DC or AC ammeter, or both?

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DC or AC ammeter, or both?

Postby wlooper89 » Sat Aug 16, 2008 10:29 pm

Has anyone thought about or installed an A/C or D/C ammeter? I was looking at them online and it seems that A/C amps might be useful to know. It could show if one is approaching the circuit breaker limit, in my case 30A. This is a link to one that is 2 3/4" size. A 2" version is also available. http://www.marinedeal.com/product_p/s9630.htm

One advantage of the A/C ammeter is a more simple hookup. Just a induction coil that slips around the wire being measured. It can be calibrated by a set screw with a known load. For example a 1500 watt heater draws about 12 amps on high. (Amps=Watts/Volts)

On the D/C side I found a link to instructions for a Blue Sea D/C ammeter. I cannot make heads or tails of it as relates to a teardrop. http://bluesea.com/files/resources/inst ... s/9878.pdf I have a converter that can power the teardrop DC and charge the battery if the battery switch is on. The battery can power teardrop D/C if the battery switch is on and the converter is not powered. I would like to read the D/C amps being used and/or battery rate of charge/discharge. Any help in this area would be most appreciated. I am totally confused on how to connect a D/C ammeter to provide useful information.

Maybe it would be nice to have both A/C and D/C ammeters if one is really into gages. I already have a D/C voltmeter and switch that can measure either battery or converter output voltage. In a previous life my work involved reference to gages and this may be part of the reason I am interested in adding one or two.

Bill
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Postby G-force » Sat Aug 16, 2008 11:37 pm

I couldn't hurt, after all, we build trailers so we can have exactaly what we want. However, I really dont see the usefullness of an AC ammeter...if your over your breaker, it will pop, if under, it won't. If you really decide to put one in, I would go with a round automotive gauge, that pannel gauge you linked to probaly is not rated for the vibration/bouncing a trailer will see.
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Postby BPFox » Sun Aug 17, 2008 7:55 am

How about this option, neither. Don't get me wrong, go ahead and knock yourself out with all of the electric goodies you want. But I can't see wasting one second of my camping time looking at a meter. If I am going to do that I might just as well stay at work. :lol:
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THE NEITHER OPTION

Postby wlooper89 » Sun Aug 17, 2008 8:58 am

Um, I think I see your point and that is cool. I looked at the Blue Sea wiring diagram again this morning, and my eyes may be focusing better as it seems a little more clear. To do what I want on the D/C side might require two D/C ammeters. One ammeter could have zero in the center with maybe plus and minus fifty amps to measure charge or discharge from the battery. The other would read maybe 0 to 50 amps and measure D/C trailer load. The two would read differently if the converter is powered and charging the battery as well as supplying the trailer. With battery only and lights on in the trailer the battery would have a negative discharge reading and the load reading would still be positive.

I think the 50 amp rating would be best for me even though my circuit breaker and fuse limit me to 30 amp. The manufacturer recommends a maximum of two-thirds full scale for continuous load.

If anyone has installed one or the other a photo would be great. This is my D/C voltmeter. It is attached to the inside of the lid of my electrical compartment on the trailer tongue, with Velcro.

PS My new plan is to move the voltmeter to a new panel with the other meters in the area where I now transport the propane tank.
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Re: DC or AC ammeter, or both?

Postby BPFox » Sun Aug 17, 2008 9:08 am

wlooper89 wrote:...... It could show if one is approaching the circuit breaker limit, in my case 30A. ......One advantage of the A/C ammeter is a more simple hookup. Just a induction coil that slips around the wire being measured. It can be calibrated by a set screw with a known load. For example a 1500 watt heater draws about 12 amps on high. (Amps=Watts/Volts)



Just a couple of thoughts; Did you really wire your trailer with a single 30 amp breaker? That would require 10 ga wire and that seems a little extreme to me. One more thing, if you need to calibrate the thing with a known load I would as you this, if you already know the load, why would you need a meter? Not being critical, just trying to understand. How many meters do you use at home? I would use the same number in your trailer. Peace.
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Postby wlooper89 » Sun Aug 17, 2008 9:38 am

Thank you very much for your input. I realize not everyone wants electrical meters, and that meters are not essential. This would be just for fun.

I did use #10 flexible A/C wire between the 30A shore power cord/inlet and the converter. From the inlet it goes first to a 30A GFCI and then to a 30A breaker. Next is a 40A A/C master switch and then the converter where A/C splits into two 12-3 wires back into the trailer. The #10 flexible A/C wire was not easy for me to find. I finally ordered some from a welding supply company online. I think the calibration of the A/C ammeter would be a one-time thing after connecting the induction coil.

