Building 30 AH Headway pack with v2.03TPpacks Goodrum BMS

[Lessss]

Building 30 AH Headway pack with v2.03TPpacks Goodrum BMS
24-Cell BMS Connection Harness-v2.3.png

No directions came with the board beyond how to put the components on the board ( and the board was bought with that already done).

What I need are the wiring directions to connect the BMS to the batteries, the BMS to the charger,the BMS to the bikes power plug.




Re-edited to make the question very simple.

 

[Lessss]

deleted

 

[fechter]

What version is the board? It is printed on the edge of the board.

I'm not exactly sure which wires you are asking about, the small black/red pair coming off the bottom left in your picture appear to be the LVC wires. These normally go to the brake input on your motor controller. Alternately, they could go between the throttle signal and ground connections if you add a 1k resistor in series between the throttle and the connection point.

Another way to use them is to wire up a Sonalert or some loud beeper and use them to trigger an audible alarm.

 

[avsmith66]

Did you ever get any feedback on this Lessss? I see you deleted your post.

I'm experiencing the same issue with my completed v2.6 TPpacks Goodrum BMS board I just recieved. I have an idea how to wire from the BMS to the battery, but am starting to question if the way I have the battery (21s2p) assembled will make any difference with how the board reads the LVC.

Also, did the additional charge wire (neg) move on the board? I can't seem to find it on my board based on the schematics from the website and posted on here, but I have found a hole on the edge of the board to the left of the chg neg hole marked with a sw by it that I thought might be it . . .


AVS

 

[Lessss]

Other than Fechters brief post, nope.

 

[AndyH]

Building 30 AH Headway pack with v2.03TPpacks Goodrum BMS
24-Cell BMS Connection Harness-v2.3.png

No directions came with the board beyond how to put the components on the board ( and the board was bought with that already done).

What I need are the wiring directions to connect the BMS to the batteries, the BMS to the charger,the BMS to the bikes power plug.

Re-edited to make the question very simple.

Lessss... Here's the copy of the build and wiring instructions for the V2.3 board. I can't say this is the last version Gary produced, but I can say this is the copy I used when I built my V2.3 boards.

There's a great diagram in the main BMS build thread that shows all the connections in a 'parts layout' sort of way, rather than a schematic, but I can't find it. In the mean time, you can find the charger connection diagram and pack positive/pack negative wiring on page 6. There's a schematic of the cell balance wiring on page 5 under the 'connections' heading.

I'd be happy to walk you thru the connections if you'd like.

Andy

 

[Lessss]

Thanks. I have that. It is mostly assembly instructions for components on the board ( bought already done) and about 4 lines re hooking up the bms, mostly on the LVC.

Yes what I need is a walk-through on the wires for charging.

Thanks

 

[Ypedal]

I'm both feet into that right now as well on a v2.1 board.. i'll take some pictures as i go along and start a thread once i get it done ( and hopefully without blowing anything up !! )

 

[AndyH]

All Righty, Lessss, let's get you wired. First, this overview. Specifics for your pack in the next post.

Some initial thoughts. Your cells can dump a lot of current - enough to melt small gauge wires. Be careful once you connect wires to the pack. Work with the wiring off the pack as long as you can. Once connected, keep wires insulated until you need to strip them. Also be careful if you choose to connect 'hot' wires to the BMS. Crossed wires can destroy BMS channels and that can lead to cell damage. It's less stressful to wire to the pack, wire to the BMS, then connect wires in the middle either with solder and shrink or with a connector.

Planning... Let's work with a 'mythical' 16s pack.

Assumptions: Goodrum/Fechter BMS V2.3. Charge thru the BMS. BMS wiring will start with Pack Negative. We'll use that a our starting point.

View attachment 4

You'll need one more wire than you have cells. 17 for our example 16S pack. Since you're charging thru the BMS, the pack positive and pack negative wires must be large enough to carry full charger current. remaining wires can be smaller gauge as they only carry shunt current. The pack positive and pack negative connections will be easy enough to figure out. The remaining wires will connect in between each cell. It doesn't matter which side we connect to - the positve of cell cell one and the negative of cell 2 are the same as far as the BMS is concerned.

Once the pack connections are understood, let's look at the BMS side.

