CellLog 8 hacking

[fechter]

I thought I understood how a Cell Log 8M connected to a battery pack (40 Volts) from reading the rather vague PDF manual but while connecting one using pins 1 and 9 I heard a spark and the cell log would not power up. The polarity was + on pin 9. The manual for the CD appears to show the full pack voltage connected between pins 1 and 9 so I do not know what caused this. The unit will power up with the USB power connected but when I opened it up it looks like a component near the pins has blown open. I have another unit but I am reluctant to try it until I understand the cause of the problem. Perhaps I misunderstand how it connects. The Cell log was new. Any ideas?

Manual says maximum voltage is 43v, so seems like it should have been OK.
If you connect pins 1 and 9 only, it will alarm on the unconnected channels. If you connect to pins 1 and 2, it should read the pack voltage.
Not sure why you got a spark and it died. Reversed polarity would do it.

[dumbass]

I thought I understood how a Cell Log 8M connected to a battery pack (40 Volts) from reading the rather vague PDF manual but while connecting one using pins 1 and 9 I heard a spark and the cell log would not power up. The polarity was + on pin 9. The manual for the CD appears to show the full pack voltage connected between pins 1 and 9 so I do not know what caused this. The unit will power up with the USB power connected but when I opened it up it looks like a component near the pins has blown open. I have another unit but I am reluctant to try it until I understand the cause of the problem. Perhaps I misunderstand how it connects. The Cell log was new. Any ideas?

As stated by Alan B the max amount of cell you can connect are 8. IT sounds like you did things correct but just to be sure I go thouth how I always connected mine. I connect to 8 cells....the CellLog8 has 9 connectors numbered "0" through "7" and a "+" mark. I wire all my cells together then attach the wire from the "0" to the negitive of my first cell (this would be considered the negitive you would use to connect to your controller...or the neg you would use to messure the total pack voltage). Then connectt the #1 to the next cell's negitive and so on. the last connection should be the "+" wire from the CellLog8 and it is connected to the positive terminal of the last cell. This is where you would connect if you were checking the total voltage of the pack.

Note: If by chance the CellLog8 was active when you started connecting it will power-up when you connect the 3rd. wire (#0, #1 and #2). It will read the voltage of the first 2 or 3 cells. Most people that have a problem connecting the CellLog8 find that they connected it 180 degrees backward. I've worked with people on the phone on a few occasion helping them connect their CellLogs just to find they started with the wrong cell. Just remember the "0" and "+" go on the terminals that are used to messure the total pack voltage.

Bob

[Samson]

I thought I understood how a Cell Log 8M connected to a battery pack (40 Volts) from reading the rather vague PDF manual but while connecting one using pins 1 and 9 I heard a spark and the cell log would not power up. The polarity was + on pin 9. The manual for the CD appears to show the full pack voltage connected between pins 1 and 9 so I do not know what caused this. The unit will power up with the USB power connected but when I opened it up it looks like a component near the pins has blown open. I have another unit but I am reluctant to try it until I understand the cause of the problem. Perhaps I misunderstand how it connects. The Cell log was new. Any ideas?

As stated by Alan B the max amount of cell you can connect are 8. IT sounds like you did things correct but just to be sure I go thouth how I always connected mine. I connect to 8 cells....the CellLog8 has 9 connectors numbered "0" through "7" and a "+" mark. I wire all my cells together then attach the wire from the "0" to the negitive of my first cell (this would be considered the negitive you would use to connect to your controller...or the neg you would use to messure the total pack voltage). Then connectt the #1 to the next cell's negitive and so on. the last connection should be the "+" wire from the CellLog8 and it is connected to the positive terminal of the last cell. This is where you would connect if you were checking the total voltage of the pack.

