Size of Alternator
I have a class B with 1 engine battery and 2 house batteries. I also have a 120-12volt Norcold fridge. My engine alternator is 75 Amps. It says that the fridge on 12v draws 4.0 amps. My house batter...
Forum Discussion
I see in the OP that the Vehicle is a 1990 dodge, essentially the same as my 89 in terms of alternator and voltage regulation.
If the circuit between your alternator/ isolation method, and house battery checks out good, which I do not believe it will based on your reports, Tricking the engine computer and using external voltage regulation is an option I can detail.
The higher rated alternator with the same voltage regulation/isolation method/product will only improve performance in a very narrow field, Like when cold at idle speed.
Not sure what a ford 3g alternator has to do with this discussion.
Much depends on the circuit thickness/distance itself and the isolation method, but cheap and dirty with a old solenoid hooked to engine battery is a recipe for poor house battery charging.
Also the house battery is likely grounded to frame. Frame grounds become problematic and highly resistive all too quickly, and dodge are notorious for ground issues. Stock, there is one 6 awg ground cable from engine battery to engine and one 10awg ground from engine battery to firewall. At 28 years old if this 6awg cable is original it insults each electron it passes.
If house battery is grounded to frame, then all alternator current to house battery has to flow over this 10 AWG ground wire, then down 6awg cable to engine block.
Upgrade grounds, or add a cable between frame and alternator mounting bolt and let those amps flow, instead of gettng bottlenecked by the OEM circuitry.
I did upgrade my original alternator from the lesser rated model when it failed, but the weak point is the voltage regulator and the poor ground path that a frame grounded house battery has to deal with. The 10AWG engine battery to frame ground is forcing the frame grounded house battery... is forcing the marathon runner into breathing through a cocktail straw.
The OEM voltage regulator in the engine computer will seek either 14.9 or 13.7 too. Not much charging happens at 13.7v through old inadequate copper and poor grounds. 14.9v is a bit ridiculous too, and mine would just decide that 14.9 was desirable, when it was not, and 13.7v was the call, when it was not.
There is all sorts of room for improvement of the charging system as there are so many incredibly inadequate areas on this chassis in regards to alternator charging. it might have been fine for the original starting battery that was never depleted and with few additional loads, but is extremely inadequate when more batteries are tacked on to the ned of the Circuit, and that circuit is nearly 30 year sold too.
Beef up your copper and grounds if you want alternator juice to make it to distant house battery.
The VR modification is not Nasa grade engineering, but not for the electrically timid either.
Start with te copper and some experiments with a voltmeter on engine battery and on depleted house battery with engine running, at idle and at higher rpm. Cold and when hot. Expect to find inadequate numbers on depleted house battery.
If the circuit between your alternator/ isolation method, and house battery checks out good, which I do not believe it will based on your reports, Tricking the engine computer and using external voltage regulation is an option I can detail.
The higher rated alternator with the same voltage regulation/isolation method/product will only improve performance in a very narrow field, Like when cold at idle speed.
Not sure what a ford 3g alternator has to do with this discussion.
Much depends on the circuit thickness/distance itself and the isolation method, but cheap and dirty with a old solenoid hooked to engine battery is a recipe for poor house battery charging.
Also the house battery is likely grounded to frame. Frame grounds become problematic and highly resistive all too quickly, and dodge are notorious for ground issues. Stock, there is one 6 awg ground cable from engine battery to engine and one 10awg ground from engine battery to firewall. At 28 years old if this 6awg cable is original it insults each electron it passes.
If house battery is grounded to frame, then all alternator current to house battery has to flow over this 10 AWG ground wire, then down 6awg cable to engine block.
Upgrade grounds, or add a cable between frame and alternator mounting bolt and let those amps flow, instead of gettng bottlenecked by the OEM circuitry.
I did upgrade my original alternator from the lesser rated model when it failed, but the weak point is the voltage regulator and the poor ground path that a frame grounded house battery has to deal with. The 10AWG engine battery to frame ground is forcing the frame grounded house battery... is forcing the marathon runner into breathing through a cocktail straw.
The OEM voltage regulator in the engine computer will seek either 14.9 or 13.7 too. Not much charging happens at 13.7v through old inadequate copper and poor grounds. 14.9v is a bit ridiculous too, and mine would just decide that 14.9 was desirable, when it was not, and 13.7v was the call, when it was not.
There is all sorts of room for improvement of the charging system as there are so many incredibly inadequate areas on this chassis in regards to alternator charging. it might have been fine for the original starting battery that was never depleted and with few additional loads, but is extremely inadequate when more batteries are tacked on to the ned of the Circuit, and that circuit is nearly 30 year sold too.
Beef up your copper and grounds if you want alternator juice to make it to distant house battery.
The VR modification is not Nasa grade engineering, but not for the electrically timid either.
Start with te copper and some experiments with a voltmeter on engine battery and on depleted house battery with engine running, at idle and at higher rpm. Cold and when hot. Expect to find inadequate numbers on depleted house battery.
