Feed an MPPT Charge controller with a forklift charger

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Feed an MPPT Charge controller with a forklift charger

Postby Ray » Mon May 15, 2017 9:26 pm

Ok i have a forklift chager it has a very very big transformer and 2 diodes wired in full wave with a centertap so it can put out about 65Volts at 50Amps. I would like to feed it into the Morning Star MPPT Charge controller but i am worried about the ripple voltager so that it can act to regulate the charge state.

Since i have forgoten most of what i have learnt back when i was an apprentice am trying to work out what would be an approprate capacitor size to smooth it out and so far looking at the web has not helped with a soild answer.

Any Ideas would be a great help :D

Ray
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Re: Feed an MPPT Charge controller with a forklift charger

Postby Gordon-Loomberah » Mon May 15, 2017 9:52 pm

Surely it needs 4 diodes for full wave rectification?

I'd be a bit concerned about what will happen if you use it for anything other than bulk charging. With solar panels the controller lets the PV voltage increase up to near Voc (and current fall to near zero) when tapering the charge to reach full charge.
With that charger transformer, it may not be able to do that to any great extend, so I'm not sure what will happen if you let it run well into the absorb stage of charging.
What voltage battery are you planning to charge? Can you remove some secondary winding turns to lower the output voltage, and use it to charge the battery directly?
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Re: Feed an MPPT Charge controller with a forklift charger

Postby Ray » Tue May 16, 2017 7:03 am

I should have said i am charging a 48v battery, the charger is designed for 48v but is unregulated so figure i might as well use the solar charger to regulate at night when the panels are not working.

Gorden have a look at this link it shows the type of diode config i have,

https://www.allaboutcircuits.com/textbo ... -circuits/

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Re: Feed an MPPT Charge controller with a forklift charger

Postby Gordon-Loomberah » Tue May 16, 2017 12:37 pm

Thanks Ray, now that I've seen that I remember I have seen it done that way in a small 12V battery charger.
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Re: Feed an MPPT Charge controller with a forklift charger

Postby davidg » Sat May 20, 2017 11:49 am

Gordon-Loomberah wrote:Surely it needs 4 diodes for full wave rectification?


No a centre tapped transformer can use just two diodes, it's rare nowadays, but it certainly produces full wave rectification. Your only using half of the transformer at a time so not the most efficient way.


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Re: Feed an MPPT Charge controller with a forklift charger

Postby Ray » Sat May 20, 2017 8:02 pm

So any ideas on a suitible capacitor (the maths has given me a headach), yes i know i am cheating but would really appreciate.

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