Triumph Repair: Battery not staying charged, newer cars, brand car

Question
QUESTION: I noticed that another owner (2006) had the same issue after installing a new stereo into the car? My new battery started draining to dead immediately after I put in a new stereo. Could it be the way it is wired? The newer stereos require a constant power to retain memory.
What do you think?

ANSWER: Hi Darren,

I have no experience on any brand car after the 1987 models but your question is a general automotive question so I will try to help.

Yes, some radios and even your car can use battery power for various memory items. A rough rule of thumb was (on older cars) that if a battery will light a test light brightly when the test light is connected between either battery post and the cable when disconnected and everything in the car is turned off, it is an indication there is too much current draw and it will run the battery down.

However, on newer cars disconnecting the battery cable can upset several things in the car including the radio which now needs a code entered to even operate again. This code is usually included in the owners manual or owners package. It may even set a code in the car computer and require a scanner to be plugged in and the code cleared so don't just disconnect a battery cable to test for a drain.

My advice is to contact a local shop familiar with your brand car and just ask how to run a test for excess battery drain with everything turned off.

You can run one test by yourself. Since you installed the Stereo just remove the power wire and put a 12v test light between the power wire and where you connected it. If it will light a 12v test light with the Stereo turned off then the Stereo itself is running the battery down not something else. This is the same as leaving a light on all the time. A Stereo should not draw enough current to run a battery down when turned off even with a memory system.

Howard  



---------- FOLLOW-UP ----------

QUESTION: For clarity, my vehicle is a 77 spitfire. The question was asked in 2006. Sorry for the confusion.

Answer
Ok, then you can just remove a battery cable (with everything turned off) and put a 12v test light between the cable and the battery post and note if it lights up a 12v test light. If it lights the light, first disconnect your stereo you installed and if the light goes out you need to read the manual on the stereo to see what the amp draw is when it is turned off. (if it has a memory) If your stereo has a high powered amp, you may have to get a high amp relay and have a switch to turn it on only after you start the engine.

If you disconnect the stereo and the test light still is lit, you first need to disconnect the large and small wires off of the alternator to see if a diode has failed. If that is not it and the test light is still on, you need to get a wiring diagram of your car and start disconnecting one wire at a time from the fuse box to try to find what is drawing the battery down.

If you don't have a wiring diagram of your car let me know and I will post one on my web site for you to copy.

Howard