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 Post subject: Charging speed for longevity
PostPosted: Tue May 28, 2013 7:17 am 
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Joined: Tue Apr 09, 2013 7:54 am
Posts: 15
I lived 1 month with only the level 1, 120v charger and never had a problem with range due to how little I drive. Now that I have a 240v charger I plug in once a week and it fills up the car in apx 5 hours.

80% of the time I would would be fine using the level 1 120v
So in the best interests of my battery, should I continue to charge in that way.
I was thinking the slow charge would keep the heat down and extend the battery life.

Obviously when I go on road trips I'm using the level 2 any chance I get.

Thanks for your thoughts.


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 Post subject: Re: Charging speed for longevity
PostPosted: Tue May 28, 2013 5:22 pm 
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Joined: Sun Mar 03, 2013 2:26 am
Posts: 305
Location: Austin, TX
Even charging it at 240V/40A is still slow to the battery pack (relatively speaking, C/5 rate), so using the 120VAC service at a C/44 rate will not benefit it even more. In fact, I think that charging at 120VAC is less efficient for the charger so you'll actually be spending more money on a $/kWh basis.

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 Post subject: Re: Charging speed for longevity
PostPosted: Tue May 28, 2013 5:34 pm 
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Location: San Diego
Yep, charging on 120 volts just wastes electricity (I'd bet below 70%).

As to "heating up the cells", there isn't anything that you will do with the slow charge rate of the FASTEST charging station currently available. The worst you could do is take a heat soaked car (sitting in a blistering hot, black asphalt parking lot) and then immediately throw the charger on it.

It will take the Temperature Management System a fair amount of time to cool the cells. If it's not hot out, charge at any time or rate you want. For the longest life of the cells, keep them at 50% State Of Charge as much as possible and as cool as possible.

HEAT KILLS THE BATTERY.

Here's what 50% looks like, with 10 of 16 fuel bar segments illuminated. Disregard what the GOM says:


Image

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 Post subject: Re: Charging speed for longevity
PostPosted: Fri May 31, 2013 10:35 am 
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Joined: Fri May 10, 2013 8:11 am
Posts: 130
Location: Ventura County, CA
Kohler Controller wrote:
Even charging it at 240V/40A is still slow to the battery pack (relatively speaking, C/5 rate), so using the 120VAC service at a C/44 rate will not benefit it even more. In fact, I think that charging at 120VAC is less efficient for the charger so you'll actually be spending more money on a $/kWh basis.


How much energy is wasted by using 120v? I'm forced to use it for another month and I'm curious as to how much extra kWh I am going to be using if Id on't use a dedicated charger.


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 Post subject: Re: Charging speed for longevity
PostPosted: Fri May 31, 2013 8:11 pm 
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Joined: Sun Mar 03, 2013 2:26 am
Posts: 305
Location: Austin, TX
I think between 25-30%. Say I get 2.7 miles per kWh when using 240VAC. I would only get 2.1 miles per kWh when charging with 120VAC. So if you use 500kWh in a month, you'd need to put in 625-650kWh if using 120VAC (or an extra $15-20). These are swags of course.

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Kohler Controller
Shoreline Blue
EVSE, AeroVironment 30A, 7.4kW
Reciever Hitch, CURT Class III Round Tube
Cargo Liner
Modified 120VAC EVSE to also accept 240VAC
Hood struts- Sokie Tech
JdeMO Level 3 Charging port
12.6kW PV system
VIN 1396
Austin, Texas


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 Post subject: Re: Charging speed for longevity
PostPosted: Fri May 31, 2013 8:27 pm 
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Joined: Fri May 10, 2013 8:11 am
Posts: 130
Location: Ventura County, CA
Ohhh ok. I understand. Thanks a lot for that! I gotta get that charger faster!


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 Post subject: Re: Charging speed for longevity
PostPosted: Sat Jun 01, 2013 9:35 am 
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Joined: Fri May 10, 2013 8:11 am
Posts: 130
Location: Ventura County, CA
Just for curiosities sake - Why does that happen?


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 Post subject: Re: Charging speed for longevity
PostPosted: Fri Jun 07, 2013 1:38 pm 
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Joined: Fri Jun 07, 2013 1:34 pm
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very nice post

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 Post subject: Re: Charging speed for longevity
PostPosted: Fri Jun 07, 2013 2:08 pm 
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Joined: Fri Oct 12, 2012 8:10 am
Posts: 218
Location: Hermosa Beach CA
Vach wrote:
.............
How much energy is wasted by using 120v? I'm forced to use it for another month and I'm curious as to how much extra kWh I am going to be using if Id on't use a dedicated charger.


I am thinking of getting a 20A 240v EVSE because of the limits of my electrical panel. Recently I have been using 12A 120V at home.

Is there any empirical data that is more specific about the relative charging rate efficiency's?

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Drove a RAV4 EV from October 2012 to November 2013
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 Post subject: Re: Charging speed for longevity
PostPosted: Sat Jun 15, 2013 10:33 pm 
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Joined: Fri Oct 12, 2012 8:10 am
Posts: 218
Location: Hermosa Beach CA
My Clipper Creek 20A 240V EVSE arrived yesterday. It cost $595 plus tax and shipping. I am getting approximately 12 miles per hour of charging (4.8kW). That is three times the speed of the 120V charger but less than the L2 Chargepoint chargers that give me over 20 miles per hour of charging (6kW). It is designed to be hard wired but I connected it to a NEMA 14-50 cord that I bought at the local hardware store. That way I can take it and the 120v EVSE with me if I ever go on a long voyage.

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Drove a RAV4 EV from October 2012 to November 2013
Driving a Smart ED since August 2013 and a Volt since December 2013.
Converting a VW to electric since April 2012
3.8KWhr Solar Panels on roof of home.


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