Bill Miller Posted December 7, 2017 Share Posted December 7, 2017 I will keep this brief, '97' Bonneville sat for 3 days and battery died. Meter read 5.56 volts, charged battery to 12.9 volts, disconnected pos. battery cable and car instantly died. Left sit overnight and meter now read 12.3 volts. Reconnected pos. battery cable and checked voltage at battery and meter read 14.6 volts with car running. So, my question is, why did the car die when pos. battery cable was removed but the meter tells me the alternator is putting out? I read somewhere that some cars will not run with the battery cable removed, could this be some kind of failsafe in the system and if so could this be the case here? Quote Link to comment Share on other sites More sharing options...
jhm Posted December 8, 2017 Share Posted December 8, 2017 Sorry, don't know about a 1997 Bonneville specifically; but I can suggest that it's never a good idea to disconnect the battery from a running vehicle. The battery and alternator work as a system to provide stable voltage and amperage to the vehicle's electrical system, and removing the battery can easily disrupt the system's stability, resulting in damage to the electrical system (particularly, the vehicle's more delicate electronics). I don't mean to sound preachy, but this forum is designed for the discussion of Datsun/Nissan Z cars, although I'm sure someone would speak up if they had specific knowledge useful to you...everyone here is a very helpful bunch. I'm just suggesting that you might find more expertise and experience for your specific issue on a Pontiac or GM forum? A quick google search yielded these top two results: www.pontiacbonnevilleclub.com/forum, and https://pontiacforum.com/pontiac. Good luck with it. Quote Link to comment Share on other sites More sharing options...
tamo3 Posted December 10, 2017 Share Posted December 10, 2017 I think your battery is old and time to replace. I thought the battery should at least 12.6-7v. Quote Link to comment Share on other sites More sharing options...
beermanpete Posted December 20, 2017 Share Posted December 20, 2017 Your car died when you removed the battery cable because the alternator was not able to "keep up" with the current demand and the voltage fell below a point that will keep the fuel injection and ignition systems operating correctly. This does not necessarily indicate a faulty alternator. If the engine were running at a higher RPM it may have stayed running because the alternator can put out more current when the RPM is higher (to a point). The battery supplies current when the alternator cannot and this keeps the voltage up and the car running. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.