Loss of Ideal Miles

[Pantera Dude]

I've had my Roadster for just over two months. In that time I have driven about four thousand miles, from 24,500 to 28,500. The ideal miles have dropped from 176 to 173. I'm not necessarily comparing apples to apples due to my charging cable issues. I was doing most of my charges at 32 amps and am now charging at 16 amps. I borrowed a charger that charged to 30 amps that was charging to 173 miles so I "think" the 173 to 176 is pretty accurate, that is, if I were to charge again at 32 amps, i believe I would still be seeing 173 miles of charge. My question is, should I do a range charge or is that unnecessary? I have not done one since I bought the car for fear of reducing battery life. What do you guys think?

Thanks

 

[Alan]

A range charge after 2 months could be good for the battery pack - if well balanced then it reduces the risk of some cells having to work harder than the others.

Try using the car until the charge is pretty low (<25%) then do a range charge with 16A (you get more miles reported at lower charge currents). I would leave it plugged in for a couple of hours once fully charged to allow balancing then drive the car to get the charge levels back down to a normal level.

 

[dhrivnak]

The ideal miles will vary and I can get mine to vary about 10 miles. Charging during the summer at 120V and I can get 183 miles. Winter charging at 40 amps with a start time of midnight and I will get 173. I think you need to plot to really see a trend and go over the full year if your temperatures vary. My ideal miles have dropped about 3 miles but I suspect I will get some back this summer. Our winter has been colder than normal so far and not sure if it is age (4 years), Mileage (14,500) or winter that is responsible for most of the drop I am seeing.

 

[Pantera Dude]

The ideal miles will vary and I can get mine to vary about 10 miles. Charging during the summer at 120V and I can get 183 miles. Winter charging at 40 amps with a start time of midnight and I will get 173. I think you need to plot to really see a trend and go over the full year if your temperatures vary. My ideal miles have dropped about 3 miles but I suspect I will get some back this summer. Our winter has been colder than normal so far and not sure if it is age (4 years), Mileage (14,500) or winter that is responsible for most of the drop I am seeing. View attachment 15996

Cool graph! Thank you guys!

 

[Pantera Dude]

A range charge after 2 months could be good for the battery pack - if well balanced then it reduces the risk of some cells having to work harder than the others.

Try using the car until the charge is pretty low (<25%) then do a range charge with 16A (you get more miles reported at lower charge currents). I would leave it plugged in for a couple of hours once fully charged to allow balancing then drive the car to get the charge levels back down to a normal level.

Thanks to both of you for your help! I'm not sure I left it plugged in for a couple of hours before driving, would that make a difference? I finally got to a full range charge after battling with my UMC that kept stopping requiring me to go start it up again. The range charge topped out at 229 then to 226 and finally 225 when I took it for a drive about four hours after the charge. Then next two times it charged to 177 in normal mode. At least one of those charges was done at 16 amps and maybe both of them? The next charges were 174 then 173 and another charge at 173, the last one being charged at 24 amps. It looks to me like my batteries must have been pretty well balanced to start? An interesting side note: I noticed my charger was slightly warm to the touch during the range charge. The UMC had never given me a problem at 16 amps until I did the range charge. When the charge got up into the 180 range, it kicked off and I had to go re-start it numerous times to get it to 208. I then decided to let the charger cool down some and then set it on top of a frozen bag of peas, I set another bag of peas on top of it. No problem after that, it charged all the way up to 229 with no problem. So apparently the problem is that the charger is getting hot which is making it shut off. Any ideas what may be the cause of this and how I might repair it? I did my charge last night for almost six hours at 24 amps with the charger iced, no problem. Well, after it was done charging, my dog walked off with one of the bags of peas. :biggrin:
Thanks again guys,
Art

 

[wiztecy]

If you ever see an MC240 for sale, pick it up. Its way better than the UMC. Granted it charges at only 30AMPS (which can be modded to do 50AMPS), but its built like a tank. Tesla service confirmed thats a way better charger than the UMC hands down.

I use my MC240 for dedicated charging at home and the UMC for when I travel since its more compact.

 

[Pantera Dude]

If you ever see an MC240 for sale, pick it up. Its way better than the UMC. Granted it charges at only 30AMPS (which can be modded to do 50AMPS), but its built like a tank. Tesla service confirmed thats a way better charger than the UMC hands down.

I use my MC240 for dedicated charging at home and the UMC for when I travel since its more compact.

Thanks Wiztecy, I'll do it!

 

[wiztecy]

I left it plugged in for a couple of hours before driving, would that make a difference?

