I have the orignial auxillary battery on 2014 Lexus ES300h. The battery suddenly died when I used it for too long to charge a flat tire. The tire is still flat, so I cannot drive my car.

Jumpstarting the car from the trunk- or the front- I am able to start my car. It does charge the battery but the charge does not hold. I can maybe start the car once, and then the battery needs a jump start again.

Question: Right now the battery is getting charged from the Hybrid+Engine= I cannot drive the car due to the flat. Is that the reason it cannot get fully charged? OR it is not getting fully charged due to the car not being driven? Remember, in Ready mode, the auxillary battery is getting charged from Hybrid Battery, the Engine runs as needed.

After leaving the car running for 3 hours, and parked in the driveway, the multimeter reading was: 9.5. OVernight it seems to have drained to 2.6!

Does that mean there is an electrical leak? Or does that mean this is a bad battery?

My JumpStarter seems to have the ability to charge the battery, should I use that to get the voltage to 12V or higher?

I do not want to replace my battery when it just needs to be charged. Maybe fixing the tire, and driving it around will charge the battery, and I can monitor its voltage. That they say is the best way to prolong battery life, as well as trickle charging it to above 12V every month or so.

 

Save a headache and the drama, change the 10-year old battery.

 

It's an old battery. It might have lasted a little longer, but running it down flat has probably effectively killed it. As joedaddy says, best to just replace it and enjoy driving again.. To be honest, you did well to get 10 years out of it.

 

Car is starting normally, voltage is 11.89V.
Everything feels nornal about the car. Not sure what is needed to push the voltage to the healthy zone.

 

That voltage is too low. You have a bad cell.

 

For all intents and purposes 11.89v is considered a dead battery. Around 12.6v is fully charged, 12v is 50%, and 11.7v is 25% charged. Whilst 11.89v might be sufficient to fire up the hybrid system, a battery loses it's ability to accept and retain a charge if it's repeatedly discharged to such a low level. So, whilst you may be able to push it to a healthy level (although it apears otherwise in your case) the battery seems to have reached a condition at which it can't accept or hold that charge.

Not sure why your'e reluctant to replace it after 10 years, as it doesn't owe you anything, and could possibly leave you expensively stranded if you keep hoping to squeeze a little more out of it.

 

What is the voltage with the car running? If it is still low then you have problems with the charging system.

Charge a battery with the car running or (better yet) with external charger. How long does it keep charge (i.e. voltage stays above ~11V) after that?

And finally - what is the current draw with the car off. Normally it should be about 50 mA. If much more than that you may have problems with parasitic draws. There is a TSB for some "gateway" computer on these cars not shutting down normally and quickly draining the battery.

If there are no parasitic drains and the battery still cannot hold the charge - then replace it. My 2014 ESh battery can still stay charged for a month - and I have run it down to total zero about 5 times already by having to much stuff hooked up to it.

 

Car does get charged all the way to 12.4 V which I thought was the maximum.
While charging it shows 14.3 V, both with the battery and with the jump starter/battery charger.
It seemed to have dropped 0.15 V in about 10 hours.

How do I test for parasitic drains?

I feel that the battery will get charged all the way to 13 or whatever is healthy, once I actually drive it when I fix the flat tire.

Thoughts?

 

Battery has either deteriorated sufficiently that it will charge fully but not hold that charge, or it has enough life left in it to hold any charge you put in it. You won't know what works till you fix the flat and drive it.

I probably wouldn't do anything about the battery until I'd fixed the tyre and the car was driveable again. If you do that and want to drive it to see if you can revive the battery, then it's probably worth buying one of those portable jump starters, just in case. Either way they're useful to carry in the car.

 

Car got charged to 12.5 V. sitting in my driveway. Fixing the flat today, and will drive it around and then we will know the condition of the battery.
i drained the battery totally when I accidentally turned on the accessory mode- I honestly thought my car did not have that mode. Car sitting in driveway. let the air pump attempt inflating the tire for an hour- drained the battery.

So what is the expected level of battery charge for a new battery? For an acceptable battery?

 

This battery got discharged fully reecntly when I tried to inflate a tire using the battery forgetting to put the car in the Ready mode.
I have fixed the tire and driving around it charged to 12.5 V . About 30 minutes of driving.

How much does a brand-new battery inflate too?

 

12.6+ for a new battery, but 12.5 is acceptable, 12 and below is considered flat. Your issue would now seem to be not the level you can charge it to, but how long it holds that charge for.

 

I seem to have a current leak somewhere.

 

How have you determined that? Have you measured it, or is the battery simpy going flat? If the latter, it could be that the battery is shot, and able to take a charge, but not able to hold it.