electrical problem, dimming at low rpm

recently (a month or two maybe?), i've noticed that when my heater and lights are on, they will dim when i hit a stopsign, and surge back up when i get going. if i'm sitting in a parking lot, in nuetral or park, and hit the gas it's very obvoius that they're getting a lot more power than at idle.

anyway, last week i took it to midas, and they checked a few things out and said that everything was fine (belts, alternator, etc) but my battery was a dud. it was pushing somewhere around 220cca while it was stated for 675cca.

i promptly went out to autozone and dropped $80 for a new battery, and now i'm back where i started. i plan on giving midas a call tomorrow and ask if they'd take another look at it, because i'm not going to be happy if i find that i blew $80 to replace a perfectly good battery (the old battery was still under warantee, though i had no papers for it(came with the car), i suppose that should have given me a clue that something wasn't right, but i just assumed it was a dud.

does anyone have any ideas as to what it might be?
sometimes when my car is running i can hear a light squeek, which seems to be coming from my belts, and while they don't look terrible (midas had said they were fine), they do show signs of cracking.

sounds like an alternator to me.

that's what i'm thinking :(

i've mentioned it to a few other people, and the alt seems to be the common response.

if it does turn out to be the alternator, i assume it would be financially benificial to locate one myself?

as opposed to going to a dealership....YES

Our cars charge at 13.8-14.5 volts after start up with no ancilleries turned on. with ancilleries on (i.e lights, heater,rear window defroster,stereo) it is quite normal for the alternator to drop its charge down to around 13.2 volts maybe even lower.

It is not possible to put the maximum charge back into the battery on idle,the alternator requires more revolutions to create a higher charge rate,also don't forget an alternator only puts a regulated charge back into a battery if it needs to.

in the ideal world,if you are sitting stationary for a long period,you really should turn off your ancilleries to help the alternator out,but no one ever does.

If you are sitting stationary with your lights on,you will see your lights surge on tickover, this is quite normal especially as most people only notice it when use your lights a lot more at this time of year. my alternator is not even a year old and my lights dim slightly in the dark at idle all the time. if you turn everthing else off i.e heater and defroster or stereo,(amps can cause this to happen dramatically) it will not surge as much but it honestly isn't a problem.

as long as the lights get slightly brighter when you blip the throttle, all should be ok, but it is wise to get your charging rate checked. this can be easily done yourself with a multimeter set at a 20 volt scale. just start the car and put the red and black wires off the multimeter on the positive and negative of the battery and see what you get.
if you get stuck or confused, post your voltage readings on here and i will let you know if its ok.

unfortunatly, it does seem to me that you may have been screwed on getting a new battery but without doing a drop test and electrolite test on your battery personally,you would probably never find out.its a shame that companies feel the need to sell you something when you go in for advice. its the same situation over here in the uk. :disappoin

ive worked in the motor trade for over 15 years and im quite lucky as i work in a place that is completly honest and only supply parts when they are needed, not when they are not, but places like these are few and far between....

BB