Analyze cycle working correctly?

[DarkSyd3D]

The first time I tried to analyze a battery with the stock settings through the bump control it brought the battery down critically low to Less Than 3 volts per cell. I am trying it again after confirming all of the settings and so far a fully charged pack is down to 3.8 volts per cell. It doesn't say anywhere in the user guide what voltage the analyze cycle will bring the discharge down to. Can someone please let me know before this battery is destroyed?

[sowersr]

I had this same problem, The default discharge voltage when setting up a new tag is 3.3 volts (I believe that is what it is, I am at work, so I don't have my bump in front of me). I usually change that to 3.8 when I set up a new tag, missed it on one new tag, of course it was for a stick pack. I ran the analyze cycle on the pack, looked over it was down to 5%, about had a heart attack. I have no Idea why the default for a lipo is that low. Programed the tag with the right voltage, all is good now.

[DarkSyd3D]

Originally Posted by sowersr

I had this same problem, The default discharge voltage when setting up a new tag is 3.3 volts (I believe that is what it is, I am at work, so I don't have my bump in front of me). I usually change that to 3.8 when I set up a new tag, missed it on one new tag, of course it was for a stick pack. I ran the analyze cycle on the pack, looked over it was down to 5%, about had a heart attack. I have no Idea why the default for a lipo is that low. Programed the tag with the right voltage, all is good now.

Totally what it was. Thanks for the help! Not if I can only get the BC to maintain comms with the 5 ferrite rings I have installed so far lol

[sowersr]

Glad that was it.

[RevoKelly]

Originally Posted by sowersr

I had this same problem, The default discharge voltage when setting up a new tag is 3.3 volts (I believe that is what it is, I am at work, so I don't have my bump in front of me). I usually change that to 3.8 when I set up a new tag, missed it on one new tag, of course it was for a stick pack. I ran the analyze cycle on the pack, looked over it was down to 5%, about had a heart attack. I have no Idea why the default for a lipo is that low. Programed the tag with the right voltage, all is good now.

3.3v is quite safe for any lipo - most ESCs can be adjusted even lower. It won't harm the battery. And the charger is monitoring each cell, unlike an ESC, so a cell won't be taken below that.

3.8v is certainly safe but that's not much below 50% for most packs, so you'll probably get capacity warnings when running Analyze because you won't be able to drain rated capacity out of the pack if u stop at 3.8v. I would go with 3.3-3.6v for cutoff unless specifically stated otherwise by the battery manufacturer.

On the Bump, there's nothing wrong with taking a pack to 0% in a discharge - it just means that it has been discharged to your specified cutoff voltage. It's not good to leave the pack completely discharged for a long duration, just like it's not good to leave it full. But fully draining it during an Analyze isn't going to hurt anything and its the only way to measure the true capacity of the pack.

[sowersr]

Thanks for the explanation, there is a lot of mis-information floating around, I know for myself learning from the guys at the field, and what I read on the forums and listen to on podcast. Taking that info and putting together a plan for charging and storing my batteries has been a huge learning curve that seems to change all the time. Somewhere along the line it has been beat into me that I should never discharge below 3.75 volts per cell. That is where he 3.8 comes from, plus the learning curve of what the charger is doing depending weather I am charging, discharging, cycling for break-in, or something else. This explains why I got some capacity warnings on some new 6s 4100s that I was breaking in.

[DarkSyd3D]

Originally Posted by RevoKelly

3.3v is quite safe for any lipo - most ESCs can be adjusted even lower. It won't harm the battery. And the charger is monitoring each cell, unlike an ESC, so a cell won't be taken below that.

3.8v is certainly safe but that's not much below 50% for most packs, so you'll probably get capacity warnings when running Analyze because you won't be able to drain rated capacity out of the pack if u stop at 3.8v. I would go with 3.3-3.6v for cutoff unless specifically stated otherwise by the battery manufacturer.

On the Bump, there's nothing wrong with taking a pack to 0% in a discharge - it just means that it has been discharged to your specified cutoff voltage. It's not good to leave the pack completely discharged for a long duration, just like it's not good to leave it full. But fully draining it during an Analyze isn't going to hurt anything and its the only way to measure the true capacity of the pack.

If it's safe to fully drain the pack on the bench why isn't it safe to do it in a flight?

[HEXAHYDRATE]

There is so much more draw in flight that the voltage drop will be enough to go below safe levels for the lipo towards the end of the flight. On the bench you are only putting a small load on the battery.

[hemp]

I'm going to restate what has already been stated, hopefully to add a little clarity.

What you have to remember is that the thing which primarily damages LiPO cells is heat. The rate heat is generated at a given rate of discharge increases as the voltage decreases. You can picture a graph with a (roughly) exponential curve -- given a constant rate of discharge, plotting voltage decreasing on the horizontal axis and rate of heating increasing on the vertical axis, you'll see a huge climb as it gets into about the 3.3V area (varies by cell health, etc -- that's just an approximation.)

So we don't want any cells dropping below that 3.3v danger zone in flight. But the cells in a pack all drop voltage at different rates due to variances in IR, etc, so you need your weakest cell's minimum voltage sag to stay at or above 3.3v. How do you do that when you only know your pack's resting voltage? You build in a giant safety margin. That's why your friends at the flying field say to land at 3.7v per cell (even though they likely don't know the reason.) Because under load, that corresponds to probably 3.3v or even lower. Once the pack is at rest, the voltage climbs back up and you read 3.7v on your checker.

