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cybermaus avatar image
cybermaus asked

Feeding a Smart MPPT with an Alternator.

So this guy is using a MPPT charger to charge his 48V bank from modified car alternator.

https://www.youtube.com/watch?v=CL8W5hipaLM


Rather then having the alternator first regulate itself down, and then a Orion regulating back up, he just rips out all regulation, feeds the resulting (undoubtly very ripply, but he does add a chunky capacitor) 90-ish volt into a MPPT to find the best volt/ampere range.


And it seems to work. Quite well even. Getting near 3KW out of a car alternator with no apparent overheating or anything.


I think the main reason he gets out more is because the original regulator was not so much a regulator but a governor, governing the rotor field, whereas now it is always on. But yes, there is also the MPPT part, you can see it seek the best volt/ampere point.


Any thoughts, comments? Not that I am going to try this, but I thought it was a very interesting setup.

MPPT SmartSolaralternator
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Justin Cook avatar image
Justin Cook answered ·

Certainly an interesting setup. As long as he never calls for support or warranty claim on the MPPT, I'm all for it - experimenting with stuff is great when done with an understanding of how things work and with full acceptance of personal responsibility if/when things go sideways.

Edited to add: also going to move this over to the "Modifications" Space for unsupported use-cases so no one in the main group gets any ideas...

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Michelle Konzack avatar image
Michelle Konzack answered ·




I am very experimental and have tried to copy many things from YouTube people claim to work.


Since the SmartSolar MPPT 250/100-Tr VE.Can is quiet expensive
you should be very careful with what you are doing.


First of all, you can NOT load a 12V/100 Alternator with 100A @24V or even @48V because it realy OVERHEAT.


If you use a SmartSolar MPPT 250/100 and you have an Alternator of 100A, the MPPT try to get 100A @e.g. 48V out, mean, 4,8kW of an alternator which was designed for 1200W.


And yes, the Voltage Regulator is a Governor which regulate the errecting field of the Alternator and the regulation is just worse! Removing the Governor is the best thing you can do. It also increase the efficiency enorm.


Then, a 12V/24V Alternator can have a Voc (without Governor of over 200V!) which has to checked before connecting it to a SmartSolar with 250V.


Usually you have to put a 3-Phase bridge rectifier between the Alternator and the MPPT and also an Electrolyt Capacitor/Kondensator, should be at least 1000uF per 10A from the Alternator.


Then since the SmartSolar MPPT 250/100 try to get on its output 100A @28V, the Alternator MUST be MUCH bigger then 100A, otherwise you cook the Alternator like me.


I used a BRAND NEW ORIGINAL PACKED 24V/80A Alternator to charge my 2940Ah @24V SOPzS Battery and the Alternator had a lifetime of around 3 hours...


I got now over the Winter an ALternator 24V (29V) with 140A which I want to try out with my SmartSolar MPPT 250/100-Tr VE.Can since the Alternator is made for a Maximum power of 3800W (140A @27,6V) I can not overload the Alternator and it should work continiously with a MPPT Output of 100A @28V.


Since the SmartSolar MPPT 250/100-Tr VE.Can is quiet expensive
you should be very careful with what you are doing.
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cybermaus avatar image cybermaus commented ·
Interesting to know more people tried this. Sorry to hear you fried your altenator, but at least you did not fry your MPPT.


Couple of notes: Your warnings are correct, and a good caution for others, but if you carefully watch the video, you'll find that this guy did a couple of things correctly:

- He indeed checked the Voc before hooking it up to the alternator.
- He chose a chunky 210Ampere alternator from the start
- He seemed to take wiring quite seriously (no dodgy wiring in a rush to do a first test)
- He slowly stepped up the amperes, and observed the result, before moving on.


Nevertheless, your warnings are correct. It would be a shame to fry a nice *expensive* 250/100

Not to worry for me. I have a 12V 95Ah system in a mini camper, I am not in need of this solution. I am even going to downtune my Orion XS to half-power when it arrives. But I though it was interesting and honestly well executed.

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