Houston, we have a problem... (another starting issue)

DVCNick · 05-19-2019, 07:49 AM

So yesterday I hop in the car (06 M roadster). Turn the key, everything lights up normally at the accessory position. As soon as I hit the starter, I hear a very faint pop and all power is lost. No click, no lights, absolutely nothing.

Any ideas what this could be? I just changed the battery a couple weeks ago, and took it out for a drive after that; it started just fine several times post-battery install.

DVCNick · 05-19-2019, 08:28 AM

Another piece of data... reading 2.4 volts on the voltage terminals under the hood.

This was at 1.7V when I replaced the old battery, and over 12V just after battery replacement. I wonder if I have a severe battery drain somewhere; that wouldn't explain why everything powered up fine and then immediately cut off to zero yesterday though would it?

v3.2mc · 05-19-2019, 09:12 AM

check this thread out from farther down the page. the pop you heard may be the BST failing.

Stranded/no start. Any brilliant ideas? https://www.zpost.com/forums/showthread.php?t=1608309

DVCNick · 05-19-2019, 09:19 AM

I will definitely check out that thread, thanks...

First, I have another interesting bit of info... reading the battery directly on the terminals, is 12.5V.

The ports up front under the hood, still 3V.

It appears the battery is not dead and something else is going on. There is no indication the car has any power at all: no interior lights, no windows indexing, nothing.

The HACK · 05-19-2019, 10:22 AM

The faint pop is the explosives going off in the battery terminal. v3.2mc has pointed you in the right direction. Once that terminal pops the entire vehicle will be without power as it is not connected to the battery.

DVCNick · 05-19-2019, 10:28 AM

Another update... I just giggled the negative terminal cable and power came back on, or at least interior lights did. I don't have time to mess with it now but will try to start it this afternoon.

I thought the cable wasn't super tight but didn't think it was loose enough to cause any problems. Will update later today.

DVCNick · 05-19-2019, 07:00 PM

So.. car started up fine after regaining power after moving the negative battery cable. So the connection must just be marginal.

I have a shim for the negative post on order and hopefully that will take care of it.

05-19-2019, 07:49 AM	#1
DVCNick New Member 8 Rep 27 Posts Drives: 2006 M Roadster Join Date: Dec 2017 Location: Greenville, SC iTrader: (0)	Houston, we have a problem... (another starting issue) So yesterday I hop in the car (06 M roadster). Turn the key, everything lights up normally at the accessory position. As soon as I hit the starter, I hear a very faint pop and all power is lost. No click, no lights, absolutely nothing. Any ideas what this could be? I just changed the battery a couple weeks ago, and took it out for a drive after that; it started just fine several times post-battery install.
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05-19-2019, 08:28 AM	#2
DVCNick New Member 8 Rep 27 Posts Drives: 2006 M Roadster Join Date: Dec 2017 Location: Greenville, SC iTrader: (0)	Another piece of data... reading 2.4 volts on the voltage terminals under the hood. This was at 1.7V when I replaced the old battery, and over 12V just after battery replacement. I wonder if I have a severe battery drain somewhere; that wouldn't explain why everything powered up fine and then immediately cut off to zero yesterday though would it?
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05-19-2019, 09:12 AM	#3
v3.2mc Not a New Member 94 Rep 925 Posts Drives: with both hands and both feet Join Date: Mar 2012 Location: midwest iTrader: (4) Garage List 2007 ///M Coupé [10.00]	check this thread out from farther down the page. the pop you heard may be the BST failing. Stranded/no start. Any brilliant ideas? https://www.zpost.com/forums/showthread.php?t=1608309 __________________ #1498E86 \| Sepang Bronze \| Dark Sepang Leather \| Carbon Leather Trim
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05-19-2019, 09:19 AM	#4
DVCNick New Member 8 Rep 27 Posts Drives: 2006 M Roadster Join Date: Dec 2017 Location: Greenville, SC iTrader: (0)	I will definitely check out that thread, thanks... First, I have another interesting bit of info... reading the battery directly on the terminals, is 12.5V. The ports up front under the hood, still 3V. It appears the battery is not dead and something else is going on. There is no indication the car has any power at all: no interior lights, no windows indexing, nothing.
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05-19-2019, 10:22 AM	#5
The HACK Midlife Crises Racing Silent but Deadly Class 1821 Rep 5,337 Posts Drives: 2006 MZ4C, 2021 Tesla Model 3 Join Date: Oct 2007 Location: Welcome to Jamaica have a nice day iTrader: (1)	The faint pop is the explosives going off in the battery terminal. v3.2mc has pointed you in the right direction. Once that terminal pops the entire vehicle will be without power as it is not connected to the battery. __________________ Sitting on a beat-up office chair in front of a 5 year old computer in a basement floor, sipping on stale coffee watching a bunch of meaningless numbers scrolling aimlessly on a dimly lit 19” monitor.
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05-19-2019, 10:28 AM	#6
DVCNick New Member 8 Rep 27 Posts Drives: 2006 M Roadster Join Date: Dec 2017 Location: Greenville, SC iTrader: (0)	Another update... I just giggled the negative terminal cable and power came back on, or at least interior lights did. I don't have time to mess with it now but will try to start it this afternoon. I thought the cable wasn't super tight but didn't think it was loose enough to cause any problems. Will update later today.
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05-19-2019, 07:00 PM	#7
DVCNick New Member 8 Rep 27 Posts Drives: 2006 M Roadster Join Date: Dec 2017 Location: Greenville, SC iTrader: (0)	So.. car started up fine after regaining power after moving the negative battery cable. So the connection must just be marginal. I have a shim for the negative post on order and hopefully that will take care of it.
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