Note: If by chance the CellLog8 was active when you started connecting it will power-up when you connect the 3rd. wire (#0, #1 and #2). It will read the voltage of the first 2 or 3 cells. Most people that have a problem connecting the CellLog8 find that they connected it 180 degrees backward. I've worked with people on the phone on a few occasion helping them connect their CellLogs just to find they started with the wrong cell. Just remember the "0" and "+" go on the terminals that are used to messure the total pack voltage.

Bob

Bob you wrote that your unit is numbered 0 through 7. Mine is marked - then 1-8 and +. This is ten markings but only 9 pins I assume the first pin marked - is pin 1 and pin 9 is the highest cell tap voltage marked +.
I stated I had connected to 1 and 9 in my post which is - and + on the cell log itself. I was attempting to use it to read the complete pack voltage of 40 volts or so. I am certain the polarity was correct. I did not have any of the other pins connected at the time. I did see that one of the diagrams in the manual seems to suggest that pins - (first pin) and 2 can be used to read from 4 to 43 volts or are they indicating that this is how to power it up?

Ken

[dumbass]

Bob

Bob you wrote that your unit is numbered 0 through 7. Mine is marked - then 1-8 and +. This is ten markings but only 9 pins I assume the first pin marked - is pin 1 and pin 9 is the highest cell tap voltage marked +.
I stated I had connected to 1 and 9 in my post which is - and + on the cell log itself. I was attempting to use it to read the complete pack voltage of 40 volts or so. I am certain the polarity was correct. I did not have any of the other pins connected at the time. I did see that one of the diagrams in the manual seems to suggest that pins - and 1 one can be used to read from 4 to 43 volts or are they indicating that this is how to power it up?

Ken

OK, I think I understand what your doing now. As mentioned you can only read up to 8 cells but you are trying to read the total pack voltage only. Sorry but I've never tried doing what your thinking of so I honestly can't advise you on it. I know you can connect in the normal way and read the first 8 cells. A lot of people will use multiple CellLogs on packs with more then 8 cells. In this manner they are connecting as if they were just several packs of 8 in the normal manner.

Bob

[pm_dawn]

I thought I understood how a Cell Log 8M connected to a battery pack (40 Volts) from reading the rather vague PDF manual but while connecting one using pins 1 and 9 I heard a spark and the cell log would not power up. The polarity was + on pin 9. The manual for the CD appears to show the full pack voltage connected between pins 1 and 9 so I do not know what caused this. The unit will power up with the USB power connected but when I opened it up it looks like a component near the pins has blown open. I have another unit but I am reluctant to try it until I understand the cause of the problem. Perhaps I misunderstand how it connects. The Cell log was new. Any ideas?

If you really look in the Manual.
On page -4- there is a pretty nice picture.
It clearly shows that when measureing a pack you should connect it to pins 1 and 2.

Also the part CW-C220 "One pack voltage measurements line with clips" pictured on Page -3- in the Manual and part of the package should give you a pretty good clue on how to use the cellog when measuring a full pack of any sort.......

To bad about the cellog.....

Regards
/Per

[EBJ]

ok, So I was out testing the CellLog LVC today. (more like abusing it)
And I was able to get the voltage below the LVC without continuing to trip it, here is how:

First, when the cell-log hits the LVC, it would pull-down the throttle line for about 1 full second (just enough time to let off the throttle).
I then proceeded to hit the LVC, wondering what would happen if I got to the "point of no return" (where you can't even accelerate at all any more).
After hitting it about 20 times, I then gradually accelerated to build up some speed, then coasted for a little bit, then "whalla", no more LVC function.
I was able to accelerate full-throttle without the LVC tripping. and I did multiple full-accelerate passes to confirm the LVC stopped working.

So, after I "tricked" the LVC to stop working (somehow).
I then took a reading and confirmed each cell was bellow the set LVC of 3.70V (they are all at 3.65ish).
I then turned off / on the main-power (and cell-logs) and the LVC function seemed to start working again,
this time cutting the throttle almost all the time (even with the most minimal acceleration).

Anyhow, I was surprised I was able to do this.

