Weakling alternator

[jhiestand]

I'm in the process of upgrading the stereo on my '01 SAN from 700W to about 1400W and last season my alternator was already struggling to provide a charge with just the heat and stereo on. Kicking on anything else (lights/bilge pumps/fan) would bring it to it's lil' 50amp knees. Anyone upgraded their GT40 alternator? I know my dealer can wrangle me a GT40 100a upgrade 'kit' but that seems pretty darn pricey. ****, I could just buy two additional yellow tops and STILL have skratch left over, just trickling my system every few days or so if needed.

A while back someone was listing a 100a direct swap for Ford PCMs at $200, but that is an old thread and appears to be dead. Anyone had their alt built up and/or know if that is a problem getting it done to marine specs?

Any guidance at all would be greatly appreciated!!

[G-man]

RE: Weakling alternator

the 05's have a bigger alternator, is the new one big enough?

[FatBoy]

RE: Weakling alternator

I think I heard that the 05's have a 100 amp. Not for sure.

[jhiestand]

Says in the 05 brochure that the electrical system is now 100amps. That's twice the current my 01 has and I'd feel pretty sure that would be sufficient. Unfortunately, that's for the GM blocks, tho.

[skinautique]

The PCM engines come standard with the 100 amp alternators on all models in 2005.

[wburg64]

Always been a problem thru history. One problem is the battery's ,if two are used they are charged in parallel. If two heavy duty 6 Volt batteries were used they would be charged in series. Thus giving 12 Volt and doubling the battery amp and longer life. End of problem, alternators work constant to keep the level high, good old generator charged them slow, much easier on battery life.
It goes on however , from experience, 2 are better however it's all about cost not performance.

[redelf75]

I added a second battery for my 2004 with ZR6 but my voltammeter drops to 0 when I turn on the tower lights. It comes right back up after a moment. I was wondering if upgrading the altinator to the 2005 100a model would resolve that problem, or if it's worth it. Your thoughts?

[jhiestand]

Sounds like the lights temporarily spike your system when you turn them on, but under normal operation the alternator does fine. I doubt a higher capacity alternator would 'fix' the spike, but I don't know that for sure.

[redelf75]

But does this spike happen to everybody? Maybe the lights aren't hooked up right.

[EchoLodge]

I had a 95 amp alternator built at a local shop ($180). He uses a stock delco 95amp and puts the spark sheilds on it. If it ever fails out in the sticks you can buy another alternator at an auto parts and swap the internals. As you can see from my signature, I have a lot going on electrically speaking. I did the math and with everything turned on I needed I needed 80 amps. The stock 51 amp could not keep up. I was told to take my stereo watts and divide by 12 to get amps needed. Then add your other items (heater, shower, blower, etc...). Remember that the stock breaker on older systems is 50 amps. I bypassed it and ran the hot wire to the alternator directly to the batts and put a 100 amp fuse. I then ran the power back to the stock breaker to run the stock acc. Stereo equipment has its own fusses.

[nms1991]

Redelf75 it sounds like the problem with not having a diode in the system to prevent spikes in the system. How do you have the lights powered? directly from the battery or off of the greyhill box?

[nms1991]

Jheistand I know Arco electrical systems off replacement altenators rated at 90 to 95 amps. If you install the higher amp altenator you need to install bigger gauge wire for the altenator to the battery and you need a heavier amp circuit breaker.