StandardProducts/Lithiumate/Service/Troubleshooting/Banks/Missing/Cell
<h1>A cell is not reporting (its bank is reporting)</h1>


<ul>
<li>Make sure that just some cells are missing, and not the entire bank; if the latter, see the <a href="../Bank">Missing banks</a> section
<li>Make sure that the problem is not due to electrical noise; if so, see the <a href="../Noise">Noise</a> section
</ul>

See also:
<ul>
	<li> <a href="Testing/Cell_Board">Cell Board testing</a>
</ul>

<h2>IMPORTANT NOTE</h2>

If a bank reports that its <strong>negative end board is missing</strong>, that's probably <strong>not true</strong>: all that means is that <strong>one of the boards in the bank is missing</strong>, and we don't yet know which one.

<h2>Introduction:</h2>

The BMS assigns IDs to the cell boards on the fly, starting from 0 for the cell board at the most positive end of the bank. If a cell board is not responding, the BMS skips it and assigns its ID to the following (more negative) cell board. Therefore, the non-responsive cell board gets no ID, and the following cell boards will have a lower ID than they should.
For example, if a bank has 5 cell board, the BMS will assign IDs 0 through 4 to them.
<table border=1>
	<tr>
		<td style="width: 50px">Position
		<td style="width: 50px">Most +
		<td style="width: 50px">2nd
		<td style="width: 50px">mid-bank
		<td style="width: 50px">4th
		<td style="width: 50px">Most -
	<tr>
		<td>ID
		<td>0
		<td>1
		<td>2
		<td>3
		<td>4
</table>

However, if the mid-bank cell board is not responding, the BMS will see 4 cell boards instead, and assign IDs 0 through 3 to them, skipping the cell board that doesn't report.
<table border=1>
	<tr>
		<td style="width: 50px">Position
		<td style="width: 50px">Most +
		<td style="width: 50px">2nd
		<td style="width: 50px">mid-bank
		<td style="width: 50px">4th
		<td style="width: 50px">Most -
	<tr>
		<td>ID
		<td>0
		<td>1
		<td>none
		<td>2
		<td>3
</table>

The BMS controller knows that a cell board is not reporting, but it has no idea which one. It just sees 4 cell boards, but it doesn't know which 4 they are. If it were the second cell board that was missing, that appears exactly the same to the BMS controller.
<table border=1>
	<tr>
		<td style="width: 50px">Position
		<td style="width: 50px">Most +
		<td style="width: 50px">2nd
		<td style="width: 50px">mid-bank
		<td style="width: 50px">4th
		<td style="width: 50px">Most -
	<tr>
		<td>ID
		<td>0
		<td>none
		<td>1
		<td>2
		<td>3
</table>

The BMS controller will report that cell board #4 is missing, but that simply means that it was not able to assign ID 4 to any cell board; it doesn't necessarily mean that the cell board that is not reporting is the last one in the bank. To know which cell board is not reporting, one must physically look at the cell boards.


Determining which cell board is not reporting:
<ul>
	<li>Turn off the BMS controller
	<li>Note that the LEDs on all the cell boards are off
	<ul>
		<li>If a cell board's LED stays on, replace that cell board (do so immediately: or it will kill the cell)
	</ul>
	<li>Turn on the BMS controller
	<li>Look for blinking LEDs in the cell boards
	<ul>
		<li>If a cell board's LED stays on, it could be that the cell is full and needs to be balanced, but it could also be that the cell board is measuring too high a voltage
		<ul>
			<li>Check if the BMS is balancing, with the terminal: Home / Status / Pack, then look at the "Loads On" line
			<li>If the terminal says that there is no balancing, the cell board is bad: it is measuring the wrong voltage; replace it
			<li>If the terminal says "balancing if &gt; x V", note x as the Balancing Voltage
			<li>Measure that cell's voltage
			<ul>
			<li>If the voltage is less than the Balancing Voltage, the cell board is bad: it measuring the wrong voltage; replace it
		</ul>
		</ul>
		</ul>
		<li>If a cell board's LED doesn't blink, the cell board is not running
		<ul>
		<li>Check the cell voltage; if it's less than 2.0 V, that's not enough to power the cell board
		<li>Try resetting the cell board
		<ul>
		<li>Disconnect one end of the cell board from the cell
		<li>Reconnect it (this will reset the program)
		<li>Check what the LED does as soon as the cell board is connected
		<ul>
		<li>If the LED blinks twice, and repeats that 3 times, then goes off, the cell board may be OK
		<ul>
			<li>If that fixes the problem, do let us know
		</ul>
		<li>If the LED doesn't come on, the cell board is bad: replace it
		</ul>
		</ul>
		</ul>
		
		<li>If all cell boards have a blinking LED, see which cell board doesn't respond to heat, using a "binary search" method
		<ul>
		<li>Find a cell board in the middle of the bank
		<li>Touch it with your finger (or some other medium heat source), to heat it
		<li>On the terminal, see which cell board's temperature starts rising, if any
		<ul>
		<li>If none, that cell board is not reporting: replace the cell board
		<li>If you're heating the cell whose ID should be N, and the BMS controller reports correctly that cell board N is getting hot, the problem is in a cell board that has a higher ID (more negative)
		<ul>
			<li>Repeat with a cell board mid way between the one you just did, and the negative end board
		</ul>
		<li>If you're heating the cell whose ID should be N, but the BMS controller reports it's cell board N+1 that is getting hot, the problem is in a cell board that has a lower ID (more positive)
		<ul>
			<li>Repeat with a cell board mid way between the one you just did, and the positive end board
		</ul>
		</ul>
		<li>Continue recursively through the "binary search", until you find the cell board that is not responding
		<ul>
			<li>Allow enough time for one cell board to cool off before starting to heat another cell board
		</ul>
	</ul>
</ul>