Charging to 100% but at only 12amps

[MurphysLaww]

Think it's OK for the battery to be charged to 100% if we’re only charging (from a solar array through an EG4 hybrid, split phase inverter) at only 12 amps? Hate to miss any free juice, and want to get to payoff as soon as is safe. We add in 10-20kW/day this way.

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[GDN]

Charging rate and what you charge the battery too aren't related. Sure DCFC isn't as good on the battery as a slow charge, but charging to and leaving the battery at 100% often or for very long is worse than anything regardless of a slow charge rate.

Leave the juice on the table. Find a hobby to burn it up.

 

[TheWoo]

Think it's OK for the battery to be charged to 100% if we’re only charging (from a solar array through an EG4 hybrid, split phase inverter) at only 12 amps? Hate to miss any free juice, and want to get to payoff as soon as is safe. We add in 10-20kW/day this way.

If you're only using 10-20% each day, why not set your charge limit to 80%? Then you charge 60-80 each day instead of 80-100. Still getting all the juice, just not taxing the battery as hard...

 

[Danface]

Mine bitcoin with the extra juice ... I got my DCFC from a guy in NH doing just that!

 

[MurphysLaww]

If you're only using 10-20% each day, why not set your charge limit to 80%? Then you charge 60-80 each day instead of 80-100. Still getting all the juice, just not taxing the battery as hard...

What we'll do. Just wondering if the charging to 100% avoidance was only an issue at higher charging rates. The Truck doesn't really sit at 100% ever for very long. There will be a mini-split A/C in the garage soon for the excess Juice, so it leaving electrons on the table won't really be an issue soon.

 

[MurphysLaww]

Mine bitcoin with the extra juice ... I got my DCFC from a guy in NH doing just that!

Might do something similar, I'm a network/systems engineer and once the mini-split is installed in the garage, I'll be moving a couple homelab servers out to the garage that use 400-500 watts continuously. Right now it puts me just over what the 600 watts of solar we have on our tool shed can provide my home office, and the home office is getting a bit toasty now that I have 60 vcores or so running 24/7.

 

[SpaceEVDriver]

Charging to 100% at a high rate can be problematic, which is why the vehicle derates the charge power (DC or AC) above 80-85%. It doesn't want to try to push more energy into the battery than the battery can take (causing it to overheat, among other issues). But this is taken care of by the onboard charge controllers; it's not something you need to worry about. You could derate your EVSE if it makes you more comfortable.

Two main issues with EV batteries are long-term storage at high temperatures with high states of charge, and very fast (dis)charging. I've been charging our Mustang on DCFCs for about 27,000 of our 36,000 miles and there's minimal battery degradation. The charge rate averages to about 80 kW, which is below the 92 kWh of the battery, which means it's charging at less than 1C (1C is a full charge from 0-100% in an hour). A larger capacity battery (with the proper cell arrangement, thermal management, and controller behavior) can accept a faster charge rate without degradation. A (dis)charge rate of 1C is the standard metric used to plan lifetimes, capacities, maximum amperage, etc. Given the 70% state of health, 8 years, 100,000 miles warranty requirement, the combination of charge curve, capacity, thermal management, in conjunction with real-life driving behaviors, etc., are designed to beat that warranty requirement.

I second the idea that you're not missing any free juice if you don't need to go to 100%. Refill what you use rather than worry about staying at 100%. You're not missing out on any juice, it's just a matter of when you pull it.

This is the charge curve from a recent Lightning charge on my ChargePoint Home Flex at 48A. Note that it slows down the charge rate as it reached max state of charge (in this case 100% since we were taking it for a ride that morning).

 

[Danface]

Might do something similar, I'm a network/systems engineer and once the mini-split is installed in the garage, I'll be moving a couple homelab servers out to the garage that use 400-500 watts continuously. Right now it puts me just over what the 600 watts of solar we have on our tool shed can provide my home office, and the home office is getting a bit toasty now that I have 60 vcores or so running 24/7.

The crypto miners are noisy too. We have winter in MA so its cooling is less of thing

 

[WilliamRobert]

Google: lithium battery dendrites, these are the critters that kill lithium ion batteries.

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