like I said that is not unique. Any of the authorized distributors from any manufacture sell packed systems for E-Bikes, vehicles, or energy storage. All do custom Turn Key packages to any specification. For example I bought my 48 volt package deal (16 cells) 100 AH battery from Elite. That same package can be used for solar. They came fabricated in a 4 x 4 block with BMS ready to drop right in place with all hardware and handles You can use any charger. Can be a plain ole 48 volt golf cart charger or a solar mppt controller. Makes no difference as the BMS is the interface. All the charger needs to do is operate at the correct voltage, and for LFP is the exact same as Lead Acid.

[northerner]

Winston aka as the Yellow LFP is a spin-off from bankrupt Thundersky. Thundersky split between three companies Sinoploy the black LFP and Winston the Yellow LFP battery, Balqon the other Yellow battery. Calb is the Gray LFP and GBS is the blue LFP battery. I do know a few EV folks that use Black LFP batteries and no real complaints. Take away here is all of the Chi-Com primatice large format batteries are copies of the original Thundersky batteries. Balqon schtick is the very large format cells of 200 AH plus intened for large EV's

.

I was actually just reading up on this. There is a short write up here but is in dutch (can click on translate): http://de.wikipedia.org/wiki/Winston_Battery

Also, I found a university that did some testing on a Winston cell. They did repeated charge and discharge cycles and posted the results. They only took the cell up/down 10% each time though:

http://www.auto88.cz/_info/Tests/GWL-Power-Performance-Test.pdf

Like I said that is not unique. Any of the authorized distributors from any manufacture sell packed systems for E-Bikes, vehicles, or energy storage. All do custom Turn Key packages to any specification. For example I bought my 48 volt package deal (16 cells) 100 AH battery from Elite. That same package can be used for solar. They came fabricated in a 4 x 4 block with BMS ready to drop right in place with all hardware and handles You can use any charger. Can be a plain ole 48 volt golf cart charger or a solar mppt controller. Makes no difference as the BMS is the interface. All the charger needs to do is operate at the correct voltage, and for LFP is the exact same as Lead Acid.

Thanks for that!