Some More Lithium Thoughts And Questions

[OceanPlanet]

Originally Posted by hellosailor

"Something to remember about Li "shelf life", is that it's not like they suddenly stop working" Are the prismatic cells really any different from the LiOn cylindrical cells that way? Because I have seen multiple brand name cylindrical cells, used in computer battery packs, that literally went from 100% charge to totally dead as they hit four years age. Kept as spares, rotated in use, and all of a sudden one that was perfectly good 2-3 months before, was totally dead.


As to how far they can be discharged and cycled...What, anyone would doubt the veracity of manufacturers' claims when they indicate ~5~8000 cycles at deep (~ 70~80%) discharge depths?


Although I seem to recall a mention on the Panbo site that at least one user thinks they will lose 10% capacity every year, no matter "it was the best of butter" how well they are treated?

I'll bet all of those Li batts that went dead on you were Li-Colbalt, not LiFePO4. Different chemistry. And yes, I was speaking of prismatics (specifically CALB's) that we have the most experience with.

[lestef]

How about Yttrium in Winston chemical composition ? Truly influence the cycle life and parameters for better results?
I'm on pace to buy a 48 V, 180/200 Ah battery bank and so far I haven't decided yet between Winston and Calb: both have same prices per Ah, same availability in Europe....Winston have better datasheet, but many people recommend Calb, and if you search on the internet for Lifepo4 battery banks you will find that many of the results are yellow... not gray, not black, not blue... Two months have passed and still I have not decided ...

[mcarling]

Originally Posted by lestef

I'm on pace to buy a 48 V, 180/200 Ah battery bank and so far I haven't decided yet between Winston and Calb: both have same prices per Ah, same availability in Europe....Winston have better datasheet, but many people recommend Calb, and if you search on the internet for Lifepo4 battery banks you will find that many of the results are yellow... not gray, not black, not blue...

If you can get the new CALB CAM series cells (aluminum not plastic case) for a good price....

[SV THIRD DAY]

Originally Posted by mcarling

I hesitate to agree with the idea that 3.6V is a safe charging voltage for LiFePO4 cells. For a relatively short time (avoiding heat build-up), it will not damage the cells, but regularly charging LiFePO4 at excessive voltages (i.e. over 3.5V per cell) may eventually push them out of balance. 3.5V per cell is sufficient to achieve a full charge. I suspect but have not confirmed that 3.45V per cell is probably sufficient to achieve a full charge. I would never ever program any charge to source to apply more than 3.5V to a LiFePO4 cell.

As Mainsails data and others have shown also...charging at 13.8v doesn't seem to do squat to bring the cells out of balance. But it is one of those things that gets said all the time...but where is the real life data to support it?

[Jd1]

I am happy to report that my Lithium system is up and running perfectly!
I am using 700 Ah batteries from Balqon and the HousePower BMS system. I am using three Tyco 200 relays which I found for a bargain of $60 each (!!!) on ebay (they have much smaller gauge wire than the full priced version you buy in the store but otherwise are identical). One of the relays is configured as the 'holy ****' relay cutting off all battery access. It is controlled by a reset switch so manual intervention is required and is tripped by individual cell voltages being too high or too low. The other two relays control the charge and load bus to the batteries and are activated by the HousePower BMS based on pack voltage. These will activate and clear by themselves for unattended operation. I have a lead acid battery system as a backup (my old house batteries) and the connection to the alternator is there all the time which means I can disconnect the charge bus to the lithium pack without worrying about blowing the alternator diodes.
I have a Cellog8 display that gives me individual cell voltages in case I am curious or want to check if I should be re-balancing the cells. Presumably this will not be required but it's nice to be able to see the voltages. I do not use the relay functionality of the Cellog8.
Last but not least, I am using a BMV-700 SOC meter to tell me what the current state of the lithium bank is (volts, amps, instantaneous watts and of course SOC). This little gem of a meter has all kinds of intelligence built in, it has a buzzer and it has a relay output! It also has a serial port output that blurbs out all of it's data every second which I hope to eventually use once I figure out how to send the data out over wifi.
This meter and it's smarts is really the cat's meow! for now I am using the built in relay for additional control of the battery charge bus. I have configured it to activate charging when the battery SOC hits 50% and to turn charging off when SOC goes up to 90%. This assumes that the HousePower BMS has allowed charging.
With the charging controlled by the battery SOC, I can rest assured that the system will even be safe with my charger running while docked. The Lead Acid bank is trickle charged and the lithiums are automatically disconnected when required and will not sit at 100% all the time which is reportedly bad for them.
I am very pleased with how everything works so far but only time will tell if everything works as well as I am expecting.
The one thing that remains is to fix up the wire spaghetti in the one locker that has all the smarts in it. For now, the lid gets closed and the system gets used

