Does it need to be plugged in 24/7? New owner, sharing charger with Model S.

We have both with a separate plug for each.

However, we used to leave the Roadster plugged in and charged and would often plug it in after short trips.

Apparently, this is not recommended for it. The Roadster does not have as big a Vampire Drain problem as our Model S and it is actually better for the range algorithm to drain it down before plugging it in. So we try to leave the car unplugged until we're at least below 80 miles of Ideal Range left, while trying to be below 60 or 40 before we actually plug it in.

If leaving the car for a while, you can plug it in and put it in Storage mode, that was also recommended.

I first reported the seemingly large number of miles lost from the time we picked up our CPO in September 2013 to July 2014...

So, I posted the following thread - Trying to see if our CPO Roadster ideal mile range loss/CAC value decrease is real...

So I did a series of posts on my blog

Rebalancing the Telsa Roadster battery pack | My ActiveE made me Accidentally Environmental

Did some tests

First Daily s Range charge test | My ActiveE made me Accidentally Environmental

Update on Tesla Roadster CAC and Ideal Miles testing | My ActiveE made me Accidentally Environmental

First Tesla Roadster range test in standard mode, July 9-July 12, 2014. | My ActiveE made me Accidentally Environmental

At the end of it, we reversed the CAC values dropping and "rehabilitated the car" to be consistently around 175-178 miles Standard mode (Range mode was as high as 235 on its annual at the service center over 110V... But often at 224 at 240v/40A)

And that's on a 7 year old 2008 1.5.

Still, worried about battery degradation and Tesla's lack of warranty on that. Hopefully they'll fix the no upgrade to 3.0 for 1.5 vehicle controversy.

 

There's no harm in leaving it unplugged as long as you're watching the vampire drain. The big problem can come if you get a heatwave and the car starts actively cooling the pack. That can drain it fairly quickly. There is a story on here of a guy in SoCal parking his Roadster in an enclosed shed (with no power) while his house was being remodeled. Shed baked in the summer, car ran the A/C to keep the battery cool and eventually bricked the car. So just check on it every few days. When it gets down to 50 or so miles (I've never let my car sit very long but my guess is it will take many weeks assuming it's not hot) then charge it.

If you want to get fancy the community here have built telemetry systems that plug into the diagnostic port so you can view status remotely. I have the original one, the Tattler (but I'm not sure if they're still selling them). The other option is the OVMS.

 

132 miles ideal range is if you drive it like a Prius (or modest driving). Your 102 Est range is based on how you have driven in the recent past (the more fun you have , the lower it goes)

 

it should be plugged in as much as possible. this will minimize the depth of charges and extend long term battery life. lots of small charges is much better than less frequent full depth of discharge cycles.

 

That's what I initially thought. My wife had a 60 mile commute and we would plug it in each day.

That's when the CAC had all the issues that I showed for the first 10 months of our ownership (second owner) that I reported on in my original response post.

Longer discharges and recharges seemed to work better on our 2008 Roadster #40

 

Yeap!

To avoid adding a new charger in your garage, if the one you have is good enough when you're actively using both cars, you can use 110V for storage mode.
In storage, there's no pack balancing (because always below 80% SOC) so no need for 220V.
It also will never charge for long period of times since it trickle charges the battery regularly once you reach a certain SOC range, so there will be no heat build up to evacuate (which would also requires 220V for AC to kick in when the pack is too hot).

 

I have to agree with this although there are different opinions and experiences. If you get home and your battery is warm, plugging in and charging will immediately cool it down. It also won't heat up as much the next time you drive it due to being at a higher state of charge. Heat is your worst enemy.

Actually that is recommended for it (by Tesla). What worked for AEdennis has not worked for everybody. There are many factors that can affect the CAC calculation. One of them is seasonal variances. Most people experience a decrease in CAC throughout the colder months of the year and then it begins to increase again some time after it warms up significantly.

 

Weird... It was our Tesla Tech that recommended that we do this behavior.

 

I have been visited by three Rangers over the years and all three recommended we keep the car plugged in as does the owners manual on page 34. So I agree with Henry.

