Trying to solve the issues of a cronicly dead battery

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Alright, I really hope that this isn't a repost. I searched and learned some but still have some questions. I just bought a new battery at the beginning of the month, and the alternator is only a few years old. Now I had issues w/ my old battery dying on me if the car sat for close to a week and I went to autozone to get the battery tested, and they said it was bad. So I bought a new (and nice) battery. After getting to school and having the car parked for a week the battery died. I jumped it and it ran fine after a few minutes, I even shut it off and started it back up a few times one of which was after a few hours (which makes me think that it's not the alternator). But before I jumped the car I decided to disconnect my amp (I took out the inline fuse) b/c I figured it was draining the battery somehow. Then the car sat for 2 days and the same thing happened (dead battery). And in both cases I mean the battery was completely dead, not even enough power to turn on any interior lights.... My question is this: could it have been that I just didn't let the battery charge up enough after the first time (I drove it for around 20 minutes)? or Is there another issue with my electrical system? And on a side note this last time that the battery died, after jumping it I noticed that my tach was exponentially off. I had this happen b4 but that was after I took apart the intake to clean it all, and it fixed itself after being shut off for a few hours... Sorry for the long post but I am a little stumped. I was thinking that maybe upgrading the grounding wires might help, but I think that there might be a bigger issue... Thanks in advance!

[hachibroku]

sounds like its a parasitic load. i cant remember exactlyhow you test for them but you pull fuses and see which system is draining your battery. sorry i wish i could remember what setting you put the mulimeter on.

[Arrow]

Anybody have any advice or insight into my tach being off??

[InsanityInc]

could be a problem with your voltage regulator. Check your battery voltage with the car running.

[Arrow]

one more bump to try to solve the battery OR tach issue... I think that the battery and tach could be linked (wouldn't surprise me) but the tach has a way of mysterically fixing itself like it did just tonight.... so I'm a little stumped... I'm hoping that someone else out there has either seen this or might have any insight into what on earth is happening w/ my car. Thanks again in advance!

[gumby]

i had a similar issue while my car was sitting in the driveway before i started driving it. what it needed was a 1-2 amp trickle charger. it took a full day to fully charge. the quick charger would get it started but it would die since it wasnt being driven. if the car is at idle its only getting 1-2 amps which isnt enough it needs to been driven to recharge after starting. also i think the stock alternators are sorta wimpy so that doesnt help either. could be it just wasnt driven long enough to replenish fully.

[Arrow]

alright guys, I figured that I should update the thread and include some of my recent findings and such...

First, I know that it's not a battery problem now and I don't think that it's an issue w/ my amp (though that could be making it worse). How I know this is that I disconnected the battery before letting it set over the week and it hadn't lost any power during the week where before that was enough time to completely empty the battery to the point of no electricity flowing into anything... So it's definately a problem somewhere in the electrical system of the car...

And about the tachometer.... well, once again it mysteriously fixed itself... go figure. if anyone has any further advice about this it'd be helpful, but since it fixed itself I figure that I'll leave it be and not worry about it.

Thanks for everyone's input!

[Chezedik]

the tach is inductive, and sensing electrical noise. get a noise killer, and put the amp on a heavy duty switch.

[Arrow]

reviving the dead thread because it's been a while since I checked it... sorry for not responding sooner to you Chezedik, but could you or someone else go into a little more detail about how the tach works for me? I want to be sure that I understand the inductive functionality of it and how my amp plays into it. I do know that the amp can cause electrical noise... But I still fall short on understanding how it messes with the tach when either A) the amp is completely disconnected and B) it somehow manages to fix itself without me doing anything (at least I'm not intentionally doing anything that I can tell).

THANKS AGAIN EVERYONE!

[Chezedik]

The tach senses signals from the coil, and each little pulse it reads as an RPM. Then it displays them. That said, if you have any electrical interference, the tach 'could' (and often does) pick it up as the same delicate signal. So, installing a noise filter on the amp should help. It is just a resistor on the hot side, that kills that radio noise.

[glassmonkey]

I once had a battery drain problem. Turns out to be the glove box light would not turn off when closed. It took several weeks to find it,so check all lights such as hood, trunk, glove box etc.