Can low system voltage (<<12V) damage the computers etc? (1 Viewer)

[e9999]

I'm trying to determine if I have a short someplace or not, because the battery has suddenly fallen down to about 4V. Dashboard looks completely dead, not a light in sight.
Possibly due to a rodent having moved in the engine bay for free housing and munching on wires for free meals.

Before putting a full 12V back on the system to try and see if I can start the engine (-again-, I tried once before and the horn / alarm went crazy so I shut everything down immediately), I am thinking about putting in a low voltage on the system with a current limit, ensure the current draw is small and then progressively increasing the voltage to 12V if nothing looks weird. I'm thinking that will eliminate / reduce the chance of a short overheating something. (What is the max draw I should see if there is nothing wrong? I'm thinking less than 100mA.)

Question: is it likely or even possible that some of the electronics can be damaged by seeing a low or moderate voltage rather than 12V? Obviously, if so, that could also happen when the battery is discharging, as it has, but I'd rather ask than take a chance with multi $$ computers. To be honest I never heard of that being a problem and it does not seem likely, but I want to ask to be safe.

Would like to do that today if I can still. Thoughts?

 

[Rebus Knebus]

A common way to power up circuits that may have a short is to put a light bulb in series with the power supply. The bulb provides a visual indication of the short as well as current limiting. Maybe grab a taillight bulb and just use that in series with the battery?

 

[e9999]

thanks.

I did what I planned. Turned up the voltage slowly while keeping an eye on the current. It did not go over 0.5 A when the relay was clicking, at 7 or 8V. So I went for it, put the full 12V on and it did lots of crazy relay noises but after I turned the key on and off a couple of times, all was well. Looks like the alarm went back to normal. And no evidence of a serious short. But need to monitor the draw on the battery. Now down to 0.1A or so after waiting a while. Still a tad high I think but nowhere close to short-high.

So, happy to report that the low voltages did not seem to damage anything so far. Great.

 

[abuck99]

Notorious for current draw: Check dome lights( switch them off) , door latches, rear hatch latch.

 

[Eicca]

Blown alternator diodes can also cause a parasitic draw too, without any other obvious symptoms.

 

[e9999]

thanks. Oddly, I just saw that after sitting for the night the draw is now about 10mA or so which is very little and probably outside the range of accurate measurements for my clamp meter. Maybe cuz it was finally truly at rest. Or maybe just caught it between two awakenings. Are there devices in there that only wake up periodically?