3.8kW vs. 7.2kW EVSE

[Gigi]

Is there any advantage to charging the FFE battery at a slower rate than the onboard charger can handle?

When I bought a Fusion Energi, I installed a Leviton 3.8kW 16 Amp EVSE. It matched the wiring and circuit breaker I already had available and was sufficient to charge the Energi. Now that I have a Focus Electric, I am thinking about replacing that unit with a 7.2 kW 30 Amp unit in order to have faster charging time for the Electric, but before I run heavier wire from one end of the house to the other (more than 60 feet) and upgrade the circuit breaker, I am wondering if the effort and the expense are worth it.

The Focus Electric charges overnight, so 6 and a half hours on the existing unit versus 4 hours on a 7.2kW unit doesn't really make a difference. It would be nice sometimes on the weekend or in the evening, though, to be able to gain 20 miles on an hour's charge between trips rather than only 11.

If putting more pressure on the battery by charging at a higher rate degrades the battery quicker, I might just live with the occasional inconvenience of slower charging and driving a backup vehicle when necessary. If there's really no difference in battery life, then all I need to consider is the cost of wire, breaker, and trading out the EVSE and the time and effort to install.

Does anybody know about charging rates and battery longevity?

 

[davideos]

Im no battery technologist, but I don't think there is any issue charging at the 6.6kw rate. My experience with many kinds of batteries is you can typically charge them at or less than the discharge rate with no problem.

 

[sefs]

6.6kW charging is still a low xC charge rate. There is no issue with charging at this speed. In my experience, it is entirely worth it to have the capability to charge at the full speed (especially when the FFE's full speed isn't that fast to begin with). Bottom line, I do not see any advantage to not going for the whole 6.6kW of available charging rate. The battery is already limited to not fully charging or discharging and you are not charging too quickly with the 6.6kW charger. Get the 8 AWG wire, 40 amp breaker, and a nice Clippercreek HCS-40 and don't look back.

 

[Lithium]

I agree that 6.6kw charging barely taxes the batteries. What you gain by going to 6.6 is several points;
3.5 hours to full
The one time you need the range you'll stand that much higher chance that you're prepared.
The charging at higher amps and volts is more efficient. 240v at 30 amps is 7.2kw but effective is 6.6kw. There is a significant gain in efficiency from 120v to 240v and at 16amps to 30amps you will further reduce energy loss into heat etc with the higher capability.
Financially it will take a while to recoupe the cost of the upgrade, maybe never, but peace of mind that you can go is valuable.
I would kick myself if a trip was possible in the focus, and had to take the ICE because it wasn't charged.
My 2cents
H

 

[Gigi]

I agree that 6.6kw charging barely taxes the batteries. . .

The charging at higher amps and volts is more efficient. . . at 16amps to 30amps you will further reduce energy loss into heat etc with the higher capability. . .

I would kick myself if a trip was possible in the focus, and had to take the ICE because it wasn't charged.

Thanks. This is what I needed to know. Now pulling wire, changing out a breaker, and installing a new EVSE goes on my list of projects that I want to do, but like other things on that list, it's not so critical that I need to do it right away.