View attachment V23_front.jpg

Notice that there's a large hole marked "Pack -", then five smaller holes marked "1" thru "5", than a pair of large connections for a positive connection. On the next four-cell segment, there are five holes marked "6" thru "10". You will not connect to all of these possible connection points. Some are duplicated - primarily to allow using larger wire for the most positive and most negative wires. Just what we need!

Here's a look at the back of my V2.3 board. Ignore the wires for now.

View attachment 3

Pack negative is to the right in this picture. See how the large "Pack -" pad is wired to the small connection marked "1" (green)? It's the same on the most positve side (blue). Also note that connection "5" is the same as the large "+" and also the same as connection "6".

SInce that enough confusion for now, let's try to sort out the spaghetti with a connection table.

View attachment connection_chart.jpg

This will help us keep things straight when we actually start to wire. Leave room for notes like wire colour. You might also want a middle column to keep track if you use a connector.

That covers the BMS to pack wiring. What about charger connections? On this BMS, Pack + is also connected to charger positive. So charger positve connects to the large pad at the most positve end of the BMS. This is immediately to the right of connection 20 in our example.

Charger negative connects to the large "Chgr -" connection on the left of the BMS. We'll also need a small gauge wire to activate the BMS's charge controller. This is soldered to the board in the small pad at the 5 o'clock position of the "Chgr -" pad.

Here's a shot of my 21 channel board. I have the charger connections soldered from the front of the board and the pack positive/negative soldered from the back.

View attachment overview.jpg

The small wires on the lower left are for the LVC brake connections.

That's a start!
Andy

 

[Lessss]

Thanks that pic makes a lot more sense than what I've seen before.

 

[Ypedal]

This may be repeating the obvious, but i'll say it here in ase it's not clear..

You have the option of discharging thru the BMS.. or you can connect the battery + and - directly to the ebike if you use the e-brake connector that will shut down the controller when a contidion occurs....

 

[AndyH]

Before we finish up, let's take a step back and look at what the Fechter/Goodrum BMS does. Please pardon the 'cave etching' graphic style...



Ok... The green thing is a single cell. The three blue boxes are the three functions 'our' BMS performs. The grey boxes are the controller and charger. The red and black lines are wires connecting various functions. The blue lines are 'signals'. Not shown are the power cables that run from the pack to the controller. This BMS doesn't control the discharge process, like limiting current, the way other BMS devices might. This BMS isn't designed to keep a 1C cell from damage if the controller tries to pull 3C from it.

The LVC function is connected to each cell. It sits quietly in the background and monitors cell voltage. Any time cell voltage drops to the set point (2.1V for cylindrical cells, for example), the LVC signals the controller thru the brake inhibit line to shut the motor off. Once the load is removed, cell voltage recovers quickly. Once the cell recovers above 2.2V, the signal is removed (the 'brake switch' is opened) and power is available for the motor.

The Shunt portion is connected to each cell. It is only activated when cell voltge increases to the set point - normally only during charging. When cell voltage reaches the 'begin shunt' phase, the orange LED begins to glow and a small amount of energy is pulled from the cell. This effectively slows the charging for this cell. Slowing the 'more full' cells allows the 'more empty' cells to catch up. Once cell voltage reaches the 'max shunt' point, the shunt portion of the BMS signals the charge control portion to stop the charger. If cell voltage drops, the shunt will release the 'stop' signal and charge current can flow again.

(A note about shunting. This isn't the same as a 'single cell charger'. The charger is connected to pack positive and pack negative and tries to push 3A (for example) thru the entire pack. It doesn't know the state of charge of any cells - it can only monitor total pack voltage and possibly current draw. When a shunt activates, it 'pulls' some power from the cell at the same time the charger is 'pushing' power in. A limitation of shunting is that a 1A shunt cannot stop a cell from being overcharged if the cell is being fed 3A - the cell still receives 2 Amps of charge current. A shunt can only keep a cell from being overcharged if it can 'remove' the same amount of current the charger is trying to 'add' - a 3A shunt and a 3A charger, for example. This brings us to the charge controller...)

The Charge Control is designed as a 'throttle' to slow the charging process when cells start to become full. This portion reduces the incoming charge current to a level the shunts can handle. Once all cells signal that they're full, the charge control portion stops all incoming charge current and lights the green LED.

