final hour of level 2 is so slow. why?

[goto35]

So i plug my car in at work. there are chargepoint stations that are $1 an hour.

So today plugged it in at 12:21 has about 50% SOC. When i left it said will be done charging at 3:05pm.

Around 2pm it went to 6kw to 3 then 2kw.

I went back at 2:30 and the car was 99.5% done (not 100%)

So my questions are:

1. Does the car ever get to 100%?
2. Is it worth it to keep charging when it gets slower than 2Kw?

What am i doing wrong here

 

[jadnashuanh]

You're not doing anything wrong...it is normal for the charging circuit to taper off as the batteries get full. THat's one reason why CCS charging is rated to 80% in the 1/2-hour...to get to 100% takes much longer. It WILL get to 100%. SOme of the other things that can slow things down is the outside and battery temperatures...the batteries can be damaged if they get too hot during charge (and, charging them does heat them up, if they aren't already hot), so slowing the charging rate also helps to manage heat, keeping it within the safe zone. The car does have active battery temperature management, but there are limits.

Note, if you were using a CCS unit, sometimes, those too get hot, and they'll limit their output. Converting acv to dcv is not 100% efficient, whether it is done in the CCS unit, or by the car itself when using a level 1-2 EVSE.

 

[bwilson4web]

To compliment Jim's post:

Charging reaches a peak rate quickly then after most of the charging is done, it begins to taper off. Note there are times when the air conditioning comes on to handle pack temperatures.

If you're faced with a fixed, $1/hr cost, it makes sense to let the car reach say 95% and then disconnect to save money.

GOOD LUCK!
Bob Wilson

 

[johnnylingo]

Yep, totally normal. The effect is more prominent with slow chargers, for example this Chevy Volt:

When I'm at a ChargePoint station I'll typically stop charging 15 minutes short of full because those final 2-3 miles gained usually aren't worth the time and money. Wish there was a way to set this automatically.

 

[Schnort]

$5.59 for ~49 miles?!

That's like...on par with the price of gas.

 

[gt1]

BEV owners often have no choice. I see no reason to charge my REX when rates are the same or higher than driving on gas.

 

[johnnylingo]

$5.59 for ~49 miles?!

That's like...on par with the price of gas.

Lol yep, I definitely experienced that facepalm moment:

https://johnnylingo.wordpress.com/2016/07/30/vw-e-golf-vs-bmw-i3-vs-chevy-volt/

Fortunately it's not an issue I experience often. I've got solar at home and ultra-cheap electricity 9 PM - 10 AM. And if I need more, there's a free L2 charger provided by the city within walking distance.

 

[busaman]

here in the uk ecotricity was free but now it costs £6($8)!!!!! for 30 mins beleive it or not it still works out cheaper than gasoline