Batter power drain

[Fohhunnid]

Hey guys, back again with yet another problem.

 

Lately i’ve noticed that when i depress the brake there is a large current draw on the electrical system and my music and A/C slowly turn off and then when i let go of the brake it’s back on like nothing happened.

I’m thinking it’s an alternator issue as it could be old, because the battery is brand new. 
 

Any help would be appreciated! 

[RX400h]

While the engine is running, check battery voltage with a multimeter. It should be a bit over 13.5 VDC. If it's not, the alternator may be bad. Incandescent brake light bulbs draw a fairly large amount of current. 

[Fohhunnid]

2 minutes ago, RX400h said:

While the engine is running, check battery voltage with a multimeter. It should be a bit over 13.5 VDC. If it's not, the alternator may be bad. Incandescent brake light bulbs draw a fairly large amount of current. 

I’ll try this tmrw and let you know the result!

[Fohhunnid]

14 hours ago, Fohhunnid said:

I’ll try this tmrw and let you know the result!

 

this is what i get 

[RX400h]

That looks about right. The next thing I'd do is to remove the brake light bulbs and repeat your stepping on the brakes while monitoring the AC and sound system. If they are not affected, then you should replace the bulbs with new ones and then repeat the test.

[Fohhunnid]

3 minutes ago, RX400h said:

That looks about right. The next thing I'd do is to remove the brake light bulbs and repeat your stepping on the brakes while monitoring the AC and sound system. If they are not affected, then you should replace the bulbs with new ones and then repeat the test.

what’s tough about testing it is, it is not happening everytime, like i’m driving today, and it only happened a couple times in the beginning, but now it’s running fine

[THEBARTMAN]

Before pulling the bulbs, you should look for a change in voltage on the meter with and without the lights/audio on. If fact, what I typically do when performing a quick test, observe the meter as you switch each component on...one by one. If the brake lights are showing a large dip on the meter or with everything on together you are dropping below 13 volts...you have a problem. It's rare, but you could have a bulb that's not lighting up and instead shorting out. If the charging system stays above 13.5 under full load than I'm leaning towards a problem with the wires coming from the battery or loose/corroded battery terminal. Most of the situations that I've worked on where there seems to be an electrical demon and all the tests are good...It's usually something like a poor body ground.