Subaru Ascent Forum banner
1 - 7 of 7 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
Twice now my 2020 Ascent (1500 miles) has suffered a dead battery at the end of a weekend camping trip. This happened after having doors and lift gate open to load the car - but not for hours, more like 45-60 minutes, on and off.
Also, on the second occasion I started the car successfully 10 minutes before it failed.
The rear cargo light was also switched off on the second occasion.

One theory I have is that charging a device via the front dash USB ports -- while the car is turned off -- results in a dead battery and a non-start. On the second occasion, with the car turned off, I plugged a walkie talkie into the USB charge port for 3 minutes prior to the dead battery. And I believe had did the same with a GPS device on the first occasion that the battery died (4 weeks prior). Despite the car being turned off, the walkie talkie was actually charging on the second occasion. I can't remember if the GPS was charging on the first occasion.

Has anyone else linked USB charging to dead batteries after 2-3 days of the car not moving? Can a USB charge drain the battery voltage that quickly? Or is the OEM battery just weak sauce?
About to head on 1,600 mile road trip - and I'd like to know if I can rely on the battery as long as I don't charge USB devices while the car is off.
P.S. I was able to self-jump the Ascent on the second occasion using this portable jump starter (BEATIT G18 QDSP 2000Amp Peak 12V Portable Car Jump Starter): https://www.amazon.com/gp/product/B07FTG9PBK/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
 

·
Super Moderator
2019 Ascent Touring (CWP)
Joined
·
4,251 Posts
You may want to read the various threads here about battery drain...

Personally, I would not leave anything charging unless my vehicle is actually running, anyway.
 

·
Registered
Joined
·
2 Posts
Discussion Starter · #3 ·
You may want to read the various threads here about battery drain...

Personally, I would not leave anything charging unless my vehicle is actually running, anyway.
Thanks. I did read the threads. I also experienced the rear gate beeping noise on the first occasion, along with the steering wheel lock - as some of those threads mentioned. During that dead battery occasion the rear gate would not open (now I store jumper cables and battery booster under the driver's seat). But I didn't see any mention of USB charging as a contributing factor - so I wanted to raise that potential factor.
 

·
Registered
Joined
·
1,182 Posts
I know of no link between USB charging and battery issues. The Watt-hr capacity of phones and small tablets is a very small fraction of the Ascent battery has, so fully charging them from dead would only put a small dent in the battery. That's not to say it's not possible for some related electrical gremlin to cause a problem...but I'm not aware of any.
 
1 - 7 of 7 Posts
Top