Battery drain advice for a rookie (Page 2/2) maryjane OCT 03, 01:02 PM I suppose, you could install a high amp capacity "master" switch as well, between battery and + cable (tho neg cable would work too). I'm not a big fan of this because of fire possibility issues tho I did do it once on a piece of farm equipment that was a wiring nightmare and had a slow drain. Jake_Dragon OCT 03, 01:42 PM quote Originally posted by maryjane: I suppose, you could install a high amp capacity "master" switch as well, between battery and + cable (tho neg cable would work too). I'm not a big fan of this because of fire possibility issues tho I did do it once on a piece of farm equipment that was a wiring nightmare and had a slow drain. Starter solenoid from an old Ford What you are looking for is a Battery Disconnect Relay. There are switched and automatic versions. New cars are a nightmare, you cant just unhook the battery without screwing up the ECU settings. So you need to figure out the feeds you don't want to kill. Back in the day the only two feeds you needed to worry about were the ECU power and the radio those days are gone. Now there can be several control boards that need power to retain running settings and will have to relearn. As well as boards that do not do well with sudden spikes of power, you disconnect something and the other components can see a spike. theogre OCT 03, 06:35 PM quote Originally posted by Kitskaboodle: Ok, so I checked the battery drain on the negative battery cable and I’m getting 0.12 milliamperes. From the thread info Patrick attached, that means I’m drawing 120 milliamperes, which is too much! If using 10a Range and shows .12 then means .12 amps and yes = 120ma and will drain the battery... Again, get the battery tested. repeatedly drain to low to start can wreck the battery. IOW Can have 2 problems to kill the battery in a few day. 90 GM cars likely have same type of ECM running the engine and a "radio" like Fiero and standby power should be < 35ma. 120ma load is like a small light bulb. Smaller then 194 uses ~ 270ma. But Most times you won't have such a small bulb On even when Dome Switches and others are F'ed. (That's ignoring LED "upgrades...") Security and other aftermarket crap often have problems and often wired so gets power w/o the I-key On. Get DC Amp Clamp to see amp draw w/o cutting or taking apart joints. 90's car likely are sim to Fiero that has a "box" near the battery or even on battery w/ fuse links etc. Clamp the meter to each wire/link to narrow down what's sucking power. Use alldatadiy.com to get accurate data for the car. You need to know how Power Distributed under Starting & Charging and likely other diagrams. Do Not trust Haynes or Chilton. Kitskaboodle OCT 03, 09:14 PM Thanks for all the input Theogre. A lot of good info. 😀 Kit