Can we charge a 48V off grid battery bank with a 12V car alternator and small gas engine? Will it overheat? What is the fuel economy (kWh/gal.)?
This video is Part 2. If you want to see Part 1, go here:    • The AlternatorGenerator, First Attemp...  

Video, Honda EU6500 Inverter Generator:    • Not what I expected.  

I bought a 12V car alternator off of craigslist for $100. Next was a Predator gas engine from Harbor Freight. In this case, I purchased the 224cc MAX engine, which is 6.6hp. The 212cc 6.5hp engine would have also worked well for this build.

The goal is to make a dedicated generator that can recharge my 48V battery bank. I'm using the EG4 LiFePO4 batteries, which is a little more than 30kWh. Sometimes, during the winter, the solar production doesn't keep up with my loads. That's when I need to supplement my solar with some generator run-time in order to recharge my battery bank. Yes, 48V generators exist on the market, but they are thousands of dollars. I built this generator for about $400.

Intro: 00:00
Mounting Alternator and Engine Together: 02:04
Assembling Components: 05:56
Cutting Aluminum Heat Sink: 07:14
Why the Buck Converter: 09:07
Rubber Feet under Platform: 10:09
Why not use a Boost converter, 12V to 48V: 10:23
Will it Overheat? Thermal IR Camera: 11:10
Capacitor sizing: 16:45
Field Winding Current and Watts: 17:55
Fuel Economy Test, kWh/gal.: 18:31
Full Bridge Rectifier, Built-in vs. External: 22:39
Conclusion: 26:51

Amazon affiliate Links:

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(Alternate to the one in the video)

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Charge Controller used in this video (Victron 250/100): https://amzn.to/40k4kNz

Less Expensive Charge Controller: https://amzn.to/3K4fZJE

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“As an Amazon Associate I earn from qualifying purchases.”

Signature Solar Affiliate Links:

Battery Bank, EG4-LifePower4, Lithium, 30.72kWh: https://signaturesolar.com/eg4-lifepo...

Inverter kit, Schneider XW PRO 6848: https://signaturesolar.com/bndl-ac-co...

Chargeverter: https://signaturesolar.com/eg4-charge...

Harbor Freight Links, Not Affiliated:

6.6 Hp, 224cc, MAX: https://www.harborfreight.com/generat...

Band Saw: https://www.harborfreight.com/power-t...

Flux Core Welder: https://www.harborfreight.com/easy-fl...

Note: I have no affiliate with Harbor Freight.

Previous Video making a battery charging generator from a free treadmill motor:    • DIY DC Generator: charge batteries of...  

Disclaimer:
My videos are in no way intended to be instructional "how-to" lessons. I am simply documenting my project for informational purposes. Property damage, personal injury, or death may result, even when following manufacturer's instructions. I cannot be held liable for such damage or injury. It is YOUR OBLIGATION to ensure that you are complying with any local and federal laws as well as code and permit requirements.

David Poz, LLC