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Up grade from lead acid.

1697 Views 18 Replies 7 Participants Last post by  remy_martian
144 volt system going with old school CALB. Read a lot about how to convert my NG3 to lithium.
Probably best I send it off and let someone else do that.
Can someone recommend a BMS that has worked well for them using CALB.
Reliable low tech blinking light will work. On the high tech end,
BMS hooked to I-pad to actively monitor each cell. (don't know if that is possible)
Reference links on where to send charger and links for BMS would be great.

Thanks you for your help.

My Daughter loves her EV

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I just want to say that's an awesome lead acid powered car. Technically you'll have about 3 times more range from the same weight of lifepo and 6 times more range from the same weight of li-ion... the choice probably depends on the charging temperature, steer clear of LiFePO4 if you want to charge near freezing temps.
 

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Discussion Starter · #6 ·
Looks like things are going to be OK. A lot of discussion on new threat.
I am trying to use existing Zivan NG3 charger. Follow there and share
what you know. Got some pretty smart members out there.
Thanks.
 

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Discussion Starter · #7 ·
Always thinking outside the box. Watch these two videos and see my post to videos below.
(No answer as of yet. Thought I would post it out there for you guys.)
Does anyone have an opinion if this will work or how to make it work.
I am looking for an alternative to spending $1500 on a BMS.


I have watched this video and the video where you put 2 BMSs in series. I have 45 (3.2v) lithium iron phosphate cells making up a 144v battery pack. I am asking can I manage all the cell with two 24s BMSs connected in series but not connected to the battery pack for charge and discharging. (use them as switches as demonstrated in video) Run 12volts through them to a solenoid contact-er that will turn off the charger when max voltage is reached per any one cell. If yes, I intend on adding a two way switch on dash. Up for charge and down for discharge. On discharge BMS will interrupt 12v to main contact-er for low voltage shut-off.

Let me know what you think. Thanks a bunch.
 

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Still Not sure how you use a bms for cell management when it isn't connected to the cells........but two 24's will work if you dummy the spare positions. You are describing typical bms operation. Otoh, Low voltage needs a generous warning so you can pull over, sucks to shut down during rush hour just because you hit the magic number and your pack disconnects 1/4 mile from home downhill.
 

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Discussion Starter · #9 ·
That is a great idea. "Low battery warning Light"
Spending a little more for a BMS that offers programmable function and bluetooth is in the budget.
Daly seems to be a popular choice.
There are a lot of affordable management options; but, the big question is.
Is the switch between P- and BL- a simple contact switch controlled by the processor?

Maybe other members will read these posts and someone will know how this switch works.
Thanks, James
 

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are your 45 LiFePO4 cells new? How much do you have invested in the cells alone?
2-4 thousand?
Is the switch between P- and BL- a simple contact switch controlled by the processor?
BL-? Daly's usually have a B-(battery negative) and a P-(power and charge negative) wire and switch isn't a contact switch but a mosfet.
Product Rectangle Font Slope Parallel

The diagram isn't to scale. and there are things that I am sure I did wrong. as noted earlier in this thred there are several bms's that are under $1000 for a 48s system, this bms looks interesting https://www.aliexpress.com/i/4001138179223.html and would be much less than $1000. Not sure if it is any good. Later floyd
 

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Discussion Starter · #11 ·
I have spent hours searching AliExpress but never came across this product. You are the man. Thanks.

It was stated in the relay contactor video that mosfet based BMS are not used by DIY EV'ers
but he did not state what kind were used. I did not know Daly used mofsets.
From what I have learned one should not use a Balancer that merely bleeds power off through resistors.
but one that transfers power from high cells to low cells. Do you have any idea what kind BMS he is referring to?
 

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Bms's typically are passive almost all balance by resistors high end/ low end Jehu says alot of stuff. Most of the bms's used by DIY EV'ers edit use (BMS) are resistor based. only recently has there been a few that use Active balancing. Active balancing can hide a problem until it is too late. Orion BMS, Batrium Bms, Emus BMS, Dilithium BMS all used passive balancing REC BMS uses both passive and active balancing active balancing is only avaiable on a 4s bms from REC last I heard.
You can also get a 24s smart active balancer standalone model that is daisy chainable. set up with an app. quality is unknown
Later floyd
 

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Discussion Starter · #17 ·
I like the relay concept then watched a demo of product on Will Prowse's channel.
Wow, really tough to get all programed in. And, you say your product has problems.
I read reviews but It is guys like you that spread the word. Thanks
 

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Discussion Starter · #18 ·
Hi guys, My batteries just arrived from China.
What is the best MAX charge voltage for LiFePo4? Tested!
That is an in-depth video! You can fast forward to end for test result if graphs bore you.

I heard back from:
ELCON / Electric Conversions
515 N. 10th Street, Sacramento, CA 95811
www.elconchargers.com www.zivanusa.com

Their Reply:

The NG3 can be reprogrammed by us for 45 x 3.65V = 164.25V charging. Cost
is $75 plus shipping back. Please ship to address below with a copy of this
email in the box. We don't sell BMSs. There is no enable/disable control
in the NG3.
You can use a relay in the AC supply to the charger which is
energized by the charger enable output of your BMS.
Regards, Sayyed A. Bashir

The BMS I am going with is from a company called BATRIUM and their product is CellMate-K9 suitable for a shared wiring harness that can be used in conjunction with the WatchMon CORE supervisor. It has all the features including cell
and pack voltage and built in relay that can turn off the charger relay when set voltage is reached.

QUESTION: If my existing Zivan, set for lead acid, charges to 159.6 divided by 45s equals 3.54 (per cell) and the BMS
will turn off the charger WHY do I need to have charger re-calibrated for lithium? Am I missing something except boosting the out-put voltage to 164.25?

Thanks for reading guys. I hope this was informative and I get an answer to my question.
 
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