theaveng
Well-known member
7 hours for 240V and 20 hours for 120V. I thought it would be exactly half for the lower voltage?
Why's 120 volt charge time so long?
- Thread starter theaveng
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ebill3
Well-known member
Looks like you thought wrong.theaveng said:
davewill
Well-known member
The 120v charging is limited to 12amps (1.44kW). 240v charging is done at 16a (3.84kW). That comes to 2.67 times slower, plus 120v charging is less efficient...there's a fixed overhead for the cooling system that brings the practical difference close to 3 times slower.
RegGuheert
Well-known member
You are correct about the voltage ratio, but there are two reasons for this apparent discrepancy:theaveng said:
1). The currents are also different. The National Electrical Code requires continuous loads to not draw more than 80% of the rated current of the plug, the 120VAC current is limited to 12A. The 240VAC setting limits the current to 16A, which is compatible with wiring gauge down to 12 AWG.
2). There is a parasitic load of about 300W that runs during charging. These pumps draw the same power regardless whether the charging is done with 120VAC or 240VAC. This power takes a larger fraction of the available power away from charging when using 120VAC, This further slowing charging. Interestingly, this causes 240VAC charging to be more efficient.
Because of these two issues, 120VAC charging tends to take about three times as long as 240VAC charging.
gaswalla
Well-known member
davewill said:
there's a cooling system?
davewill
Well-known member
For the charger, motor and inverter, not the batteries.gaswalla said:
derkraut
Well-known member
Hey RegGuheert---I've gotta hand it to you; your post here is the first one that I can actually fully comprehend. I'm "electrically challenged" you see. YOU DA MAN! :mrgreen:RegGuheert said:
RegGuheert
Well-known member
I'm glad it was useful for someone. After I composed it I saw that Dave had said the same thing in about one-third as many words, but I posted anyway in case someone cared about the additional details.derkraut said:
I guess Dave's reply was L2 while mine was L1! :lol:
gaswalla
Well-known member
davewill said:
that's a shame..
RegGuheert
Well-known member
Please note that the LEAF uses a more traditional automotive cooling system which is only capable of moving the temperature closer to ambient. It does NOT have a refrigeration system in the loop like the Volt so it would not very useful for cooling the batteries.gaswalla said:
ksnogas2112
Well-known member
Great post guys. Thanks for the details. I was wondering that myself. Now I can explain to others.
theaveng
Well-known member
For 120 volts I'm surprised the charger needs a cooling fan. I can't imagine much heat being generated at that low voltage.
surfingslovak
Well-known member
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The voltage is stepped up to 400V in order to feed the pack. Obviously, the current will be a lot lower when the power is supplied from a regular outlet. I can't speak for the heat losses, but I suspect that the pump was specced for the typical use case (i.e. level 2 charging), and it does not have a low cooling and high cooling mode. The charger wires are routed on the top of the pack through the emergency disconnect hatch, and you can get a good sense of heat losses. These wires get pretty toasty on 240V, and the hatch cover get significantly warmer.theaveng said:
