OT My second electric bike

I seem to recall its working pretty well, no?

--

Rick C

Easy to do. A shunt is nothing more than a piece of conductive material with a known resistance.

With a known resistance it is easy to determine current by measuring the voltage drop across the resistance.

Basic Ohms law. V = I X R

Say you have a shunt with a known resistance of .001 ohms. If you pass a current of 50 amps across that shunt you would be able to measure a voltage drop of 50 millivolts.

BUT to make this a bit simpler, Go grab a automotive maxi-fuse that will handle the load (keep in mind that Li-ion batteries can put out a LOT of current.) Now visit

and download the correct chart.

Connect the fuse in the positive power feed from the battery. Connect a millivolt meter to the fuse terminals. Now compare the voltage you measure to the chart for a maxi-fuse. It will tell you the current flow.

Another option is to make a high current shunt. 4.83 inches of 4 gauge copper wire = .001 ohm resistance. This will handle a 130 amp draw continuously.

--
Steve W.

On Fri, 10 Jun 2016 19:26:30 -0700, Jeff Liebermann Gave us:

On Fri, 10 Jun 2016 22:42:57 -0400, snipped-for-privacy@snyder.on.ca Gave us:

When I said that he called me a troll.

He is worse than Donald J. Trump in that respect.

On Fri, 10 Jun 2016 21:06:15 -0700, Gunner Asch Gave us:

Of course they do. Where have you been for the last several decades?

On Fri, 10 Jun 2016 21:08:24 -0700, Gunner Asch Gave us:

Says the retarded idiot who thinks that most handheld meters will not read DC current.

You are an idiot.

I didn't have a 3PDT switch handy to try, so the DPDT proved the concept despite the sense voltage error. A 3PDT switch would cost about as much as a second meter anyway. Separate meters for charge and discharge will totalize the energy in and out of the battery separately while a single meter with a reversing switch will add them together, which isn't very useful.

I settled on a 100A Bayite meter to monitor discharge and a 20A one to monitor charge. The 100A one is on a long cable so I can see how much battery power the inverter's loads draw as I turn them on and off, the

20A one on the charger whose constant output doesn't need watching. Both show the battery voltage. They aren't as informative as the industrial datalogger I installed on an experimental electric vehicle but they are good enough for home projects.

A possible fault condition with the reversing switch is the B- contact open and the meter's operating current trying to pass through the sense leads, which might overload the input clamp diodes.

--jsw

DecadentLinuxUserNumeroUno wrote in news:9dcnlb15aihasp9gd506asaihhlos99liu 4ax.com:

Click on the specs tab:

DC Current Range 999.9 A Resolution 0.1 A

There have been no intelligent reasons given for why a cordless drill won't reliably power a bike. One said it's not good for continuous use, but that line is copied from a disclaimer in the manual. So far, the DCD995 brushless motor doesn't even get warm. The gearbox gets warm, but it was chewed up from trying to remove the chuck. It will be swapped for a better one that's on hand, if need be. I suppose gearboxes tend to get warm anyway.

The drills are $90 new on eBay for the bare tool. Including the case, motor, controller, gearbox, and battery holder.

As for making the bike, the only difficult part to make is the front sprocket holder, cutting a neat square hole through a 3/8 inch thick aluminum disk.

Having to remove the battery when it's parked isn't ideal, but it's versatile. One small battery is enough for short trips. The batteries can be used with tools. They are ultra easy to upgrade. Dewalt has an adapter so they can serve as a 5 V USB power supply or charger.

Such homebrew lashups are OK on a lab bench but not in a road vehicle.

I was building production test stations for GM in the mid 70's when they first incorporated vehicular electronics more complex than a purchased radio and the freshly minted electrical engineers they hired had to learn about real-world environmental conditions the hard way. I had been an Army electronic repairman and already knew about mud and rain and bouncing down dirt roads, but GM couldn't afford to use Mil-$pec connectors.

--Sgt JSW

Choke on the price:

LOL Amazing Electrician/Electronics tech Wieber has yet to learn about the popularity of Hall Effect clamp meters.

Here, Wieber. Welcome to the 20th century.

And amateurs needn't pay Fluke prices.

It can be had for less, though:

So far the UT210E has been fine for my hobbyist use:

It won't measure car starting current but I have other ways to do that.

It -will- show the key-off drain from a car battery without disconnecting the battery and triggering the radio's anti-theft lockout.

It zeros to within a few milliamps. The main error seems to come from changing its orientation in the Earth's magnetic field between zeroing it and clamping it on the wire.

It immediately became my favorite ammeter, though the autorange-only voltage is less impressive. Uni-T makes a superb meter for voltage and you need two meters to measure both voltage and current at the same time anyway, for example checking battery or solar panel output under varying loads.

*Version*=1&*entries*=0 The specs don't mention that it displays 4-1/2 digits.

--jsw

Good find. I missed that one.

However, there's a problem. If you look at the photos of their wiring diagram, you'll notice that there's a connection between the DC Load resistor + terminal, and the power supply + terminal, while the negative wires are split between the load resistor and the power supply. In other words, this is a positive common ground system and may NOT work with a common negative ground for both the battery (power supply) and load. That's not a problem with a solar charger, floating charger, or no charger as in the electric drill, but will be a problem if you have a negative ground system.

I've run into the same problem with the LED meter modules that have both a voltmeter and ammeter in one package.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

I don't have any experience with brushless motors, but have played with various brushless drills. However, that's never stopped me from offering a bad guess(tm) based on Googling and reading.

Brushless seem to have one big advantage. Thanks to tachometer feedback, they're constant RPM. This video shows it better than I can (also with some interesting drill related stuff): "Advantages of a brushless cordless drill" (7:32)

A typical brushless torque-power curve at: shows that the brushless motor is more efficient at high RPM's, and delivers an output peak in the middle of the operating range. Offhand, I would think it would not do well on hill climbs, where the RPM's might drop too low to deliver max power.

It's possible that the DeWalt drill has the same 11 step speed motor controller as shown in the video, which would make tolerable throttle control. However, that eliminated the possibility of using the drill motor as a "pedal assist" type eBike, where the motor only supplies enough power needed to keep the pedal torque (and pedaling effort) low. That won't work if the effort required is variable, such as an uneven or bumpy road. The idea is to use as little motor power as possible to extend battery life.

Offhand, I would say the motor is just fine and probably superior to a brush type DC motor, but the drill speed control might be a problem matching it to variable loads found on a bicycle.

Good luck.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

I'm working with DeWalt on a related article, and I'm going to ask for their reaction to the bike. I can't wait to hear what they say about it. d8-)

--
Ed Huntress

They may have to limit their approval for safety reasons. We did some stunts with the lab Segways that we would never suggest to customers.

--jsw