[Maine Sail]

Originally Posted by Jd1

I am happy to report that my Lithium system is up and running perfectly!
I am using 700 Ah batteries from Balqon and the HousePower BMS system. I am using three Tyco 200 relays which I found for a bargain of $60 each (!!!) on ebay (they have much smaller gauge wire than the full priced version you buy in the store but otherwise are identical). One of the relays is configured as the 'holy ****' relay cutting off all battery access. It is controlled by a reset switch so manual intervention is required and is tripped by individual cell voltages being too high or too low. The other two relays control the charge and load bus to the batteries and are activated by the HousePower BMS based on pack voltage. These will activate and clear by themselves for unattended operation. I have a lead acid battery system as a backup (my old house batteries) and the connection to the alternator is there all the time which means I can disconnect the charge bus to the lithium pack without worrying about blowing the alternator diodes.
I have a Cellog8 display that gives me individual cell voltages in case I am curious or want to check if I should be re-balancing the cells. Presumably this will not be required but it's nice to be able to see the voltages. I do not use the relay functionality of the Cellog8.
Last but not least, I am using a BMV-700 SOC meter to tell me what the current state of the lithium bank is (volts, amps, instantaneous watts and of course SOC). This little gem of a meter has all kinds of intelligence built in, it has a buzzer and it has a relay output! It also has a serial port output that blurbs out all of it's data every second which I hope to eventually use once I figure out how to send the data out over wifi.
This meter and it's smarts is really the cat's meow! for now I am using the built in relay for additional control of the battery charge bus. I have configured it to activate charging when the battery SOC hits 50% and to turn charging off when SOC goes up to 90%. This assumes that the HousePower BMS has allowed charging.
With the charging controlled by the battery SOC, I can rest assured that the system will even be safe with my charger running while docked. The Lead Acid bank is trickle charged and the lithiums are automatically disconnected when required and will not sit at 100% all the time which is reportedly bad for them.
I am very pleased with how everything works so far but only time will tell if everything works as well as I am expecting.
The one thing that remains is to fix up the wire spaghetti in the one locker that has all the smarts in it. For now, the lid gets closed and the system gets used

Can you explain how you are using the HPBMS with a Tyco normally open relay for the charge bus HVC? Did you find a Tyco that is N/C? Did you find the economizer coils for $60.00? That's a steal if you did!!

The BMV-700 is a great tool. Folks must remember though that it is only as smart as the person programming it and resetting it every time the battery meets full parameters. What did you set for a Peukerts constant?

[Jd1]

Originally Posted by Maine Sail

Can you explain how you are using the HPBMS with a Tyco normally open relay for the charge bus HVC? Did you find a Tyco that is N/C? Did you find the economizer coils for $60.00? That's a steal if you did!!

The BMV-700 is a great tool. Folks must remember though that it is only as smart as the person programming it and resetting it every time the battery meets full parameters. What did you set for a Peukerts constant?

I splurged and spend $3.80 on a little two relay board out of china to reverse the action of the HPBMS for the Tyco. Both HV and LV are run through reversing relays. Yes, these are economizer coils
Peukerts is 1.10, automatic reset is set for 14.8V which would only happen if I was top balancing.

