How manyy amps am I pulling?
03-07-2009, 04:59 PM
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How manyy amps am I pulling?
Hey guys, maybe someone can help me a bit. Flew my twinjet yesterday for first time in long time. Running stock multiplex twin 480bb's on a 3s 2100mah 20c lipo. Flew fantastic! Used to fly with 33oo nmhd and it was way over weight and a slug basically. Now it has some decent zip, but worried about battery, so I set my handy egg timer for 5min just to be safe. Battery came out slightly warm, no way near hot, but still worry about it. Any one have a clue what kind of current I am pulling? Oh, these are with the push on gunther props, I think they are a 5x4.5. Any help would be awesome.
03-07-2009, 05:13 PM
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RE: How manyy amps am I pulling?
Hi
I read this in a bmw forum, but the question is the same irregardless wether its car or rc. What you need to do is use a multimeter that measures amps, and place it between battery, and esc. this is from the site "To measure the current drain from your battery you will need to connect your multi meter in series with the battery and NOT in parallel across the positive and negative terminals. This would be OK to do this if you are measuring voltage. To measure current disconnect the negative terminal (I use the neg but you can use either), set your millimeter to measure amps and connect the meter between the battery terminal and the disconnected cable. "
I hope this helps, ask some more before u do this, i dont think its wrong, but i dont want you to fry anything.
I read this in a bmw forum, but the question is the same irregardless wether its car or rc. What you need to do is use a multimeter that measures amps, and place it between battery, and esc. this is from the site "To measure the current drain from your battery you will need to connect your multi meter in series with the battery and NOT in parallel across the positive and negative terminals. This would be OK to do this if you are measuring voltage. To measure current disconnect the negative terminal (I use the neg but you can use either), set your millimeter to measure amps and connect the meter between the battery terminal and the disconnected cable. "
I hope this helps, ask some more before u do this, i dont think its wrong, but i dont want you to fry anything.
03-07-2009, 07:06 PM
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RE: How manyy amps am I pulling?
Most digital multimeters (DMMs) have a maximum current rating of 10A. So you want to be sure your DMM can handle the current before using it as described in amen's post
You can extend the current-measuring capability of a DMM by using a current shunt. You either [link=http://www.rcgroups.com/forums/showthread.php?t=393591]make a shunt[/link] or [link=http://www.fmadirect.com/detail.htm?item=2111§ion=57]buy a shunt[/link].
An even better solution is to get a wattmeter designed for use with electric plane power systems. Something like an [link=http://www.astroflight.com/index.php?main_page=product_info&cPath=2&products_id=17]AstroFlight Super Whattmeter[/link] or a [link=http://www.powerwerx.com/product.asp?ProdID=3809]Watt's Up Meter[/link] will do the job easily and conveniently and show you voltage and power at the same time. A wattmeter is an essential tool for checking and troubleshooting e-flight power systems. If it prevents you from frying even one power system, the wattmeter will have paid for itself.
Why guess about your power system when you can know?
- Jeff
You can extend the current-measuring capability of a DMM by using a current shunt. You either [link=http://www.rcgroups.com/forums/showthread.php?t=393591]make a shunt[/link] or [link=http://www.fmadirect.com/detail.htm?item=2111§ion=57]buy a shunt[/link].
An even better solution is to get a wattmeter designed for use with electric plane power systems. Something like an [link=http://www.astroflight.com/index.php?main_page=product_info&cPath=2&products_id=17]AstroFlight Super Whattmeter[/link] or a [link=http://www.powerwerx.com/product.asp?ProdID=3809]Watt's Up Meter[/link] will do the job easily and conveniently and show you voltage and power at the same time. A wattmeter is an essential tool for checking and troubleshooting e-flight power systems. If it prevents you from frying even one power system, the wattmeter will have paid for itself.
Why guess about your power system when you can know?
- Jeff
03-07-2009, 08:10 PM
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RE: How manyy amps am I pulling?
I hear ya guys. Problem is my multimeter toasted the fuse 3 days ago testing a bl system. As mentioned it is only good for 10amps continuous and 20 amp bursts. Had it at 9 amps at half throttle and wanted to see burst of wide open, read 22 amps for 1/2 second and "tink", the fuse popped[:@]. Was just hoping someone new offhand what the current might be, thanks anyway.
