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Power Systems Talk about motors, ESC speed controllers, gear drives, propellers, power system simulators and all power system related topics

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Old 11-26-2012, 09:17 PM   #1
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Default Newb with a mysterious problem

Hello, I've been a lurker, but decided to post on a problem to see if anyone could help. Have been having difficulties with a group of 20A Saker ESCs. Seems they test LIPO V before arming motor. Anything 8V or above, they detect battery as 3S, anything below 8V they detect as 2S. I'm running them with 2S batteries, which come off my Bantam charger at a default top-off of 8.4V. The ESC's interpret this voltage as a 3S battery with very low voltage. The motor (if it arms at all) will do a one second blip, then shut down. In order for my motor to arm and run I have to discharge my batteries down below 8V, or monitor them manually to insure they don't charge above 8V (a hassle). I assumed 8.4V was probably a standard cut-off for most chargers. My Bantam BC6-10 seems to offer no max V upper cutoff adjustment. Is this a common problem, or do I perhaps have a batch of ESCs that have been mis-calibrated at the factory? Even the vendor I purchased from is scratching his head over this one. Thanks
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Old 11-26-2012, 09:33 PM   #2
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Check the programming on the ESC. Hopefully, you got a manual with it that gives you the procedure and codes. I would try setting it to the factory default first. If that doesn't work, then manually set the battery type to lipo and try that.

Wouldn't be the first time an ESC was bad from the start.

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Old 11-26-2012, 09:43 PM   #3
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Programming may be set to LiFe type battery, which have lower cell voltage. Try re-programming to LiPo. The manual is here: http://www.kedamodel.com/product/doc...%20advance.pdf

Reading the manual it sounds like the procedure to set to LiPo is:
  1. Remove prop
  2. Put the throttle to wide open position and turn on Tx
  3. Plug in the Battery to the ESC
  4. ESC/motor will beep four times to signal entry into program mode
  5. ESC/motor will then emit a series of five single beeps, during these beeps close the throttle fully
  6. Wait for arming tone.


ESC is now programmed for LiPo
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Old 11-26-2012, 09:58 PM   #4
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That was tried and confirmed many times. The Vendor was the one who actually figured out what the ESC was doing (from one I returned). At this point HE still has no Idea what's going on. He thought maybe my charger was in error, but cross-checking battery voltages with a digital multimeter shows very minor differences between the meter and the charger. IS 8.4V a common cut-off for 2S on most chargers? Or should my Bantam be auto-charging to a lower V cut-off?
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Old 11-26-2012, 10:12 PM   #5
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Maybe, if you have carefully followed the steps I outlined, the manual has an error and you need to set it to one other the other settings. Possibly the manual has LiFe and LiPo mixed up? Unlikely I know but that's really the only thing that could be causing this, short of the ESC's all being faulty (I'm reading you have tried more than one?).

All LiPo chargers by default charge to a target of 4.2V per cell, which generally drops back to around 4.15-4.18V per cell after the battery rests.
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Old 11-27-2012, 12:05 AM   #6
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The ESC's MCU (microcontroller) is probably getting bad voltage information from a faulty component. I'd ask the vendor to replace it. If this has happened with several examples of this ESC, I'd ask for a different make or a different model from the same maker.

Probably got a bad lot of some component during it's manufacture.

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Old 11-27-2012, 12:29 AM   #7
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Originally Posted by maxflyer View Post
Hello, I've been a lurker, but decided to post on a problem to see if anyone could help. Have been having difficulties with a group of 20A Saker ESCs. Seems they test LIPO V before arming motor. Anything 8V or above, they detect battery as 3S, anything below 8V they detect as 2S. I'm running them with 2S batteries, which come off my Bantam charger at a default top-off of 8.4V. The ESC's interpret this voltage as a 3S battery with very low voltage. The motor (if it arms at all) will do a one second blip, then shut down. In order for my motor to arm and run I have to discharge my batteries down below 8V, or monitor them manually to insure they don't charge above 8V (a hassle). I assumed 8.4V was probably a standard cut-off for most chargers. My Bantam BC6-10 seems to offer no max V upper cutoff adjustment. Is this a common problem, or do I perhaps have a batch of ESCs that have been mis-calibrated at the factory? Even the vendor I purchased from is scratching his head over this one. Thanks
If you are in the USA, check out the Castle Creations Thunderbird ESC's. More $$$$, but they can be programmed with their USB type programmer and your computer. And, they work. Their Thunderbird line allows either an automatic LiPo LVC (Low Voltage Cutoff), or a fixed voltage adjustable by 0.1 volts.

I've got their ESC's from their 18 Amp Thunderbird to their 80 Amp ICE series High Voltage unit running on my 12S2P a123 battery packs.

http://www.castlecreations.com/produ...nderbirds.html

DennyV
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Old 11-27-2012, 04:25 AM   #8
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Thanks for the help guys. I have to go with the theory that these ESC's are faulty. So far I have set up and run a T-bird and two differently-rated Turnigys and haven't had an issue. All three of the 20A Sakers I have tried have exhibited this weird behavior. Might be wise to avoid this particular unit for now. I'm sorry for the vendor, who has been very helpful, but it appears he has an inventory issue to deal with.
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Old 11-27-2012, 07:35 AM   #9
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It's a shame if the ESC's all prove to be faulty because on paper they look like excellent bang for buck. I notice that from 20Amp and up they have powerful switching mode BEC's (SBEC) installed. This is much better than even the premium brands like Castle Creations who still use crappy linear BEC's in their smaller/cheaper products. Plus the Saker are dirt cheap. Lets keep fingers crossed that the problem is just with one batch.
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Old 11-27-2012, 02:22 PM   #10
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You noticed! That's why I tried so many of them, and invested so much time trying to get them to work. Hard to find more capability for the price. Vendor has offered credit or refund on all of them.
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Old 11-28-2012, 05:44 AM   #11
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Follow-up:

OK, out of four of these 20A Sakers I ordered, two of them exhibited normal behavior and two were funky. That was bad news for me, but perhaps not as bad for the vendor. He says he hasn't had any other negative reports besides mine. That could mean I was just unlucky in getting the two bad ones, and the current supply might not all be affected. Of course, if people ordered these and connected them only to 3S or larger packs, they might never know that there was a problem with 2S packs.
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Old 11-28-2012, 06:31 PM   #12
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Originally Posted by maxflyer View Post
Follow-up:

OK, out of four of these 20A Sakers I ordered, two of them exhibited normal behavior and two were funky. That was bad news for me, but perhaps not as bad for the vendor. He says he hasn't had any other negative reports besides mine. That could mean I was just unlucky in getting the two bad ones, and the current supply might not all be affected. Of course, if people ordered these and connected them only to 3S or larger packs, they might never know that there was a problem with 2S packs.
H'mmm
Makes you wonder if having to buy four units to get two that work is less expensive than buying other brands?

On the other hand, I had to send in one of my Castle Creations 80 Amp HV ICE ESC's last spring on their factory recall. Took CC near two months to get it back. And absolutely ZERO communication from CC, could not even find out if they even had my ESC in the first place. Even though I'd put a received delivery response from CC on the package.

When I finally got it back, they did include a very nice transmitter neck strap with the ESC.

DennyV
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