Electrical system help

[stormsearch]

An alternator is only so efficient, 50 - 70% depending your model. Assume that your alternator is 50% efficient, rated at 100A. For the alternator to produce 50A @ 14v, it is producing that same amount of heat (efficiency loss mainly produces heat but there are mechanical losses also). So 50A x 14 V = 700W of heat output. If you drive your alternator to the max at 100A, it will produce 1400W of heat energy. Just like the vast majority of electroncis, heat is the number one killer. If I saw my headlights dimming every time I slowed down, I would be worried or at least not take an extended trip until remedied.

 

[bubbagumper6 5,000+ posts]

An alternator is only so efficient, 50 - 70% depending your model. Assume that your alternator is 50% efficient, rated at 100A. For the alternator to produce 50A @ 14v, it is producing that same amount of heat (efficiency loss mainly produces heat but there are mechanical losses also). So 50A x 14 V = 700W of heat output. If you drive your alternator to the max at 100A, it will produce 1400W of heat energy. Just like the vast majority of electroncis, heat is the number one killer. If I saw my headlights dimming every time I slowed down, I would be worried or at least not take an extended trip until remedied.

I can't say anything about how they rate stock alternators, but most aftermarket alts are actually bench tested. So I know that my 225A alt will put out 225A.

 

[Bumpin' Goalie 10+ year member]

Luckily i do not show any symptoms of dimming. so i'm hoping my 80a alt is able to keep up for a while longer. And my voltage stays relatively decent at moderate levels. When i get to pounding it drops slightly, but still no physical signs. Sorry for the thread hijack :/

 

[stormsearch]

I can't say anything about how they rate stock alternators, but most aftermarket alts are actually bench tested. So I know that my 225A alt will put out 225A.

Stock alternators (well at least the ones I deal with) are rated at a certain temperature and speed (80 °F and 6000 alt rpm are common) and tested according to an SAE test method. They can produce slightly higher current, but generally at higher temperatures they will produce lower current. My pontiac vibe will have dimmed headlights if I turn on the back light defroster - poor design. If ever added a sound system to that vehicle, will definitely need a bigger amp. What alt do you have. Even my truck, always wish for more power.

 

[bubbagumper6 5,000+ posts]

Stock alternators (well at least the ones I deal with) are rated at a certain temperature and speed (80 °F and 6000 alt rpm are common) and tested according to an SAE test method. They can produce slightly higher current, but generally at higher temperatures they will produce lower current. My pontiac vibe will have dimmed headlights if I turn on the back light defroster - poor design. If ever added a sound system to that vehicle, will definitely need a bigger amp. What alt do you have. Even my truck, always wish for more power.

Holy hell, 6k rpm? That's awfully high to rate an alt at. Mine is a DC Power alt, I don't remember it's exact rating but it was something like 225A normal engine speeds and 175A at idle.

 

[Bumpin' Goalie 10+ year member]

I wish there were H/O alternators more readily available for Suzuki's. Looks like I'd have to take a more custom approach. And due to the location of my stock alt, i doubt i'd be able to perform the install myself.

 

[audiolife 5,000+ posts]

Battery acts as a ripple filter for an alternator. If you hook electronics up directly to an alt you can be asking for a lot of trouble. In new cars you can blow up things like ECMs by removing the battery in newer cars (many car manuals have warnings on this) and if you have an older car and you remove the battery you can easily blow the diodes in the voltage regulator/alt depending on the set up of where the regulator is.