Alternator and radio questions

[Easyloadunload]

I don't know if this is where I should be on this, but here I am. I have a 91 gl1500 and I'm trying to wire an amp to my radio. Here's where I am so far. I've pulled up the wire diagram for the tape deck etc. Wired all my speaker wires, the remote wire and am putting another battery just for my amp. How do I charge this extra battery off my alternator I can't seem to find any diagrams for this. Any help will be greatly appreciated. And my apologies, I'm not at all tech savvy with these phones and all one more thing my fm radio is not picking up any channels. I've checked the antenna hook ups and all seems to be fine but it won't pick anything up. Anyone had this problem

 

[Dusterdude]

You might look at some drag car stuff on wiring dual batteries.drag racers do that all the time.

 

[dan filipi]

I'd get something like this:

https://www.tindie.com/products/batteksystem/atv-utv-motorcycle-smart-battery-isolator-mini-vsr/
I googled “Motorcycle battery isolator”.

 

[Dusterdude]

I'd get something like this:

https://www.tindie.com/products/batteksystem/atv-utv-motorcycle-smart-battery-isolator-mini-vsr/
I googled Motorcycle battery isolator.

Thats pretty slick dan