My best guesses as to WHY I was able to do this:
1. the cell-log only trips the LVC X-number of times ?
2. the cell-log got confused and really only trips when it goes from ABOVE LVC to BELLOW LVC ? (in which case I must have gotten my pack to always be bellow the LVC and that was why it stopped cutting the throttle)
3. the relay stopped working (seems unlikely, especially since the LVC function started working again after I cycled the main power-switch)




Anyone else ever tried (and succeeded) in fooling a cell-log LVC ?

[itchynackers]

This may help you. I connect a cellog 8 (setup for 8s) to my 5s pack just to get some quick measurements. Obviously the LVC trips, making the beeping noises for a while. However, after a period of time (maybe 5 minutes, didn't really track it) the beeping will just stop. Then after another period of time (maybe 10 minutes) it will start beeping again, for no apparent reason. I wasn't discharging the pack. It was just sitting on the table with the cellog on it. I haven't tested it, but it seems like the cellog will beep a certain number of times, then wait for a while, then start beeping again.

[EBJ]

thanks for the info.
That could be what I am experiencing.
but it would be more about the number of times it goes off instead of how long, because technically i am above LVC, then below and LVC triggers, then repeat.

another cell-log related issue I may be having:
I was having strange (what seems like) motor-controller issues,
but they only happened periodically. Mostly when I leave the pack for a while, or when I am at the low-end of the pack.
I had set my "difference-in-voltage" alarm on the cell-logs to something like 0.025V , which I know now is too strict towards the end of the pack battery-life when it easily hits a v-difference of .03 or .04 V.

Another question: Does the cell-log "Low-Voltage" alarm act differently than the cell-log "difference in voltage" alarm ??

example: when LOW voltage is detected, the throttle is cut for what seems to be at least a full second ("one one thousand"), this tells me the cell-log must "alarm-out" for at least one second upon even the slightest 'blip" of LOW Voltage detection, but does it do the same for the slightest "blip" in "voltage-difference", from what I am experiencing, I would guess not.
If this really is my problem then I would guess the "voltage-difference" alarm only sounds as a "blip" when it detects a "blip" in voltage difference between cells (in other words: it alarms for less than 1 full second) ?

I'll pull open my battery-pack and change the "voltage difference" alarm setting to something higher (like .05V) , but I'm waiting for the problem to happen again so I can take cell-level voltage readings and confirm it is my problem.

[itchynackers]

Maybe I'm wrong, but I always thought the "difference in voltage" was the amount of voltage drop you want the total pack to experience. Example, my parallel pack is 20.5V hot (4.1v/cell). If I want the pack to drop only to 18.0V (3.6v/cell), then the difference alarm should be set to 2.5V. That being said, I don't enable the difference alarm, so I can't say for sure. Anyone else?

[jonescg]

So guys, what's your advice in my situation - I will have 170 cells, split up into four female D-Sub44s with 42 or 43 cells wired up to them. I'm thinking I would take 6 cell-log 8s and wire them up into a male D-sub 44 plug so I can get an instant diagnostic on one quarter of the pack. Alternatively, I can get 7 or 8 battery medics to tell me the same thing. I don't know which is cheaper or more reliable, but some kind of instant readout for 43 cells at once would be great.

Which do you think would be a better option?

[Alan B]

Cell logs are smaller and take longer to boot up which is noticeable when plugging in four times. Medics are much larger, easier to read and boot faster. Medics are cheaper. Accuracy is not perfect on either. Either will unbalance packs if left connected.

My choice would probably be Medics.

[itchynackers]

My medics aren't as accurate as my cellogs (as compared with my Hyperion 1420i balance charger). Just yesterday my charger balanced to 2mv, and my cellog was off 3mv at most. My medic seems to unbalance the pack.

[bobale]

Cell logs are smaller and take longer to boot up which is noticeable when plugging in four times.

