scENFORCER

Have had my carPC system running without a problem for about 7-8 months now. However in the past week or so, when sitting in traffic (idling at low rpm's) the battery light has come on and the car almost died. CarPC shut itself off, windows and lights died, etc (typical dead alternator symptoms). I kept it running by keeping the rpm's up, however the car eventually completely died on me. Battery was completely drained and would not even turn over.
Today I had a mechanic look at it, and he says the alternator is fine. He said the carPC is somehow draining the battery. He's going to recharge the battery and told me to run without the carPC for a few days.
I dont think its the carPC. I dont understand why it would work fine for 7-8 months, then all of the sudden decide to drain my battery? I am having a slight ground problem (static through the speakers while amp & car are on and carPC is off), but I dont think that's the problem either.

Anyone have any suggestions for me? I still think its the alternator despite what the mechanic says..

ZhiuPei

iTrader: (18)

what year is ur car..

Test of alternator:

Turn on the car go to the engine bay, take out the negative pole of the battery.

If the car shuts down is ur alternator.

Someone correct me if im wrong.

88supramki

Are you running anything extra along with the carpc? Check your grounds. Look for something that is a parasitic drain

Gregz_IS

This is a great test if you want to do mega $$$ damage to the electronics on the vehicle.

This type of test hasn't been done since the dark ages.

Disconnecting the battery with the car running will cause system voltage to spike very high (if the alternator IS working) causing over voltage to all systems that are running.


DO NOT DO THIS!!

Find a shop that can diagnose the problem properly.






...

ScBouncE

take it to sears auto center, they will check your alternator and battery for FREE! dont waste time going anywhere else.

scENFORCER

Well the mechanic I originally took it to charged the battery and the car ran fine after that. I did unuplug the carPC though.
I took it to another mechanic and he also blamed the carPC as well as the ground issue I'm having. He said that if I run the carPC too much without the car being on (which I guess I have been doing) it will kill the battery really quick. Also, the ground issue will mess with the way the alternator works and other electronics in the car, if its a really bad ground.
So I guess I'm gonna take it back to a shop and have them check/fix all my grounds. Anyone else have any input on this?

Kohinoor

iTrader: (22)

i had similar problems after i got my car out of the shop and it was the battery(ies). it was just kept at low voltage for way too long. get a new die hard or something, they are fairly cheap and have a very high cca rating. even if you keep recharging the one you have, it will keep discharging since it has been fully drained a few times. is your carpc on a remote wire so it is only on when the car is in acc/on? most pc's are still 'on' even when they are off. if this is true with yours, i would install a switch directly on the power cable so it is truly off when your car is off and doesnt slowly drain the battery like leaving a light on would.

your alternator is likely fine, but look into upgrading it. its worth the money, especially if you have accessories.

thechadsSC

thats a good idea with the remote wire for the power. (like an amp) make sure all of your ground are in good shape. just because you run the carPC with the car off whenever you start the car and drive the alternator should recharge your battery unless your charging system or battery isnt operating correctly

scENFORCER

Ya they said a beefier alternator would help.
The carPC goes into Hibernate when the car is turned off (I'm using a Carnetix P2140 DC-DC regulator which sends the signal to the computer), according to the MP3car guys 'Hibernate' drains almost no power from the battery when the car is off (can last over a week before it drains the battery). 'Sleep' drains a lot more power (drains the battery in a day or two).
Crappy thing is just now I tried plugging the carPC in and booting it up, and nothing ..worried something mighta fryed. Look like I'm gonna have to tear everything apart and see whats wrong. Might as well fix my gounds while I do that.

pieisgude

iTrader: (2)

My CarPC killed my battery too. I went to a local interstate battery, and they had some snazzy battery/alternator tester that helped me determine whether or not it was my alternator. They made you do a full load on the battery, i had the music blasting, computer running, A/C up. That worked really well to see if my alternator was going bad, turns out it was a battery with 63 CCA. So i ended up buying their econo-battery for $40 with a 2 year warranty. I've let my CarPC sit for an entire week in hibernate and it started back up, and mine's a cheaper M3-ATX power supply.

Kohinoor

iTrader: (22)

you may want to add a second battery in the trunk with a battery isolator. this would likely solve all of your issues as the car-pc and any other accessories connected to the second battery would only be draining that battery and not the one that is being used to power the rest of your car.

scviolence

iTrader: (17)

what kind of battery do u have and do u own a voltage meter??? is it an optima???? if u have a voltage meter just check it yourself....turn the car on see what voltage u have at the battery...should be at least 13.5...if u dont give it some gas and see if it jumps up to that....turn car off check voltage at battery it should drop but no go past 11.8-12 volts.... if it goes lower then go get a new battery...i only ask what kind cause if its an optima they have gel cells....u have to slow trickle charge them for a few hours before there full again not like a regular battery u can go for a drive and itll charge back up quick...good luck...

scENFORCER

^ not too sure about what kinda battery I have, all I know is that "its a good one".

Since the battery was recharged the car seems to be running fine now. Looks like 'pieisgude' and 'kohinoor' were right about the carPC draining my battery.
I'm gonna be looking into installing a second battery in the trunk. I'll look up info on doing that in a when I get a chance, but what exactly does in entail? How does the second battery connect to the car? Is it wired to the same alternator?
A quick rundown would be nice, thanks guys..!

AlpineAndy

To wire a second battery in your trunk you need to wire the two batteries in parallel (positive to positive and negative to negative). Doing this will keep your battery voltage the same (~12V) and add the current of the two batteries together. If you wired the two batteries in series (positive to negative) you would get around 24v and tear most of your cars electronics up.

To wire the two batteries in parallel you can run 4 gauge (or larger) from the front battery's positive to the battery in the trunks positive and ground the negative terminal off. The proper and safe way of doing this should have any wire coming from a positive battery terminal with a fuse six inches or closer to the battery.

After you do that your power wire from your amp can come straight off of the battery in the trunk. I would always recommend a sealed spill proof battery when being installed in the cargo area and make sure to bolt it down. I would recommend a kintik 600 because they are small and easier to hide.

scENFORCER

^ great. Thanks for that. Doesnt sound too complicated or expensive at all. Looks like I'm going to go this route.
I'm sick of driving my car around worrying the battery is gonna die on me anytime I come to a stop.

Gonna take it to my buddies audio installation shop next week and get the ground problem fixed, and install another battery.