How to measure DC current

[bukzin]

I am wanting to measure some of the loads (amps) on my coach.

My standard multi-meter does not support this.
Thinking about options.


What are you folks using and any tips on ways
to get reliable readings?

Thx

[jrnymn7]

there are several clamp meter reviews on youtube, comparing different models.

[RV_daytrader]

this is the one I am getting. Has mostly good reviews.

http://www.amazon.com/gp/product/B009CNYJG2/ref=ox_sc_act_title_3?ie=UTF8&psc=1&smid=A1155GBV4DPEXU

[Snowman9000]

Raften wrote:
Question about the meter that rjfishing put the link for. It seems to say you would need to power it from a separate battery.

No, that's not right. The seller's diagram is confusing. It can measure 0-100V, but it needs 7-24V for power. Since you have 12V, you can just tie the power wires into the circuit you are measuring.

I have one of those. I also have a more sophisticated one that keeps track of cumulative amp-hours net in and out. About $40 on ebay.

[jmccen58]

I'd recommend installing a TriMetric 2030 Battery monitoring system. It's not difficult to install, it's very accurate and does more than just read amperage. I wouldn't leave home without one.http://www.bogartengineering.com/content/trimetrics

[jrnymn7]

That's just plain weird. The Trimetric's pos lead, for example, must be connected to the bank being monitored.

[tenbear]

Raften wrote:
Question about the meter that rjfishing put the link for. It seems to say you would need to power it from a separate battery.

You can use an isolator. Here is a link to one.

Lots of others on eBay.

[Raften]

Question about the meter that rjfishing put the link for. It seems to say you would need to power it from a separate battery.

[jrnymn7]

Not sure if all meters are wired the same, but as for the shunt, the neg cable from the battery post goes to one post of the shunt, and ALL other neg leads go to the other post of the shunt; this includes all loads and all charging sources.

This causes everything going in or out of the batteries to pass thru the shunt.

[tenbear]

Raften wrote:
When you install a shunt in the negative battery lead, do you cut the big wire or run a smaller wore in parallel?

You put the shunt in the big wire so all the current goes thru the shunt. Then you run 2 small wires, one from each side of the shunt, to your meter. You can attach your meter to the 2 wires so either the charging current can be positive or negative. You should put a small fuse in the wire to the meter from the hot side of the shunt.

[Raften]

When you install a shunt in the negative battery lead, do you cut the big wire or run a smaller wore in parallel?

[RoyB]

I use the portable SEARS inexpensive CLAMP-ON AC-DC Ampmeter. Looks like this


I also have a three panel meter setup installed that has 12VDC VOLTMETERS for each bank and one DC CURRENT meter installed to monitor my Battery Bank Setup...



Roy Ken

[SCVJeff]

It has to be unless you have a secondary ground cable on the frame from the battery.

[jrnymn7]

I'll double check, but I'm pretty sure I get the same reading, either way, with the uni-t, but with a (-) sign. One would think the current should be equal across both the pos and neg battery cables.

And its good up to 600 amps, with a 40a setting for more precise readings to a hundredth of an amp, for lower currents.

[Snowman9000]

wa8yxm wrote:
Most standard multi-meters will meter up to 10 amps wheh put in series with the load (Easiest way is to pull the fuse and repalce with the meter and an in-line fuse holder).

However for bigger loads go to Sears. A Crafstman model 82369 will do up to 400 amps clamp on, However it does NOT indicate direction of flow when used clamp on.

It reads + or -, though. Same thing, right? What I find funny is that when I flip it around and take the reading in the opposite direction, the absolute values are never equal. I can't recall which way it is... I think the negative reading always shows fewer amps.