On Fri, 26 Jun 2015 23:50:43 +0200, Robert Roland
wrote:

On Fri, 26 Jun 2015 10:46:48 -0700 (PDT),
wrote:

I was under the impression that parallel charging was not the way to go because it is difficult if not virtually impossible to equalize the current through each battery.

Lead (and lithium) based batteries are charged to a specific voltage,
and are therefore well suited for parallel operation.

During standby charge, you want to control the voltage, not the
current. In fact, even if the batteries are not closely matched, you
can perfectly well keep them on standby charge in parallel. The
battery that has more self-discharge will then automatically draw more
current.

You can run batteries in series, but they must then be closely
matched. A battery is simply a set of closely matched cells connected
in series.

In your situation, just hook several batteries in parallel and use one
charger to keep them all fully charged.

To be completely safe, you might want to fully charge them
individually before you connect them together. If you connect two
batteries with considerably differing charge state, one battery will
charge the other at an uncontrolled current.
And if the batteries are charged in parallel it makes no difference if
one is removed. But if charged in series once the customer needs
another battery the customer must remove ALL the batteries in that
series string from the charger.
Eric