Some say there's balancing that occurs when plugged in, I've seen no change between removing the connector or leaving it plugged in. When you charge in Range mode it balances faster. You don't know how your pack is really doing 'balance' wise unless you're view the Technician VMS screen (diags). If you're at Tesla you can ask them to check on how well you're pack it balanced. If you're Roadster is still under warranty they'll also run a bleed test on the pack for free to do a quick health check.

I finally got to a full range charge after battling with my UMC that kept stopping requiring me to go start it up again. The range charge >topped out at 229 then to 226 and finally 225 when I took it for a drive about four hours after the charge. Then next two times it charged to 177 in normal mode. At least one of those charges was done at 16 amps and maybe both of them? The next charges were 174 then 173 and another charge at 173, the last one being charged at 24 amps. It looks to me like my batteries must have been pretty well balanced to start?

I wouldn't think 16 vs 24 amps would make that much of a difference range wise. The pack can falsely report higher miles until it gets better information to calculate the full available amp-hours of the pack that the balancing process helps with.

An interesting side note: I noticed my charger was slightly warm to the touch during the range charge. The UMC had never given me a problem at 16 amps until I did the range charge. When the charge got up into the 180 range, it kicked off and I had to go re-start it numerous times to get it to 208. I then decided to let the charger cool down some and then set it on top of a frozen bag of peas, I set another bag of peas on top of it. No problem after that, it charged all the way up to 229 with no problem. So apparently the problem is that the charger is getting hot which is making it shut off. Any ideas what may be the cause of this and how I might repair it? I did my charge last night for almost six hours at 24 amps with the charger iced, no problem. Well, after it was done charging, my dog walked off with one of the bags of peas.

Be careful of the Peas, for one you're dog will be hiding them here and there, but most importantly putting a colder medium on top of a hotter medium where there's air pockets between the two is a recipe for condensation and that little cooling is not fixing the issue but rather masking a larger issue. I have a feeling your UMC is going bad and that you are charging longer ( are you ? ) when you're doing a range mode charge is causing the internals of the charger to push a load on a fatigued / defective circuit that gets exposed over time. Possibly Tesla has the means to properly test it? Or you can lend it out to a fellow Roadster owner to verify a range mode charge.

As I mentioned the MC240 is a more robust charger, same with Eberhard's Foundry Charger. Either way I'd have your UMC checked out.

Lastly the most accurate way of knowing the true health battery pack condition is knowing what your amp hour (Ah) capacity is on a fully balanced pack.

 

[hcsharp]

... So apparently the problem is that the charger is getting hot which is making it shut off. Any ideas what may be the cause of this and how I might repair it? I did my charge last night for almost six hours at 24 amps with the charger iced, no problem. Well, after it was done charging, my dog walked off with one of the bags of peas. :biggrin:
Thanks again guys,
Art

There are several things that could cause your UMC to overheat and all of them should be taken seriously. First thing to check is the high voltage connections inside including the crimp and screw connections. If a crimp is not tight enough, it will overheat. If a screw on one of the SSR's is coming loose, it will heat up. Then I would check the SSRs to make sure they are properly mounted. They have a heat sink on the bottom and you might need to re-mount it with a little thermal grease under it. If one SSR is heating more than the other, it might be going bad and need to be replaced.

 

[Pantera Dude]

Be careful of the Peas, for one you're dog will be hiding them here and there, but most importantly putting a colder medium on top of a hotter medium where there's air pockets between the two is a recipe for condensation and that little cooling is not fixing the issue but rather masking a larger issue. I have a feeling your UMC is going bad and that you are charging longer ( are you ? ) when you're doing a range mode charge is causing the internals of the charger to push a load on a fatigued / defective circuit that gets exposed over time. Possibly Tesla has the means to properly test it? Or you can lend it out to a fellow Roadster owner to verify a range mode charge.

It seems that the UMC isn't taking any longer to charge. I had another Roadster owner use my charger and he had the same results.

Thanks again!

- - - Updated - - -

There are several things that could cause your UMC to overheat and all of them should be taken seriously. First thing to check is the high voltage connections inside including the crimp and screw connections. If a crimp is not tight enough, it will overheat. If a screw on one of the SSR's is coming loose, it will heat up. Then I would check the SSRs to make sure they are properly mounted. They have a heat sink on the bottom and you might need to re-mount it with a little thermal grease under it. If one SSR is heating more than the other, it might be going bad and need to be replaced.

I'll check it out, thanks,
Art