LJRockstar
NAXJA Forum User
- Location
- Hunterdon County, NJ
I went down a bit of a google/amazon rabbit hole last night looking for a way to monitor my alternators performance in real time.
What started all of this is I don't trust the volt meter in my gauge cluster. Every other gauge seems to have a significant but consistent "fudge factor." The coolant temp gauge reads pretty consistently 10ºF hot. and the oil pressure is about 17psi high. So while keeping an eye on the volt meter during DD duties, if I have all the lights off and not running the HVAC or wipers, I get a nice strong 14vdc displayed. If I switch on the A/C even with the fan on low, the gauge displays down around 11.5vdc sometimes even less. Add in the wipers and headlights and we're down to 10vdc or even less. I don't notice the headlights getting browned out, or hear the blower motor changing tone, but low numbers like that on the volts gauge concerns me. I just put a super pricey Odyssey battery in the rig and id hate to shorten it's life by abusing it.
When I test the system with a multimeter the numbers are better but still not where I'd like them to be. I plan on installing a high amp winding and re building the alternator, I have no interest in hit-or-miss parts store alternators, I'd rather do the rebuild myself where I control the quality of the parts being used.
In my experience an ammeter is the best way to monitor the alternators performance. I'm not keen on the way a traditional ammeter is connected. I don't want that heavy wire run up into the dash. So I started looking at the high current shunt, digital options. There seems to be nearly endless options for setting up an ammeter and all of my searching ended up bringing more questions than it answered.
Most of the ones that I saw online are intended for solar arrays. In theory they should work fine for everything I could throw at them except for the big hit of the starter. All of the pre made shunt models I saw look to have a 100A limit I'm not sure what the draw is for the starter but I'm pretty sure it will exceed that 100A limit. I may be wrong but I don't think you can bypass the shunt for the high amp draw of the starter without bypassing the measured voltage drop across the shunt and rendering it useless.
I have a pretty good understanding of the theories involved with this, and maybe I'm totally over thinking this. I'm hoping theres an electrical guru on the forum that might be able to connect the last few dots for me, or at least shed a little more light on the situation.
Some of the solutions that have come to mind are:
Set up a second starter solenoid on the ground side that bypasses the shunt under cranking conditions. (downside - added complexity)
Making my own shunt from 2ga wire that could handle the load (downside - having to re arrange grounds so that all current flows through the shunted part of the ground cable.)
Just say "screw it" and throw a totally overkill power master alternator at it (downside - those alternators are crazy money and I have to do all kinds of work to make it fit)
Any valuable input is greatly appreciated!
What started all of this is I don't trust the volt meter in my gauge cluster. Every other gauge seems to have a significant but consistent "fudge factor." The coolant temp gauge reads pretty consistently 10ºF hot. and the oil pressure is about 17psi high. So while keeping an eye on the volt meter during DD duties, if I have all the lights off and not running the HVAC or wipers, I get a nice strong 14vdc displayed. If I switch on the A/C even with the fan on low, the gauge displays down around 11.5vdc sometimes even less. Add in the wipers and headlights and we're down to 10vdc or even less. I don't notice the headlights getting browned out, or hear the blower motor changing tone, but low numbers like that on the volts gauge concerns me. I just put a super pricey Odyssey battery in the rig and id hate to shorten it's life by abusing it.
When I test the system with a multimeter the numbers are better but still not where I'd like them to be. I plan on installing a high amp winding and re building the alternator, I have no interest in hit-or-miss parts store alternators, I'd rather do the rebuild myself where I control the quality of the parts being used.
In my experience an ammeter is the best way to monitor the alternators performance. I'm not keen on the way a traditional ammeter is connected. I don't want that heavy wire run up into the dash. So I started looking at the high current shunt, digital options. There seems to be nearly endless options for setting up an ammeter and all of my searching ended up bringing more questions than it answered.
Most of the ones that I saw online are intended for solar arrays. In theory they should work fine for everything I could throw at them except for the big hit of the starter. All of the pre made shunt models I saw look to have a 100A limit I'm not sure what the draw is for the starter but I'm pretty sure it will exceed that 100A limit. I may be wrong but I don't think you can bypass the shunt for the high amp draw of the starter without bypassing the measured voltage drop across the shunt and rendering it useless.
I have a pretty good understanding of the theories involved with this, and maybe I'm totally over thinking this. I'm hoping theres an electrical guru on the forum that might be able to connect the last few dots for me, or at least shed a little more light on the situation.
Some of the solutions that have come to mind are:
Set up a second starter solenoid on the ground side that bypasses the shunt under cranking conditions. (downside - added complexity)
Making my own shunt from 2ga wire that could handle the load (downside - having to re arrange grounds so that all current flows through the shunted part of the ground cable.)
Just say "screw it" and throw a totally overkill power master alternator at it (downside - those alternators are crazy money and I have to do all kinds of work to make it fit)
Any valuable input is greatly appreciated!
