I am fairly certain my wife's BMW X1 needs a new battery, but cannot get into NTB for another couple of days. If I give the battery a bit of a boost with my external charger for the next two nights, will that help prevent her from getting stuck during routine errands? Just to "top off" the voltage? Or is that pretty much a waste of time?

The resting voltage is showing up as 12.3v. The car is never in the shade and we live in record-hot Texas. It's a 2018, so it's about time for a new battery. The primary symptom is a sporadically sluggish start.

  • Welcome to Motor Vehicle Maintenance & Repair! Commented Sep 12, 2022 at 10:39
  • 1
    If you're worried about her getting stuck, you might hedge your bets by buying a jump battery. They're the size of a book, you just clip them to the battery and try to start (much like a jumper cable, but without needing another car to help). I started my car three times in a row and it started straight away and the jump battery didn't lose much of its charge. You can find them with your preferred search engine or Amazon with string "car batteries jump starter".
    – gowenfawr
    Commented Sep 12, 2022 at 19:17
  • Its a known issue of hot states cooking car batteries to a premature death. You can search forums to verify this from others living in Texas, Arizona, New Mexico, etc. The suggestion for a portable jump box fitting into a glove box may serve you needs but it would be wiser to simply replace the battery rather than risk random stranding. The battery is probably not holding a charge and will strain the alternator.
    – F Dryer
    Commented Sep 12, 2022 at 21:43

1 Answer 1


If the battery is going bad, more than likely an external charger isn't going to do too much good. The reason I say this is because the vehicle itself will do this job while the engine is running. If the battery isn't keeping the charge or doesn't have the reserve capacity, charging it isn't going to help much.

The 12.3vdc at rest isn't a bad voltage, but in most cases, resting voltage is not the entire picture. Most failing batteries, when under load, drop their voltage during use. This is why it's "sluggish" when you're trying to use it.

All I can say is, using the charger on it is not going to hurt anything. It'll help the battery when trying to start first thing. Other then that, it's pretty much a crap shoot.

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