Issues with alternator?

[Rob (215)]

On my 00 xlt 4.0sohc everythings pretty much stock. However, the only thing i've upgraded and added was my 5000k xenon headlights and 100w foglights and a modest 400rms mtx thunder amp, 2 farad cap., and a 600rms 12'' kicker solo baric for my system.

When driving, everythings cool. lagging some hp but everythings fine except at night and when engine's idling and not moving. I'm getting the 'normal' voltage drop and all lights take it hard, headlights and dash/interior lights, and it's really annoying! Please mind i got a brand new interstate mtp batt. and i believe the alt. is the stock and if it is... it's got 180,000mi on it. I'm sure its doing it's job to an extent but i don't know how long i got or how long i should wait to replace the alt. and if it's worth gettin a new 130a replacement or bump it to a ho 160a or higher. I am aware of the output decreasing at idle but i get a drop with nothing but the headlights and the system at a decent level (not blasting). I tried the real test and turned everything you can imagine on at night, system blasting my voltage gauge was near the red and dosen't normalize til you turn everything off.

If any of this sounds familiar and if whether or not i'm diagnosing this right please let me know. I was told from an electrian to upgrade all wiring to thicker gauge running to amp/cap from batt. as he said my system may have some resistance and may draw even more but i'm not sure if thats even necessary, it's already like 8/6 gauge. I'll take any advice ....thanks.

 

[marragtop]

Are you sure you have a 130 amp alternator now? I believe some of them came with a 95 amp. If that's what you have, you could upgrade to the 130. I'm not aware of a 160 amp, but I guess for the right $$ you can get anything.

 

[Rob (215)]

yeah u kno what.... good question, more than likely it may be a 95a with the issues i got but i'll test it to be sure. if it's a 130a then i may have a faulty diode which could explain also, i believe it is the original and if so.. 180k mi. means this was a good one i'm also thinking with the system and xenon upgrades it was probably the sticks that broke the camels back oh yeah, they do have a 160,170, and a 200amp ho available for my 4.0 sohc on ebay! i think it's dbelectrical. but from what i hear it involves upgrading all wiring between alt. and batt. to support the extra amps as well as tension issues with them having a smaller than stock pulley. it may be better to just get a new 130a but again i don't know how long i should wait. it's not like it's causing a problem just yet, just an annoyance.

 

[CDW6212R]

You can get any alternator with any pulley, you usually have to ask for a smaller pulley. I have two of the DB units, one died in Winter after two years. I put the other one in as a spare, and with a normal pulley I see about 12 volts at a low idle. If you have extra accessories running at idle, the overdrive pulley would be a wise decision.

The aftermarket alternators with higher amperage can make more at idle, but you don't necessarily have to have bigger wires. If you have significant extra current loads, then it would be wise to add another power wire to the alternator. Try to match the stock wire in size, it's at least a 6 gauge. On yours it goes to the PDB, terminal with the fuse bar going to the main PDB terminal next to it. Thus you can add just the one wire, if you support proper grounds for your added circuits.

 

[Rob (215)]

if I do get a h.o. With a smaller pulley would I really have any issues with the belt and the rpm at idle, given I put a new serp. Belt of the same size.

 

[CDW6212R]

The belt can stay the same if you use the same size alternator pulley. Most people who have a lot of extra loads(current) at idle choose the smaller pulley, which requires a slightly shorter belt.