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48/72amp Charger - Longevity, Best Practice, Durability, Failure Rate, etc.

houstonian

ಠ_ಠ
Sep 2, 2013
225
194
Houston. Duh.
Saw various reports of the 1st gen charger - or chargers, if equipped - failing. As the 1st generation chargers (40 or 40x2) were replaced with the 2nd generation chargers (48 or 72) earlier this year (I think?), I am seeking information as to how the 2nd generation chargers have held up.

Prior threads concerning the 1st generation charger speculated reducing the charging rate to be less than 40amps lessened the stress/wear on the charger. As such, is it best practice to generally charge beneath the maximum of the charger - i.e. limiting charge rates on a 48amp charger to 40 amps or 60amps max on a 72 charger?

FWIW I opted for the 72amp charger and am somewhat concerned about this critical component not being covered under the unlimited mile battery/drive-train 8 year warranty. Obviously still covered under the 50k / 4 year factory warranty - and then the extended warranty, if purchased - but if regularly baslting a 72amp charger with 72 amps (or 48 amp charger with 48amps) will degrade it faster, I can throttle back for my regular charging.

Thoughts?
 

AEdennis

Active Member
Jul 23, 2013
2,719
948
Saw various reports of the 1st gen charger - or chargers, if equipped - failing. As the 1st generation chargers (40 or 40x2) were replaced with the 2nd generation chargers (48 or 72) earlier this year (I think?), I am seeking information as to how the 2nd generation chargers have held up.

Prior threads concerning the 1st generation charger speculated reducing the charging rate to be less than 40amps lessened the stress/wear on the charger. As such, is it best practice to generally charge beneath the maximum of the charger - i.e. limiting charge rates on a 48amp charger to 40 amps or 60amps max on a 72 charger?

FWIW I opted for the 72amp charger and am somewhat concerned about this critical component not being covered under the unlimited mile battery/drive-train 8 year warranty. Obviously still covered under the 50k / 4 year factory warranty - and then the extended warranty, if purchased - but if regularly baslting a 72amp charger with 72 amps (or 48 amp charger with 48amps) will degrade it faster, I can throttle back for my regular charging.

Thoughts?

We have dual chargers, but mostly charge at 30A because I park the Model S where I used to park a BMW Active E and its easier to use the Chargepoint CT-500 that I had installed at that side of the garage.
 

GSP

Member
Supporting Member
Dec 28, 2007
2,577
832
Heat kills electronics. I think it makes sense to only use 80-90% of rated current of the charger or UMC when faster charging is not helpful.

When faster charging is helpful, charge at max rate.

GSP
 

tga

Supporting Member
Supporting Member
Apr 8, 2014
4,023
2,988
New Hampshire
Prior threads concerning the 1st generation charger speculated reducing the charging rate to be less than 40amps lessened the stress/wear on the charger. As such, is it best practice to generally charge beneath the maximum of the charger - i.e. limiting charge rates on a 48amp charger to 40 amps or 60amps max on a 72 charger?
*inaccurate statement removed at poster's request.

You could argue that older cars, with dual 40A chargers, are best charged at >40A. At currents <=40A, only the primary charger is used, and the secondary sits idle. At >40A, both chargers are online and sharing the load equally (lots of past discussions/evidence on TMC). So, for example, a 2013 car with dual chargers charging at 48A is running 24A through both, splitting the heat load across both chargers. It also allows you to test the second charger, so you don't find out the hard way when you actually need it.

The higher rate runs the charger for less time. Nearly all electronic components are rated in hours. I plan to use my car at the highest available charging rate at all times.
Lest I ignite a debate over "is it better to leave my PC on 24/7 or turn it off at night", heat and number of on/off cycles come into play as well.
 
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Rocky_H

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Feb 19, 2015
6,765
8,354
Boise, ID
Keep in mind, all new cars come with a 72A rated charger. If you don't have the high current option, it's disabled in software, but it's the same charging hardware.
Before you go telling everyone that, we should probably note that that is not true.

It got very confusing because there was a period of time where they were doing that. The Model X, when it was coming out had flip-flopped on that a little, where they had some that were hardware different and some that were the 72 either locked or unlocked, but by the time they ported over most of the changes to the refreshed Model S, they were doing two different part numbers that were the separate 48 and 72 version with either 2 or 3 sub-units in them, and there is no software unlocking on them. Here is a post that describes the approximate time windows of when the various parts were being installed in what vehicles.
Did anyone upgrade from 48 to 72 Amps?
 
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houstonian

ಠ_ಠ
Sep 2, 2013
225
194
Houston. Duh.
From the thread @Rocky_H notes:
The Model S is now using the same part. The refreshed S can only accept one charger, either the 2x24 or the 3x24. A second charger is no longer supported.
It appears refreshed S's can have a 48amp (24x2) or 72amp (24x3) charger. Very few (no?) refreshed model S's had a 72amp-software-limited-to-48amp charger and no current model S builds (Q3-2016 and onward) have this.

Thus with the current model S's - and the foreseeable future - what you opt for is what you get?

Therefore would best practice for chargring would then be to limit charge to less than the max rated option supported by the charger?
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,765
8,354
Boise, ID
Therefore would best practice for chargring would then be to limit charge to less than the max rated option supported by the charger?
That might be hard to say. The old 40A one seemed to be one main unit, so you could pull it down from the maximum level, and that would make sense. With the new one, it seems to have a few separate sub-modules inside it. I looked and looked, and I can't find the thread now where someone was taking efficiency data on the input and output energy through the onboard chargers. It hit a few separate points (24, 48, and 72A) that were most efficient as it was fully utilizing each of the three modules within the 72A charger. So perhaps if you are a little under one of those points, it might be not "maxxing out" that particular module. But my opinion would be that it is probably not as much of an issue now with this new design. Tesla has probably learned more about making a better unit, and this method of distributed among a few smaller pieces may be a bit easier on the components within it(?).
 

tga

Supporting Member
Supporting Member
Apr 8, 2014
4,023
2,988
New Hampshire
Before you go telling everyone that, we should probably note that that is not true.
Oops. Mea Culpa. This is news to me; I haven't been paying attention to the X forum lately. I'd edit my post to remove that incorrect statement, but the editing window has passed. Maybe if I report it, I can get it edited by a mod.
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,765
8,354
Boise, ID
Oops. Mea Culpa. This is news to me; I haven't been paying attention to the X forum lately. I'd edit my post to remove that incorrect statement, but the editing window has passed. Maybe if I report it, I can get it edited by a mod.
Well, the update/correction immediately follows it, so it's probably not a big deal. I know that has been a really confusing thing where they were doing that for a while, so that information got stuck in a lot of people's heads as "the way it is". It's kind of like the "below 0 reserve" that got removed in a software update years ago, but people still swear by it.
 

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