I got this 24S BMS a few weeks ago. Initial set up so it would charge and discharge took a few minutes to figure out, but otherwise it was pretty straight forward to set up for someone who knows what they are doing. The BMS won't charge if you have the pack OVP set lower than the actual pack voltage. It also won't discharge if pack LVC is set higher than current pack voltage. The BMS can't know what are "normal settings" since it's wide open to setting changes... how ever you set them...correctly or not. You can make setting changes that create conflicts and the software deals them by NOT letting you charge or discharge under certain circumstances. Be smarter than the BMS.
These BMS includes a tiny button that allows you to turn it on or off. It makes for an easy way to cut all power in and out of your EV. There's no need to disconnect the battery for long storage events, just press the button until the BMS shuts off.
These are highly flexible and adjustable BMS. They can't know you have LIFE chemistry connected to it and then in settings you have HVC set to 4.5 volts. It's going to try and charge each cell to 4.5 volts. Miss-charging lithium batteries tends to be VERY bad!!! This is NOT a beginners BMS. If you can't intelligently make good choices for the settings, then get a dumb BMS that makes all the choices for you. If you make incorrect settings, the BMS will try to follow them...regardless of the end results...fire, cell damage, good operation, whatever.
These BMS have a brilliant feature IMHO. They are battery chemistry agnostic. You enter in the setup program the specifics for your cell type and then it balance charges and discharges according to those settings. For example, LTO can go dead flat to zero volts without harm and charges to full at 2.8 volts. This BMS will allow you to set LVC to 0v and HVC to 2.8 volts for LTO. HV LIPO wants 3 volts as it's LVC and 4.36 volts for HVC. Set it in the BMS and you are good to go. LIFE wants 3v for LVC and 3.6v for HVC...set it and you are done. HVC can be set as high as 4.5 volts. Like I said...chemistry agnostic. This is brilliant but dangerous functionality! The BMS has BT and an android application that does everything you need to set up, monitor and use the smart BMS. See the below screen shots of the app. There is one exception which is odd. You can't see anything like this in the android app. It's not for lack of data incoming from the BMS either.
So then the actual BMS. Nothing new here...posted this pic already.
The B- connection with a 5.5mm bullet added by me.
This bullet is soldered to C- which is for charging, NOT for discharging. The unused pad behind it is P-. That's what you power your EV from, NOT C-. I'll get to my gripes about P- shortly.
This is one of the areas that these BMS are really strong...mostly. The copper reinforcing is well done and securely soldered to every mosfet for best heat and current transfer. However, the middle buss is P- and for whatever dumb reason has no copper on it at all. This is a big oversight since you want to power your EV from P-. I will be adding copper here as soon as the longer M3 screws arrive. Grrr!
This BMS comes in several current ratings. This is the 200 amp version and as a result not all the mosfet positions are filled. It uses the MDP1991 100 volt mosfet which is decent. To get the 300 amp version uses a better mosfet and all positions filled. It also has 2 rows of copper at C- and B- and still nothing at P-...go figure! They do this so that when soldering down the P- buss, they don't have to deal with solder leaking through the board and messing up the flat surface that the mosfets need to sit on. Tha't fine, don't solder it down, just put the copper UNDER all the screws (same difference) and then solder to the P- pad only.
This is the brains of the BMS. There's an atmel 328 running the show, BT module and various support IC's.
This side of the balance board is mostly balancing components. I'm not dead sure, but I believe those resistors are 3-5 watts each. This thing can run down an over charged cell at something like an amp at least. The resistors have a heat path to the heat sink cover. In most BMS, you get something like 300mA at most. Discharge rates for balancing can be set in the app.
The LCD.... IT has 2 buttons, but they do not set the BMS in any way. They are merely up and down and LCD power only.
I live in the USA where MPH is still used. Unfortunately you can't change the speed to MPH or temps to Farenheit. Honestly though, I will never look at the BMS to tell me my speed, just to tell me battery status. I took all these pictures moments after connecting up a 24S pack. The settings have not been set yet so the BMS has no clue what anything is yet. This is the default page that the LCD displays when it powers up.
Maybe someone that can read squiggly can tell me what these say? I would have preferred all the screens be in English, but no one asked me (I'm really crushed! No really, life is OVER. I will never recover. No seriously...life is really over. I will now go into a deep funk and never get better....for the next 10ns). Supposedly there is an English version of the balance board that corrects this. What I don't get is there is plenty of English elsewhere, why not on these pages?
This one of those things that I'd like to have control over. This page is all about battery and BMS status and nothing about EV speed. Why can't this page be the default page on the LCD. You have to select up or down several times to get here.
Cell voltages. Minor oversight since this is a 24S BMS, not a 32S BMS. At least cells 25-32 don't show any voltage!
Finally, some pictures of the android app. This is the home screen or "MainView". I'll get back to this later.
Param 1....lots and lots and lots of settings for anything you can imagine. Be careful!!!
Param 2 is more of a status page. There's no settings here...thank god! I'll show this later in MainView, but you can turn off/on the charge and discharge mosfets...as seen here. This is a great way to disable your EV or to cut power without the need for a contactor. It really works...or at least does on the bench. I'll try it for real later.
There is also this log page (SysLog button on MainView). It lists charges, discharges, run times and so on. It's history and NOT current events like Param 2.
I didn't want to get lost in the MainView details until I had shown the rest of the screens. There's LOTS here! It does a running log of BMS update and change events in the large pane. I'd prefer if everything was in English, like all the rest of the pages in the app, but this is a firmware issue with the supposedly non-English balance board.
1. The Visible button makes your phone visible to other BT devices so that discovery can happen. It's an odd option since you really need to go to BT settings in android and find the BMS and pair to it from there before you can do anything else.
2. Connect does exactly that, It lets you select what BMS the app is connecting to. This is NOT BT pairing. I have 3 of this style BMS. I'm grateful for this feature so I know what BMS I am connecting to!
3. Syslog gets you to the running historical log.
4. Since the BT pairing password is 1234, please set a password so some random person can't hack your BMS.
5. LI-ION and FE-LI param do pretty much the same thing. They set the BMS to the parameters needed for those chemistries. I went into Param 1 and changed them to what I wanted, but it was a good starting place.
6. Modify BT address lets you name the BMS to something meaningful for discovery and later reference. Mine is still defaults, but I'll probably name this one 24S200A. BMS-ANT doesn't really mean anything to me.
7. Reboot does exactly that. I had an issue with BT not connecting correctly. Reboot got BT working again. There's no OS on these BMS, but you can use this option to get it to reinitialize itself.
8. Charge on/off and Discharge on/off set the states of the C- or P- mosfets. This is where you can disable the BMS outputs...sort of like a contactor. Let's say you charge at C- and then want to disable the battery charge port so that a random person can't put a paper clip across your charger port and create a giant spark, select Charge Off. Later on select Charge On so you can charge again. Discharge on/off is like your main battery contactor. The EV is not going anywhere without this on.
9. Completely screw up the settings or changed something by accident, just hit Factory Reset and start over again.
10. I have no idea what Flip Screens does.
11. Auto Equalization allows you to turn off balancing. I don't know why you would do this, but you can. IMHO balancing is the primary function of a BMS. Everything else is secondary. Param 1 has settings that effect this option and general balancing.
12. Current Zeroing allows you to adjust the current reading of the BMS. Not all shunts work identically, not all current sensing works identically and sometimes they can be off. This allows you to set it accurately if needed.
13. MainView, Param 1 and Param 2 let you select the 3 main pages in the app.