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Amp-Hour meter

Posted: Tue, 13 Jan 2015, 14:23
by Nevilleh
Back in 2013 designed an AH meter which was covered in the forum forums.aeva.asn.au/wanted-an-amp-hour-meter_topic3368.html.
Jonescg bought a couple to use on Voltron and found it not totally satisfactory as it didn't handle regeneration, so I thought I'd modify it to make it bi-directional. With a small change to some of the op-amp components and some new software, it now covers the range +- 511 Amps. Or, with a different current sensor it can do +-255 Amps with twice the resolution which may be better for high voltage, lower current systems.
This is aimed at the DIY enthusiast and everyone who converts any vehicle to electric power needs one!
If you want to build your own, send me a PM and I'll give you all the files.

Amp-Hour meter

Posted: Fri, 16 Jan 2015, 18:12
by jonescg
Thanks for putting these together Neville! And it was great to meet you when you were over here. The Ah meter is a pretty good system for simple machines like the race bike. We don't need to know how many Wh/km are being achieved, or even watt-hours, just a coulomb counter serves as a pretty useful range estimator. In the case of the race bike pack, when the number approaches 9 Ah, it's time to come in. There are other great products out there which connect to the fuel gauge of older vehicles, but this device is perfect for machines without such a meter.

Hope to put it to use this year!

Amp-Hour meter

Posted: Fri, 20 Mar 2015, 12:45
by Drew
Hi, are you still selling the plans, circuit board or notes on the bidirectional Ah meter? It sounds like you have designed something that seems to not be available commercially.
Many thanks
Andrew

Amp-Hour meter

Posted: Fri, 17 Apr 2015, 15:42
by Nevilleh
Sorry to not have replied sooner, I haven't looked on here for a while.
Yes, I have the plans for the AH meter. Drop me a PM with your email and I'll send them to you.

Amp-Hour meter

Posted: Fri, 17 Apr 2015, 16:33
by Drew
Hi

Thanks for replying. My email address is doctordrewmoore@gmail.com

Regards

Andrew

Amp-Hour meter

Posted: Fri, 17 Apr 2015, 16:36
by Johny
I'd edit that email address before a web crawler find it Andrew.
Common practice it to separate the username and domain name with plain english.

Amp-Hour meter

Posted: Fri, 17 Apr 2015, 16:38
by Adverse Effects
doctordrewmoore (AT) gmail.com

is more like what you want to put in

Amp-Hour meter

Posted: Fri, 17 Apr 2015, 16:44
by jonescg
Oh, thanks for the reminder guys!

I actually connected my bi-directional Ah meter from Neville to a battery discharger and watched it count. Unfortunately the currents, and therefore the Ah values were about two times more than the value I read on the current clamp. I know my clamp isn't the most accurate measure either but a difference of 2x is pretty noticeable. Any idea what's going on?

Image

Amp-Hour meter

Posted: Fri, 17 Apr 2015, 16:49
by Johny
Sounds like the AH software doesn't match the current sensor.

Amp-Hour meter

Posted: Fri, 17 Apr 2015, 17:11
by jonescg
I forgot which meter was for which sensor (500 A vs 100 A), so I tried both, but the other one didn't work at all.

Amp-Hour meter

Posted: Fri, 17 Apr 2015, 21:09
by Richo
I thought it was the 100A version.
I'll assume you zero'ed it before applying a load.