i have a 2005 525efi. I want to install a battery charging isolator to charge multiple batteries. Where is the charging wire located is it landed on the starter main power lug?

It does go back to the starter, depending on your application and rigging, it may be better to disconnect it at both ends and run a new wire to the isolator from the alternator. I believe it’s an orange wire.

Thanks I will check into running a new wire.

Is this a single engine multiple battery? Or twin engine?

Isolators work, but a Automatic Charge Relay (ACR) does a better job. The ACR automatically connects to charge the battery(s) and disconnects when charging stops or if a battery goes bad (shorted cell or other).

I have 6 or 8 gauge running from my alt. to the isolator charge post. Funny this came up... I'm switching from the diode style to digital soon. My iso has seen better days. Going with the Promariner #23126 1-alt, 3-battery 130amp

A few things to think about with a 130amp ALT. The standard lead acid BAT can only take current so fast, if it pushes more then it can take it will heat up. AGM BATs can take current faster but not a lot. The wire size for 130amps if kept under 10 feet should be at least 2AWG and maybe 1AWG

https://www.bluesea.com/resources/1437

Just the 130amp iso... alt is 70amp. Was told to rate iso over actual alt amperage. Figured 130 would be good in case I up the amperage of the alt if it takes a dump

Agree, I misunderstood your comment

No worries and thanks for looking out! That link is a great reference by the way... thanks!!!