Designed to be plugged in
The Tesla Roadster is designed to be plugged in when not in use. This ensures that the next time you use the vehicle, it is fully charged and ready to go. There is no advantage to waiting until battery level is low before charging. Plugging in every night eliminates the risk of damage that could be caused by over-discharging the battery. When plugged in, the vehicle optimizes the lifetime of the Battery by managing its charge level and temperature. The vehicle wakes up every 24 hours and, if needed, automatically initiates the charging process to keep the Battery at an optimum charge level.

That said I doubt there is any real issue charging every other day, but it is designed to be kept plugged in.

 

I agree... That was my behavior on the Roadster for the 10 months before we started to see the lower CAC... I do leave it plugged in once it is charged, but don't start a charge until it's been drained down to at least 60... If we can.

With our vehicle the CAC recovered after we did this (wait until it's lower than the daily 60 mile commutes that we were doing before)

 

This was discussed in another thread, and (others, please correct me!) I believe the conclusion was that CAC is, after all, a calculated capacity, and that the algorithm can only make a best guess at what the actual capacity of the battery is. Depending on a lot of factors, including your charging habits, that calculation can result in a different number for the same battery state. So, says the thread, since the actual capacity of a battery never really increases once it wears, all you did by changing your charging ritual was game the CAC algorithm to give you a better number.

What was explained was that the two biggest killers for battery life are high depth of discharge and extremes of temperature. So, keep the battery reasonably charged, and when you've driven it, get the heat out of the battery as soon as you can. Charging it (standard mode, 240v) whenever you get home is the simplest rule to accomplish this. You can probably do a bit better with more active management of things (like deciding when to plug it in), but then you're bypassing a lot of the engineering Tesla built into the charging algorithms in the car.

So, back to the original question... I believe if you need to share the plug, make sure the Roadster's been allowed to manage its affairs first. Then you can buddy-breathe electrons with the other car. I wouldn't let the SOC get down too far in between charges. As was stated here earlier, higher charge state makes the battery more efficient, and therefore cooler running. Charging at 240v allows the car to use the A/C to actively cool the battery, if necessary, to regulate temperature.

 

As a counter example, the only time I plug in my Roadster is about once a week to charge and my battery seems to holding up better than most. I've seen zero range loss over the past five years.

I think the Tesla recommendation to keep it always plugged in is to prevent the battery from been bricked by draining to zero, especially if the circulating pump is continuously running when the temperature is over 30C. If you can manage the pack temperature and SOC on your own, then there's no need to always keep it plugged in.

My car is a daily driver, but with a short commute. My routine is:

• When the SOC reaches 40%, charge to 60% (generally once a week)
• If I'm planning to use the car on a weekend, charge in Standard mode on Friday night (generally once every two weeks)
• Run a cool down cycle if the pack temperature is over 30C after a long drive

Besides that the car is always unplugged, and the pack is doing fine.

 

One key reason to remain plugged in for an S is due to the 12v battery cycling. When plugged in the 12V takes no power from the main battery pack, but takes it from the charging source. I often use 110v overnight at hotels that have no level 2 capability. The car gains 2-5 mph depending on temperature and quality of connection, but even when very cold, say below freezing, it prevents vampire drain. For long term storage 110v is just fine.

 

As mentionned by some of the guys, active cooling when returning from a drive with the roadster requires 220V.
I've never seen the front fans quick-in on 110V to cool down the pack.
Using OVMS, you can force cooldown cycles before charging on 220V as soon as you get home.
There's a couple of threads on just that.

On the other hand, for your time capsule state, if your garage is temperature controlled, 110V will do just fine to prevent the pack from bricking.
This is what I do during winter, the garage is nice and cool around 15C so there's no danger of overheating in there!
The car sits at a storage SOC around 30%... which could be a bit low if you live in an area with risk of electricity shortage, like a rural area!
If so, while still using 110V, you probably want to maintain a somewhat higher state of charge, like 50%.

...and Congrats on your new Roadster and welcome to the original duo family! :wink:

 

But plugged in and set to which mode? Tesla created storage mode for a reason. Keeping the battery at high states of charge for a long time will degrade Li-Ion batteries, hence Storage mode that aims to keep it in the 50% SOC range.

I would be careful about having the car completely sealed under a cover as it needs airflow to run the A/C. I don't think it needs the fans to heat the pack (doesn't get that cold here ) but maybe some Northerners can comment. Tesla's car cover has openings for the fans.