[Maine Sail]

Originally Posted by Jd1

I splurged and spend $3.80 on a little two relay board out of china to reverse the action of the HPBMS for the Tyco. Both HV and LV are run through reversing relays. Yes, these are economizer coils
Peukerts is 1.10, automatic reset is set for 14.8V which would only happen if I was top balancing.

Sweet deal! Do you have a link for those reversing relays. I can think of a couple of uses for them on other projects..

[Jd1]

Originally Posted by Maine Sail

Sweet deal! Do you have a link for those reversing relays. I can think of a couple of uses for them on other projects..

12V 2 Channel Relay Module with Optocoupler H L Level Triger for Arduino New | eBay

[Reed and Elaine]

It was noted earlier on this thread and elsewhere that one should not try charging LFP at temperatures below 0 C (32 F). Should like to know if this is true for all charging rates or only for high rates (0.1 C and higher). We left our rig at son's place at 8000' in northern New Mexico when we took off for a trip to Guatemala and Honduras. The battery bank was left on and the temperatures dropped to -25 F (-32 C) and the system cycled every day for the 3 months we were gone. Things have worked quite well in the eight months since. The charging rate was probably below 600 W 0.06 C).

Reed and Elaine

[Maine Sail]

Originally Posted by Reed and Elaine

It was noted earlier on this thread and elsewhere that one should not try charging LFP at temperatures below 0 C (32 F). Should like to know if this is true for all charging rates or only for high rates (0.1 C and higher). We left our rig at son's place at 8000' in northern New Mexico when we took off for a trip to Guatemala and Honduras. The battery bank was left on and the temperatures dropped to -25 F (-32 C) and the system cycled every day for the 3 months we were gone. Things have worked quite well in the eight months since. The charging rate was probably below 600 W 0.06 C).

Reed and Elaine

There is some evidence that small c-rates at +/- 32F may not be as damaging as high c-rates, but still, every cell maker I know of strongly suggests no charging at cell temps sub 32F. -25F charging is not good for them......

You likely have done some damage, how much damage would be impossible to say especially if you don't have a baseline capacity figure to compare against.

This is why I have continually suggested anyone venturing into DIY LFP set up a repeatable capacity test. Without a baseline, and a good A to A capacity test, that is easily repeatable, you really have no way to know how much damage has been done.

[mcarling]

Originally Posted by Reed and Elaine

It was noted earlier on this thread and elsewhere that one should not try charging LFP at temperatures below 0 C (32 F). Should like to know if this is true for all charging rates or only for high rates (0.1 C and higher). We left our rig at son's place at 8000' in northern New Mexico when we took off for a trip to Guatemala and Honduras. The battery bank was left on and the temperatures dropped to -25 F (-32 C) and the system cycled every day for the 3 months we were gone. Things have worked quite well in the eight months since. The charging rate was probably below 600 W 0.06 C).

Lower charging rates are less stressful (less damaging) to LiFePO4 batteries than higher charge rates at all temperatures. I'm glad to read that your cells seem to be ok after 90 cycles at less than 0.06C with temperatures down to -32C.

I agree with Maine Sail that having a baseline is useful and would allow you to quantify any damage that may have been caused -- if it is enough to be measurable.

[canadian cat]

What are peoples thoughts on these relays. New White Rodgers 586 911 Solenoid Relay 200A 12 VDC SPDT Contactor | eBay

Is White-Rodgers a decent product or is Tyco and other brands worth the extra money?

[offpist]

Hi.
I have installed an 30KWH battery using modules coming from Nissan Leaf wrecked cars.

My setup is 48V/640AH but it could also work on 12V or 24V.

As a 12V setup this would be 2560AH.

I have paid as low as 400 dollar for one complete battery pack.

So far i have picked up 4 battery packs from different wreck dealers and i have a plan to do an similar setup in an 44`sailboat.

[Jd1]

Great price!! Only thing that you have to consider is that it draws around 1A. The Tyco (with the economizer attached) is about a quarter of that.
I wonder if you could use a separate economizer in which case it would be a great alternative especially considering it is double throw!