Andy

 

[AndyH]

... I'm experiencing the same issue with my completed v2.6 TPpacks Goodrum BMS board I just recieved. I have an idea how to wire from the BMS to the battery, but am starting to question if the way I have the battery (21s2p) assembled will make any difference with how the board reads the LVC.

Hey AVS, If you connected your cells in parallel first, then assembled the parallel segments in series, you'll treat each parallel group as a single cell. In that configuration, the BMS will correctly respond to LVC events.

If cells are in series first, then parallel, each series string will need a BMS for proper management.

Also, did the additional charge wire (neg) move on the board? I can't seem to find it on my board based on the schematics from the website and posted on here, but I have found a hole on the edge of the board to the left of the chg neg hole marked with a sw by it that I thought might be it . . .

AVS

You've got it! The latest version of the BMS instructions (V2.6c) shows the relocation of the 'sw' pad. That is indeed the wire you connect to charger negative to enable the charge control portion of the BMS.

(As an aside, I'll bet the guy that built your board will support you. I expect he doesn't have a way to 'connect' E-S handles with 'real names' so it might be difficult to keep everyone straight. :wink: )

Andy

 

[Lessss]

Ok got it all wired up and I am now sure that these boards should not be sold without the wires already being soldered to the board.

If you are not separating the boards then use the double positive connection holes instead of holes 5&6 - - 10&11 - - 15&16 - -20&21 etc.. to give some separation and make soldering easier.

I know sellers may think this is a pain for them to do but it is seriously not something a novice should be doing and it will reduce warranty claims.

Will any part on this board get hot enough to burn cardboard or plastic or wood?

 

[AndyH]

Congrats Lessss for getting wired! Thanks for the wiring feedback - I really do understand what you're saying here. It would be much easier if one could order a package tailored to their individual pack - maybe with standard wiring and connectors. So far, though, the only folks that I've built BMSs for that have standard, repeatable installations, are the scooter owners with larger Thunder Sky packs.

You might have been a novice a few months ago, but you aren't any longer - you took the time to understand your pack, your BMS needs, and you learned how to connect the bits together. Not only are you better able to understand how the parts connect, but you can troubleshoot your installation as well. I'll guarantee you that your next wiring project will go much, much faster! Kudos to you for conquering the unknown!

 

[bonzo]

So, If I want to use a 15A or 20A charger, on my 24S pack, will I have shunting problems because my charge current is to high?

Can I use about any lifepo4 charger, or will the charger shut off while it's shunting?

 

[AndyH]

So, If I want to use a 15A or 20A charger, on my 24S pack, will I have shunting problems because my charge current is to high?

Can I use about any lifepo4 charger, or will the charger shut off while it's shunting?

I use this BMS in a 21 channel version with a 15A charger. The pack is 60Ah and has been significantly out of balance due to a voltage monitor pulling power from cells 1 thru 4. Here are some observations:

- The control section of the BMS was designed for power supplies, lead acid chargers, and LiFePO4 chargers. For chargers - the dumber the better.
- LiFePO4 and lead acid chargers will maintain constant current until the pack averages about 3.6-3.7V. The charger or power supply will then move to constant voltage mode and the current will drop. Your pack will be nearly completely charged (if fairly well balanced to begin with) once the charger moves from CC to CV mode. This move is also when the shunts are designed to activate. So...if your pack is fairly well balanced, the charger will be completely unthrottled for the main part of charging.
- Once any one cell begins to shunt, the control section will start to cycle on and off at a fixed rate. This significantly lowers the charge current to the pack. The charge rate slows from this point on. If the pack is fairly well balanced, the shunting point should correspond fairly closely with the charger moving to CV mode - and the charger will continually reduce the current as well (or the cells will continually reduce their current draw ).
- If the pack is out of balance - say you have one cell that's lower than the rest - you'll have 23 shunts on. The charger, reacting to pack voltage rather than cell voltage, will be in a lower current stage of the CV mode (slow charging rate). The BMS control section will also be cycling on and off to limit incoming current to a point the shunts can handle. The single low cell will charge slowly, the pack will balance, and the shunts should be able to keep the 'full' cells around 3.7V until the straggler catches up.

