Alternator upgrade thoughts for Yanmar

Maine Sail · May 18, 2022

dLj said:
@Maine Sail What's your opinion on the WakeSpeed 500?

dj

Best regulator money can buy..We are still technically a Wakespeed and Balmar dealer..

kappykaplan · May 28, 2022

SycloneDriver said:
I'm now the proud owner of a Balmar alternator and regulator.

Congratulations. I don't think you'll regret it. :beer:

mic98034 · Jun 6, 2022

Davidasailor26 said:
I plan on documenting the whole architecture and code at some point and I’ll be sure to post a link when I do.

Yes, please. As a recovering engineer I love data. I've been thinking using a Rasp-Pi and I'm interested in what you've done.

Davidasailor26 · Jul 31, 2022

Davidasailor26 said:
It’s still early in the year so the air is pretty cool, and I haven’t had a chance to run the engine from a lower SOC for a longer period. I’m curious to see how the alternator output responds once it’s more challenged.

More Data!

Anchored out last night and brought our house bank of two Deka Intimidator Group 31 AGM's to 53% SOC. Today there was no wind, so the long motor back gave us a good chance to see what the 80A Hitachi alternator would produce. Ambient temperatures were in the low 80's. Temperature in the engine compartment was over 100 I'm sure. Here's what the plot looks like for State of Charge and House Voltage during recharge:

And here's the plot of load (mostly refrigerator and instruments) and net current:

It looks like the output of the alternator stayed pretty constant as load changed. For example when the refrigerator turned off the load would drop by 4.5 amps and the net current would go up by almost as much. That suggests that the alternator was basically putting out all that it could, and that the batteries weren't the bottleneck. Around noon it looks like the alternator finally got to a point where it was able to keep up with both the load and the batteries' ability to absorb current.

Davidasailor26 · Aug 1, 2022

SycloneDriver said:
Took the boat out yesterday and with only 5 amps load my house bank fell very quickly to 12.0 volts. It looks like I need to replace the batteries.

Yep, sounds like they’re worn. I should add that my graphs above are brand new batteries. The graphs I posted back in post 7 were 8 season old batteries. A few weeks after I posted those we noticed that our voltage was dropping to 12.0V or below a lot faster than it used to, just like you describe. I separated the two batteries and found one of them flat dead. I did a 20 hour load test of the other and found it only 75% of it’s labeled capacity. With our new batteries even at 53% SOC they were still above 12V with an 8 amp load.