Hi
I replied earlier but my posts are held 'awaiting moderator approval', presumably because I am a new member?
so by the time my posts are published the conversation has moved on, and my comment missed.
What prompted me to join and post was the question of how to test the alternator didn't seem to have been answered. So I just wanted to say you can do it by creating the conditions where its being charged by regenerative braking - when I do that the voltage goes up to somehing approaching 15 volts (unless all batteries are fully charged) - proving the alternator is OK. I hope that answers the OP's question.
Yes, the batteries are not usually fully charged, they are connected in parallel with the main
battery so they only get fully charged when decelerating in gear (slowing down or going downhill) with regenerative braking. But, like the main
battery, they don't go flat - if they did the main
battery would be flat too (since they connect in parallel) and the engine wouldn't start. But there has always been plenty of power to start the engine.
I'm not sure of the exact percentages, but its something like 80% charged when the engine is running, with regenerative braking providing the top up as and when it is working. I have a voltmeter connected to the secondary batteries, and the main batteries, so I can keep an eye on both. With 400ah of secondary
battery capacity I don't need them fully charged every time I stop.
I can see this wouldnt do for a professional installation, because you need something you can fit and forget. If you did it like that the customer would bring it back saying the start stop was not working (which I don't need anyway). Although I don't know whether fitting a B2B charger would solve that problem.
Could I spend £600 on a B2B charger and still have the start stop inoperative (engine management) warnng light coming on?
Other than that it seems to be more environmentally friendly than a B2B charger set up. The B2B charger wouldn't make use of regenerative braking.
The B2B charger would also consume so much extra power it needs a fan to cool it down - Increasing the work of the alternator and possibly shortening its life?