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

[RE Ellison]

I have built several DC chargers using various forms of control basically before the MX 60 and the classic were available

What would happen is you had to control their upper limits with something either a dump load or if all else failed a rheostat and constant attention!
it would just run the keep running the voltage higher and higher I was doing it on 12 and 24 V battery banks

You have to have a way to limit it or you would overvoltage the bank seriously

There used to be a unit called the incharge, I believe trace originally built it but it’s no longer available
I played with one it was a bear to program all magnetic switches and everything had to be done in order and if you got anything out of place you had to go back to the start and start all over again.
It was more aggravation than my meager mind wanted to tolerate.

Just more thoughts,
Bob Ellison

> On Sun, Jan 28, 2018 at 9:23 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
>> 
>> 
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