Sitting on a slow discharger with each cell's voltage being monitored, those concerns aren't concerns. That's why Kelly can say it's safe.

[DarkSyd3D]

Originally Posted by hemp

I'm going to restate what has already been stated, hopefully to add a little clarity.

What you have to remember is that the thing which primarily damages LiPO cells is heat. The rate heat is generated at a given rate of discharge increases as the voltage decreases. You can picture a graph with a (roughly) exponential curve -- given a constant rate of discharge, plotting voltage decreasing on the horizontal axis and rate of heating increasing on the vertical axis, you'll see a huge climb as it gets into about the 3.3V area (varies by cell health, etc -- that's just an approximation.)

So we don't want any cells dropping below that 3.3v danger zone in flight. But the cells in a pack all drop voltage at different rates due to variances in IR, etc, so you need your weakest cell's minimum voltage sag to stay at or above 3.3v. How do you do that when you only know your pack's resting voltage? You build in a giant safety margin. That's why your friends at the flying field say to land at 3.7v per cell (even though they likely don't know the reason.) Because under load, that corresponds to probably 3.3v or even lower. Once the pack is at rest, the voltage climbs back up and you read 3.7v on your checker.

Sitting on a slow discharger with each cell's voltage being monitored, those concerns aren't concerns. That's why Kelly can say it's safe.

Thanks for explaining that. I didn't see your post about it before. But it makes sense

[DarkSyd3D]

So I received a brand new BC from revo the other day. Decided to try to do another analyze cycle again. The BC brought the pack down to 3.5v per cell and then began to give me error code 17 "cells don't add up". I checked with a cell checker and while the percentage is low all cells are between 3.45 and 3.52v per cell and all 6 register.
My problem now is I'm not able to charge the pack back to storage because the error code keeps coming up after a few seconds.
How can I get this pack back into storage charge safely???????

I'm done with trying to do pack analysis as I believe there are still bugs to work out :/

[hemp]

Originally Posted by DarkSyd3D

Decided to try to do another analyze cycle again. The BC brought the pack down to 3.5v per cell and then began to give me error code 17 "cells don't add up". I checked with a cell checker and while the percentage is low all cells are between 3.45 and 3.52v per cell and all 6 register.

I ran into the same issue a couple days ago. I think it may be a new issue introduced with firmware v2.16. Kelly, would be great if you could look into that! Happened during an analyze cycle (on the discharge) for me also.

[sowersr]

I had the same problem after updating the firmware. Also got the error 17, for some reason on the bump it would not show cell 6, after getting the error. Using a cell checker, all but one of the cells was at 3.4, one cell was at 3.3, can't remember if that was cell 6, 3.3 is where I have the low voltage set. I could not get any charge cycles to start after I got the error using the Pl8 and the bump. This was a stick pack, I was doing a analyze cycle with the bump, one Pl8 and one Pl6 connected to the bump. The Pl8 was on channel 1, Pl6 on channel 2. I was doing a single charge with one side of the pack on each charger. I got the error on the Pl8. I tried using the bump connected to only one charger at a time, continued to get the the error and could not get either charger to start a charge cycle. So once I got the error I could not get either charger to charge the pack using the bump. I put the battery on a non FMA charger to see if it would charge, no problem, let it charge to 3.5 volts per cell, then through it on the Pl8 with the bump removed, hit the storage charge preset, worked just fine. Going to test the same pack tonight to see if I get the same result. If I do get the error, I will put it on the Pl8 without the bump to see if it charges without putting it on the third party charger first, my hunch is that it will charge just fine.

[sowersr]

Little more info....... I did a analyze cycle on a stick pack that is just the same as the one I had the problem on Saturday. I was using the same setup, Bump, Pl8, Pl6....... no problems worked just fine. That was before the last software update.

[RevoKelly]

Sorry for the hassle, but upgrade to v2.17 and it will fix that problem.

Part of the change/fix for the Analyze fuel table problem affected cell volts detection setting and introduced this new bug that causes safety #17 in some cases.

[sowersr]

Thanks for getting on this Kelly.

[RevoKelly]

Originally Posted by DarkSyd3D

I'm done with trying to do pack analysis as I believe there are still bugs to work out :/

FYI - I'm pretty confident that the Analyze problems are behind us with v2.17. We did tons of testing with that release with just about every type of pack and all different settings and scenarios, so we're pretty confident in it ... I wouldn't give up just yet

[RevoKelly]

FYI - The Android app 3.11 which included Bump firmware 2.17 to address the safety #17 issue was supposed to have posted Tuesday .... but a Google Play snafu kept it from actually updating.

That should be fixed now, so update to app 3.11 to get the new firmware, or run the Windows firmware installer.

[DarkSyd3D]

Originally Posted by RevoKelly

Sorry for the hassle, but upgrade to v2.17 and it will fix that problem.

Part of the change/fix for the Analyze fuel table problem affected cell volts detection setting and introduced this new bug that causes safety #17 in some cases.

Thanks kelly. I'll give it a try again after I download the update.ill do it on a battery I don't use anymore to test it first
Thanks for being so prompt