Dead battery, but car won't boost - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

NorthFool · 01-03-2020, 12:45 AM

Looks like I popped the trunk with my FOB in my pocket last night, trunk was open and battery was dead.

I tried boosting it this morning with my wife's car, but nothing. Lights don't turn on or anything even with jumper cables connected. Double checked connections and they seemed fine. Checked the 80 &120a fuses attached to battery and they are intact, as is the 80a one in the box.

Any ideas? I do have a voltmeter to test things, but without any charge from the battery, it would probably only be useful when cables are attached

Stomachbuzz · 01-03-2020, 01:10 AM

When completely discharging a lead acid battery, it is possible to create an internal short between the cells. In this case, the battery will never accept a charge and it is ruined for good.

This is why car batteries are only intended to be used momentarily, and always immediately charged back up to full capacity.

86MLR · 01-03-2020, 01:22 AM

Leave it connected for a while with the car running, it might take a while to put enough charge into to run the ECU.

A trickle charger is the next step, at least a good trickle charger with diagnose the condition of the battery and maybe save it.

Good luck, dead batteries suck arse.

01-03-2020, 12:45 AM	#1
NorthFool Junior Member Join Date: Jan 2011 Drives: 17 86 Base \| MK7.5 GSW Location: Calgary, AB Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Dead battery, but car won't boost Looks like I popped the trunk with my FOB in my pocket last night, trunk was open and battery was dead. I tried boosting it this morning with my wife's car, but nothing. Lights don't turn on or anything even with jumper cables connected. Double checked connections and they seemed fine. Checked the 80 &120a fuses attached to battery and they are intact, as is the 80a one in the box. Any ideas? I do have a voltmeter to test things, but without any charge from the battery, it would probably only be useful when cables are attached

01-03-2020, 01:22 AM	#3
86MLR Senior Member Join Date: Aug 2018 Drives: 2002 VX Commodore SS LS1 Auto Location: Sydney Posts: 2,203 Thanks: 500 Thanked 2,185 Times in 1,111 Posts Mentioned: 13 Post(s) Tagged: 0 Thread(s)	Leave it connected for a while with the car running, it might take a while to put enough charge into to run the ECU. A trickle charger is the next step, at least a good trickle charger with diagnose the condition of the battery and maybe save it. Good luck, dead batteries suck arse. __________________ Disclaimer: This post represents the official views of the voices in my head at the time of posting. http://www.ft86club.com/forums/showthread.php?t=133311 I'm only here for the biscuits

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01-03-2020, 01:10 AM	#2
Stomachbuzz Senior Member Join Date: Apr 2019 Drives: 2013 FRS Location: Washington DC Posts: 177 Thanks: 93 Thanked 61 Times in 38 Posts Mentioned: 2 Post(s) Tagged: 0 Thread(s)	When completely discharging a lead acid battery, it is possible to create an internal short between the cells. In this case, the battery will never accept a charge and it is ruined for good. This is why car batteries are only intended to be used momentarily, and always immediately charged back up to full capacity.

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