[RE-wrenches] Direct PV-EV charging: possible?

[Hilton Dier III]

As a former EV builder, the big question that comes to my mind is the 
battery type. Lead acid is possible, lithium ion, not.

  If the EV has lead acid batteries, then a high voltage DC charge 
controller will work. It will have to handle voltages in the 195 range 
to equalize a 156 volt pack. If it is a sealed L-A pack, then it will 
have to reach ~185V.

The problem comes with the modern lithium ion batteries. They can't just 
be strung together and bulk charged. They require intelligent battery 
management systems, generally integrated into their AC source chargers. 
Even a little overcharging can result in a very expensive boat anchor. 
Worst case, a pricey road flare - the size of your car. Finding an 
intelligent DC-DC converter based charger with an integrated battery 
management system would be tricky - custom work. Many dollars. Most of 
the high voltage cars have lithium packs.

Given the efficiencies of modern high voltage utility tied inverters, 
your client isn't really losing a lot. He'd probably lose as much 
through a DC charge controller.

Hilton

-- 
Hilton Dier III
Renewable Energy Design
Partner, Solar Gain LLC
453 East Hill Rd.
Middlesex, VT 05602

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