If your electric car isn't holding a charge like it used to, the cause is usually one of four things: normal battery degradation over time, cold weather temporarily reducing range, a parasitic drain from onboard systems, or a failing 12V battery that's separate from the main pack. Figuring out which one applies determines whether this is a minor annoyance or something that needs attention soon.
Main Battery Degradation
All EV batteries lose some capacity over time and mileage — this is expected and gradual, not sudden. If your range has been slowly declining over months or years, that's likely normal degradation. If it dropped noticeably overnight or over a week, that points to something else.
Cold Weather Effects
EV batteries are less efficient in cold temperatures, and heating the cabin draws additional power. It's common to see a real, temporary range drop in winter that has nothing to do with the battery's health — it recovers once temperatures warm up.
Parasitic Drain
Some EVs draw a small amount of power even when parked and "off," to keep systems like security, connectivity, or climate preconditioning ready. Software issues can occasionally cause this drain to be larger than it should be, draining the battery noticeably even when the car sits unused for a day or two.
The 12V Battery — A Common, Overlooked Culprit
It's easy to assume "not holding a charge" means the main battery pack, but the 12V battery is a completely separate system that powers the computers, locks, and contactors that let the car wake up and communicate with the main pack at all. If the 12V battery is weak:
- The car may seem "dead" even though the main battery shows a reasonable charge level
- It may fail to wake up after sitting overnight
- Charging sessions may fail to start properly even when plugged in
This is one of the most common reasons an EV that "won't hold a charge" is actually just fine on its main battery — it's the small 12V battery that's failing. 12V battery assistance starts at $99 and resolves this quickly without needing to diagnose the main pack.
How to Narrow It Down
- Sudden loss, car still wakes up normally — likely main battery or a charging habit issue.
- Car won't wake up or respond at all — check the 12V battery first.
- Loses charge fast while parked and unused — look at parasitic drain or software.
- Range drops mainly in cold weather — likely normal cold-weather behavior, not a fault.
When to Get It Checked
If the range loss is sudden, severe, or paired with warning lights, don't wait for it to get worse. Our EV emergency FAQ covers more on troubleshooting common charging and battery symptoms.
If your EV won't charge, won't wake up, or is losing range fast, call 321.662.1053 or request help and a technician can diagnose it on-site.