briannutter1

Hey there, we put a U1 sized miata battery in my '02 Z rated at 370cca. It's enough to start the engine but it's not enough to keep the column lock from locking up after overnight running. I believe the column locker needs to see 12.7 volts. The wierd thing is how fast voltage drops from 13.8 down to 11.8 just after the car has been run.

So can I check amps across the fuses in an easy way to see if I've got current draw somewhere?

I can get the column lock bypass or I may just get the correct size battery and mount it in the RR. Dunno if anyone has a nice battery hold down kit for that location, but it might save me some fab work.

c4cruiser

Disconnect the negative battery cable and place a DVM between the cable and the negative post. Set the DVM to the milliamps setting and see what the value is. C5's do have some current drain simply because of the large number of systems that always need power to maintain settings and values.

Is the battery new? Is the voltage reading from the DIC display? Check the battery voltage with the DVM with the enging running and then with it off. A fully charged battery should show about 12.7v by itself. With the engine running, that 13.8 is OK and would normally indicate the alternator is working properly. After you start the engine, voltage should be 14.1. to maybe 14.3. It wouldn't hurt to check the alternator output with the voltmeter to in

That 11.8v would indicate a discharged battery so either something is sucking a lot of power or the battery may have a dead cell. If the battery is easily starting the car, the small CCA value should not be a real problem if you are not using accessories like the HVAC, radio or such.

briannutter1

Thanks for the reply. New battery. I'll get a dvm and check it out. I'm going to order the column lock bypass from thunder racing as well just to be safe.

briannutter1

wow, tried the milliamps setting first and that didn't work so tryed 10a fused setting and it registered a 1.3A draw. Wow. I'm going to spend some time tonight pulling fuses until I find out what circuit(s) is responsible for it. Hood is up, so maybe the light by itself pulls something, but I'll know soon.

If anyone would do me the favor of checking the amps across their negative battery cable for me to compare to, it would be nice.

UstaB-GS549

I have had column lock issues 3 times in 8 years. Each time is has been a battery problem.

I recently checked my battery draw and it was about 1.2 amps with hood light on. Pull the bulb and drain is about .5 amps. These numbers agree with a friend who has a 98 C5.