G voltage drops and ABYC standards

[nyryan2001]

So, doing a little reading, after having near 300hrs on Gs.... ABYC specs there should be no more than a 3% voltage drop on boats from the power source to the powered ute
.. Else you need a bigger power source or thicker gauge wire.

So the average running voltage on Gs with engine running and only the blower on, at idle is around 14-14.2v, or a 2.3 - 2.8% voltage drop. Ok.

Put the 3 pumps on and you are in the 13-13.5v range, or as much as a 10% voltage drop, well below established industry specs.

Lights, stereo and a few others and you are 5x beyond established industry specs.

So either the alternator isn't within spec of the minimum prescribed loads, or the gauge of wire to/through the distro panel isn't sufficient.

What am I missing? How would this not be considered a manf defect considering ABYC standards are clear as they are?

[nauty220]

3% max voltage drop for conductors providing power to panels and switchboards, navigation lighting, bilge blowers, main DC feeders, and any other circuit where voltage drop should be kept to a minimum
10% max voltage drop on conductors used for general lighting and other non-critical circuits


Sent from my iPhone using Tapatalk

[xrichard]

I was curious and googled. ABYC E9-14 specifies the voltage drops mentioned above (3% and 10%), but only in relation to conductor size...not in relation to voltage drop due to load. ABYC provides a table of amps v. length of cable to determine the appropriate conductor size to meet the requirements. Is there another section that discusses voltage drop unrelated to conductor size?

[MLA]

Under what conditions does the ABYC say there should not be a voltage drop, static or under load?

How are you getting a 2.3% to 2.8% voltage drop right off the bat at 14.0-14.2? What were the conditions and where was the two measurements taken?

[azeus17]

Has this caused you some sort of problem? I am seriously struggling to understand what would possess you to post this.

[Dandy21]

I was curious and googled. ABYC E9-14 specifies the voltage drops mentioned above (3% and 10%), but only in relation to conductor size...not in relation to voltage drop due to load. ABYC provides a table of amps v. length of cable to determine the appropriate conductor size to meet the requirements. Is there another section that discusses voltage drop unrelated to conductor size?

Any chance you could share a link that provides the amps v. length of cable? I did a quick search on ABYC and didn't stumble across anything. Thanks in advance.

[Tallredrider]

I think you are talking about checking the battery voltage with various items turned on, right?

Otherwise you should get near simultaneous readings at the battery and at the end of the line.

If that is true then you are talking about something entirely different. I think those standards would refer to measuring voltage at both ends of a wire. For example, if my battery voltage is 14 volts, then my voltage at the amps when running should be less than X% of that voltage. If I lose voltage along the wire, then my wire gauge is too small.

I would not read into it much about the alternator not keeping the exact same voltage to the batteries while various items are on.

[xrichard]

@Dandy21--I found it here:

https://law.resource.org/pub/us/cfr/....E-09.1990.pdf

and here:

http://www.ecfr.gov/cgi-bin/text-idx...e46.7.183_1340

It doesn't appear to me that the 3% and 10% numbers have to do with anything but conductor size.