# Cell log 8 alarm signal



## evmetro (Apr 9, 2012)

In case that was too much info and was overwhelming, I just want to know if the positive wire in alarm port signal works the same as the positive terminal input of the last battery in the series in regard to the drain on the alarm port.


----------



## major (Apr 4, 2008)

RTFM  Page 9 in particular. The alarm is an open collector circuit. Limit 500mA/50V. It is like a switch. Needs a source and load. Remember when I told you? 



major said:


> So you'll have to wire your pushbutton switch to the load side of the main contacts instead of the battery positive to prevent contact bounce, second trigger or noise from turning it back on. Also, if coming from the CellLog, the trigger would be continuous and not a pulse, unless the relay also turns it off.


----------



## evmetro (Apr 9, 2012)

Although I am not an expert on the collectors yet, all the outputs on the Orion bms that I use are drains, so I have the general feel for them. I do in fact have the manual hanging out on the bottom of my screen, and I see the diagram. If these collectors work the same way as the ones on my Orion, (and I don't know for sure if they do), The "negative" wire on the alarm output would be the collector, and the 12 volts could come from somewhere else besides the red positive wire on the output. The step up relay that I have between the cell log and the battery disconnect relay is the load. Since the alarm signal wont stop until the cell log is disconnected, I figured that if I can de energize the step up relay coil, it would get rid of enough load to make my battery safe from further drain. 

If I only used the cell log as a pack voltage switch, I could wire in a relay between the load side of the solenoid and pin 2. Since I want to use the individual voltages, there is no way that I can see to shut down the cell log or the steady alarm signal, unless my suspicions of wiring the coil of the step up relay between the black collector wire on the alarm port and the load side of the solenoid are correct. 

I have the "fm" open to page 9, but am not 100% clear on how it works. "RTFM" coming from you is exciting, since this is usually where I learn something new. I have to be 100% sure before I wire something up, this is one thing I am clear on.


----------



## evmetro (Apr 9, 2012)

Note: the momentary pushbutton I intend to wire in is only meant to be a way to re sequence the solenoid, once the LVC or HVC situation has been remedied.


----------



## major (Apr 4, 2008)

The second diagram on page 9 under "ALM Output typical application" is exactly what you want. The black wire on the alarm plug goes to the 12V negative of the monitored battery. The red wire goes to the CDU coil. The other CDU coil terminal goes to the switched output from the positive of the monitored battery. CDU = coil drive unit or the small relay controlling the big latching relay. 

The open collector inside the celllogger acts like a switch. But the emitter of that transistor in there is at the negative potential of the monitored battery so the black wire on the alarm plug should not be used for an external connection to 12V negative. That is shown below:












Diagram from: https://www.tumblr.com/search/celllog

I did find diagrams showing the external negative connection. It seems to me that would defeat the action of the internal switch. Give it a try without. I just tested one on a 5 cell battery. I got the alarm to activate by shorting cell 6 input on the celllogger to cell 5 positive. That makes the celllogger think cell 6 (which really doesn't exist) has gone to zero volts and it gives a LVC alarm. 

Good luck  Thank God for those FMs.


----------



## evmetro (Apr 9, 2012)

It is beginning to sink in. I had not paid attention to that diode either until I read the bottom of your link that you provided. That diagram above that you posted has already been formatted so that a layman can read it. One thing that still is challenging me is I still can't see how the CDU coil gets de energized. From what I can tell, I was on the right track with wiring the CDU coil between the positive of the highest cell in the stack and running that lead to the alarm output, but I was proposing the wrong polarity. It needs to go to the red wire of the output, not the black. That, and I need the diode. Sound right?


----------



## major (Apr 4, 2008)

evmetro said:


> It is beginning to sink in. I had not paid attention to that diode either until I read the bottom of your link that you provided. That diagram above that you posted has already been formatted so that a layman can read it. One thing that still is challenging me is I still can't see how the CDU coil gets de energized.


In that diagram, the CDU would be the relay shown there and its contacts would then trigger the latching contactor. That CDU coil (shown with the diode across it) is de energized because the upper connection goes to the positive on the load side of the latching contactor instead of B+ directly as shown. 

Once the celllogger alarms and energizes the CDU coil, it throws the latcher and it disconnects the supply to everything including the CDU coil, de energizing it.

Get that?


----------



## evmetro (Apr 9, 2012)

Yep! It feels good to have it clear now, and thanks for your help on this.


----------



## evmetro (Apr 9, 2012)

I wired it up like the diagram below, and bench tested it. It works great when I test it with no load, but when I load it up with a 12 vdc light bulb the solenoid does not complete its open cycle and the coil of the solenoid stays energized. I can hear it make the correct "thump" sound when the coil gets energized by the alarm output, but not the last little "click" sound that it makes as the coil is de energized. When I take the light bulb back off, the circuit works perfectly. Any thoughts?

I am not a master of drawing diagrams, but here is what I wired up:


----------



## evmetro (Apr 9, 2012)

I forgot to write "latching solenoid" in the diagram in case somebody wants to take a crack at this without going back through the whole thread to see that I am using a latching solenoid.


----------



## evmetro (Apr 9, 2012)

I just tinkered with it some more, and it looks like the HVC alarm will make it work right, even under load, while I have my bench DC power supply running to trigger the HVC. The LVC alarm should do the same thing, but this is where it gets hung up and the coils stay energized. I don't see where it should make any difference if what triggers the alarm, but the LVC does not work as it should. I have my LVC and HVC set pretty close so that I can trigger it with my light bulb with alligator clips or my bench DC power supply, so 3.28 volts and 3.32 volts.


