Home Charging Poll: How much power?

[ChasingCoral]

We're getting lots of questions from BEV newbies in here, often asking the same questions over and over rather than searching. To help with that, let's pull together some central data gathering on home charging here. I'll start with some polls regarding charging type, charger brands, charging rate, etc.

Here's the second one: How much power are you using?

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[dtbaker61]

We're getting lots of questions from BEV newbies in here, often asking the same questions over and over rather than searching. To help with that, let's pull together some central data gathering on home charging here. I'll start with some polls regarding charging type, charger brands, charging rate, etc.

Here's the second one: How much power are you using?

I just use the MME plug-in charger..... so far just the 120vAC since I have not installed my 240vAC 50amp outlet in the garage yet.

My average day is <30 miles... easily charged overnight on 120vAC. averaging around 600 miles/month (200 kWhr).

 

[dbsb3233]

I'll assume this poll is asking how much am I typically USING, rather than how much it's CAPABLE of.

I have a 40A EVSE on a 50A circuit installed.
But I have it set to deliver 24A, so I chose that in the poll.

 

[ARK]

I'll assume this poll is asking how much am I typically USING, rather than how much it's CAPABLE of.

I have a 40A EVSE on a 50A circuit installed.
But I have it set to deliver 24A, so I chose that in the poll.

That’s how I’m reading the poll too.

I am charging at 32 amps though my wiring is capable of more. Mostly because some discussion in other threads that the slower the L2 charge, the ever so slightly better it is for the battery’s long term health, but at the same time, the slower the charge, the higher the electric running costs are just to keep your EVSE and the car’s internal charger ‘on’ as they supply power to the battery as it charges up, so more efficient to do it quickly.

So 32amps seemed like the compromise position but don’t know if this really makes any meaningful difference. Importantly, for me, even with 32amp charging, I have no issue waiting for the charge to complete before I have to drive again.

 

[dbsb3233]

That’s how I’m reading the poll too.

I am charging at 32 amps though my wiring is capable of more. Mostly because some discussion in other threads that the slower the L2 charge, the ever so slightly better it is for the battery’s long term health, but at the same time, the slower the charge, the higher the electric running costs are just to keep your EVSE and the car’s internal charger ‘on’ as they supply power to the battery as it charges up, so more efficient to do it quickly.

So 32amps seemed like the compromise position but don’t know if this really makes any meaningful difference. Importantly, for me, even with 32amp charging, I have no issue waiting for the charge to complete before I have to drive again.

For me the decision to drop to 24A was more about reducing the demand charge (peak draw) on my electric bill.

But it might be ever so slightly better for the battery too (albeit negligible). Either way though, it's still plenty fast enough to charge to target% by the next morning.

 

[DBC]

I am charging at 32 amps though my wiring is capable of more. Mostly because some discussion in other threads that the slower the L2 charge, the ever so slightly better it is for the battery’s long term health, but at the same time, the slower the charge, the higher the electric running costs are just to keep your EVSE and the car’s internal charger ‘on’ as they supply power to the battery as it charges up, so more efficient to do it quickly.

IMO you are doing the right thing for the wrong reasons. The battery health won't be affected by the difference in charging at 32A vs 40A AC. At 40A you are charging at 1/10 C. That won't be an issue, and dropping it to 1/11 C won't effect cell health one way or the other.

On the other hand, charging losses are directly related to amps, which means that charging at 32A will be more efficient than charging at 40A. The issue of the fixed charging overhead usually comes up with 120v charging. In this case the power is so low that 12A will be more efficient than 8A. That doesn't apply with 240v charging since the power is so much higher the overhead isn't significant.

 

[ARK]

IMO you are doing the right thing for the wrong reasons. The battery health won't be affected by the difference in charging at 32A vs 40A AC. At 40A you are charging at 1/10 C. That won't be an issue, and dropping it to 1/11 C won't effect cell health one way or the other.

On the other hand, charging losses are directly related to amps, which means that charging at 32A will be more efficient than charging at 40A.

Thank you. Putting aside time constraints someone might have, do you have a thought on what the most efficient charging rate is if the lowest speed (i.e. L1 charging) is a poor choice because of the electrical running costs to have the charging gear operating and if you also lose efficiency the higher you go with the amps? If it makes a difference here if we are talking about the SR or ER battery?

 

[DBC]

Thank you. Putting aside time constraints someone might have, do you have a thought on what the most efficient charging rate is if the lowest speed (i.e. L1 charging) is a poor choice because of the electrical running costs to have the charging gear operating and if you also lose efficiency the higher you go with the amps? If it makes a difference here if we are talking about the SR or ER battery?

Doesn't matter if it's an SR or ER battery. Just to back up for a second, the equation would be: P(losses) = I^2R, where I is charging current and R is internal resistance. We don't know R but that doesn't matter since it's a constant.

Let's say you can charge at 10A for an hour, 20A for two hours, or 40A for one hour. The losses would be:

10^2X4=400R
20^2X2=800R
40^2X1=1600R

This is oversimplified, but basically charging losses are proportional to amperage, meaning charging at 40A will have 4X the losses of charging at 10A. From this standpoint the most efficient charging is the highest voltage and the lowest amperage.

However, as you mentioned, at low power there is the overhead issue, which is why charging at 120v 12A is more efficient than charging at 120v 8A.

At some point the efficiency gains from lower amperage are offset by overhead losses. I don't know where that point would be. Maybe 240v 12A? 240v 15A?240v 8A? Somewhere in there, which is likely way lower current than you would want to use.

 

[ChasingCoral]

I'll assume this poll is asking how much am I typically USING, rather than how much it's CAPABLE of.

I have a 40A EVSE on a 50A circuit installed.
But I have it set to deliver 24A, so I chose that in the poll.

The poll is set up to allow multiple votes so you could vote 24 and 40.

 

[generaltso]

@Florida7382 , please tell us more about the DCFC station you have at your home. Do you live in a large complex that has one?

 

[Florida7382]

@Florida7382 , please tell us more about the DCFC station you have at your home. Do you live in a large complex that has one?

That vote was meant for humor only. I drive an etron and charge with 120V outlet- it does the job 99% of the time.

 

[JoeDimwit]

I haven't actually installed a home ESVE yet because I have access to a free level 2 ESVE at work. I am planning on putting in either a ChargePoint HomeFlex or a Ford Connected Charger system later this summer so I can Precondition during the colder months, and charge very occasionally to 100% for road trips. I have toyed with the idea of running a 100A circuit to a sub panel in the garage in anticipation of a time where 2 ESVE's may be necessary.

It helps that I have the skills necessary to do this myself, and that I have a brother that is even better at residential electrical than I am. So, basically it'll only cost me parts and a pizza.


EDIT:
Before you ask... No. I will not come install yours for parts and pizza. In fact, you couldn't afford pay me to install yours.

 

[JoeDimwit]

That vote was meant for humor only. I drive an etron and charge with 120V outlet- it does the job 99% of the time.

I do wish I could have my very own DCFC at home.

 

[VaderMachE]

Just waiting on the MME to arrive.?‍

 

[JoeDimwit]

Just waiting on the MME to arrive.?‍

A plywood backer board? You must be wealthy... ?