Post-Prolong Charger Bad MPG

Hey all,

I recently bought a Gen II (2006) Prius w/ 211k for next to nothing because it had a bad cell and was throwing the P0A80 code. It ran and drove; the battery indicator would show full green bars to no bars at all.

Fast forward to this past week, I pulled the battery and tested cell voltage and resistance. All were good except one. I replaced it w/ a refurbished one (which tested well). It was ~0.1 volts off from the majority of the other cells.
After putting it back in, I hooked up the Prolong charger and checked on the battery every once and awhile.
At 9PM I was at 238 volts and by 1AM I was up to 244 volts.
As per the Prolong documentation (4-12 hours), I let it sit overnight and when I checked it this morning, it was at 240 volts (which I thought was strange).

I drove it about 120 miles today (conservatively driven on relatively flat ground) and only managed to get 35.2 MPG. In my other Gen II w/ similar miles, I never got under 40 MPG.
The battery indicator consistently stayed within the middle blue bars (+/- 3).
The tire air pressure is good & the oil and air filter has been recently changed.
My Prolong kit also came with the auto-discharger. I do not have 3-4 days to complete all cycles now but I will in the coming months.

I know the Prolong owner is on this forum but I am unsure how to tag him.
As far as I know, after the balancing phase, the MPG should not be this low. Any ideas?

TL&DR
2006 Prius. Replaced bad cell and used Prolong charger to charge/balance. Getting 35 MPG.
Why so low? ​

 

Thank you! Excited to be here. As they say- longtime lurker, first-time poster.

• The bars stayed pretty consistent and did not bounce around (all in the blue)
• They stayed just below to just above the middle
• I did disconnect the 12v battery during charging (ground wire)
• I'm unsure if you mean how many miles are on it or how many I drove for the test today (perhaps I'm missing something). It's 211k and 120 miles respectively.

Thanks for your prompt reply

 

Oh, I gotcha!
My reference point was what the previous owner told me and (more anecdotally) my other Prius of approx same year/mileage.
The P.O. has had it since it was new.

I did figure that was the answer (discharge cycles). I'm currently finishing up my undergrad thesis and have little to no time to be out of a vehicle.
Since I've balanced (but have yet to do the discharge cycles), can I safely drive it for another month or so? I think I should be able to get to it during spring break but don't want to risk messing up more cells.

And you most certainly did help!

 

Haha when you put it like that, maintenance sounds like a better option for sure.
I can probably swing getting my partner to drive me around for a couple days.
I'll just go ahead and do the 134/84/17 volts cycle.
Oh, I know that Prolong states that the charger should never be on for more than 48 hours.
If I'm on a charge cycle and happen to leave it 12-14 hours after it's plateaued, can any harm be done?
I can certainly do the cycles but do not have time to constantly babysit.

Thanks

 

Okay, perfect! Thank you so much for your help! I do indeed have the smartie discharger and I went ahead and started the first cycle
I wasn't so much worried about the discharger as I was the charger; I am afraid to leave it too long in the balancing phase (and if that fear is ill-founded, which I hope it is, please let me know)

I'll go ahead and do the first two cycles as per your suggestion and keep you updated

 

I don't think I have LRR tires but I think (if I did it correctly) I've attached a pic of them.
Are there any LRR tires that you would recommend? We do get ice/snow/floods where I'm at in Texas so I'm looking for something that will hold up in those conditions.

Car was idle approximately two months before purchase/when the cell was bad.
The 12v battery is an Optima Yellow-Top that was put in about 5 months ago. (I did forget to charge it while I charged the HV battery but I plan to do so on the next charge cycle).

And in regards to your first post: okay! It's great to hear someone who has had a similar experience.
Unfortunately, I had to charge it back up last night b/c I had a meeting this morning (that I forgot about) and couldn't miss/get a ride.
I'm planning on starting the cycle on Wed. now. Do you think two cycles with two 40-hour charge sessions will be sufficient or should I do the third one as well?
On the last cycle (I'm assuming 3rd) was it necessary to babysit? Hypothetically, if I just let it charge for 40 hours and called it good, would that cause any issues? Since it bleeds off the heat, I don't see why not but I'd love to get your opinion.

Additional question: did you see any change in MPG after your first (and also second) set of cycles?

Hehe yeah, I read his original post when I was lurking. I will most certainly try and avoid that and thanks for the heads up![/MEDIA]

 

Got the previous post edited. Still learning the proper way to insert links apparently.

 

Just checked again. They are "Defender XT"s.

 

Totally. I started doing some digging and came across those as well. My current tires still have quite a bit of tread left so I cant justify spending $480 on new tires for an increase in MPG until these are worn down.
Those will be what I go to after.