On 02/04/2015 10:15 AM, Lee Hart via EV wrote:
Jay Summet via EV wrote:
I'm looking to buy a kit (or an assembled) battery charger for a 120v
lead acid system, with an eye to upgrading to a LiIon system in the
future (also near 120-130 volts, limited by my controller/motor combo).
Hi Jay,
If you want to build it yourself, have you considered an "old school"
charger as an alternative? A 120vdc pack is the "sweet spot" for making
very simple chargers.
In the extreme, a "bad boy" charger is just a bridge rectifier off the
120vac line. Or a half-bridge from the 240vac line. Add a series
inductor to handle the current peaks (a "Bonn" charger), and you have a
decent charger. Add a plain old 60 Hz transformer, and you have
isolation (a "third world" charger).
The easiest way to regulate it is with phase control. Use two SCRs in
place of the diodes in the bridge. This makes it equivalent to the
Russco or K&W chargers.
Keeping things simple has some advantages, but I can't think of a way to
do it safely without a quite large transformer. (I'm not comfortable
with just a phase controlled SCR directly to mains....then you lose the
isolation protection from ground...)
My 110V charger is transformer based, and I certainly wouldn't want a
LARGER transformer in my truck.
I suspect that simply by adding a solid state input cutoff relay and a
voltage sensing circuit to one of my existing chargers I could get the
same general price/performance as a "bad boy" charger.
Jay
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