Older home with old wiring

[house9]

Took delivery of model 3 on 12/21.

Was planning to just use 110 charging but I rent an older house and it didn't go so well:
- was drawing at 9/12 A (+2kWh)
- charge speed reduced warning messages
- went on for hours, noticed some minor flickering of lights in garage and then it just stopped

So it was pretty obvious 110 was not going to work. Too many plugs and lights running of same circuit is my guess.

We have a gas dryer and there was a 10-30 plug not in use (dedicated circuit), Tesla online was sold out of this adapter, but luckily the local service center had one in stock.

So far I have only charged once using 10-30, everything seemed great 24/24 A (+16kWh). I checked the cord(s) every hour or so, the Tesla cord was warm (maybe normal) and the 10-30 cord is partly exposed (not up to code) it got a little bit warm as well but not nearly as warm as the Tesla cord.

My question: since this is an older house should I drop the amps when charging (say from 24 to 18)? I know it will slow down charging speed but is it safer? (less heat)

Thanks

 

[TydalForce]

The wire in the wall that’s exposed - does that get hot?
I wouldn’t worry about the mobile connector so much as the stuff past it.
Disclaimer: I am not an electrician. If you suspect trouble, call one

 

[Akikiki]

Would be a good idea to dial it down and slowing back up as you learn its not hurting anything.

But you first concern should be that 240 dryer plug. If you are unplugging your adapter often (to plug dryer back in), you are going to wear the contacts out quickly. Not designed to be unplugged/plugged often. You should consider something like this.
Will allow both to stay plugged in and switch to the one you need at the time.
Dryer Buddy™

Me too - I am not an electrician.
I would discuss this with my landlord. Any improvements you make will help him after you leave. And you could at least ask for consideration from your rent for improvements. But if you make changes, get permission. I think I read that CA law provides you some latitude in requesting EV charging upgrades. Don't depend on me, check it out.

 

[ralph142]

Would be a good idea to dial it down and slowing back up as you learn its not hurting anything.

But you first concern should be that 240 dryer plug. If you are unplugging your adapter often (to plug dryer back in), you are going to wear the contacts out quickly. Not designed to be unplugged/plugged often. You should consider something like this.
Will allow both to stay plugged in and switch to the one you need at the time.
Dryer Buddy™

Me too - I am not an electrician.
I would discuss this with my landlord. Any improvements you make will help him after you leave. And you could at least ask for consideration from your rent for improvements. But if you make changes, get permission. I think I read that CA law provides you some latitude in requesting EV charging upgrades. Don't depend on me, check it out.

op said he had a gas dryer, but agreed, he should not plug and unplug often, leave the Mobil connector plugged in, and install or have installed a heavy duty receptacle

 

[house9]

The wire in the wall that’s exposed - does that get hot?

Not hot, a little bit warm, barely noticeable; the mobile connector was definitely warm to the touch.

But you first concern should be that 240 dryer plug. If you are unplugging your adapter often (to plug dryer back in)

No worries there. Dryer is running on gas, so plan to leave the adapter plugged in.

Our lease is up in June, if we stay longer I might pursue getting a 14-50 plug installed.

 

[eevee-fan]

Start with your requirement. How many KWh do you need to recharge each night?

 

[dhrivnak]

If the grey dryer plug is not warm, and the outlet does not get warm I think you will be fine at the 24 amps. If the temperatures rises above say 90F then I would dial back. The car will normally do this like it did on your 120V charge attempt.

 

[house9]

Start with your requirement. How many KWh do you need to recharge each night?

Good point

I'll know more after the holidays, but my guess is not much: my wife will be using for short commute to and from work plus errands during the week; then we'll be taking longer drives on the weekends. I'm not worried about 'falling behind' on charge during the week even with low home charging capability, we also have 3 super chargers within 1/2 hour drive so easy to quickly 'top off' if needed.

 

[eevee-fan]

As mentioned on post #6, if the house wiring is fine at 24A (80% of 30A peak), then you should be fine.

If you worry about electrical fire, set the car to accept 16A (53% of 30A peak) or 10A (34% of 30A peak).

 

[ElectricIAC]

Interesting setup. Your mobile connector is smarter than it looks and will dial itself back if all is not kosher. Keep it at 24A.

I’d definitely look into NEMA 14-50+ Gen1 UMC or HPWC hardwired in the future though especially if you have a car with a 48A onboard .

 

[israndy]

Your mobile connector is smarter than it looks.

The UMC adapters come with pre-made settings, it doesn't sense an outlet, it's just based on the kind of outlet the adapter is made for. This is communicated to the car so it knows the max the outlet should be able to provide and lets you dial it back from there if conditions are not ideal.

I’d definitely look into NEMA 14-50 Gen1 UMC or HPWC hardwired in the future though especially if you have a car with a 48A onboard [charger].

