Is this normal?

[wellcraft]

Hi guys, I have a 1999 mexican beetle and i just replaced the alternator, I had a 51 amp and put a brand new bosh 55 amp al82n.

I needed to replace the voltage regulator in my old alternator as it was overcharging, with the old alternator I was getting 13.5v all the time but dropped to about 12.8 when i turn the headlights on and to about 12.5v with headlights and fog lights. If i hit the gas while idling with everything off it stay at 13.4v but if I do it when the fog and driving lights are on it goes up to about 13v. I'm using a digital voltmeter as it seems that my vdo is not accurate. When I turned on the fan of the ac it drops to about 12.4 volts. The problem was while idling.

At this time I didn't have the sound system connected as I didn't think it was appropriate, didn't want to damage the amp.

The other day I decided to install a brand new bosh 55 amp al82n and now I'm getting 14.4 volts with the digital volt which is good but if I turn on the headlights it drops to about 13.6 and if I turn the rest (fog lights ac fan as the compressor isn't working, high beams) its drop a lot and still I haven't connect the small sound system. It looks like the headlights on this car draw a lot of power. While idling it's about 12 volts and if I keep the car at about 1000 rpm it stay at around 13.5 volts

So is this normal on this beetles?

Or it was a better option to go with a bigger alt or do I have something else wrong in the car?

Yesterday I got the readings of the charging system of my 1999 mexi beetle.

Alernator Battery

Nothing on. 14.60. 14.49
Just fan of the ac. 13.32. 13.25
Just Fog lights. 13.14. 12.94
Just High beams. 13.00. 12.78
Just low beams. 13.12. 13.03

Everything on with high beams at the alternator is 12.54 and with cabin lights at the battery is 12.25 volts.
Everything on with low beams at the alternator is 12.66 volts and at the battery is 12.25 volts with or without cabing light.

All these was done while idling at +/- 800 rpm's and at the stud of the alternator. I couldn't see what wattage my headlights are. How can I tell?

I know it will drop more if I hookup my small amp and sound system.

If I keep the revolutions at 1000 rpm's the voltage go up. How can I increase the rpm's on the is 1600i engines?

So what do u guys think?

Thanks in advance.

[Red1600i]

Nothing wrong, quite normal.

At 800rpm there is not more power.

1000rpm? Not possible or you must reprogram the ecu.

[wellcraft]

Thanks for replying, what's the lowest voltage I should have? I'm a bit worry when hooking up the sound system, don't want to damage it.

Thanks again.

[wellcraft]

Nothing wrong, quite normal.

At 800rpm there is not more power.

1000rpm? Not possible or you must reprogram the ecu.

Didn't know I have to reprogram the ecu for that.

[wellcraft]

I just measured again, while keeping the rpm's at 1000 the voltage is 13.30 volts at the alternator and 12.50 volts at the battery.

[Red1600i]

That means 0,8V loss at a ground strip... quite a lot.

Not good.

That means more measurements, which ground strip is dead?

Batterie, gearbox...