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14-50 vs HPWC dropping 25%

SabrToothSqrl

Active Member
Dec 5, 2014
4,009
3,521
PA
So.. my 14-50, due to reasons beyond my control, and investigated by PP&L (power company), my car keeps dropping from 40 to 30 amps.

and it's stupid. There's nothing wrong with my connections, wiring, outlets, etc. etc. etc. (6 gauge, (even though it's all of 3', and could be 8), nothing gets hots, etc etc)

So, here's my question.

Since I have dual chargers, and (should) be able to use a HPWC to the max of 80 amps. when it detects a voltage issue, will it drop to 60 amps?

So I'd see 60 amps over my 30? or am I just waiting my time/money?

I have space in my breaker. It was setup for a 240v stove, but we use propane, so that breaker has been off for... since the house was built!

I'll need to replace it w/a 100 amp, but still I have the space.

has anyone successfully asked Tesla to make their car less sensitive to voltage?

it always starts just fine. 240-248v and can suck down 40 amps just fine. Within an hour it kicks to 30. I can't isolate it to any other things running.

I do live in an area with mostly 1-5 acre lots, so it's rural... but I just want to suck 40 amps!

I'd put the HPWC within 3' of the box, and still use the suggested (I think it's 3 gauge) wire.
 

Cosmacelf

Well-Known Member
Supporting Member
Mar 6, 2013
9,881
28,071
San Diego
Yes, if the car suspected a problem, it would reduce amps from 80 to 60. So that would work for you. I too have my charging routinely cut from 40 to 30, but it doesn't bother me, it still charges overnight fine. The issue the car is detecting might be in the UMC or 14-50 adapter, so switching to a HPWC might solve the problem completely.
 

SabrToothSqrl

Active Member
Dec 5, 2014
4,009
3,521
PA
The UMC that came with the car was getting quite hot back in March, however it was replaced, and no longer gets hot.

I've been holding off on the HPWC route thus far because I know I want a CPO Model X, and have no way to know if it will have dual chargers, as it's not on my required list... (assuming charging is the same).

So I don't want to buy it if it won't make a difference for my X either...

Tough Choices lol.
 

SabrToothSqrl

Active Member
Dec 5, 2014
4,009
3,521
PA
I had a similar issue with my 14-50. I had the power company (PG&E) investigate and it turned out to be an overloaded neighborhood transformer. Once they upgraded their equipment, my charging has been rock solid ever since.

I worked with PP&L who's measuring equipment was down to the narrow scope of several hours! vs Visible Tesla, which records much more often. PPL said everything is within spec and go away...

yes, I manually set it to 40 now like 2-3x a night, and i'm sick of it.

maybe if I complain more. I did also install a heat pump and new heat pump water heater (both to reduce my propane usage).
(car did this before these changes, but seemed more rare).
 

tomas

Out of warranty...
Supporting Member
Oct 22, 2012
4,345
4,263
Santa Barbara/New York
I worked with PP&L who's measuring equipment was down to the narrow scope of several hours! vs Visible Tesla, which records much more often. PPL said everything is within spec and go away...

yes, I manually set it to 40 now like 2-3x a night, and i'm sick of it.

maybe if I complain more. I did also install a heat pump and new heat pump water heater (both to reduce my propane usage).
(car did this before these changes, but seemed more rare).

OK, here's the history in case you didn't know already. People with EVs (not necessarily Tesla) had garage fires early in the MS rollout. Naturally, certain media outlets figured they should make it about Tesla. I believe this was shortly after the 2 MS road hazard battery penetrations, which caused similar uproar. Out of an abundance of caution, Tesla took immediate action on all of these things. Rapid software release to adjust ride hight, followed by additional battery protection. Very tight electrical fault detection to reduce current in event of any anomalies. Much, much tighter tolerances than any appliance you have plugged in. They just did not want the company to go down because of somebody's faulty wiring, or some high-draw appliance kicking in combined with marginal wiring, or utility co issues or, or, or... none fault of Tesla, but all impacting PR. So, the MS software is extremely sensitive about bumping down from 40 to 30... doesn't take much, and probably is not worth pulling out your hair to find it. 30 is enough for overnight charge. If you ever need quick boost during day, reset to 40 and hopefully it will stay for duration of charging session.

This is not a case of Tesla providing something sub-standard, it's more like providing something way above normal standards... and in the end, a small compromise for us.
 
I worked with PP&L who's measuring equipment was down to the narrow scope of several hours! vs Visible Tesla, which records much more often. PPL said everything is within spec and go away...

yes, I manually set it to 40 now like 2-3x a night, and i'm sick of it.

maybe if I complain more. I did also install a heat pump and new heat pump water heater (both to reduce my propane usage).
(car did this before these changes, but seemed more rare).

@SabrToothSqrl, although not a perfect solution, next time you charge, set the charge current to 38 amps instead of 40, and see if it can hold it there. If it doesn't, drop an amp at a time to see what it can actually maintain. I had a slightly different problem than you, and my current was dropping from 40 to 30 as well. At the 38 amp setting, it was able to maintain it.
 

qwk

P130DL
Dec 19, 2008
3,024
857
OK, here's the history in case you didn't know already. People with EVs (not necessarily Tesla) had garage fires early in the MS rollout. Naturally, certain media outlets figured they should make it about Tesla. I believe this was shortly after the 2 MS road hazard battery penetrations, which caused similar uproar. Out of an abundance of caution, Tesla took immediate action on all of these things. Rapid software release to adjust ride hight, followed by additional battery protection. Very tight electrical fault detection to reduce current in event of any anomalies. Much, much tighter tolerances than any appliance you have plugged in. They just did not want the company to go down because of somebody's faulty wiring, or some high-draw appliance kicking in combined with marginal wiring, or utility co issues or, or, or... none fault of Tesla, but all impacting PR. So, the MS software is extremely sensitive about bumping down from 40 to 30... doesn't take much, and probably is not worth pulling out your hair to find it. 30 is enough for overnight charge. If you ever need quick boost during day, reset to 40 and hopefully it will stay for duration of charging session.

This is not a case of Tesla providing something sub-standard, it's more like providing something way above normal standards... and in the end, a small compromise for us.
You left out the part about an underengineered UMC that is prone to melting.....
 
This is not a case of Tesla providing something sub-standard, it's more like providing something way above normal standards... and in the end, a small compromise for us.

In my case, I took the amperage drop to mean there was something, uh, not wrong, per se, but maybe something needing attention. I had noticed before that my voltage at my home would run up fairly high, as in, I have seen it at 256 volts. I wondered if that could be the problem. I charged at a friend's house, and at an RV park and it stayed at 40 amps. Finally I decided that it might be the circuit breaker, although the one in the panel was fairly new.

I now charge at 40 amps.
 
Mine has worked flawlessly too. Have you tried another UMC in your outlet? It may be your wiring (nail or staple through a wire?) or your power supply fluctuating causing it to downgrade. No really worry as, at least for me, charging at 30 vs 40 would never have made any difference ever.
 

FlasherZ

Sig Model S + Sig Model X + Model 3 Resv
Jun 21, 2012
7,030
1,029
Mine has worked flawlessly too. Have you tried another UMC in your outlet? It may be your wiring (nail or staple through a wire?) or your power supply fluctuating causing it to downgrade. No really worry as, at least for me, charging at 30 vs 40 would never have made any difference ever.

...or an undersized transformer, or undersized feeders, or a misbehaving appliance, or you share a transformer with a neighbor and they have a misbehaving appliance...
 

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