I do like my US Gen1 UMC, I paid less than $300 used (obvs): tesla umc gen 1 | eBay

This frees up the Gen2 that came with the car to STAY in the car if I need it while traveling. It came with the 14-50 plug and provides my TM3 with 40 amps, not just the 32 amps provided by the Gen2. This is almost the max (48 amps) the car can take, for a lot less than any other charging solution. I am not sure how easy it would be to find the 10-30 plug for it anymore, but you already have a charge-adapter that gives you the max from that outlet.

I also use the Gen1 with its 120v plug when I don't need to charge quickly, I run it thru an HS110 energy monitor/remote switch and I can start/stop charging to use any extra solar-generation as it's available. Not so useful if your 120v outlets are already maxed out.

Also, if you are going to have to wire a 14-50 circuit that doesn't already exist it may make more sense to pay the full $500 instead and get the Tesla Wall Connector and run the wire directly to it. The savings on not adding the neutral wire, i.e. buying 6/2 not 6/3 Romex, can make up the difference over installing a full 14-50 outlet over a 75-foot+ run. Just run the wire straight from the new 2-pole 60-amp breaker circuit into the TWC and you are done. No ground fault breaker required.

 

[ElectricIAC]

That’s what I went with not wanting to run another line out to the garage to hardwire a HWPC after striking out trying to buy a 14-50 Connector HWPC. I may change my mind on hardwired however down the line should I find a reasonably priced Model X P90/100D or if we get a Model Y down the line as one of our cars will have to sit outside at which point I’ll have ONCOR run a second 125/150A service with its own meter and panel.

 

[Electric700]

Took delivery of model 3 on 12/21.

...
My question: since this is an older house should I drop the amps when charging (say from 24 to 18)? I know it will slow down charging speed but is it safer? (less heat)

Thanks
...

I think that's a good idea, or may be leave it at 20 A. That setting will be less stressful on the older wiring you have (or even new wiring).

 

[user212_nr]

I'm surprised no one has mentioned this yet, but you need to charge at 80% of the capacity of the circuit for "continuous" loads. The UMC adjusts to the proper 80% number for your plug, but it is assuming that there are no other loads on your circuit (80% of 15A = 12A). Even 1 device running on the same circuit puts you over 80%. So you got the right idea, but that's the math behind it.

Try seeing, if you dial the amps back, how close can you get to 240V (right now you have 232V).

I doubt you have a problem, but you always want to have proper smoke alarms for the chance that you are that 1% of persons who experiences a fire (of any sorts, not just the EV). Your wall-wire being less warm than the UMC wire sounds like it is fine.

 

[davewill]

I think that install is actually up to code, or at least was when it was done. I think that Romex can be exposed in an unfinished wall. Sounds like everything is fine and no need to stress.

 

[hezza8]

A nema 10-30 on a 10 gauge wire charging at 24amps will eventually get a little warm, but not hot to the touch.
It is normal.

 

[house9]

Just wanted to say thanks to everyone on this thread for your input.

I have throttled down from 24A to 20A and the charge cable barely gets warm at all. This drops me from 6kW to 5kW which is plenty for our current usage, we don't even need to plugin every night.

I have been topping off at a nearby SuperCharger but it is not needed, I just want to use up our free charges before the 6 months expiration.

 

[Tron 3]

I have the same situation with an unused 30A outlet for the dryer. I installed a junction box in the wall there and ran the circuit through the wall to the garage. We just use the portable charger left plugged in there unless we take a road trip, and bring it with. 12,000 miles and have only removed the plug twice. It's been working like a charm for us.

BTW, the 10-30 outlet is marked with "top" on one end, but I installed it upside down so the charger hangs down from the outlet instead if pointing it up. I also laser engraved the cover plate. The dryer is on the other side of this wall.

 

[ChrisMPK]

I would let it ride at 24A and make sure your renter's insurance is up to date. The exposed wire isn't an issue if you just don't whack it with anything sharp. That's exactly what it would look like behind the drywall if it were up to code.

@Tron 3 I dig the engraved plate. You should sell those online

 

[jerry33]

So far I have only charged once using 10-30, everything seemed great 24/24 A (+16kWh). I checked the cord(s) every hour or so, the Tesla cord was warm (maybe normal) and the 10-30 cord is partly exposed (not up to code) it got a little bit warm as well but not nearly as warm as the Tesla cord.

My question: since this is an older house should I drop the amps when charging (say from 24 to 18)? I know it will slow down charging speed but is it safer? (less heat)

Your Tesla will automatically drop the charging amps if it detects an issue (typically voltage sags or surges). What's not shown is what kind of breaker and panel there is. Check the brand of the panel, as some popular ones have been shown to cause fires (Federal-Pacific and Zinco). If you have one of those, you should get in touch with your landlord and have them changed out. I'd say there's no reason to drop the amps unless the wiring gets excessively hot (ouchie hot). The wiring will get warm, that's normal. If you can hold it for an extended time, then it's not too warm.