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Common voltage drop during cranking

Old Jun 11, 2019 | 07:31 PM
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wherestheboost's Avatar
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Default Common voltage drop during cranking

From an old topic started earlier in the year, I was having cranking issues. tl;dr, I killed the battery from the repeated failed tests earlier in my megasquirt experiences. Battery is replaced, and car hasn't needed a jump start since then. Regardless, it does feel like my car takes "longer" to start. It "feels" like it might not start at some point. Regardless, I've seen other datalogs posted here, and the voltage drop I get doesn't seem to be all that common (see attached).

Battery typically is sitting at ~12.5V, and when I crank, it drops down to 9.2-9.5V. Is this normal? If not, where should I start looking? Battery and starter terminals look good.
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Old Jun 12, 2019 | 06:44 AM
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Those voltages, if measured at / by the ECU, sound normal. I have never measured at the battery terminals.
Old Jun 12, 2019 | 11:03 AM
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Originally Posted by wherestheboost
From an old topic started earlier in the year, I was having cranking issues. tl;dr, I killed the battery from the repeated failed tests earlier in my megasquirt experiences. Battery is replaced, and car hasn't needed a jump start since then. Regardless, it does feel like my car takes "longer" to start. It "feels" like it might not start at some point. Regardless, I've seen other datalogs posted here, and the voltage drop I get doesn't seem to be all that common (see attached).

Battery typically is sitting at ~12.5V, and when I crank, it drops down to 9.2-9.5V. Is this normal? If not, where should I start looking? Battery and starter terminals look good.
According my my brothers datalog, those are exactly what we are seeing at the ECU with a new'ish battery. I'd say those are normal.
Old Jun 13, 2019 | 05:44 PM
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Well..then - alrighty. Thanks!
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