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› Measuring Amperage and Mili-Amps
10-21-2016 07:29 AM  13 months agoPost 1
DennisH

rrApprentice

Baton Rouge​Louisiana USA

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How do you measure your amperage and milliamps on your batteries.

I am especially interested in 2 - 22.2v 8000mAh batteries hook up in series which should equal 44.4v 8000mAh's. Normal pack for a TRex and many other large Heli's.

Then if you made up 2 of the above batteries packs (44.4v 8000mAh's) parallel, you should have a battery that produces 44.4v's with 16000mAh's, correct?

Or if you hook up 2 - 22.2v 8000mAh batteries parallel which should equal 22.2v with 16000mAh's.

Is there a meter out there that will give the measurements? Or have you made your own shunt and used it with your current volt/ohm/amp meter?

Dennis

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10-21-2016 08:06 AM  13 months agoPost 2
Pistol Pete

rrProfessor

Seffner, FL

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Perhaps THIS may be "watt" you're after and some.

I picked one up when I got into brushless over 10 years.

Maybe hobby king has already cloned it.

~~Enjoying the hobby one flight at a time~~

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10-21-2016 09:46 AM  13 months agoPost 3
wjvail

rrKey Veteran

Meridian,​Mississippi

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Most Castle Creations ESC log quite a bit of information. I'm sure other ESC do also. Simply fly a flight and download the stored data. That will include data on voltage, current, capacity, power, temperature, etc...

I'm not sure what you really want to know. Are you trying to test your batteries to verify there specifications? For that sort of thing I use my charger (iCharger 4010Duo).

Bill

"Well, Nothing bad can happen now."

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10-21-2016 02:08 PM  13 months agoPost 4
DennisH

rrApprentice

Baton Rouge​Louisiana USA

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Pistol Pete, Yes, this is close to what I am looking for. Do you hook it up inline? I see you have a red/black coming in, and the same going out. Just verify how your are hooking it up.

wjvail: The castle has a mini USB port? I have never downloaded any information from mine, just need instructions or direction to do so.

Also, I am looking for "total Amperage" from the battery, or if I hook up batteries in parallel, I am looking for the total amperage/miliamps.

Example: If I am hooking up 2 5000mAh batteries in parallel, I should have a reading of 10000mah's. I just want to verify this reading.

I have the 406, I will study up on the readings today as well. Hopefully I will find what I am looking for.

Dennis

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10-21-2016 03:01 PM  13 months agoPost 5
wjvail

rrKey Veteran

Meridian,​Mississippi

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wjvail: The castle has a mini USB port? I have never downloaded any information from mine, just need instructions or direction to do so.
You need a small device that plugs into the ESC lead that would normally be connected to the receiver. That adapter has a USB port. The software is free. You'll end up with something that looks like the picture below.
http://www.castlecreations.com/en/c...kit-010-0005-00

------------------------------------
Also, I am looking for "total Amperage" from the battery, or if I hook up batteries in parallel, I am looking for the total amperage/miliamps.
We might be getting tangled up in terminology here.
--"Total Amperage" will very widely. The current of the battery can be just about anything. In any particular application, average and max current are valuable things to know. The crazy green line in the picture above is representative of a battery installed in a model helicopter.
-- The battery's total "Amp*Hour" will, as a generality, be the sum of the two batteries if hooked up in parallel or the simply the capacity of the batteries if hooded up in series. I think what you'd like to do is do some real world testing. See below for a few thoughts on that...
-- The voltage of a battery can be read by using an inexpensive multi-meter.

Testing the capacity of a 22 volt 10 amp*hr battery is not easy. That is a lot of energy and most chargers will only discharge at around 50 watts. You will likely only be able to discharge at around 2 amps and that'll require around 5 hours to complete.

As I said, I often use my charger for the type testing you are asking about. Below is a video I made a few years ago.

Watch at YouTube

The meter Pete suggested is a very valuable tool. The small meter I used in the above video does record capacity but you will still need to find somewhere to dump the energy.
http://www.buddyrc.com/skyrc-watt-meter.html

Bill

"Well, Nothing bad can happen now."

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10-21-2016 07:21 PM  13 months agoPost 6
DennisH

rrApprentice

Baton Rouge​Louisiana USA

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Thanks Bill,
Testing the capacity of a 22 volt 10 amp*hr battery is not easy.
YES, I have found this out, and is the reason for my questions.

I don't think I will go to the extremes you have, which by the way was "VERY" interesting in the video.

You had a single 4000mAh battery, and while discharging, you almost pulled all of the current out of the battery, I believe 38??mAh's, I forget the exact mAh's pulled which was very quickly.

If a battery has a 4000mAh, 5000mAh, or 8000mAh rating, how does the battery manufacture determine these figures?

