OT My second electric bike

It displays voltage as ##.##V, current to #.##A with decent accuracy, plus power (Volts * Amps) to 0.1W and the accumulated energy in Watt-hours since the last reset. The Watt-hours consumed in a mile, divided by the battery voltage, gives you the Amp-Hours used.

--jsw

The battery will be inserted and removed several times per day. Should I put capacitors across the current meter power supply inputs? Anyplace else? What value? Thanks.

The meter's microcomputer stores the accumulated energy value in nonvolatile memory so it doesn't need to be powered continuously. I plugged mine into the nearly dark solar panel a few minutes ago, without a load, and it still shows 1041Wh from when I discharged a battery through it last winter.

The only real electrical consideration is to be aware that the thin wires to the display are directly connected to the battery and could burn if shorted to each other or the frame. I made the connections at the conduit tee fitting that encloses the shunt with in-line fuseholders similar to these:

--jsw

On Fri, 10 Jun 2016 16:05:41 -0000 (UTC), John Doe Gave us:

You ain't real bright. Ever heard of a shunt and a voltmeter?

Sheesh.

On Fri, 10 Jun 2016 16:19:17 -0000 (UTC), John Doe Gave us:

With your lack of grasp of electronics, you should be over in the basics group.

On Fri, 10 Jun 2016 17:29:21 -0000 (UTC), John Doe Gave us:

The fact that you are oblivious as to this BASIC electronic principle proves you should not be in this group.

BASICS is the group you should be in, and you barely qualify for that one.

Yes, then you measure the *voltage* across the shunt. This can be done with small wire. The primary concern is mechanical.

That's exactly what it means. ;-)

Ignore AlwaysWrong. He doesn't how to do this anyway.

I usually just Ignore Subthread on his posts. I would reply more often, but replies are probably the only time most people see his posts.

Difficult to believe anyone would dispute such a simple and clever idea.

DLNO, let me just say, when I want someone to go away, I ignore 'em.

George H.

Just use a decent reader and dispose of DecadentMentalCaseNumeroUno permanently... never see his rants... except, of course, when someone like you feeds the troll >:-} ...Jim Thompson

"This group" happens to be two newsgroups. It is cross-posted. The newsgroups header is:

====================================================================== Newsgroups: rec.crafts.metalworking,sci.electronics.design ======================================================================

He started out discussing this in rec.crafts.metalworking and I don't know whether *he* added sci.electronics.design to the newsgroups list, or whether someone else added it, expecting it to be a better place to get the needed information. If the latter, he may not even have noticed the addition of your newsgroup, just as *you* did not notice rec.crafts.metalworking was part of the cross-posting.

You could add the basics newsgroup to the Newsgroups header, and result in even more vituperation -- especially from those who do not notice the other newsgroups.

And -- you could add a "Followup-To: " to the headers, which would make only the replies to your articles go to the named newsgroup(s), and other replies would still be cross-posted as before, so it is a loosing battle.

Yes, a good shunt down at the motor/battery interface to measure current, and two more leads for the voltage across the motor should allow display of everything he wants. (Actually, three leads would suffice, if done right) But if routed up to the handlebars, while light gauge wire would do nicely to carry the voltage signals up to the meter on the handlebars, I would advise fuses in all wires, in case they get pinched together. (I don't know whether anything is grounded to the frame, but a pinch which cuts through the insulation could get exciting if the wires run along the frame near his thighs.

Enjoy, DoN.

JT, sorry yeah I should just ignore all flame wars.

I've had this totally crazy (well some is OK) circuit plopped on my desk to layout... make into a pcb. I've become a flunky for the genius, who knows everything, and can't ask for help.

I'm complaining, but if the man writing the checks wants it done.... (I'll post my schematics and you can giggle.) (To be honest I don't have a good idea of what the circuit is doing.. but SNR is being thrown away all over the place. A noisy attenuator/ phase shifter.. Volts in and uV out?? )

George H.

I tried three leads so I could exchange the shunt connections with a DPDT switch to read current in the Charging direction. The backlight draws enough current to significantly offset the sensed shunt voltage, which is only 75mV full scale, and 75uV at 0.1 Amp. It really needs separate power and sense wires.

--jsw

On Fri, 10 Jun 2016 20:21:06 -0400, krw Gave us:

You're an idiot, and you know nothing about my abilities.

Yes, the shunt has to have a separate high current path with no terminals in common with the sense leads, but also the meter power should not run on the sense wires to limit the meter reading its own power draw since the sense voltages are so small. When I looked at the diagrams for the various modes of wiring none show sharing of the sense and meter power leads.

On Sat, 11 Jun 2016 00:32:08 -0000 (UTC), John Doe Gave us:

After you re-quote and re-post them? You are a hypocrite.

You have been listening to the idiots again.

I was using precision current shunts before you knew what a nine volt against the tongue was like, little boy.

On Fri, 10 Jun 2016 17:33:58 -0700 (PDT), George Herold Gave us:

As if I gave a shit what you do with your news client. Newsflash... still here regardless, so you do not "make someone go away" either, putz.

In this power meter, the shunt is inside the meter enclosure. That means you do have to run heavy gauge wires from the battery to display. I couldn't find anything with similar features and with an external shunt.

It's not too clear on the Amazon page, but is mentioned on the BangGood page as: "Bult-in shunt design, no extra needed" also:

and a drill motor is not the most intelligent solution for an electric bike either. - - -