Burnt-Out Isolator - Alternator / Diode Isolator Amperage Ratings

[Zteven]

My diode isolator (as part of my electrical charging system in my new boat) has failed.

The factory equipment is an Indmar 5.7 inboard with a 95 amp alternator, wired to a diode isolator rated at 70 amps, which in turn is wired to two batteries. (all of this is from the boat manufacturer).

The diode isolator has failed and the dealer has provided a replacement, however, the replacement is again rated at 70amps. I've expressed my concerns to the dealer regarding the isolator being under rated and most likely burning out again, however, the dealer has indicated this is all the manufacturer is willing to supply as a replacement.

Am I wrong to expect an isolator with a higher amperage rating? What rating should the diode isolator have at a minimum relative to the alternator?

 

[sam am I]

Re: Burnt-Out Isolator - Alternator / Diode Isolator Amperage Ratings

You are correct in that......If your alternator can do 95 amps, there is those situations where the Iso's 70 amps limit can/will be exceeded.

What do you want the dealer to do? Isn't he limited by the Manu? Who is limited by the designers? Could be a losing battle......I hear your frustration thou, you probably paid a few bucks for this setup, been there done that. Engineers mess up man.

Soooooooo, You can perhaps keep going back and getting new ones and beating this guy up for a while, or perhaps the dealer will work with the manu and they'll work with the engineers to re-spec you one (fat chance) or get a good lawyer and class action/sue them, or cut your losses............ limit the loads for now(turning big amps up, discharging your batt too deeply and the like) savoring this replacement and spec in something better yourself?

Lots of good info/folks here(out there) willing to help ya and this option will probably cost less in the long run anyway to just spec in something waaaaay nicer and reliable that you designed

 

[Zteven]

Re: Burnt-Out Isolator - Alternator / Diode Isolator Amperage Ratings

I'm basically looking to get my facts straight before I present my situation to the manufacturer as the dealer has provided me their contact info to see if I can get a solution... Seems like the dealer can't be bothered with what probably is a small problem to them.

I'm not sure why they insist a 70amp diode is acceptable on a 95amp alternator... Seems like simple math to me...

 

[sam am I]

Re: Burnt-Out Isolator - Alternator / Diode Isolator Amperage Ratings

Oh, I knew what you were doing and had got the infamous brush off ........ya sounded a bit like me in that respect. So, take heed of my advice........approach them(if ya get that far, ya might be dealing with some real winners here) calmly and with respect, don't go in carrying and swinging a big stick. Ask them polity how they'd react and what they'd do if this were them in this situation, get what ya can, be happy with maybe 10 free wax jobs and just bail!! They may get all cocky and just install a 60 amp inline breaker and say "now shoo or else". Might just save ya a bit of frustration(and Jail time......yes, i'd go that far back in the day. Better life through Rx's these days...J/K, hehehe), just say'n.

Besides, we can design you something here much better anyway, just ask us, we know it all!! GL

 

[UncleWillie]

Re: Burnt-Out Isolator - Alternator / Diode Isolator Amperage Ratings

Design by committee.

The Battery Isolator Committee didn't read the memo from the Alternator Selection Committee, when they changed the Alternator from the more common 65 amp one, to the upgraded 95 amp alternator.

So now they only stock the "One Size Fits All", 70 amp isolator.