Shunt-type ammeter

[Rocinante33]

Has anyone converted their ammeter to a shunt type? I am in the middle of upgrading my alternator (and its bracket) on my M25. It seems that a shunt type ammeter would be far superior with one of the alternatives;
1. a long run of wire up to the instrument panel & back with the ammeter in series (the stock system), or
2. direct , short, heavy wire from the alt. to the solenoid, and the loss of the info about the charge rate via the ammeter.

This second option is ala the Tom Metzger owner's project. I have already made this change prior to my current alternator upgrade. I seems to me that adding a shunt ammeter from the alt. in parallel to the load would get my charge rate information back for me. It allows the use of small gauge wire up to the instrument panel.
I like option 2 with the shunt ammeter. Any thoughts on this idea?

Thanks,
Keith
E33

 

[Captron]

Shunt

Wouldn't you put the shunt between the battery and the negative distribution bus? That way all of the goes-into and goes-outta passes thru the shunt regardless of what charging system is feeding batteries and regardless of what appliance is using power.

Of course, the ammeter then reads the net power either positive or negative.

 

[Tom Metzger]

Food for thought

Keith - The real question is what do you want to monitor? The obvious choices are:

1) what the alternator is putting out. This doesn't give you much bang for the buck as it only reads when the engine is running.

2) what the battery is load is. This is what the breaker panel meter reads without the engine loads. Good to know, but already available.

3) what the net gazinta - gazouta of the house bank is. This is what most people want to know because it relates to battery state of charge.

The latter choice is what Capt Ron is recommending, and I agree. If you have refrigeration, and why upgrade if you don't, you should consider spending some bucks and buying a real battery monitor rather than an ammeter. It will tell you how many amp-hours you have used and put back into the battery. Xantrex XBM - $220 @ Defender is a good one. It will come with a shunt. There are others out there which are good also. I would put the shunt here even without a full blown monitor.

This arrangement will not tell you what the starting battery is doing, but the starting battery gets so little use that it is not worth monitoring, IMNSHO. Starting the engine takes less than a quarter amp-hour.

BTW, the shunt goes in series with the load, not in parallel as you suggested. The ammeter goes in parallel with the shunt.

 

[Rocinante33]

shunt - keep the 'trons flowin'

Capt Ron & Tom,

Right you are, on all counts. Yes, I agree the best thing to know is gazinta & gazouta the battery banks. I wasn't thinking clearly about the shunt position in the circuit, but your comments make sense.

I also didn't realize the battery monitor could be had for so little. I will look into that option.

Thanks,
Keith

 

[rssailor]

Shunt shifter

Blue Sea makes a device that can be used for reading Alternator output if you want it with one of their digital DC amp meters. Its called a shunt shifter, most "normal" shunts are on the negative side of the circuit. Good luck. Ryan