How do you fix this?

[nrb's70gmc]

Anyone with an old car knows about this.
when you rev the moter up the headlights get brighter and so on.

in my case when i have the radio turned up (with amp) heater on with head lights also on.

at a stop light (with heater and lights on) i can see the lights on the radio dim (when the bass hits) and when the volume is really up the radio will turn off.

during the day with no headlights and no heater i can blast the radio no problems.

its sort of funny when im at a stop light the blower motor for the heater slows down and speeds up when i take off.

any way what is the reason this happens in older cars? and what is the difference in new cars?

i have a 140 (internal reg) powermaster alt and the amp for my radio is connected directly to the battery.

i think the specs for the alt are IDLE-80 CRUZING-100 HIGHWAY-140

[OhOneWS6]

Separate battery for the radio and amp and an electronic battery isolator will fix it.

[michael bustamante]

you need to get a cap (capacitor) also make sure youre running at least 8 guage wire as positive and negative, depending on your amp. lets see your box if you got one

[nrb's70gmc]

Originally Posted by OhOneWS6

Separate battery for the radio and amp and an electronic battery isolator will fix it.

are "electronic battery isolaters" what new cars have? What does it do?

[OhOneWS6]

New cars do not have isolators. In a new car the circuits, wiring and charging systems are sized for the current technology in the car. 40 years ago high power audio systems didn't exist.

A battery isolator allows you to charge two batteries with one alternator while keeping the circuits to each battery isolated.

http://www.northerntool.com/webapp/w...3388_200343388

[nrb's70gmc]

ok thanks

[Mike J]

yeah, having a power cap will help a lot with keeping the amp supplied with enough voltage. A 1/2 farad cap is usually plenty.

[nrb's70gmc]

ya thanks, im going to look into it.

[fixit-p]

Curious is your alternator a one wire??

[D.PASSMORE]

Where does the capacitor go in the circuit?

[nrb's70gmc]

Originally Posted by fixit-p

Curious is your alternator a one wire??

yes it is a 1 wire

On a side note
i had a shop install the it, a few years back- and the wires that are connected to the alt go down by the stock external regulator and may be spliced in to it (covered with tape) is it possible to do this or a reason to do this?

[dirtyd_nd]

Before you add a cap try upgrading your wiring. Replace your pos, neg, and alt wires. You wouldn't believe how often this will fix a lot of the light dimming problems. If the electricity can't get to your different components(radio, lights, heater) then something is going to suffer. Upgrade to a larger gauge wire and then add the cap if it is still needed. Depending what all you have I doubt if you will need the cap.
Dale

[72 cheyenne pdx]

I agree with dirtyd_nd on this one. Without knowing what type of Amp you are using it is a little difficult to say what size wiring is needed. I would upgrade all the + & - wiring as this will be a lot better than putting a band aid on with using a Cap or dual battery set up. If after you upgrade the wiring and you are still seeing the dimming of the headlights, then put a cap in or run a dual battery set up. Me personally, I would go to 0 gauge wiring for the grounds and at least 4 gauge (probably 2 gauge) on the positive side.


Most vehicles (New and Old) are not adequate with the + & - for the battery, alternator, ground straps, and what nots when it comes to upgrading any part of the systems. Vehicles are only adequate for power as the most power optioned that car line offers.


Good luck with this adventure.

[fixit-p]

Originally Posted by nrb's70gmc

yes it is a 1 wire

On a side note
i had a shop install the it, a few years back- and the wires that are connected to the alt go down by the stock external regulator and may be spliced in to it (covered with tape) is it possible to do this or a reason to do this?

That's part of your problem 1 wire alts make great battery chargers but are not very efficient power sources. At 140 amps you should have plenty of power to supply your accessories. I would consider changing it to a 3 wire system with a three wire system you could connect the sense wire at the main buss connection that way with every thing turned on and engine running your alternator is going to power your accessories and the sense wire will adjust voltage accordingly at that point

[nrb's70gmc]

thanks everyone, im sure its not a big problem (i will sometime) upgrade to bigger battery & alt cables. Currently the Amp power wire is the same size as the battery cables.

[TheSunDanceKid]

um if its just your lights on your radio dimming and turning off you have a **** ground on the radio if other things are dimming headlights and dash lights upgrade by going down to your local audio shop grab a piece of 4gage or 8gage wire 2feet or so with a connector on both ends and run a second ground from the negative on the batt to a good solid metal i usally go with the radiator support theres usally a bolt easy access just clean the paint off real good and this will fix your lights dimming and upgrading the radio ground not the amp but the radio good scraped off bare metal will fix the radio

a 140amp alternator is damn decent for a pretty big stereo and alot of other shiot dont use a cap thats just a bandaid for the problem a second battery and isolator is just a little over board and the cost it will how ever fix the issue why? you will be adding a new ground strap in the prossess clean your stock ground strap and just run a second gound for a perment quick and like 10 bucks fixes the issue CORRECTLY