Lovely Ep and troubleshooting, The specks say 15amps output for a 70. I've never run anything off my 60 yam 4/ only a sounder and GPS but souder gets turned off just before I anchor. Hope you get it sorted.

Current is your issue more than voltage. The Yamaha 70hp only outputs 16A, the Redarc pulls 12A from your alternator (not your house battery) which only leaves 4 Amps to run everything else. Voltage would come into play if your wires are maybe too small. I would recommend changing to a smaller DCDC charger that also has an Ignition feed wire. I believe Victron may have a 10A model with Ignition detection. I understand that the Redarc needs a certain Voltage level to turn on, but the current issue is what keeps making the voltage drop below 13.3V or whatever the Redarc needs. Good luck with it all, must be frustrating when you can’t maintain charge in your batteries when travelling long distances up at Limmen Bight etc. love your videos👍

Cheers for the video, hopefully my 200hp will be okay with charging the system in my boat just getting ideas not sure weather to go vuctron, redarc or bep VSR system cheers

Have you checked the amps the 70 is putting out at different revs rather than reading the volts? I don't have a DCDC charger only the Blue Sea 7650 automatic charging relay. Just connects and disconnects to save the start battery. Its only as good as the amount of amps the rectifier will charge though. I suppose its the same as the Redarc...you can't make power from mid air, it has to have a source...a larger rectifier/alternator? You can have a larger capacity battery which will last longer but you still need to find amps from somewhere to put back in.

You nailed it. Go Lithium.... they charge quicker and they have way more useable power. :)

I run a 24volt 100a/h lithium get 3 days with fridge minnkota without any charge minimum , barely ever use my onboard charger on a 5.4m boat , i had 2 yamaha 60s they only put out about 16amp from memory a good sounder killed them batteries easy

Why is the alternator only outputting such low voltage it should be outputting more than 13v surely? I haven’t paid much attention to mine but I know the Garmins are showing over 14v when I am on the plane (Suzuki 140). I will pay more attention when its at idle next run.

I'm told my Yamaha F60 will output a maximum of 8 Amps of charge ( that's about 100Watts ) so that's why it cannot build a charge. And I'm trying to find out how much power my electronics uses. I want to G\go Lithium and keep the 2 batteries separate. Had to be towed back to ramp last week with a flat starter battery