[RE-wrenches] Is there a charge controller do this?

[Chris Mason]

PWM chargers should work fine, dial the generators to about 50V. Then the
batteries will charge to 50V float, and the solar will manage the stages
after that. 4 x 60A PWM charger should do what you want. You can buy a 20A
and see how that works so you don't waste much money.

On Sun, Jan 28, 2018 at 11:23 PM, Mac Lewis <maclewis1 at gmail.com> wrote:

> Hello wrenches,
>
> I'm working on 3 off-grid telecom sites.  They are designed to operate
> solar only under most conditions but the project manager ordered a
> custom-built 48 VDC generators, intended to be used as the battery
> charger/backup power for the site.  These are ~20 kW generators, and can
> probably do about ~350Adc at 48 Vdc at the elevation that these are sited.
> The battery banks are 4 x 1000 Ahr GS Nanocarbon 48 battery strings and can
> gobble up the 350Adc easily when they are discharged.
>
> While discussing the generator operation with the generator supplier, we
> have found this generator isn't capable of charge control, or limiting its
> own output.  The charge control functionality isn't necessary at this site
> because we really just need it to keep things online until the sun returns,
> a simple 54 VDC float voltage would work.  However, without the generator
> being able to self-limit its output, we expect this generator to stall when
> started because it can't regulate its output current and will immediately
> become overloaded by the discharged batteries.
>
> I am trying to come up with some options to rectify this serious design
> issue.  One idea that immediately came to mind was putting in some parallel
> solar charge controllers between the DC generator output and the battery
> bank.  If the generator output could be dialed up to around 60-70 VDC,
> could parallel solar charge controllers be used for charge regulation?  It
> would be kind of like charging a 48 V battery bank from a 70 V battery
> bank.  MPPT isn't applicable, could the max current limit in the charge
> controller(s) be used to regulate charge rate?  Will the charge controllers
> blow up?  If not, what brand might work.  Each site has 8 x Midnite Classic
> 150s but I'm open to other manufacturers if it would work.  I am open to
> blowing up a charge controller in the shop but I thought it best to ask
> first.
>
> What are other ways to put this generator to use, and limit its load?
>
>
>
> Thanks for your input/comments
>
>
>
>
>
>
> --
>
>
>
> Mac Lewis
>
> *"Yo solo sé que no sé nada." -Sócrates*
>
> _______________________________________________
> List sponsored by Redwood Alliance
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.
> org/maillist.html
>
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
>
> Check out or update participant bios:
> www.members.re-wrenches.org
>
>
>


-- 
Chris Mason
NABCEP Certified Solar PV Installer™
Solar Design Engineer
Generac Generators Industrial technician

www.cometsolar.com <http://www.cometenergysystems.com>
264.235.5670
869.662.5670
Skype: netconcepts
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches_lists.re-wrenches.org/attachments/20180129/b670f0b2/attachment.htm>