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The 12V battery problem hasn't gone away so I want to monitor actual current into/out of the battery. Measuring voltage, although helpful, has problems. It can be OK one evening and dead the next morning if there is too much current flowing all night. Here's what I've done so far. Removed the big plastic cover/tray that goes across the back. There are 3 screws along the front edge and one 10mm(?) nut in a deep pocket near where the ground cable bolts to the frame. The two outside rear corners are held in place with spring clips - you pull the whole thing straight up once the screws and nut are removed. Connected a two conductor wire to each end of the big ground cable that runs from the negative post to the car's frame. The ground cable now acts as a current "shunt" producing a very small voltage that is proportional to current per good ol' ohms law. Ran the wire under the rear compartment "flooring" into the rear seat area where it could be connected to a digital multimeter set for DC volts. You need one that can indicate down to 0.1 millivolts. DO NOT CONNECT ANY WIRES TO THE POSITIVE TERMINAL! Calculated the resistance of the ground cable by measuring the current through a light bulb connected across the battery and the voltage drop across the "shunt". Two different bulbs gave the same value of 0.54 milliohms (0.00054 ohms). Now you have the value so "don't try this at home"! Current can now be calculated as: 12V Battery Current (amps) = Voltage Reading (millivolts) / 0.54 Or in "round numbers", just take the DC millivolts and multiply by 2 to get amps. If the car's frame is positive (relative to negative post), the battery is discharging. If the battery post is positive (relative to car's frame), the battery is being charged. With car OFF, opening/shutting the door sends the current to about 8 amps. After a minute or so it steps its way down to about 0.4 amps. Then after maybe 30 minutes or more it finally drops to under 0.01 amps. (Used a very high resolution meter here as you are down in the microvolts.) The rear cargo lights appear to draw a bit over 1 amp. They eventually turn off if hatch is left open (at least it happened once while testing). Next step should be to build a little micro-power monitor I can run from the accessory jack that can stay in the car all the time. Just look through the window and see how it is doing. But we shouldn't have to do any of this!!!Here are the monitor connections. For the curious, here is the sticker on my new battery. The bar code number you can't read is 31508 53155. Note the 100 month warranty (36 months free)! Since it doesn't start the ICE it should almost last forever. Quite a pity we're having ANY dead battery problems. The left side of the battery compartment looks like this with the HV battery fan (Made In USA!). It should point straight out the back for a bit of jet assist! :lol:

I hope someone on this forum can tell me what just happened today. hubby driving, I passenger, going about 40mph on county paved road. when all at once, dash info screen on my-sync goes blank, then message like this: battery saver - system shutting down. A blue line moves across (similar to your computer showing length time loading file). all info screens going blank at driver dash - battery icon showing in red, and NO power steering, but car still moving, engine is on. Turned off a/c, and about 2 minutes later, dash comes back on all info screens normal looking again, and my-sync screen returns to the normal "home" screen. also, two days ago, when we got in c-max, noticed the clock in dash my-sync screen was "off" by about 6 hrs (Ie, clock said 8:30 am, actual time was about 2:00pm). we have no idea if two are related. don't know why today's screen/power steering all shut down? 7200 miles today. suggestions welcome:-). thanks to all! Creeping me out - what if We had been on interstate highway near where we live, on it often, and lost power steering like this / battery saver-system shut down thingy again?

Ok so today in the middle of the day my 12volt battery went dead. Its night now so I will not call for service untill the morning, but how do you open the hood with no juice.? the car is not locked so thats good, I had left the keys in the car and im not sure thats what happened. But the other day I noticed the tail lights on for no apperant reason. I'm wondering about the foot on the break thing. Im sure I leave my foot on the break when I shut it off. I love the car but someone eles I know had the dead battery too. Anyway any help with the hood would be great. Ziggy