CellLogs can boot up immediately if you disable spash screen and warning about logging.

[EBJ]

Maybe I'm wrong, but I always thought the "difference in voltage" was the amount of voltage drop you want the total pack to experience. Example, my parallel pack is 20.5V hot (4.1v/cell). If I want the pack to drop only to 18.0V (3.6v/cell), then the difference alarm should be set to 2.5V. That being said, I don't enable the difference alarm, so I can't say for sure. Anyone else?

definitely not the case for me, or I wouldn't get very far having 'em set to delta .025

[EBJ]

ok, just confirmed the voltage-difference alarm isn't my problem.
I believe it to be a motor-controller issue.

[heathyoung]

For the more adventurous there are some 'interesting' hacks that can be done - I modified an 8S unit for checking the balance across 8S 12V batteries - its pretty simple to do, just some resistive dividers and some unity gain opamps.

[EBJ]

Do you think the cell-log could handle switching a relay for throttle cut-off AND sounding an alarm ?
..granted I could just use the same LVC relay to sound an alarm, but It would be easier wiring if I could just have the cell-log switch the LVC relay while also sounding an alarm.

[fechter]

The alarm output is rated for 500mA. If your throttle pull down circuit uses a 1k resistor, the maximum it will take is less than 5mA. Many piezo alarms will be well under 500mA, but check the ratings.

[EBJ]

The alarm output is rated for 500mA. If your throttle pull down circuit uses a 1k resistor, the maximum it will take is less than 5mA. Many piezo alarms will be well under 500mA, but check the ratings.

Thanks, but I just decided to run the alarm off the relay I was already using for the throttle pull-down.
(which is something like 25mA) It's a sure-bet this way since I know my cell-logs are able to power these relays.

[Pir]

For the more adventurous there are some 'interesting' hacks that can be done - I modified an 8S unit for checking the balance across 8S 12V batteries - its pretty simple to do, just some resistive dividers and some unity gain opamps.

Is this external circuit, or modification of cellogs schematic? May you describe your hack in detail?

[heathyoung]

Its an external circuit. I'll find the schematic and post it up. Very simple, I used it to help out someone trying to find a battery that was dying under load. He had 8 12V batteries in series.

[dumbass]

The alarm output is rated for 500mA. If your throttle pull down circuit uses a 1k resistor, the maximum it will take is less than 5mA. Many piezo alarms will be well under 500mA, but check the ratings.

Thanks, but I just decided to run the alarm off the relay I was already using for the throttle pull-down.
(which is something like 25mA) It's a sure-bet this way since I know my cell-logs are able to power these relays.

What type of relay are you using? Got a pic or link? I'm asking because I am intending to use a common ice cube relay and it's not power draw isn't indicated.

Bob

[EBJ]

i'm using the relays that used to be at AllElectronics surplus store....
I think they sell 'em at mouser. Lemme go find it...

http://www.mouser.com/ProductDetail/NEC/EA2-12NJ/?qs=BFfLPGsFlNdZQua2EckYEg%3d%3d

I believe these pull 11mA ... check the data-sheet.
I'm using 'em w/ the cell-logs and can confirm no problems.

[__Tango]

Just wondering...I want to access the data stream from my six CellLog 8s from my mac. I'm a coder, so once i get the device attached and i can talk to it, i should be able to make it happen. The problem is that i don't know much about connecting USB devices to computers and getting them to look like serial devices (like how the Arduino serial monitor works).

I'm assuming there's a chip driver i need or something, but i'm not sure. Anyone have any ideas? Or has anyone already done this?

Thanks!

[EVPowers]

Its an external circuit. I'll find the schematic and post it up. Very simple, I used it to help out someone trying to find a battery that was dying under load. He had 8 12V batteries in series.

I am very interested in this circuit.
Was the schematic posted somewhere?

I actually need it for 7, 12v cells in series, but hopefully there would be a way to adapt whatever you have already done.

Thanks in advance.