multiple charging source problem

[Iggy]

I am some where in-between the 2 last post. I do use my genset, not a whole lot. In 3 years I put about 65hrs on it. It came with the boat and in great shape. Motors like to be used rather than sitting still. On that thought, I did put in a solar charger, but never mounted the panels.

Oh well.... Maybe for the moment, the genset battery will stay.

 

[CharlieJ]

Twisted Tree #14 +1
You need almost no current to replenish a starting battery. Here is an example that I use to educate clients on why I connect all charging sources to the house bank and then use any number of methods to charge the starting batteries.

Let's assume it takes 1,000A to start your engine.
It takes 3.6 seconds for your engine to start.
Total power out of the starting battery is 1000A x 3.6 seconds = 3,600Asec
There are 3,600 seconds in one hour

Start battery will be depleted by: 3,600Asec / 3,600sec/hr = 1Ahr.

 

[luna]

Although I agree with CharlieJ’s example calculation of the amount of energy removed from the start batteries, these batteries have another important and larger job.

They power the electronics (ECM including all sensors) to run the engine, likely the helm mounted engine gauges, possibly the shifters & throttles and in my case, the ER air vent door hold open magnets. This run load on my ride exceeds 10A @ 24V per engine and needs to be replaced if you want to go far. Fortunately lots of ways to do that exist, just don’t forget it.