My goal: If I hook up two 22.2v 5000mAh batteries in parallel, I should have a pack that produces 22.2v with 10000mAh's available. I thought there might be an easy way to check to see if I had 10000mAh's available. Apparently not.

Some of the articles I have read don't even come close to this figure, as it's a very powerful source to read. It's very hard to find a multimeter that goes above 20amp's.

I will study the castle set up and see about getting the USB adapter. This looks interesting.

Thanks for the time explaining and sending the video. I am sure it will help many. When I do recharge my batteries, I put about 3700 to 4000 mAh's back in a 5000mAh battery. So you're saying this will be my best option without getting elaborate?

I am just tinkering, and I am very curious as well. I am setting up blocks of 18650 Li-on batteries in series now, and I can test the mAh in every single cell, which varies sometimes greatly. Most Multimeters will only go up to 20 amp's, or 20000 mAh's. Voltage is simple to check, and I guess is most important building battery cells.

Have you ever repaired any of your LiPo batteries. I means replace one bad cell out of 6 in a 22.2v battery? I wonder if 3.7v individual cells are available for purchase?

I was/still am a certified automotive technician with Hybird and Electric vehicles, but we handled those in a very different way. Their cells produced sometimes over 7000 volts! I have been through all the safety classes plus training with these batteries, and also was responsible for training my employees as well, and making sure they had the right equipment to work on them. If a cell was bad, we just replaced it. Working around all the orange wires was tricky sometimes.

I am disabled and retired, so I have plenty of time on my hands to pursue projects like this.

Again, I also find it very interesting. I wish I would have dug into it further while I was working on the automobiles.

Thanks Again,
Dennis

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10-22-2016 06:42 PM  13 months agoPost 7
Pistol Pete

rrProfessor

Seffner, FL

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Dennis, yes on placing watt meter in-line between battery and ESC.

Pro about this meter is that it gives you a live reading at-the-field.

Some of the best features I like are that it latches to MINimum VOLTage under load and MAXimum Amp.

Of course the main thing and what you seem to be after is that it also displays actual milliamps used.

*********

Real example based on a 5000mAh: (voltage does not matter)

Since the rule of thumb is to only use 80% of capacity, that left me with 4000mAh to play with.

So I would fly for two minutes. Land and view how many milliamps I used and divide by two.

If I used 1000mAh in those two minute of flight and divide it by two (minutes), meaning Im using 500mAh per minute.

Since I have 4000mAh to play with, dividing it by 500mAh tells me I can fly for 8 minutes.

I would then set my radio timer to 7 minutes giving me 1 minute to land or plenty time to spare before going over the 80% rule.

**********

You could use a lipo alarm, but would need one for every balancing cable per battery. Downside no actual amperage reading, just lowest voltage of any single cell under load. My watt meter pre dates lipo alarms.

Yes, castle will give you same info (and more) AFTER flight and connecting to a PC. Great thing about that it's a neat graph and an electronic record vs pencil and a pad. Then again you can take a photo of watt meter screen with cell phone.

What neither will give you is actual milliamps stored in battery. For that is where your charger comes into play after discharging and charging several times where you will gauge the actual amount that your battery is capable of storing.

******

As for purchasing single cells to repair packs. Problem with that is matching size and mainly OHM reading to existing pack so that they discharge equally. A quest that will drive you nuts.

What I have done instead is remove the bad cell thus downgrading to next voltage down. So a 6S becomes a 5S. Given what you have done, no big deal, just need to be just as careful not to short anything.

Best of luck!

~~Enjoying the hobby one flight at a time~~

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10-27-2016 01:38 PM  12 months agoPost 8
Richardmid1

rrProfessor

Leeds, England

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My goal: If I hook up two 22.2v 5000mAh batteries in parallel, I should have a pack that produces 22.2v with 10000mAh's available. I thought there might be an easy way to check to see if I had 10000mAh's available. Apparently not.
If you hook up 2 5000mah pack in parallel you WILL have 10000mah, it's just basic maths.

A 5Ah (5000mAh) pack will be depleted in 1 hour at 5 amps load. A 10Ah pack will be depleted in 1 hour at 10 amps load or 2 hours at 5 amps load.

To pull 100% capacity out of a Li-po you would need to discharge it to 3v/cell. It is perfectly safe to do so at a slow discharge rate. It is safe to do it at a high dicharge rate but don't expect the battery to last very long!

It is also possible to pull more than 100% capacity out of a pack, it depends if the manufacturer under or over estimates the cells capacity! Those packs you see that are suspiciously smaller or lighter than they should be probably have less capacity than is printed on the label!

60% of the time, it works every time!

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02-21-2017 11:08 PM  9 months agoPost 9
EEngineer

rrProfessor

TX

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"Perhaps THIS may be "watt" you're after and some."

Good one...that was "punny".....

Logo 600SXs, 800XX, TDR IIs

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