I only have one battery on my boat at the moment, and when i start the engine it just about kills all my electronics. I want to add another battery but i dont want the two batteries connected. Have you guys ever used split charging diodes, or any other means of having the alternator charge two seperate batteries. Thanks,
Check and clean all grounds , sometimes a faulty ground or positive connection will cause this . Load test the battery as well as it is easier to rule out as to chase your tail. I've used isolators with good results in the past.
You should not be starting your engine with your electronics turned on.When the alternator kicks in it can send a voltage spike and posibly harm electronics.This is what I was told from a electronics guy.I know of many that do it and I have never heard of any thing going wrong.If you hook up a battery switch and only have on 1 battery at once they would be isolated,and switch to both just for starting.I never run on both at once,and alternate batteries day to day.I would not like having just one battery,no back up if some thing goes wrong.
This set up is great. It isolates your starting and house batteries so one can not drain the other, but can emergency combine if you have discharged the starting battery. Also has an automatic charging relay which senses when the battery needs to charge. Will not over charge.
If the two batteries you have are about the same age you can parallel them as you house side and buy a new starting battery and replace you battery switch with the new blue seas switch. If you add a new battery to an old battery in parallel the old battery will draw down the new battery. The new battery will be protected from this if isolated with the blue seas system.