----------



## evmetro (Apr 9, 2012)

I suspect that putting a slight delay on de energizing the relay coil so that it is energized for longer than the solenoid coil may do the trick.


----------



## Finn DK (Apr 7, 2011)

Hi evmetro

I've added a diode and an electrolytic capacitor to your schematics, that should make the thing work.
Problem is, that the unlatching pulse is too short because the unlatching relay also breaks it's own supply.
The capacitor stores a small amount of energy which will extend the length of the pulse.
The diode is there, to make sure that the stored energy is only used for the pulse, not for the normal consumption.
Size of the capacitor may need to be adjusted, depending on requirements for the contactor coil.
Please don't forget to add a fuse or 2 to your circuit.

Best regards,

Finn


----------



## evmetro (Apr 9, 2012)

Thanks. I just tried one, and then two 330 uf 16 volt caps, and it still does not hold the coil long enough. I will have to go and get the caps that you specified and try them.


----------



## Finn DK (Apr 7, 2011)

Hi again

I just looked at the schematic with fresh eyes.
I've made a mistake, minus of the capacitor must be connected to battery minus/chassis ground, not to the Cell log red wire.
Sorry for the confusion.

Regards, Finn


----------



## evmetro (Apr 9, 2012)

I have the capacitor ground wired to the ground now, the positive is wired in between the diodes. I could not find the capacitors that you specified, but I have a 470 uf 50 volt cap in there. It seems like it is trying, but still not right. The relays cycle now. The solenoid does not quite finish, and lets the capacitor recharge for another attempt that does not quite happen and it keeps repeating this cycle.

My thoughts are that I need more capacitors because the one I have is not keeping the relay coil energized long enough. I don't know if the capacitors will ever provide more volts than their input voltage that charges them, so I don't know if I can hurt anything by adding more. The cell log collector only likes up to 50 volts if I understand the manual correctly. My assumption is that I only get 13 volts or so out of them since that is what I charge them with.


----------



## Finn DK (Apr 7, 2011)

Hi again

Seems that you're getting closer.
You can add capacitors as wanted/needed that does not affect the voltage for the Cell Log.
The voltage marking on the capacitors is the max. operating voltage, and in your circuit they will never see more than the 12-13 volts that your aux. battery delivers.
The other marking, micro Farad, is the actual energy storage capacity of the cap.
This means more micro Farads gives a longer reset pulse.

Hope this brings you forward.

Regards, Finn


----------



## evmetro (Apr 9, 2012)

This is pretty cool learning about capacitors, I appreciate your help here. I will pick up a few more caps at lunch time to see how more of them work out. I do have a few others laying around, but I don't know if it is ok to parallel mismatched caps.


----------



## Finn DK (Apr 7, 2011)

You can parallel without problems, the total capacity is the sum of the capacity of each.

Regards, Finn


----------



## glyndwr1998 (Apr 27, 2013)

Hi, I use 11 cell loggers on a 76 lifepo4 pack set to charge to 3.5v.

What I have done is simply taken the alarm signal positive wire and used opto isolators. There is a great diagram on the net with this set up, Google it.
All I have is 11 opto couplers in series, they are isolated from the pack voltage, and work very very well. 

My circuit is very simple, a pcb hobby board, 11 opto isolatos, they signal from the opto isolators are in series to a relay in the charger power cord, plus a switch that latches the relay, once the cell log alarms the opto isolator sends a 12v signal to the relay to cut the charger, charge sequence cannot start until cell log stops alarming and the start button is again pressed, very simple, very cheap.

None of my work, just copied from a guy on endless sphere forum much cleverer than I am.

Google it and see what you think, no need for capacitors, resistors etc... And the opto isolators are only about 20p each, really cheap to set up too.

Thanks.


----------



## evmetro (Apr 9, 2012)

I may look into the opto couplers. I have tried all kinds of different capacitors and diodes, and nothing is working. I have tried increments from 100 uf to 2200 uf, and have tried them on the relay coil and the solenoid coil, and nothing seems to work.


----------



## major (Apr 4, 2008)

evmetro said:


> I may look into the opto couplers. I have tried all kinds of different capacitors and diodes, and nothing is working. I have tried increments from 100 uf to 2200 uf, and have tried them on the relay coil and the solenoid coil, and nothing seems to work.


Not sure what optos will do for you. The problem is you want everything shut off including the "device" which controls the shut off. The caps didn't work to store energy to keep it alive long enough to disengage. Perhaps an inductor could do it. Maybe use an inductor adjacent to the CDU coil (in series with it). The inductor needs to increase the time constant of the CDU coil decay so it will hold the latcher a bit longer. To do that, the inductor needs to be higher inductance and lower resistance than the CDU coil.

If that bombs, then maybe look for a time delay relay. That may require an extra latching relay circuit.

You just can't unplug the darn thing


----------



## evmetro (Apr 9, 2012)

Checkmate! I finally noticed that when I push the momentary button, for the solenoid reset, the solenoid goes "clunk" and the main circuit does not disconnect until I release the momentary button and hear the final "click". The solenoid was never going to shut off the CDU coil. I wired up a pair of relays in a way that would normally just make them buzz from feeding each other, and stuck a capacitor and diode on the second CDU coil to hold it while the solenoid coil finishes its cycle. It works great, and I cycled it several times.


----------



## evmetro (Apr 9, 2012)

poof poof poof


----------

