T-Pain Is On A Boat: Re: [Electric Boats] 39 dollar clamp on ebay ammeter.

Monday, August 10, 2009

Re: [Electric Boats] 39 dollar clamp on ebay ammeter.

Paul,

I tried these same meters from ebay365. I fried them. The problem was that the panels need separate power input to run themselves from the circuit they are measuring. Also, and this seems ridiculous to me, you need seperate power sources for each meter. I tried to make simple isolated circuits with some doides, but i fried the panels anyways. My diode isolated circuits were sort of hipshots, but I thought it was worth a try.

I used power from my 12-48DC-DC converter to power the meters. This is ostensibly an "isolated" circuit. I don't know if my DC-DC converter creates a short circuit or my diode isolated circuit was worthless, but I fried two sets of these types of meters (also a set from another ebay seller).

One can purchase "self-powered" meters of this variety. I am sure this would work much better, but they only seem to be available for lower voltages. I have also seen small dc-dc converters which are tailor made for these kinds of meters. They use them on electric golfcarts.

Surely though, your electrician son will do much better.

Good luck,

Hans

--- On Mon, 8/10/09, Paul C. Smith <paul136mc@yahoo.com> wrote:

From: Paul C. Smith <paul136mc@yahoo.com>
Subject: Re: [Electric Boats] 39 dollar clamp on ebay ammeter.
To: electricboats@yahoogroups.com
Date: Monday, August 10, 2009, 12:29 PM

hI , I've purchased some digital volt and amp gauges from these folks on ebay example: http://cgi.ebay. com/50A-DC- ON-OFF-BLUE- LCD-DIGITAL- PANEL-CURRENT- AMP-METER_ W0QQitemZ2604467 30465QQcmdZViewI temQQptZLH_ DefaultDomain_ 0?hash=item3ca3d 5b8e1&_trksid= p3911.c0. m14 Have volts and amps for motor and house battery banks. i have them mounted on the boat (in the cockpit behind a removable plexi panel) but not yet hooked up . Waiting on my son Nolan, the electrician, to help out. Anybody else tried their gauges? Their shipping was fast, although from Hong kong, not from Ireland as the ebay ad suggests.

Best Regards,

Paul <paul136mc@yahoo. com>

Paul C. Smith 707 874 2112

PO Box 120

Camp meeker, CA 95419

____________ _________ _________ __

From: Matthew Geier <matthew@acfr. usyd.edu. au>

To: electricboats@ yahoogroups. com

Sent: Sunday, August 9, 2009 8:56:22 PM

Subject: Re: [Electric Boats] 39 dollar clamp on ebay ammeter.

Hans Kloepfer wrote:

> Thanks George.

>

> I tried some of these types of units, and I burnt them all out. I talked to another guy who had the same bad luck with these types of instruments. Unfortunately, I have to keep them installed so I don't have holes in the custom made instrument panel on my boat. This annoys me. The problem is the power supply. It works fine with a 9 volt battery, but if you want to wire it your boats house power, as in my situation, it creates a short circuit condition.

>

> Anyone else have any input on these things (shunt-wired, ebay variety LCD digital volt/amp meters). I would still like to get something in those holes that actually works.

>

> I would still like a handheld multimeter for analysis/ diagnostics that I could just clamp around a cable to check DC amperage on different legs of the electrical system on the boat. Usually these are pretty expensive. Maybe I will just have to pony up the dough for a nice Fluke or similar.

>

A 'clamp' DC ammeter is a far more complex beast than a clamp AC ammeter.

The AC ones effectively make a one turn transformer and measure the

induced voltage. This doesn't work on DC. I think they measure the

magnetic field or something like that.

It's quite common to have a DC amp function on a AC/DC clamp meter

where the only the AC amps is via the 'clamp probe'. DC current

measurements require breaking the circuit.

A too-cheap AC/DC clamp meter may only measure AC current via the

clamp. Read the specs carefully. :-)

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