Electrical upgrades necessitated by 80 amp alt?

[turkishpress]

Would the use of an 80 amp alternator for an e30 318i neccesitate any upgrades to the electrical system? I hear flasher relays are always good, any other general upgrades i should.

The wire harness in my carb'd 71' apperars to be in fair enough shape, besides being 37 years old.

I'm also looking for someone who would carry a suitable speedo and afore mentioned alternator, or the e21 320i models andmaterials to do flasher relay (and any other suggested upgrades) In the Toronto Area.

thanks, happy motoring

[Chris_B]

There are no "upgrades" required to your electrical system if you install an 80 amp alt. What you are doing is adding capacity. This has a positive impact on your electrical system. Think about it in the context of installing a larger battery- installing a bigger battery requires no changes whatsoever to your electrical system. Having that extra storage capacity or capability to generate more power just means that your have more reserve if you need it.

Of course, if you install features to take advantage of the increased capacity (e.g., higher wattage headlights) you will need to upgrade your wiring and switching capacity.

[Chris_B]

There are no "upgrades" required to your electrical system if you install an 80 amp alt. What you are doing is adding capacity. This has a positive impact on your electrical system. Think about it in the context of installing a larger battery- installing a bigger battery requires no changes whatsoever to your electrical system. Having that extra storage capacity or capability to generate more power just means that your have more reserve if you need it.

Of course, if you install features to take advantage of the increased capacity (e.g., higher wattage headlights) you will need to upgrade your wiring and switching capacity.

This presumes that you have healthy wiring and a good ground between your alternator and the chassis (usually to the motor).

[turkishpress]

What's involved in upgrading wiring and switching capacity? (Electrics aren't my specialty beyond electrolysis) I may be able to deduce that upgrading wiring involves the replacement of some wiring with a higher capacity variety? Is this a difficult procedure when armed with well studying diagrams and biblical amounts of friction tape?

[JohnC]

What's involved in upgrading wiring and switching capacity?

A quick search of the archives will reveal quite a lot. It's a topic that comes up frequently.

[turkishpress]

Thanks, Archives I'll delve into.

[ingraham]

As Chris B. wrote, there is no reason to 'upgrade' any electrical part that's working correctly. The bigger alternator does NOT put any greater stress on the electrical system.

About amps: Your 80 amp alternator is able to supply more CURRENT (amps) than the original 35-45 amp alternator. That means it can charge the battery faster and not much else (unless you have some radical mods like offroad rally lights or ear-busting stereo stuff). The existing electrical devices will not draw more current no matter the alternator size.

About volts: The 80 amp alternator supplies the same VOLTAGE as the original. The voltage is set by the voltage regulator. At the same voltage, the existing electrical devices act the same as before.

Adding an 80 amp alternator to a car that uses 30 amps is like adding a larger gas tank to a car that never goes more than 10 gallons between fill-ups. There is no need to upgrade the fuel lines, fuel pump, carburetor, etc, because those parts continue to operate as before.

[PeterVarga]

(nt) sorry about the chaotic posts - I think my keyboard is sticky!

[PeterVarga]

(nt)

[PeterVarga]

Most of the references toward 'upgrading the wiring' concern headlamps. The original equipment lamps draw a certain amount of CURRENT (as the previous poster explained.) These, especially at idle produce that softer 'yellow' glow that was welcome when the car was made. These days, there are many excellent upgrades that fit into the headlamp sockets. They draw much more CURRENT than the originals did. That means that the original wiring was not designed to provide current for the modern bulbs. Therfore, in the lignthing circuits the talk is adding higher current wiring between the battery and the lamps. This higher current wiring is switched by relays so as not to overheat the original wiring.

The original wiring provides the signal for the relay (a modest current service) and the contacts of the relay handle the large headlamp current. One or more relays are necessary and they must be rated at the headlamp current with some extra headroom so as not to create a meltdown situation.

Over prolonged driving, the larger alternator keeps the battery voltage sufficiently high to keep them burning at their rated color. The vintage 35 amp alternator may not keep the charge rate in pace with the draw from the extra-bright headlamps.

Thats why there is talk about the 80amp alternator and the heavy duty wiring and relays. Those bright lamps draw a large amount of

current.

[PeterVarga]

(nt)

[turkishpress]

Awesome, thanks for the palpable metaphors and examples everyone, I think I've got a much better understanding of things now.

It's my intention to install modern head lamps, an electrical engine fan, badass electric ignition and maybe foglights. But I figure I'll just get her running safely and certified for now - my current 'vintage' alternator isn't working (probably just worn out metal brush thing) so I figured I'd preemptively make the upgrade.