Long term charging of 2014 Plug in Prius

Will you have access to the car during that time? That affects my answer.

Don't use that 12V charger continuously, unless it is rated for continuous charge maintenance. Some other devices are meant for that use. But if you have access to the car, just plug in the chargers you already have once every month or so, just for a single day at a time.

 

You don't want either battery to run down. The hybrid battery will maintain itself if you leave it plugged in to the charger. The auxiliary battery can be maintained with a battery-maintainer (or battery-tender). I wouldn't recommend a regular battery-charger, because even if you remember to test the battery, and top it up occasionally, it's likely to be harder on the battery than using a maintainer.

I have found over the last 40 years that batteries can be quite unpredictable with regard to draining themselves. They seem to have become even more fickle in recent years.

 

read your manual. when leaving the car for an extended period of time: run the hybrid battery down to the hv portion (no ev miles left). as for the 12 volt, i would connect a smart charger to it.

 

I would have agreed with that before I read this sad posting by Shirjeel Agha. Apparently the hybrid battery can become depleted to an unrecoverable level if left too long, and then requires a costly replacement. Unfortunately, there's no reliable information for how long a Prius can be left unattended before such a mishap occurs, therefore I'd leave it plugged in during my absence.

 

i can't really comment on advice given against toyota's. you could be right, i don't even leave mine plugged in overnight. i wonder how long it would take for the system to sense a reduction and fire up again on it's own.

 

It would be good to know such things. I know the dealer where I purchased mine had left it plugged in for months at a time. I'm sure some long-time Prius owners have done so also.

As it stands, I'd like to err on the side of caution by leaving it plugged in, until I hear some some greater wisdom on the subject.

 

oh yes, there are many varying opinions here.

 

For what it's worth, my PiP sat for nearly 9 days recently. Because of poor communication between me and my wife, it was fully charged on the front end. Registered 82.9% SOC on the scangauge when fired back up.

 

I would highly advise against leaving the car plugged in. Even though it isn't at 100%, the battery isn't very happy that full. For long periods of time I would suggest maybe a mile or two left on the EV range. I realize the manual states slightly otherwise.

 

Given the discharge rate I observed, I would second your sentiment. 40 or so % SOC seems reasonable to me.

 

Ya, I believe that is what most Li-ion batteries are shipped at.

 

Are they charged to that level intentionally, or is it a function of manufacture? That's how it is with lead-acid batteries.

 

'Yes' to the former, but can't discount the later. So it could be yes to both.

These batteries have their best shelf life when charged to some mid level, neither fully charged nor discharged. It would make manufacturing sense to formulate the components to automatically be at that level when assembled.

 

LiIon batteries don't self-discharge, do they? Since the battery is disconnected from the system by a relay when the car is not READY, isn't self-discharge the only possible mechanism for it to lose charge? It's not like the 12V battery, which has all sorts of parasitic loads dribbling the charge out of it. I am not sure how much weight we should put on the situation described in Hybrid System or Traction Battery Failure - Japanese Import | PriusChat . We really don't know the history of that car, and how the traction battery may have come to be so discharged. For example, was it ever driven with an empty gasoline tank?

 

this is why i follow the manufacturer's advice.

 

Everything I've ever owned which had a lithium-ion battery, has always gone dead in a few months.

 

All batteries available on the consumer market suffer self discharge, and most rechargeable types do so significantly faster than non-rechargeable types.

 

has anyone actually watched their hv battery without using it?

 

isn't 83% a full charge?