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Tesla Roadster Battery Care

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#61
What heychubs says: thanks for the info Tom!

tomsax said:
Our coolant pump died after just over 5 years and 42,000 miles with most of our charging done at 238V/32A.
Click to expand...

I can acknowledge that out pump still lasts after approx. 40K miles, with all charging being done at 230V/10-32A (usually 13, fair amount 16 and some occasional 32A when i need fast recharge).

As for 'overhead', I noticed some overhead too depending on the Amperage. When charging at 230/13A I gain some 14 KM per hour. At 32A this is close to 40KM/hour which is slightly better.
 
#63
heychubs said:
Thanks for the info Tom. Both blogs were interesting reads. I never even thought about the excess cooling the ESS needed when slow charging... I guess I'll use the higher amperage charging option as much as possible.
Click to expand...

Higher voltage/amperage charging is def better - not just based on all the excellent efficiency info from Tom, but also for temperature management of the pack (apologies for any redundant info below...).

When using 120V 15amp or lower, the system will allow pack temp to float higher, up to 40 degC, until it gets near completion of charging. At that point the compressor and front fans kick on, bringing the pack temp down to eventually settle a full charge at 25 degC. In contrast, the compressor and fans stay involved and hold the temp lower the whole way when the extra volts/amps are there.

This is pretty invisible in the winter, but a hassle in summer (esp in a garage). Having lived with trickle charging for 3 yrs, it works but I wouldn't recommend it over using more juice.

- - - Updated - - -

Thus far pump still intact (knock wood).:frown:
 
#65
So, here is my general charging routine, as a relative newbie. I drive to/from work each day, a 70 kms (44 mile) round trip. I charge using a normal 13A plug, dialed down to 10A, overnight at home. Charging from around 10 PM to 7 PM puts back in the 70 kms I used the day before.

So, I charge overnight to around 70%, drive 35 kms to the office, at which time the battery is around 55%. The car is then parked in secure underground parking from around 8 AM to 8 PM standing at 55%. By the I time get home, the battery level is around 40%. I plug in after dinner, and the car charges back from 40% to around 70%, ready for the next day's trip.

I don't use the car at the weekends, so on Friday night through Sunday night, I leave the car at 40% (she seems to lose next to no charge sitting for 2 days), then charge Sunday night for Monday morning, per the above.

So, the car is never charged above 70% or below 40%, and mainly sits at 55%.

It seems ok, but is there something I should perhaps do differently, assuming I have no other charging options?

I had a couple of thoughts:

1. Should I instead charge up to 80%, let the car sit at work at around 65%, never going below 50%? Just a little concerned that I have seen a couple of people suggest on this site that you shouldn't push it when the battery charge is below 50%. I may perhaps do that on the run home :biggrin:. Sometimes. But is letting the car sit for 12 hours at 65% worse than letting her sit at 55%?

2. I tend to unplug the car in the morning, when she is at 70%, and drive straight off. Should I unplug an hour earlier to allow for balancing? Or does that only happen if you fully charge the car?

3. Is it good for the battery for it to be balanced from time to time? If so, how is it best to do this - fully charge the car from time to time? I could do that at the weekend, quite easily, if it is better for the car. Does the car need to be fully charged for balancing to take place, or will this automatically happen from time to time?

As you can see from these questions, I still have much to learn. So, apologies in advance for my uninformed questions. I stand ready to be enlightened.

Thanks, in advance.
Volta
 
#66
@Volta, can you run a 240V circuit to your charging location? As mentioned above, charging at 120V is less efficient and lets the battery reach higher temperatures, which isn't ideal for longevity of the cells. (Edit: sorry I didn't realize you're in Hong Kong and already at 220V - you're fine)

Your charge range is fine. Punching the accelerator at extreme low SOC stresses the battery by drawing more current than at high SOC, but I wouldn't worry about the 40-50% range. The car will limit power when the SOC gets close to zero to protect the battery.

Balancing only happens at a Standard charge or higher. I'd run a balancing cycle about once a month or so. Being unbalanced isn't necessarily a bad thing, but you won't be able to access the full potential capacity of the pack when you need it. Also the longer it drifts out of balance the longer it'll take to bring back into balance.
 
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#68
Volta said:
...
1. Should I instead charge up to 80%, let the car sit at work at around 65%, never going below 50%? Just a little concerned that I have seen a couple of people suggest on this site that you shouldn't push it when the battery charge is below 50%. I may perhaps do that on the run home :biggrin:. Sometimes. But is letting the car sit for 12 hours at 65% worse than letting her sit at 55%?
Click to expand...

I would do this (charge to 80%) for two reasons that are beneficial to your battery. Many people like to talk about how it's better to keep your battery around 50% or so for longevity but they fail to realize that an EV stays cooler when running at a higher state of charge. Keeping your battery cooler is more important than resting SOC unless you leave it resting for several days. The other reason is that it's important to keep your battery balanced, which it won't do very well at 70% SOC. You should charge to 80% (full std mode) and let it sit for an hour before leaving for work. It won't balance if you're charging and just unplug and go.

Letting it go unbalanced for a few days is no big deal. But if you are driving/charging with some cells lower than the others, those cells could potentially wear out at a different pace than the rest of the pack. There's a reason Tesla recommends a full std mode charge every day unless you don't plan to drive it for a week or so.
 
#69
hcsharp said:
I would do this (charge to 80%) for two reasons that are beneficial to your battery. Many people like to talk about how it's better to keep your battery around 50% or so for longevity but they fail to realize that an EV stays cooler when running at a higher state of charge. Keeping your battery cooler is more important than resting SOC unless you leave it resting for several days. The other reason is that it's important to keep your battery balanced, which it won't do very well at 70% SOC. You should charge to 80% (full std mode) and let it sit for an hour before leaving for work. It won't balance if you're charging and just unplug and go.

