I meant the efficiency of the electrical transfer of energy to the EV
battery, not necessarily total system efficiency. In general, higher
charge rates means more heat, more line losses, etc. Just look at the
efficiency specs vs charge rate for any battery; its basic physics. The
lead acid battery side of the system especially works better at lower
rates, but in your case you have surplus PV, so the house batteries are
no longer really part of the equation. Again, electrical efficiency
is not always the end all, beat all; taking advantage of excess PV in
the summer is improving overall system efficiency by utilizing power
that would other wise be wasted, even if the efficiency of the energy
transfer itself from one battery to another is a bit lower.
On the other hand for a typical customer leaving the EV plugged in over
night to go to work the next day, a lower charge rate will be better.
Ray Walters
Remote Solar
303 505-8760
On 6/8/20 3:54 PM, Chris Mason wrote:
>Lower charge rates are more efficient both for the car's battery and
the solar/ battery system
I don't get that. Our house battery is full at about 11 a.m., so we
have about four hours to charge the car. During that time we make
about 6KW, so the car uses 5KW of that and charges up. If I went to
the 120V charger, I would be charging all day and it still would not
be charged.
On Mon, Jun 8, 2020 at 1:05 PM Ray <[email protected]
<mailto:[email protected]>> wrote:
Also have a customer with a Leaf that can charge from a dual GVFX
system. He uses the 120 vac charger. Lower charge rates are more
efficient both for the car's battery and the solar/ battery
system, so I recommend sticking to the 120 vac chargers if possible.
Ray Walters
Remote Solar
303 505-8760
On 6/7/20 6:04 PM, Darryl Thayer wrote:
I was trying to charge a Nissan Leaf with a ? Iam not sure but
two VFX i think old age.. i mostly rember having the problem. I
think the car harger had a max of 2kw
On Sun, Jun 7, 2020, 3:41 PM Jay <[email protected]
<mailto:[email protected]>> wrote:
I’ve got offgrid 2 clients and they have no issues.
They each have a Bolt and can choose the charging rate. They
can run it at either power. But only use higher power when
they have lots of sun.
Older Stacked vfx and Schneider xw, no issues.
I would expect the SW to work, however it’s an odd beast as
it’s waveform steps change with load. More load, more steps,
therefor cleaner so maybe at lower charge rate it’s not clean
enough.
As to your issue it could be power factor Being really poor.
Can you tell us what inverter, yea 5 years ago is a long time.
Jay
Peltz power.
On Jun 7, 2020, at 11:53 AM, Darryl Thayer
<[email protected] <mailto:[email protected]>> wrote:
I think you said it well, about 5 years ago I tried to
charge a car from an off-grid system. I did not record my
events but the inverter had twice the power of the level two
charger, yet the inverter would get hot and trip out. I was
told a ferroresonant transformer may help, and it might be
different with different cars. However, I was warned the
ferroresonant was to stop input wave problems from arriving
at the output not to prevent the output wave problems
showing up on the input. The off-grid customer gave up.
On Sun, Jun 7, 2020 at 6:36 AM Hilton Dier III
<[email protected] <mailto:[email protected]>> wrote:
The issue with EV chargers is that they create a lot of
reactive power. Think of it as "slosh" in the waveform.
That means that charging at 2,000 watts sloshes a lot
more than 2kW through the cable, plug, outlet, and from
the inverter. If you've got a reasonably good sinewave
inverter the charger will like it fine. However, the
inverter might not like the charger if you cut things
too close. Make sure to have a lot of top end left in
your inverter. Always use a transformer based inverter.
The SW series has a big chunk of metal in it, so that's
good. At 120V the Bolt will only draw 1440 watts max.
An aftermarket Bolt 240V charger can draw up to 32 amps.
That's 7.7 kW, so too big for an SW. Treat it more like
40 amps. The OEM 120/240 EVSE (smart charging cord) that
comes with the car can draw 8 or 12 amps at 120V or 12
at 240V. Assume that the 8 amps is really 12 and the 12
is really 15 or a bit more. I have seen 15 amp plugs and
outlets with the hot prong melting plastic around it.
The plug on the OEM EVSE is 20A rated but make sure your
outlet is as well.
--
Hilton Dier III
Missisquoi River Hydro
Renewable Energy Design
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Chris Mason
Solar systems designer
Generac Generators Industrial technician
Comet Systems Ltd DBA Comet Solar
Anguilla Cell 264.235.5670
WhatsApp 264.235.5670
Skype: netconcepts
www.cometsolar.com <http://www.cometenergysystems.com/>
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