It depends on what's making the whirring noise. If it's the fans in front then it's cooling the battery down. The rear fans are only cooling the PEM and motor. Regardless, when you shut off your car it will not cool the batteries down as much as it will if you plug it in and start charging, especially at a low charge rate. This has a big impact on battery life.
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Best way to charge for battery health?
- Thread starter Pantera Dude
- Start date
-
- Tags
- Roadster
It depends on what's making the whirring noise. If it's the fans in front then it's cooling the battery down. The rear fans are only cooling the PEM and motor. Regardless, when you shut off your car it will not cool the batteries down as much as it will if you plug it in and start charging, especially at a low charge rate. This has a big impact on battery life.
wiztecy
Active Member
The whirling sound is most likely the normal operation of the coolent being circulated thru the battery pack. Its not kicking on the fans in the front which means the condenser is not being used. That takes energy and like Henry said, to initiate that you need to plug the roadster in. Otherwise the car wants to conserve the battery and won't start the condenser unless its a dire situation.
Last edited:
As far as I know the fans in the front are only for the AC condenser. I have never seen my front fans run when the AC compressor wasn't running.
wiztecy
Active Member
Johnny at Menlo park said the roadster will drop the driver's comfort and tend to its critical needs first meaning no AC for the driver and only for the roadster and this is if the battery is really really hot, in that case the condenser will fire up and fans will run. I think this is an extreme case.
This happens regularly here in PA. All output of the AC compressor is taken to cool the battery pack when it's temperature reaches 40C. When the outside temperature climbs into the upper 90s and the dark colored car is parked in the sun all day the AC will actually come on when the roadster is off and the pack temperature goes over 40C. In those conditions it is normal to have no AC available for cabin cooling for the first 10+ minutes of driving.
The whirring I hear when I shut the car off is the same noise I hear after I open the door or the trunk or unplug the car. In that case, I don't think it's cooling the PEM or motor, which have been sitting idle in my cool garage. I assume it's pre-cooling the battery pack. And I assume that the forward fans only run if the coolant running through the condensers is over a defined temperature, as the condensers will dissipate heat even without the fans running.
Charging the car produces a significant amount of heat, causing the cooling system to run harder. But I cannot imagine that Tesla would have neglected to have the car cool the pack as soon as the car is plugged in if that would make a significant difference in pack life. I have the car set to charge at 1:00 a.m., when I presume it's easier on the grid. I'm not going to futz around every day, starting the charging, then stopping it, and then having it charge at night.
I figure that if it was that important for battery longevity to do a brief charge immediately after driving, they'd have given the car firmware to allow me to program it to do that. It would be a simple matter.
Anyway, Spokane is a mild climate, and I'm gone (with the car plugged in and in Storage mode) for the hottest part of summer.
Next time we have a really hot day (probably next year) I'll look at the temperature gauge after driving. I don't remember ever seeing it particularly high, though.
Charging the car produces a significant amount of heat, causing the cooling system to run harder. But I cannot imagine that Tesla would have neglected to have the car cool the pack as soon as the car is plugged in if that would make a significant difference in pack life. I have the car set to charge at 1:00 a.m., when I presume it's easier on the grid. I'm not going to futz around every day, starting the charging, then stopping it, and then having it charge at night.
I figure that if it was that important for battery longevity to do a brief charge immediately after driving, they'd have given the car firmware to allow me to program it to do that. It would be a simple matter.
Anyway, Spokane is a mild climate, and I'm gone (with the car plugged in and in Storage mode) for the hottest part of summer.
Next time we have a really hot day (probably next year) I'll look at the temperature gauge after driving. I don't remember ever seeing it particularly high, though.
Your battery can be almost 95 deg F and only be on the 2nd blue bar. If you turn off the car it won't do anything to cool itself. But if you plug it in and start charging at a low rate, low enough that the charging itself wont generate heat, the cooling system will cool the battery down another 10 - 15 deg F in about 30 minutes (give or take). You can deny it all you want but that will make a big difference in battery life if you live in a mild or warm climate.
I agree that it's a PITA to get home and manually charge for 40 min at low amps, futzing around to use your words. That may be the best reason to get a Tattler. That's why I built my own HPC with "one button cool down" feature.
I agree that it's a PITA to get home and manually charge for 40 min at low amps, futzing around to use your words. That may be the best reason to get a Tattler. That's why I built my own HPC with "one button cool down" feature.
I totally agree! It was rather disturbing to me to discover that my pack would sit for hours at over 100F after returning to my garage after a normal summer day of parking in the sun and driving 20 miles to home. With no active AC cooling that big pack looses very little heat in a 80+ degree garage. The circulator pump will run but that just keeps the pack temperature even throughout. I feel the cooldown mode is one of the most valuable features of the Tattler and the thing I really miss with OVMS since I am now back to manual charge control for cooldown.
strider
Active Member
That's not exactly true. The car will continue to run the pump and circulate coolant through the pack until it cools down (as I mentioned in my post above I haven't hung out in the garage long enough to figure out where it cuts off). However it won't run the A/C unless the pack is over 40C. So if the pack is at, say, 36C when you come home, the coolant pump will run so it will cool the pack (Assuming your garage is less than 36C) it's just slower than kicking on the A/C. Bottom line is that we (and Tesla) are all learning about how best to take care of these packs. The Tattler's cooldown function does cool the pack more quickly than just running the coolant pump but then who knows what lots of starting and stopping charging does to things like pack balance? Lots of trade-offs...
