A Forum run by Enthusiasts of MidNite Solar

Battery talk (A place to discuss any and all battery technologies where the discussion may not fit into other topic areas) => Lithium => Topic started by: mahendra on June 13, 2018, 07:40:44 PM

Title: New lifepo4 battery bank
Post by: mahendra on June 13, 2018, 07:40:44 PM
It been a while my lead acid battery failed after 5 years of somewhat abusive cycling.

I am posting my experiences so far with my CALB lifepo4 battery bank commissioned a few days now.

Recommended voltage setting used by persons with similar chemistries and brands seemed to have worked for me as well,however I will continue to monitor and post updated.

I still have concerns about cell voltages imbalance even after opting to use a bms.

However,123smart bms seems to have a few wonderful features:
1.Automatic load shut down for inverters like OuTback.
2.Charge termination for the CC ( which I did not use because of limitations of my midnite classic and bms).
All of the above is turned ‘ off ‘ or ‘on’ base on user setting of the bms based on soc,voltage and temperature.

The Wbjr does a wonderful job in monitoring but still has its limitations for cell monitoring which a bms does.

I wish there would be a Whizz bang senior which can monitor individual cells so that the present features of the classics and kid can be fully relised.

So far performance is extraordinary as it relates to capacity,depth of discharge, and optimum voltage for my inverter to function when given large loads.

The test of longevity is still yet to be fully proven for lifepo4.

Hope this helps .Will update in the future.

Title: Re: New lifepo4 battery bank
Post by: mahendra on June 13, 2018, 07:46:13 PM
Oh I forgot there is a gain in kwhr produced by your panels since lifepo4 does not require equalization and absorb stage so far has been ridiculously short.

Translation less charging time to full or 90% safe soc for lifepo4.
Title: Re: New lifepo4 battery bank
Post by: ClassicCrazy on June 13, 2018, 08:41:59 PM
A few years ago I bought 48v 100 ah calb pack to try out. I did not get any bms and decided to bottom balance them. I made a couple mistakes where they got really low - I suggest having at least a fail safe to shut off on low voltage so cells don't get damaged. One time I had shut off the input and the inverter but I think the Midnite Classic took them down too low - darn  - I should have shut that off too. Anyway I recovered them and used them . The other day after they have been off and just sitting all winter I decided to check the bottom balance again just to see if all is okay . So I drained them with inverter watching the voltage and SOC and shut them off before pack voltage got too low. I checked individual cell voltages but found one that was below 2 volts - all others were still okay. So I am thinking I need to get a new cell to replace that one - may have gotten damaged in the past mistakes I had made.

So having a BMS is probably not a bad idea - certainly brings the cost up . At the very least a low voltage cut off. There are a number of LiFePO4 batteries with built in bms on the market now I see advertised - Battleborn I think was one and also AltE is selling a different kind too. I guess it just depends if you want to put together your own pack or buy one premade - there is a cost to having it all done and packaged  - but there might be a warranty they give too.

Lithium are not as forgiving as lead acid to mistakes.

Larry
Title: Re: New lifepo4 battery bank
Post by: RossW on June 15, 2018, 05:48:15 PM
I invested in 48V/300AH of LiFePO4 cells in early 2014.
I used a bus-style true balancer that moves charge from "high" cells into "low" cells continuously - while charging, discharging or just sitting static. It's kept all the cells within about 10mV.
A year ago, I added another 600AH in the form of a parallel bank, taking me to 900AH @ 52V (usually sits between 52.2 and 53.0V when not charging, and up to 55.5V as they reach fully charged).
I built my own per-cell monitoring system for confidence, and it's great peace of mind!
LFP rock. They're so stiff, so efficient and so "maintenance free", I'd certainly recommend them to anyone who asks!
Title: Re: New lifepo4 battery bank
Post by: mahendra on June 16, 2018, 06:01:34 AM
 ;D what brand of cells are you using if you don't mind me asking Ross?
Title: Re: New lifepo4 battery bank
Post by: grgdgreek on June 16, 2018, 08:47:04 AM
Quote from: RossW on June 15, 2018, 05:48:15 PM
I invested in 48V/300AH of LiFePO4 cells in early 2014.
I used a bus-style true balancer that moves charge from "high" cells into "low" cells continuously - while charging, discharging or just sitting static. It's kept all the cells within about 10mV.
A year ago, I added another 600AH in the form of a parallel bank, taking me to 900AH @ 52V (usually sits between 52.2 and 53.0V when not charging, and up to 55.5V as they reach fully charged).
I built my own per-cell monitoring system for confidence, and it's great peace of mind!
LFP rock. They're so stiff, so efficient and so "maintenance free", I'd certainly recommend them to anyone who asks!


Hi Ross,
Do you have any pics. of the balancers?
Also where can I buy them?
Thanks
George.
Title: Re: New lifepo4 battery bank
Post by: RossW on June 16, 2018, 05:16:09 PM
Quote from: mahendra on June 16, 2018, 06:01:34 AM
;D what brand of cells are you using if you don't mind me asking Ross?

The first lot were from a company that's since gone bust, or been taken over by someone else. I spent almost a year trying to find their product to buy more, ultimately gave up. The second lot were another company - also in China - who seemed very much more "with it". Responded to my queries for details and specifics each time quickly and generally with all the requested details. While they couldn't do the 300AH prismatic cells I wanted, I ended up settling for 200AH cells and making a 3P16S bank. The interconnects they provided were great. They also picked matched cells for me from the factory, so I got two lots of 48 factory-matched cells. I'll find their name and PM you.

Quote from: grgdgreek on June 16, 2018, 08:47:04 AM
Hi Ross,
Do you have any pics. of the balancers?
Also where can I buy them?

(http://house.albury.net.au/31mar2017/IMG_2875.jpg)

I got them direct from the factory - again, in China - they also were great to deal with. Put whatever lugs on them I wanted, offered me two variants (one with LEDs, one without), arranged express airfreight etc. Not as cheap as those horrible "top balance" toys that most people persist with, that only balance when you have enough power to get all the cells full and then some. I think they ended up costing about $25 per cell (so 16 required in a 3P16S battery)

They will fit neatly down between the cells if you want.
(http://house.albury.net.au/01apr2017/IMG_2877.jpg)

The company I got them from didn't want to deal with "small" orders - because I was doing a bunch of packs, I made their MoQ of 50. I'll ask them if they have a USA distributor and get back to you if thats ok?
Title: Re: New lifepo4 battery bank
Post by: grgdgreek on June 18, 2018, 12:46:34 AM
That would be great!
Thank you,
George.
Title: Re: New lifepo4 battery bank
Post by: bigal on September 14, 2018, 11:58:24 PM
These balancers available Alababa, in qty 1 and up.
I just ordered 16 at $20 each. They work great.
Electric Car Parts Company has them in stock, salt lake City
Title: Re: New lifepo4 battery bank
Post by: RossW on September 15, 2018, 08:12:53 AM
Quote from: bigal on September 14, 2018, 11:58:24 PM
Electric Car Parts Company

I don't want to get the forum in trouble so I'll tone it down... but after my dealings with them, I would go to *ANYONE EXCEPT* those lying swine. And if there was nobody else on the planet could provide the parts... then I'd make my own or go without.

Honestly.
Title: Re: New lifepo4 battery bank
Post by: bigal on September 15, 2018, 08:57:09 AM
That's pretty severe..don't think name calling is appropriate.

I've been treated with courtesy and had a very successful experience. Top notch folks.

Title: Re: New lifepo4 battery bank
Post by: TeraWales on April 01, 2019, 02:01:06 PM
Hi...Lithium cells typically have a 3.7V nominal voltage, and when charging, almost all Lithium batteries are safe to be charged at at least 1C (A 1000ma battery charged at 1A, is 1C). When they are assembled on pcb they have better efficiency. The PCB Assembly (https://www.7pcb.com/PCB-Assembly-Service.php) of the charger should also be efficient one with better rating of components. They are typically brought to 4.2/cell and then monitored for current drop off at the end of the charge until next to zero.
Title: Re: New lifepo4 battery bank
Post by: tecnodave on April 01, 2019, 08:04:23 PM
TeraWhales,

Some chemistries of lithium are 3.7 volt, not all.......be careful recommending. That voltage would destroy Lithium Ferro Phosphate cells.  LFP,s  ,  what we're talking about here

These are entirely different than 18650's  , etc.

