What should the voltage be at 4k RPM? also battery upgrade?

[JohnZ]

A great day out with the radio on I found myself with dead batteries and don't want that to happen again! I got a jump from a guy, enough to start one motor and while heading home, running @ 4k RPM, my volt meter slowly climbed to 12VDC... normal? It appeared to be very slowly climbing higher but shouldn't it be showing more while at that RPM?

I know one of the batteries is bad but just checking into all possibilties.... I'm thinking its not charging at all and all I was seeing was the battery rebound from putting the starter load on them.

I don't want to have to worry about this ever so I was looking at marine batteries - "Optima/12 Volts, 750 CCA (870 CA) BlueTop marine dual purpose battery with post and 3/8 in. stainless steel stud terminals" - has anyone put something similar in their boat???

 

[Dr Honda]

You should see 13.5 to 14.5 volts at 5000 rpm. BUT... at 4000 RPM... you should be above battery voltage. (+13 volts)

 

[JohnZ]

For those boaters that have a stereo system and have it on the whole time your out - what do you use for a battery? 2 OEM's with a cut off, or a dual purpose or what?

 

[Gamerse]

From my reading, many people install a standard size marine battery box, and standard marine battery. A great benefit of the speedster is a maximum charging output of about 390watts. So a marine stereo of 200watts is not out of the question. This is a project you can go as mild or wild as you like. A standard marine CD player will only draw 15 amps at max volume. This is half the standard amp/hour rating of most marine batteries, and half the available charging output of the speedster. Being the 717 does not use the battery for ignition, you can drain the battery quite a bit and still have a good start as long as you have enough reserve cranking amps to spin the engine over.

One option is the highest cranking amp batteries you can fit in the factory locations. The other is convert to a single marine battery. There is no real since in going with two full size batteries unless you decide to go huge on the stereo, and even then it would only be for extended use at high volume while anchored.

I too am considering how to add another song to my boat besides vrooooom. Good luck.

:cheers:
Ernest