[RE-wrenches] Two batteries with an MX60 in between (was big bank)

[Phil Undercuffler]

Hi Mark,

Sorry for the delay in responding, but I've been offline for a bit.  In
short, the answer is no.  The original problem was too much battery for the
charging source, no absorption time to the charge,  the battery sitting too
long at deep discharge voltages, and too many parallel strings.  Taking
energy from a battery that is already suffering from an inadequate charge
and running it through a 90-some-odd-percent efficient conversion device to
attempt to charge an "off-line" string is like taking out PayDay loans from
the local legalized loanshark, and calling it a raise.  It's just a losing
proposition.

IMO, you need more incoming electrons, and less lead.

Phil Undercuffler.



On Sat, Jun 26, 2010 at 6:40 PM, Mark Frye <markf at berkeleysolar.com> wrote:

>  Folks,
>
> As you may recall I have 4 strings of 4 batteries parralleled into a single
> bank. Each string is 1690Ah @ 48V.  The charging system for this bank is
> undersized. I think I would do better by reducing the bank size by running
> only 3 strings. However, I don't want to strand the fourth string.
>
> I am wondering what rotating the strings might look like.  One string would
> be removed from the bank for a period of perhaps a month. Then it would go
> back on-line and onother string would be taken off-line, and so on.
>
> Right away I worry about accelerating the divergence of the strings in
> terms of resistence to charging. Going to three stings would reduce this
> problem, but trying to rotate strings might
>
> make it worse.
>
> In any case, I would want to float out the dormant string as best I could
> while it is off-line.
>
> Would it work to attached the DC input of an MX60 to the on-line bank of
> three strings, and the output to the off-line sting, and let the MX keep the
> off-line string in float?
>
>
> Mark Frye
> Berkeley Solar Electric Systems
> 303 Redbud Way
> Nevada City,  CA 95959
> (530) 401-8024
> *www.berkeleysolar.com* <http://www.berkeleysolar.com>
>
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