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

[Ray]

HI Mac;

I don't think the generators will be overloaded.  i may be wrong, but I 
believe they will just put out what they can, and the batteries will 
slowly come up in voltage.  I have a large fork lift battery charger 
that is essentially unregulated, and it never has been overloaded.  It 
will definitely over charge the batteries if left on too long, however.

The dead batteries are not going to act like a short circuit, they will 
have quite a bit of internal resistance that will limit the total 
current flow when charging.  Again, you didn't mention the brand or type 
of generator, so I can't say if I have experience with it, so this is 
just my uninformed  0.02 worth.

Ray Walters

Remote Solar


On 1/28/18 8:23 PM, Mac Lewis 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
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches_lists.re-wrenches.org/attachments/20180128/6406e669/attachment.htm>