You are quite right, I could mentally add up the loads. It is just that late in the day my mental addition is not very good. I am sure it has nothing to do with the beverages I consume. ;)

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Re: DC or AC ammeter, or both?

Postby wlooper89 » Tue Aug 19, 2008 5:54 am

BPFox wrote:Just a couple of thoughts; Did you really wire your trailer with a single 30 amp breaker? That would require 10 ga wire and that seems a little extreme to me.

Your mention of my 30A breaker caused me to think about breakers some more. My use of #10 wire is all within a tongue box. The change to #12 wires occurs inside the converter. I now realize that I should have two 20A breakers to protect the two #12 circuits from overload. I was thinking the two circuits together could handle 30A, but I might possibly try to use more than 20A of loads on a single circuit. The converter has slots for two breakers and it should be relatively easy to make this change. This photo shows the electric compartment and converter. The two breaker slots are under the converter lid with yellow label. The 30A one that I will leave in place is at another location. Thank you for giving me this idea about the 20A circuit breakers. Wish I had thought of it earlier. I guess ammeters will be on the back burner for now, as the circuit breakers seem more important. Not many people seem to be using ammeters.

Bill

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Postby Alphacarina » Tue Aug 19, 2008 6:04 pm

Is your shore power cord a 10 gauge?

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Postby Sonetpro » Tue Aug 19, 2008 6:47 pm

wlooper89 wrote:Thank you very much for your input. I realize not everyone wants electrical meters, and that meters are not essential. This would be just for fun.

I did use #10 flexible A/C wire between the 30A shore power cord/inlet and the converter. From the inlet it goes first to a 30A GFCI and then to a 30A breaker. Next is a 40A A/C master switch and then the converter where A/C splits into two 12-3 wires back into the trailer. The #10 flexible A/C wire was not easy for me to find. I finally ordered some from a welding supply company online. I think the calibration of the A/C ammeter would be a one-time thing after connecting the induction coil.

You are quite right, I could mentally add up the loads. It is just that late in the day my mental addition is not very good. I am sure it has nothing to do with the beverages I consume. ;)

Bill


:shock: WOW you have alot going on there. You could have just went to a RV shop and got a 50 amp power cord for your shore power.
I want to know what in the world you are going to be running that takes so much power.
I would be more worried about that propane tank you have in there with all of the relays and switches you have in there that can cause a spark. :thinking:

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Postby mechmagcn » Tue Aug 19, 2008 7:42 pm

Sonetpro wrote:
I would be more worried about that propane tank you have in there with all of the relays and switches you have in there that can cause a spark. :thinking:

My thoughts exactly, I don't want something as explosive as propane and all of those electrical connections in the same box :o
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Postby wlooper89 » Tue Aug 19, 2008 9:48 pm

Yes, the propane tank. It is just that it fits so nicely in that corner and appropriately right next to the fire extinguisher. ;) I know it looks bad. :o I had thought it would be OK to place it there for transportation only, but am beginning to rethink this and will try to find information on possible hazard from the tank even with the valve closed. We use the propane for cooking at a picnic table or at the folding camp kitchen table we sometimes carry.

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Postby wlooper89 » Tue Aug 19, 2008 10:02 pm

Alphacarina wrote:Is your shore power cord a 10 gauge?

Don


The shore power cord is 10 AWG and 30 amps. Stamped on the cord along with made in China. The price was not too awfully high. Cannot remember exactly how much. I may have gotten it on ebay. I carry adapters for 20A and 50A outlets, in case the campground lacks 30A. To date I have only used the 20A one at home and the 50A pigtail not at all. This is a photo of my cord and adapters.

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Postby ARKPAT » Tue Aug 19, 2008 10:28 pm

I'm kinda cheeeap! I have used Amperage meters salvaged from car's instrument panels ( I know the needle swings both + and - < charge and discharge> hmm could be handy indication ) cheap or free. Some go 30 +- amps and others go higher depending on the size of the altenator capacity of the car or truck or RV it came from. Just food for thought. :thinking:

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Postby Cliffmeister2000 » Tue Aug 19, 2008 11:12 pm

God Bless

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Postby ARKPAT » Tue Aug 19, 2008 11:25 pm

General Electric AC Ammeter. Model number 3689112. 40 to 70 hertz. 5 amp current equals 50 amps on the meter. Of course you will need a shunt resistor to have the meter read correctly.


You might need to know. :thinking:

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