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Old Jun 22, 2015, 02:31 AM
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Looking for cheap charger with discharge function that can send measured data to PC

I would like to test some batteries, by discharging, and then putting the results in a graph. Mostly for my quads and helis, so I can compare these, and spot bad ones before I get to fly a battery, and then have to make an emergency landing. At the moment, I just use the discharge function of my B6, and note down voltages at regular intervals, but this requires constant monitoring of the charger. So it would be nice if you could just set it to discharge, and have the data sent to a pc instead.

I've seen the new SkyRC B6 Mini has this option, using the Charge Master software, and my regular B6 chargers have served me well, as most of my batteries are 1 or 2 cell anyway, except some 3 cell LiFe transmitter batteries. So I would happily get an updated B6. But there might be options that are more versatile.

For instance, the discharge program for LiPo of the regular B6 doesn't allow to set end voltage, and is at only 3.0 volts, which I think is too low. So it would be nice if the charger I intend to purchase, would have the option to change this voltage at where to stop the test.

With cheap, I mean preferably under 50 USD, unless you get some great extra features above that, to justify the extra money spent.
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Old Jun 22, 2015, 03:07 AM
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Most cheap chargers under $50 won't allow high enough discharge rate to do some meaningfully load test to find bad lipo although any of these chargers that provide USB connectivity will spit out real-time data to log by PC software like "logview".

However, if you want some load test with some real-world load, I recommend the Reaktor 300W 20A charger. You can enable datalog and then run "monitor mode" which monitors indivdual cell voltages while you can still hook up discharge leads to say your quad and run it under load. You can then hook up USB to "logview" on PC to download the logged data AFTER you finish the test. No need to hook up USB while testing. Yes, the charger is $10 over your budge but it's a way much better charger than the B6 in every way. It's worth the $60 even without the monitor mode feature.

Here're some discharge test logs I've done for my nanotech thread.
http://www.rcgroups.com/forums/showp...9&postcount=21
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Old Jun 22, 2015, 03:46 AM
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I should have mentioned that most of my batteries when it comes to flying, are 1S 150 mAh to 600 mAh. So it doesn't take a heavy load to see difference in performance. For my 2S car batteries, I have different methods, like measuring top speed with gps logger, and also, if a battery is bad, a car will not fall from the sky.

Does the Reaktor 300W need a seperate power supply? And how straightforward is working with Logview? 10 above budget is certainly an option if it adds more funtionality. Can it be set to stop at 3.5 volts per cell, when running a discharge program in LiPo mode?
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Old Jun 22, 2015, 04:15 AM
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For 150mAh lipos the Reaktor may be overkill. The "monitor mode" I mentioned just monitor (and log) cell voltages. It doesn't do any discharge function. You'll hook up the discharge leads (say to the quad) to discharge the lipo while the charger logs cell voltages over time. Unfortunately, monitor mode uses balance leads of the packs. For 1S, that doesn't work obviously. You can use discharge mode and voltage and you can set terminal voltage for discharge function.

Perhaps you may want to consider this charger on sale for ridiculously low price of $20 (international warehouse though).
https://www.hobbyking.com/hobbyking/...dProduct=58187

This one will graph charging sessions on the unit itself. I think it'll do the same for discharge session but not sure if available and how accurate you can retrieve values from it. Doesn't show discharge graph functionality in the manual.
http://www.hobbyking.com/hobbyking/s...1649667X31.pdf

For any other cheap 4-button charger that has USB connectivitiy, running it with logview is easy. Just download the free/donation-ware software and follow instructions to set up.
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Old Jun 22, 2015, 07:37 AM
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Thanks for the suggestions. Shipping cost might be a killer for that 20 usd charger, plus I read it can't do storage charge for 1S.

The other could be an option, but currently no stock in EU warehouse. Btw, you don't happen to know if you can set the cutoff voltage for lipo discharge program on the B6 Mini? I could alternatively use NiMh discharge, for 1S, as you can set the cutoff voltage for that in 0.1V increments.
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Old Jun 22, 2015, 01:42 PM
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Oh yeah that's right I remember reading the X120 needs to see cell voltage(s) on the balance leads even when charging 1S. You can make a harness to do the job but as you said shipping cost is a bigger issue.

I have no experience with the B6 mini. Your suggestion sounds like a good workaround. But to be honest, if it was me for the small 1S lipos I'll probably just notice the voltage ramp-up when starting a charge session. The higher the voltage jump during the initial charge current ramp-up will suggest higher IR.
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Old Jun 23, 2015, 05:21 AM
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Originally Posted by SoloProFan View Post
I should have mentioned that most of my batteries when it comes to flying, are 1S 150 mAh to 600 mAh. So it doesn't take a heavy load to see difference in performance. For my 2S car batteries, I have different methods, like measuring top speed with gps logger, and also, if a battery is bad, a car will not fall from the sky.

Does the Reaktor 300W need a seperate power supply? And how straightforward is working with Logview? 10 above budget is certainly an option if it adds more funtionality. Can it be set to stop at 3.5 volts per cell, when running a discharge program in LiPo mode?
Save your money and just get an Accucel ECO6 charger ... such as the 80W .... this will connect to PC via Charge master and give you all the info needed.
The Reactor is a good charger IF you need higher rates .... but costs a lot more.

Nigel
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