David
Title: Re: New lifepo4 battery bank
Post by: mahendra on April 01, 2019, 08:51:19 PM
True. The chemistries stated and is used by most of our members are 3.2 nominal .So charging to those voltages would destroy them.
Title: Re: New lifepo4 battery bank
Post by: mahendra on June 06, 2019, 06:12:10 PM
So I am updating on the performance of my CALB lifepo4  batteries and 123smart BMS.

Batteries seems to be performing well .None or minute differences in voltages at different SOC.Basically like new.

123 Smart BMS however,has been greatly disappointing.
After measuring voltages at different socs and at rest on many occasions I have concluded that this BMS is not accurate in measuring voltages.Readings are all over the place .I even borrowed a fluke just to ensure my radio shack DMM wasn't giving incorrect readings.Turns out my radio shack is as accurate as a fluke and even a klein tool DMM.

This, I have been noticing for nearly a year ,yet I didn't remove it because it was still giving so level of monitoring.
Finally , for two days one of the the boards kept reading a high voltage shutting down charge to the system.Upon removal and verifying on a different cell it was found that the board was defective .Because of this I have now choose to bottom balance and use the SOC setting on the classic to disconnect the inverter.

Bottom line the 123 smart BMS is not worth the money($500+) US.
I support again when I said I wish there was a wb Sr. that has all the features of the wbjr but with individual cell voltage monitoring and temperature.
Calibration setting would be nice too.

123 smart BMS lack this feature .Board cannot be calibrated.
Title: Re: New lifepo4 battery bank
Post by: ClassicCrazy on June 07, 2019, 08:15:35 PM
Quote from: mahendra on June 06, 2019, 06:12:10 PM
So I am updating on the performance of my CALB lifepo4  batteries and 123smart BMS.

Batteries seems to be performing well .None or minute differences in voltages at different SOC.Basically like new.

123 Smart BMS however,has been greatly disappointing.
After measuring voltages at different socs and at rest on many occasions I have concluded that this BMS is not accurate in measuring voltages.Readings are all over the place .I even borrowed a fluke just to ensure my radio shack DMM wasn't giving incorrect readings.Turns out my radio shack is as accurate as a fluke and even a klein tool DMM.

This, I have been noticing for nearly a year ,yet I didn't remove it because it was still giving so level of monitoring.
Finally , for two days one of the the boards kept reading a high voltage shutting down charge to the system.Upon removal and verifying on a different cell it was found that the board was defective .Because of this I have now choose to bottom balance and use the SOC setting on the classic to disconnect the inverter.

Bottom line the 123 smart BMS is not worth the money($500+) US.
I support again when I said I wish there was a wb Sr. that has all the features of the wbjr but with individual cell voltage monitoring and temperature.
Calibration setting would be nice too.

123 smart BMS lack this feature .Board cannot be calibrated.
There are some other less expensive BMS on the market now  - and also a different technology that Ross talked about which balances cells. Sorry to hear your BMS failed.
I tried doing bottom balancing on my Calbs following advice by someone else doing that. I had a few things mess up - might have been my fault but I didn't have any low voltage disconnect. I think the Classic itself took my cells down too low once because it will run to a very low voltage just to be on . So you probably want something that will cut off everything  like maybe contactor in battery line .  Wish I had one then - and also wish I knew what I was doing ! ha ha but they were kind of an experiment .
Check out this store on Aliexpress - this is just one of the many configerations they have listed
I bought a little bms from them and it arrived pretty quickly
https://www.aliexpress.com/item/32888385718.html?storeId=4165007&spm=2114.12010612.8148356.1.388f37feRnpYy4
I have also seen some BMS mentioned in ebike forums that you can connect to via bluetooth via smartphone and the app will show you each individual cell data - not sure if there are those available for bigger size packs like you want but worth checking into .

Larry
Title: Re: New lifepo4 battery bank
Post by: RossW on June 08, 2019, 02:44:34 AM
Quote from: mahendra on June 06, 2019, 06:12:10 PM
I wish there was a wb Sr. that has all the features of the wbjr but with individual cell voltage monitoring and temperature.
Calibration setting would be nice too.

123 smart BMS lack this feature .Board cannot be calibrated.

http://support.rossw.net/batterymonitor/ (http://support.rossw.net/batterymonitor/) are monitoring only of voltage (and optionally temperature) of each cell and cascadable for basically any practical voltage bank or chemistry. Can be (re)calibrated in-situ if its ever required.