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-   -   Basic Programmable BMS (http://www.buggiesgonewild.com/lithium-ezgo/149434-basic-programmable-bms.html)

agpfl 01-16-2019 09:36 PM

Basic Programmable BMS
 
I am just wondering if anybody else has used an inexpensive programmable BMS. Over the past year I have built 4 Leaf module based packs utilizing a BMS that can be programmed via a USB cable and has some Bluetooth functionality. I keep seeing what looks like overkill when it comes building the BMS.

BobBoyce 01-17-2019 03:48 AM

Re: Basic Programmable BMS
 
Quote:

Originally Posted by agpfl (Post 1578302)
I am just wondering if anybody else has used an inexpensive programmable BMS. Over the past year I have built 4 Leaf module based packs utilizing a BMS that can be programmed via a USB cable and has some Bluetooth functionality. I keep seeing what looks like overkill when it comes building the BMS.

I have seen the overkill as well. Spending way more than required to convert to Lithium. Lower cost Lithium conversions are more appealing to the public. With lower cost Leaf modules available, there should be no reason that a 7 module conversion should cost more than buying a new Lead/Acid pack. The original Lead/Acid 48V pack charger should be fine for most of these conversions if you put the BMS in control of it.

I used a preprogrammed simple 14 cell BMS PCB on my 7 Leaf module RXV conversion. I retained my Lead/Acid charger.

I would be interested in a simple programmable BMS for my 2Five conversion that will use 16 of the 100 A/H GBS NiFePO4 cells.

Bob

agpfl 01-17-2019 10:44 AM

Re: Basic Programmable BMS
 
I read your install. Your configuration was even more advanced than what I normally do because you are cutting off the AC side of the charger. You have used relays for interlock and bypass.

I have the BMS cut off power on the DC side of the charger if any cell hits 4.2v, or the pack reaches 58.8. I purchase a new Li-on charger for less than $200 that is programmed to turn off about .5v shy of max voltage. So for a 14cell Leaf pack I have the charger cut off at 58.3. This gives me two different forms of protection from overcharging. My charger is the one that normally stops the charging, but the BMS can shut down charging as well if the charger does not do its job.

izzybird 01-17-2019 11:15 AM

Re: Basic Programmable BMS
 
W
Quote:

Originally Posted by agpfl (Post 1578441)
I read your install. Your configuration was even more advanced than what I normally do because you are cutting off the AC side of the charger. You have used relays for interlock and bypass.

I have the BMS cut off power on the DC side of the charger if any cell hits 4.2v, or the pack reaches 58.8. I purchase a new Li-on charger for less than $200 that is programmed to turn off about .5v shy of max voltage. So for a 14cell Leaf pack I have the charger cut off at 58.3. This gives me two different forms of protection from overcharging. My charger is the one that normally stops the charging, but the BMS can shut down charging as well if the charger does not do its job.

I don’t know what charger you’re using, but a lot of these cheaper Chinese chargers can be easily adjusted to different end of charge voltages if you even slightly know what you are doing. I think charging to 4.1v and never dropping below 3.65v will keep a person in a very safe range and keep balancing to a absolute minimum. There are tons of very inexpensive RC gadgets out there that are very useable on leaf modules as well. I’ve read scores of builds from electric motorcycles to the solar dudes using leaf modules and some go all out while others KISS. I’m keeping it simple.
What BMS are you using if you don’t mind me asking?

agpfl 01-17-2019 11:48 AM

Re: Basic Programmable BMS
 
Just google 14S smart bms. I used one like this: https://www.aliexpress.com/item/14S-...794186005.html

brad2388 01-17-2019 09:27 PM

Re: Basic Programmable BMS
 
Quote:

Originally Posted by agpfl (Post 1578471)
Just google 14S smart bms. I used one like this: https://www.aliexpress.com/item/14S-...794186005.html

What does the bluetooth function give you?

yurtle 01-17-2019 10:50 PM

Re: Basic Programmable BMS
 
It doesn't appear to have an HMI, or display/touch panel.

agpfl 01-17-2019 11:18 PM

Re: Basic Programmable BMS
 
2 Attachment(s)
Quote:

Originally Posted by brad2388 (Post 1578701)
What does the Bluetooth function give you?

You can view your cells, protection occurrences, and even modify some parameters.

I hardly ever connect to it, but its there for the occasional spot check of the cells. I use my in-dash ScottyB voltage meter to view my pack voltage to get a sense of when to charge.

agpfl 01-17-2019 11:30 PM

Re: Basic Programmable BMS
 
Quote:

Originally Posted by yurtle (Post 1578707)
It doesn't appear to have an HMI, or display/touch panel.

What is HMI?

Do I really need a display/touch panel? No, operationally it has no effect on the pack. Its not like I had a backlit display for my each of FLA batteries, so why would I need or want one for my Lithium modules? I spend around $120 per leaf module which is a similar price per FLA battery, so why would I over-complicate it with an elaborate battery management system that costs more than the whole battery pack itself?

yurtle 01-18-2019 02:09 AM

Re: Basic Programmable BMS
 
Quote:

Originally Posted by agpfl (Post 1578720)
What is HMI?

AN HMI is an industry term. Human Machine Interface.
http://bfy.tw/LDEp

Quote:

Originally Posted by agpfl (Post 1578720)
Do I really need a display/touch panel? No, operationally it has no effect on the pack. Its not like I had a backlit display for my each of FLA batteries, so why would I need or want one for my Lithium modules? I spend around $120 per leaf module which is a similar price per FLA battery, so why would I over-complicate it with an elaborate battery management system that costs more than the whole battery pack itself?

Someone asked why Bluetooth. I answered. Maybe I should have been clearer. So you can use a smart phone, laptop, tablet, anything you already have. Never said you needed it.


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