Confusing advice about prolonging Prius' lifespan? #motorbiscuit.com

Yeah, poorly written. Cooler temps=battery longevity. No secret, just science and the chemistries used in the battery. Yes, PriusChat members have always advise using a/c to help protect the battery (it's in the owners manual). Some folks even hack the fan modes to increase them during hotter seasonal periods.

 

Hack which fan modes the battery fan or AC heater fan ?

 

Battery.

 

We are in the heat in North Carolina generally around in the hundreds and near 100% humidity in the summer We run the air conditioner reasonably and quite a bit keeps the interior cool and therefore the air getting sucked to blow on the battery is quite cool probably a good idea I have not fooled with turning my battery fan on full blast or any of that it's still set like factory and I never hear it unless the battery is going bad everything seems to stay green and cool and run well but I don't beat on it in the summer not trying to run up pikes peak or anything like that it's a car that we drive to and from service calls not running the pikes peak race so therefore things stay reasonably well I have not tried to run it up in the mountains in North Carolina at breakneck speeds or save that for the motorcycle or the V8.

 

it may also just be heat build up inside the car if it is parked in the sun, or anywhere in warmer climates

 

i assume he means inverter coolant, not transmission fluid

 

For those of us teetering on 50% remaining capacity it is best to go easy on the A/C as much as possible when at a red light or stopped. I have been driving in B when going stop and go and that not only helps charge the HV battery with engine braking (more so than the ICE engine does) but it also keeps the car running at a stop while in gear. I am not sure if I get much charge out of the ICE anymore though, but maybe it just adds bars much slower than engine braking does.

 

You don't say where you are or what outside air temperatures you are dealing with, but unless the OAT is 34ºC+ (93ºF+), you are probably still better off keeping the cabin (and therefore the HV battery) cool. If you run the A/C at no more than 4ºC (7ºF) lower than OAT you should not be taxing the A/C too much. It can be a tricky balance depending on the climate.

You might want to research that a bit better, but this old chestnut keeps popping up. The short story is B gives you less regeneration braking, not more. A good article by Hobbit explains it here. You are hitting yourself with a double whammy by getting less regeneration in B and running the engine when stopped. If the A/C running modestly causes the engine to run constantly you have bigger HV battery worries.

 

In the context of a 2008 Prius, most of the things you'd do to preserve and extend battery lifetime have already been done or not.

It's never too late, but this is a little like a 75 year old suddenly taking up tofu and cardio.

 

I’m rarely using AC in summer; use it more in winter, by setting vent mode to heat/window, which does run the AC (without lighting the AC indicator on the button). This is tested with Scangauge II, monitoring wattage being used by AC compressor.

This premise, that steady AC use is going to preserve the battery, sounds “plausible”, but I’m sceptical: I’ve also (with SG II) started the car after a heat-soak, driven about 10 min without AC, then turned it on, all the while monitoring battery temp. After a further 10 min or so with AC (set quite cool) battery temp dropped one or two degrees. Inconclusive?

Even in easy driving, cool evening, no AC, battery temp would stabilize around 35C, with fan speed one or two, fwiw.

I think @bisco’s onto something, the mention of parking the car and it’s sitting in slow-death hot condition, say an uninsulated garage in summer.

 

Thank you, I am on the edge of having HV problems, but still A-OK most of the time. I do leave the A/C on most of the time due to the convenient steering wheel button, but I lower the temp so it still blows cold but not full blast, assuming the variable speed compressor and fan are using less HV power. That way neither the car or I break a sweat. Living in CA outside air is rarely above 80F, and I rarely go on the touch screen to disable A/C and keep fan on, so A/C is used quite a bit as a result of the easy AUTO button. I just turn it down.

So as original owners I remember the ICE engine would kick on and off as needed, you could sit anywhere with the A/C on and the ICE engine would cycle to keep the HV battery charged. That doesn't seem to be the case anymore, maybe if I wait long enough the ICE will kick on, but it goes down to a bar or two on the battery meter and then I have no torque for acceleration, only the is ICE moving the car until the battery gets back up a few bars. Just driving alone doesn't seem to add bars very fast, but decelerating in B will add bars quite quickly. So something must be wrong with what ever is supposed to tell the ICE engine to start on it's own, or it doesn't put out enough volts/amps. Most of the time I have 70%-90% full battery capacity when in motion, main problem is when car is in park, it'll hold the charge but I can deplete stored HV battery power by using AC.

I appreciate any input or suggestions, I will read the Hobbit link.

 

have you considered reconditioning?

 

No, The main point is that the battery shouldn't be hot. You can avoid that by (among other steps) moving farther north (not south!) in the summer, or using air conditioning enough to keep the battery happy.

 

What you describe sounds like normal operation- the car will let the battery go down to 1-2 bars then only charge it slightly. It won't charge more because that would "waste gas". (0 miles traveled divided by any gas used equals zero MPG). Happens in bumper to bumper traffic or sitting with the A/C on.

1-2 bars is quite close to the point where the ecu limits motor operation to prevent the battery from going too low.

It might be more noticeable now because an older battery has less capacity, so you have less boost available than before.

Posted via the PriusChat mobile app.

 

Lowering the HVAC thermostat temperature setting increases energy consumed by the compressor.

The behavior you're describing seems perfectly normal, to me. At least it's the way mine always behaved. No surprise that using air conditioning with the engine off and car stationary depletes battery charge faster than without the air conditioning.

 

Do you recommend that I do a basic clean-up recondition and balance? Does that not involve major disassembly, if not I might do that? Since the car runs great now if I am careful with it, I hesitate on pulling the HV battery apart.

Thank you, I should update that you are correct that it does still seem to start and run when it needs to, just not filling up to green unless I drive a bit. I'll do another Dr. Prius test and see if it changed at all.

Thank you, got confused, I meant that I raise the temp to a few clicks under the outside temp so it blows low speed cold air.

 

i was thinking a grid charger like prolong, but i think you have to open the battery to make the connections

 

You don't, the connection is made at the relay in the electronics bay. You still need to remove a good amount of the trim, though, to get the electronics bay.

 

thanks dolj!