Dashboard Alternator light

BFL13 wrote:

This only happens when the batts are nearly full. If they are low when starting out, you can set the controller to 14.6 and unless they get nearly full while driving, no light. Unless there is still some sun or if gen is allowed on arrival that's as high as it gets that day.

You real problem is getting them full while driving when starting low. Your alternator charging will be lamed by the solar's higher voltage, but it has low amps. You need lots of amps to get them up before arrival at the next site.

Your best amps would be from gen charging with a high amp converter. But high amps gets you to Vabs sooner at a lower SOC so the light comes on, and stays on during the Absorption the rest of the way there.

You could isolate the engine batt, and go with a high amp converter off the gen with solar added by setting solar and converter to the same high voltage. With a DC-DC you could have three chargers adding their amps and no light.

Your only limit is the gen watts as to how big an amp converter it can run, and to have the converter voltage adjustable. So toss the PD unless it is as high amp as the gen can run, and get an adjusatble voltage PowerMax LK model with as high amps as the gen can do. Set it to 14.6, the solar to 14.6, and any Dc-Dc to 14.6.

Note that a PowerMax 75 amper pulls 1700VA set to 14.6v doing 75 amps on a low battery. If your built -in gen is one of those non-inverter types it will likely not run as high an amp converter as an inverter-gen of the same |"watts" (acting more like it is MSW -it is not but it acts in a similar way for this exercise), so it can get tricky picking how big an amp converter you can run. The PowerMax 100 amper is PF corrected so it can be run by almost the same inverter-gen as the 75 amper which is not PF corrected. A Honda 2200 portable does 1800VA but my B&S 2200 does 1700VA. Gotta watch out when running things to the max you can get away with.

Of course it is no good having a converter with too high an amps that you can't run it at home on an extension cord, but only off your RV gen. BTDT. Have to have a lower amp portable charger to do the RV at home. Keeps you busy making sure you are using the right charger for where you are.

Or just accept a lower amp charging rate while driving and get by somehow with however full the batts get on arrival.

I think I'll give up RVing and take up something simpler like rocket science.

I've learned a lot since I started this and I think the ultimate solution is to install B2B charger like Pianotuna suggested many posts ago.

What I once saw as a daunting task, is really simple. If I were to buy the non-isolated version of Victron's charger I would only need to remove my isolation solenoid and add one wire, a wire from a good chassis ground up to the unit. I could probably wire in a Trik-L-Start like you would if you had a iso. solenoid. I would probably wire in a switch instead of relying on auto voltage sensing so I could turn the thing off if I though my alternator needed a rest.

Thanks all for your contributions in this thread. It's been an education.