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How to Achieve 33v Charge with Victron Buck Boost Converter

ThirdEyeSamuel

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Jul 5, 2021
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I am using an 8S4P Nissan Leaf Battery configuration with 16 modules and so my operational voltage is around 28-33v. I use a Victron MPPT and Buck Boost converter to charge the system but the Buck Boost can only be programmed to charge up to 30v normally. I'm curious if it's possible to increase the charge to closer to 33v without damaging the unit.

Or if there is another solution for alternator charging that can get me from 12v starter battery voltage to 33v house battery I'd love to hear it as well.
 

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Leaf cells are best suited for 48V. 8S is desirable for higher voltage/lower current, but 6S is slightly more compatible with typical 24V hardware and avoids theses issues (though it has its own).

Don't know the specific hardware you're using, so I can't comment.

Presuming your MPPT can achieve the desired voltage, have you considered a second MPPT fed by a 12-48V buck boost converter?


Can feed 8A/48V into a MPPT from a 10-25V source.

Kinda spendy and inelegant, but that plus a little 75/15 MPPT would do the trick for about $150. VictronConnect demo library had no issue with me setting absorption to 33V on the 75/15.
 
Leaf cells are best suited for 48V. 8S is desirable for higher voltage/lower current, but 6S is slightly more compatible with typical 24V hardware and avoids theses issues (though it has its own).

Don't know the specific hardware you're using, so I can't comment.

Presuming your MPPT can achieve the desired voltage, have you considered a second MPPT fed by a 12-48V buck boost converter?


Can feed 8A/48V into a MPPT from a 10-25V source.

Kinda spendy and inelegant, but that plus a little 75/15 MPPT would do the trick for about $150. VictronConnect demo library had no issue with me setting absorption to 33V on the 75/15.
An awesome idea to use the converter to feed an mppt which can then bring the voltage to 33v!

I’m using a 12/24v 100/50A victron buck boost converter and plan to continue using a 24v nominal system.

If my converter outputs 50a at 24v Im assuming the 100/50 will do the trick but maybe give a buffer and use 150/60?

Thanks for the great suggestion!
 
An awesome idea to use the converter to feed an mppt which can then bring the voltage to 33v!

I’m using a 12/24v 100/50A victron buck boost converter and plan to continue using a 24v nominal system.

If my converter outputs 50a at 24v Im assuming the 100/50 will do the trick but maybe give a buffer and use 150/60?

Thanks for the great suggestion!

No. Victron MPPT must be fed with voltage +5V over battery voltage. They don't step up, they ONLY step down. That's why I linked a different boost converter.
 
No. Victron MPPT must be fed with voltage +5V over battery voltage. They don't step up, they ONLY step down. That's why I linked a different boost converter.
Ah yes of course, my initial excitement of the possibility clouded what I know to be true
 
Leaf cells are best suited for 48V. 8S is desirable for higher voltage/lower current, but 6S is slightly more compatible with typical 24V hardware and avoids theses issues (though it has its own).

Don't know the specific hardware you're using, so I can't comment.

Presuming your MPPT can achieve the desired voltage, have you considered a second MPPT fed by a 12-48V buck boost converter?


Can feed 8A/48V into a MPPT from a 10-25V source.

Kinda spendy and inelegant, but that plus a little 75/15 MPPT would do the trick for about $150. VictronConnect demo library had no issue with me setting absorption to 33V on the 75/15.
I like that buck boost converter, thinking about using one for my MPPT hooked to the car for charging my solar power generator while on the road.
 
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