Hi guys, i have a problem, i use my 91 n/a for deliveries and its been raining a lot where i live, Ive never had problem with the alternator but all of a sudden my car wont start, like its not charging my battery, my windshield and rear window get really foggy so i use the defroster in the rear and windshield defroster, could this draw more power from the battery and be drawing more power than what its charging back, I still have the regular 50amp alternator and the battery is a new rebuild battery that i got a month ago, if its the alternator should i get a place to increase its amps

 

Your alternator can be tested to see if it's output is correct.
Your S5 should have an 80A alternator, the easiest upgrade would be the 100A FD unit (plug-n-play after the pulley is bored out), the Taurus alt upgrade brings you up to 130A but needs brackets fabbed to fit.

I didn't know batteries could be rebuilt.

 

You can also have the alternator rebuilt for more amperage. I forget the name of the company, though.

 

so it might be possible that the defrosters are taking a lot of battery juice

 

A stock alternator and battery in good condition should easily power the rear defrost element and the blower motor.
Check your alternator.

 

50amp Alternator? rebuild battery ?

are you serious ?

like others here said, stock is 80 amp and i really never heard of "rebuild/recondition battery"

check the alternator. its really easy. and ... return your "rebuild" battery for a "real, new" one. cost less than 90 bux and comes with full 3 yr replacement warranty.

 

Any battery you buy is probably "rebuilt". You guys do know that 95% of all batteries sold are recycled. That is why there is a core charge.

All the draining and charging had probably fucked the battery. Fix the alternator or whatever issue you are having and get that battery swapped or replaced.

When you discharge and charge a battery like you are describing causes dendrites to short the plates...wikipedia explains it well.

 

TRUENO.
I got an Idea for ya,while you are waiting to fix your alternator Stuff up.
Get the RAIN-X Interior Anti fog Solution..you rub it into the interior glass and it prevents the glass from excessive fogging up due to Moisture/heat etc.
My First RX was a real Pig when I drove it in the rain,.,Couldn't see Crap out the back,or sides.I got the Interior Rain-X and it Really Works!..(it's like 5 bucks a bottle.)
By the way,You should consider an FD alternator,as they are Minimum 100 amps..and are pretty well plug and play on an s5.

 

RainX is great ****, both the anti-fog and the stuff for the outside.
Also, you can take a hint from our waterlogged British brethren and put a box of dehumidifier crystals on the back (theory being that fog requires moisture which the crystals absorb).
Dunno if the crystals work but the Brits know all there is to know about being cold, wet and miserable.

 

oh i meant the stock 80amp, but i will check the alternator again and battery, and the battery i just bought a month ago so no need to buy another one, but will also have the battery tested just in case

 

drove the car for a bit in the rain, i had the accessories on to check if it would drain the battery again but didn't, but i did notice that my rpm will get lower when i use the accesorries, the windshield blower and the rear defroster will lower the rpm a bit more than the other. And it wont return the rpm back to normal until i shut everything off, will updater later

 

This is somewhat deceptive.
Batteries are recycled for the materials, they are completely destroyed in the process and little to none of the material actually goes back into another battery.

A "rebuilt" battery sounds like it's been refilled and brought back into service, which is definitely not the case.
There is no such thing as a "rebuilt" car battery.