Letting it go unbalanced for a few days is no big deal. But if you are driving/charging with some cells lower than the others, those cells could potentially wear out at a different pace than the rest of the pack. There's a reason Tesla recommends a full std mode charge every day unless you don't plan to drive it for a week or so.
Click to expand...

djp said:
@Volta, can you run a 240V circuit to your charging location? As mentioned above, charging at 120V is less efficient and lets the battery reach higher temperatures, which isn't ideal for longevity of the cells. (Edit: sorry I didn't realize you're in Hong Kong and already at 220V - you're fine)

Your charge range is fine. Punching the accelerator at extreme low SOC stresses the battery by drawing more current than at high SOC, but I wouldn't worry about the 40-50% range. The car will limit power when the SOC gets close to zero to protect the battery.

Balancing only happens at a Standard charge or higher. I'd run a balancing cycle about once a month or so. Being unbalanced isn't necessarily a bad thing, but you won't be able to access the full potential capacity of the pack when you need it. Also the longer it drifts out of balance the longer it'll take to bring back into balance.
Click to expand...

djp/hcsharp: thank you both for your guidance. Very helpful. I can certainly charge my Roadster up to 100% standard (80% full), and then run to down to 85%, where it will stand for 12 hours whilst I work, and run it down to 70% by the time I get home. Charge up to 100% overnight, unplug around 6:20 AM and set off for work again at 7:20 AM. Glad I asked!

Ta.
Volta.
 
#70
So, quick question. To get the benefit of balancing, do I need to hit the 'top off' button and fill her to the very brim (well, the standard mode brim) before unplugging and letting her rest for an hour before driving off? I didn't do so this morning, when the charge indictor showed that charging had stopped overnight (because then I wouldn't have had the hour between unplugging and driving), but if I need to I can do at the weekend, and will generally do that each weekend.

Or, put another way: "to top off or not top off, that is the question ..."

Appreciate any further guidance you can give, hcsharp (or indeed anyone), on this.

Best.
Volta.


Volta said:
djp/hcsharp: thank you both for your guidance. Very helpful. I can certainly charge my Roadster up to 100% standard (80% full), and then run to down to 85%, where it will stand for 12 hours whilst I work, and run it down to 70% by the time I get home. Charge up to 100% overnight, unplug around 6:20 AM and set off for work again at 7:20 AM. Glad I asked!

Ta.
Volta.
Click to expand...
 
#71
Volta said:
So, quick question. To get the benefit of balancing, do I need to hit the 'top off' button and fill her to the very brim (well, the standard mode brim) before unplugging and letting her rest for an hour before driving off?
Click to expand...

No need to top off, the balancing program starts as soon as the Standard charge completes. Just set it for a Standard charge, leave it plugged in, and let it rest for a few hours after the charge completes. If you want to run multiple balancing cycles over the weekend you can restart the charge (or top off) to kick off another cycle.
 
#72
Thanks so much, djp. Most helpful. So, am I right to understand, from what you say, that I don't need to physically unplug? Once the charge cycle stops because the pack is full, the pack will automatically start to rebalance even if left plugged in, and that might take a few hours?

Volta.

djp said:
No need to top off, the balancing program starts as soon as the Standard charge completes. Just set it for a Standard charge, leave it plugged in, and let it rest for a few hours after the charge completes. If you want to run multiple balancing cycles over the weekend you can restart the charge (or top off) to kick off another cycle.
Click to expand...
 
#73
Volta said:
Thanks so much, djp. Most helpful. So, am I right to understand, from what you say, that I don't need to physically unplug? Once the charge cycle stops because the pack is full, the pack will automatically start to rebalance even if left plugged in, and that might take a few hours?

Volta.
Click to expand...

Correct, the balancing happens as soon as the charge cycle finishes - no need to unplug or hit "top off". If the pack is balanced the rebalancing could finish in as little as 15 minutes. If it's out of balance, it could take several rebalance cycles of a few hours each to bring it back into balance. I'd let it sit over the weekend in Standard mode, and restart the charge a few times over the weekend to kick off new cycles.
 
#74
Again, thanks so much djp. How will I know when the pack is balanced? Do I need to check the log, or is there a visible/audible sign which will make me go 'a-hah: the pack is now balanced!'

Volta.

djp said:
Correct, the balancing happens as soon as the charge cycle finishes - no need to unplug or hit "top off". If the pack is balanced the rebalancing could finish in as little as 15 minutes. If it's out of balance, it could take several rebalance cycles of a few hours each to bring it back into balance. I'd let it sit over the weekend in Standard mode, and restart the charge a few times over the weekend to kick off new cycles.
Click to expand...
 
#77
Unfortunately there's no easy way without going into the service diagnostics menus.
Click to expand...

ecarfan said:
IMO, you really don't need to concern yourself with that question. The car will take of itself. Just leave it plugged in, if possible, when you aren't driving it.
Click to expand...

Thanks both, and understood. I shall do as you suggest - and shan't worry; but instead simply enjoy what must be THE most fantastic car in the world to drive ...

Thanks again.
Volta.
 
#78
> You can buy the pump online for $100 (Bosch PCA 12V Part number 0 392 022 002), but I wouldn't let anyone but a Roadster service tech do the swap because you have to bleed the air bubbles out of the coolant lines. It's not difficult to do, [tomsax]

You could series in an elevated hose loop maybe with a reservoir* at the top. Then do an overnight 120v charge. By next day all the air should be in the reservoir.

*reservoir from manual vacuum kit, used for brake bleeding etc - among several choices (no home should be without one):

Amazon.com: Brake Bleeder and Vacuum Pump Kit: Everything Else
--
 
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#80
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