I've used fixed power supplies (Mastech 5005), the HiPower LiFePo4 chargers, and Thunder Sky chargers with this BMS.
- The fixed power supply works just as one would expect - it doesn't care about the pack state of charge or the cycling from the BMS - it's just pushes electrons into the pack.
- The HiPower chargers work fine as well. They have an 'end of charge' detection built in - and by default will end the charge just before the BMS does. If one prefers the BMS to end the charge, the charger can be adjusted a bit.
- The Thunder Sky charger has the most 'smarts' and appears to be designed to specifically NOT work with an external BMS. It does things like stop during charging to apparently check pack voltage. Instead of following a standard CC/CV charge curve, it makes multiple voltage and current adjustments during charging based apparently on state of the pack. Sometimes my charger will go into an error condition near the end of charge when the BMS is shunting. I think it's because the charger cannot understand the pack condition info it's getting thru the BMS. I normally charge 'around' the BMS when using the Thunder Sky charger. In other words - I normally use the BMS as a shunt and not charge thru the BMS controll section.

I hope that helps,
Andy

 

[Barry]

Question from a novice about testing of the LVC portion of the Goodrum/Fechter BMS V 2.6c.

I hope this is the appropriate place to ask these questions. If not please point me in the right direction.

I have finished assembling the board and would like to test the LVC portion of the circuit. I am not sure where to connect the wires.

I think I have the pot connected to the battery in accordance with the diagram on page 6 of the instructions. Correct me if I’m wrong.
The pot has three legs, two together and one that stands alone. I connected the pot in parallel, one of the two legs to the positive side of the circuit and one to the negative side of the circuit. I also connected a wire to the stand alone leg. With my volt meter probe on the positive leg of the pot and stand alone wire I get a reading of 3.3volts and can adjust the voltage up and down with the Pot.

Am I correct so far?

If I have the pot connected correctly then my next question is where do I connect the three wires to the board to test the individual channels.

My best understanding of the instructions is that the negative side of the circuit attaches to the pack negative and the positive side connects to the pack positive and the stand alone connects to one of the four channels being tested. Is this correct? If not please give me a hand.

Thanks in advance.

 

[Lessss]

I connected my cutoff to a LED light.

 

[AndyH]

I connected my cutoff to a LED light.

Why Lessss? When a LVC event happens, the cell will be well under LVC before a human will notice the light and then react. Even when paying 100% attention in driver reaction testing, it takes about a second just to recognize a light and start to raise an arm or leg to react. In that amount of time, an LVC connected to the ebike brake inhibit line will have cycled off and on three times.

Andy

 

[AndyH]

Hi Barry,

The easiest way to test is by clipping to the 'top' leads on the shunt resistors.

To use the 10K pot, you'll connect the cell providing power across the pot. The pot's center tap becomes the variable voltage output.

Here are a couple of pictures - one with a bench supply and one with a cell and 10K pot.

Andy

View attachment LVC_PS1.jpg
View attachment LVC_cell1.jpg

Question from a novice about testing of the LVC portion of the Goodrum/Fechter BMS V 2.6c.

I hope this is the appropriate place to ask these questions. If not please point me in the right direction.

I have finished assembling the board and would like to test the LVC portion of the circuit. I am not sure where to connect the wires.

I think I have the pot connected to the battery in accordance with the diagram on page 6 of the instructions. Correct me if I’m wrong.
The pot has three legs, two together and one that stands alone. I connected the pot in parallel, one of the two legs to the positive side of the circuit and one to the negative side of the circuit. I also connected a wire to the stand alone leg. With my volt meter probe on the positive leg of the pot and stand alone wire I get a reading of 3.3volts and can adjust the voltage up and down with the Pot.

Am I correct so far?

If I have the pot connected correctly then my next question is where do I connect the three wires to the board to test the individual channels.

My best understanding of the instructions is that the negative side of the circuit attaches to the pack negative and the positive side connects to the pack positive and the stand alone connects to one of the four channels being tested. Is this correct? If not please give me a hand.

Thanks in advance.

 

[Ypedal]

8)

 

[AndyH]

8)

Dude! In what museum will that work of art be displayed?

 

[Barry]

Andy,

Thank you for the pictures and your help. Testing the LVC will be a cinch now.

Barry

 

[AndyH]

Andy,

Thank you for the pictures and your help. Testing the LVC will be a cinch now.

Barry

My pleasure! May all your LEDs blink on command.