Yep, and keep in mind that lithium batteries typically follow Arrhenius equation which means that (approximately) every 10C reduction in temperature, you double the calendar life of the battery.
If this means you get home at 7pm in the summer and don't start charging until 1am to take advantage of off-peak rates, this is like adding 6 hours of life to your battery every day - or about 25%. So if doing nothing results in your battery degrades your battery to 80% in 5 years, now you might get 6.25 years before you reach 80% capacity.
Since battery calendar life is also extended by keeping them at low SOC in addition to keeping them cold, ideally you could configure the car to cool the battery pack whenever you plug in in addition to using an end-time timer (say at 6am) so that the car automatically starts charging in time to finish charging by 6am regardless of the starting SOC.
Now Advanced Charge Control and Cooldown is here for OVMS, here are my settings for home (where I do 99% of my charging):
1. Cooldown on plugin. Target 28C for 60mins maximum.
2. Charge at 40A (to limit pack heating and be easy on the grid).
3. Limit charge to 90% standard mode SOC.
My reasoning is:
The car will run that little pump when max brick is above 31C (approximate), and (most importantly) won't even bother monitoring temperature below that. Cooldown will reduce max brick temp by about 1C per 10 mins. I guess Tesla know what they are doing, and figure I'll just help them to get battery temperature down below the level they don't care about it.
The efficiency difference for charging 40A vs 70A is minimal, so I choose the former. Easier on the grid and car, although I don't think it makes much practical difference.
I don't need extreme range, day-to-day, so limit to 90% standard mode SOC, to avoid storing the car overnight and at work (where it is unplugged and hot) at highest SOC. Standard mode is already conservative, so this gives it a little bit more conservatism.
I am concerned about balancing, and whether the above practices impact that negatively. I'm keeping a close eye on it.
1. Cooldown on plugin. Target 28C for 60mins maximum.
2. Charge at 40A (to limit pack heating and be easy on the grid).
3. Limit charge to 90% standard mode SOC.
My reasoning is:
The car will run that little pump when max brick is above 31C (approximate), and (most importantly) won't even bother monitoring temperature below that. Cooldown will reduce max brick temp by about 1C per 10 mins. I guess Tesla know what they are doing, and figure I'll just help them to get battery temperature down below the level they don't care about it.
The efficiency difference for charging 40A vs 70A is minimal, so I choose the former. Easier on the grid and car, although I don't think it makes much practical difference.
I don't need extreme range, day-to-day, so limit to 90% standard mode SOC, to avoid storing the car overnight and at work (where it is unplugged and hot) at highest SOC. Standard mode is already conservative, so this gives it a little bit more conservatism.
I am concerned about balancing, and whether the above practices impact that negatively. I'm keeping a close eye on it.
wiztecy
Active Member
S - W - E - E - T Thanks Mark, Been waiting for this for a long time!!!!
Mark. I don't think this will impact balancing for a conscience user. That's up to the Driver/User to manage balancing and understand those dynamics. If we can get feedback from the balancing grid in Diags that would be great, but I'm sure that's not avail via the CAN bus. Something Tesla should have made public.
The key is to always do std mode charges when you use your roadster and allow at least 30 min (my avg) or 1 hour to balance. More if you do partial charges allot. I make sure not to do little charges and know they'll throw you pack out of balance... and users must understand the Pack WILL NOT balance if you're under 80% SOC.
Last edited:
My concern is the forced charge stop before 100% complete. The car is still plugged in, but the charge has been stopped, so not sure if the car will balance or not. Does it balanced after an interrupted charge, or only when 100% complete?
The diags balancing grid is available on the can bus. I'll be keeping an eye on it.
wiztecy
Active Member
From what I've observed and recall from Tesla, the pack will balance whenever its above 80% and never when its below that threshold. From all the times I've used "manual" cool-down I've never seen my balancing becoming worse. I do a cool-down every time I arrive home from work, pulling the pack down from 35C down to 23-26C. On the weekend I'll do 1-3 cool downs if I've done a few trips and noticed the pack's above 26C. When I initiate a cool-down it its typically between 50-65% SOC. Upon each view of the grid once the Roadster had time to balance after my next full Std. Mode charge (which would be always on a Monday, I'd leave it at 50-60% SOC over the weekend, I've never seen my pack become out of balance. My pack would / will always take 15-30 min tops to fully balance after a full std. charge. Even Tesla commented how balanced my pack was.
Tesla noted that the packs they see that become out of balance are from people who never allow the Roadster to sit 30-60 mins after a full std. charge to allow this balancing and that they just typically drive off. They say you can do many under 80% SOCs but to always give the pack time when its above 80% to balance. They also told me that they've seen packs that always charge off 110v to be out of balance. I don't think that's a 110v issue but rather impatient Roadster owners driving off too soon!
Cool on access to the balancing grid on the Can-Bus. Would be super if we can display that on the OVMS. If not possibly an alert to notify the user that they need to perform a balance on the pack and how they can do that.
Thanks!
shrink
Member
Outstanding! Thanks so much, Mark!
Has the iOS app been updated yet with this feature? Hard to tell now that iOS 7 updates in the background automatically.
wiztecy
Active Member
Similar threads
