Best way to hook 6 guage wire to power supply

[2NC995]

I’m still not sure I understand why it would not help on AM.

I had a small car with a tiny alternator at one point, and ran a amp with 4X2879s. Wire size wasn’t an issue, I overshot that by a mile. The dome light and all the dash lights were in synch with the modulation. Adding two 15000uf caps on the positive buss inside the amp, and a half farad outside the amp, and no more dimming lights with modulation.

I don’t think this did anything worth mentioning for output power, but it must have done something.

 

[Shadetree Mechanic]

The car stereo guys debate this a lot. In the scenario where the alternator is too small, a big capacitor will help. It will help with driving the load which means that it will help the alternator stay at 100% duty cycle. The capacitor will be charging between peaks and this gives the alternator no break. People have reported that the capacitor killed their alternator and this is why. Most people switch to a bigger alternator when this happens.

 

[2NC995]

A bigger alternator is never a bad answer. I think that in a mobile application, whether for audio or radio, an alternator just can't respond fast enough to changes in demands to meet the rapid peaks.

It makes sense when you think what needs to happen....the change in potential has to be felt at the regulator, the regulator changes its output to the field, and then the output of the alternator increases. Those things need to happen, sure, but while that happens a capacitor discharges more or less as fast as the voltage even begins to change.

 

[Captain Kilowatt]

The car stereo guys debate this a lot. In the scenario where the alternator is too small, a big capacitor will help. It will help with driving the load which means that it will help the alternator stay at 100% duty cycle. The capacitor will be charging between peaks and this gives the alternator no break. People have reported that the capacitor killed their alternator and this is why. Most people switch to a bigger alternator when this happens.

What he said.

 

[Shadetree Mechanic]

A bigger alternator is never a bad answer. I think that in a mobile application, whether for audio or radio, an alternator just can't respond fast enough to changes in demands to meet the rapid peaks.

It makes sense when you think what needs to happen....the change in potential has to be felt at the regulator, the regulator changes its output to the field, and then the output of the alternator increases. Those things need to happen, sure, but while that happens a capacitor discharges more or less as fast as the voltage even begins to change.

Yes all that is true but don't forget the vehicles battery. The battery does a good job stiffening the power supply from the alternator. While the capacitor has a very quick response to a transient load, a battery is not much slower and has the capacity to sustain the current while the alternator brings the voltage back up. Bigger wiring from the load to the battery makes the battery appear closer to the load. Some people put extra batteries at the load too.

 

[Redbeard U812]

Yes all that is true but don't forget the vehicles battery. The battery does a good job stiffening the power supply from the alternator. While the capacitor has a very quick response to a transient load, a battery is not much slower and has the capacity to sustain the current while the alternator brings the voltage back up. Bigger wiring from the load to the battery makes the battery appear closer to the load. Some people put extra batteries at the load too.

I've run my linear off battery being maintained by supply, while radio running of same 50 amp supply (rv system ). You can get out short time, but no sustainable load capacity.

 

[2NC995]

Yes all that is true but don't forget the vehicles battery. The battery does a good job stiffening the power supply from the alternator. While the capacitor has a very quick response to a transient load, a battery is not much slower and has the capacity to sustain the current while the alternator brings the voltage back up. Bigger wiring from the load to the battery makes the battery appear closer to the load. Some people put extra batteries at the load too.

I agree, but a battery won’t hold the voltage up at the alternator’s output level, only at battery voltage.

The other benefit with a cap is that it keeps the alternator from overshooting the voltage as it tries to respond to a load that suddenly drops. My current vehicle has a bit of that problem, but I haven’t done anything with it yet.

 

[Slowmover]

Just need a 55SI-series DELCO for a Freightliner fire truck chassis.
Rated 43OA at high idle.

It’ll run ya a couple grand, (but, hey, it’s a hobby).

Aaaand . . you might need a second car engine to start the first one.

.

 

[2NC995]

Just need a 55SI-series DELCO for a Freightliner fire truck chassis.
Rated 43OA at high idle.

It’ll run ya a couple grand, (but, hey, it’s a hobby).

Aaaand . . you might need a second car engine to start the first one.

.

That wouldn’t be the biggest alternator I’ve ever worked on...that trophy goes to a 1.8 megawatt unit turned by a V16 Cat engine.

 

[2NC995]

Here’s an example of an alternator hunting (I suppose this is not technically “hunting”, as that would mean a variation in frequency, which isn’t happening. It is chasing the voltage all over, however).

This is with a DX500, producing about 350 watts, 190 amp alternator, engine idling at 1100RPM, and 2 awg cable feeding the amp. There’s enough power here, and adequate means to get it there, but voltage still drops on the peaks, and overshoots on the lulls. A cap would stabilize this.

 

[Slowmover]

That wouldn’t be the biggest alternator I’ve ever worked on...that trophy goes to a 1.8 megawatt unit turned by a V16 Cat engine.

Wow! One handed removal once bolts loose?

 

[Slowmover]

Here’s an example of an alternator hunting (I suppose this is not technically “hunting”, as that would mean a variation in frequency, which isn’t happening. It is chasing the voltage all over, however).

This is with a DX500, producing about 350 watts, 190 amp alternator, engine idling at 1100RPM, and 2 awg cable feeding the amp. There’s enough power here, and adequate means to get it there, but voltage still drops on the peaks, and overshoots on the lulls. A cap would stabilize this.

What capacitor are you looking to as remedy?

.

 

[2NC995]

Wow! One handed removal once bolts loose?

Lol. You know they can still run after launching a 12" dia piston out the side of the block?

I don't know what I'll do with my pickup. Truth is, I may not change anything. If I get froggy, I'll probably try 1/2 to 1 farad right at the amp.

 

[543_Dallas]

That wouldn’t be the biggest alternator I’ve ever worked on...that trophy goes to a 1.8 megawatt unit turned by a V16 Cat engine.

No 3mw c175s?

 

[2NC995]

No 3mw c175s?

I don’t know much about the motors as that wasn’t my end of the machine. Been a long time, but the whole plant was 7 machines running in parallel. Quite a sight.