2000 maxim 2100sr. Battery gauge falls when running accessories at cruise speed

[Ironside]

Hello again
I have a maxim 2100sr
Year. 2000
Motor 5.0 carbureted with alpha one gen 2 drive
65 amp stock alternator

I cannot run accessories like lights or under dash heaters even at 3000 rpm cruise speed for very long
The voltage gauge falls instantly and continues to drop until alarm buzzer sounds
Battery seems fine and have never had an issue even with extended cranking
It is like there is not enough amps to the fuse panel
Any thoughts are as always appreciated

 

[foodfisher]

Re: 2000 maxim 2100sr. Battery gauge falls when running accessories at cruise speed

That seemingly fine battery needs a load test.

 

[NYBo]

Re: 2000 maxim 2100sr. Battery gauge falls when running accessories at cruise speed

Sounds more like the alternator needs testing. However, the first step is always making sure all connections are clean and tight.

 

[Ironside]

Re: 2000 maxim 2100sr. Battery gauge falls when running accessories at cruise speed

Thank for the info guys
I will get them both tested
I do not know if this has always been an issue or not I bought the boat used 2 years ago and it has done this from day one with me
Previous owner put two forced air heaters under the dash that get heat from engine water
Also some crazy high power docking lights in the front
Either will cause the alarm to sound in about two to five minuets
The alternator is rated at 65 amps is this very strong or should it be heavier?

 

[Ironside]

Re: 2000 maxim 2100sr. Battery gauge falls when running accessories at cruise speed

Also only has one battery
Looks like Costco special. Rv/deep cycle At 750 cca

 

[NYBo]

Re: 2000 maxim 2100sr. Battery gauge falls when running accessories at cruise speed

If it's functioning properly, 65 amps is enough for most boats. There are more powerful ones available, but that's not your problem right now.

 

[Ironside]

Re: 2000 maxim 2100sr. Battery gauge falls when running accessories at cruise speed

Thanks again
I will get some testing done and see what comes of it

 

[Silvertip]

Re: 2000 maxim 2100sr. Battery gauge falls when running accessories at cruise speed

If you have more than one blower motor for the heaters, that is a relatively high current draw item. High power docking lights is another adder. You need to add up the current draw of the items you are using when the voltmeter starts to drop. The engine itself is consuming a fair amount of power so all of that 65 amps is not going to power accessories. In fact the alternator is not likely putting out 65 amps at 3000 rpm. I think the situation is that you are consuming more power than the alternator can keep up with.

 

[NYBo]

Re: 2000 maxim 2100sr. Battery gauge falls when running accessories at cruise speed

Okay, after reading Sivertip's reply, I see I misread your original post:facepalm:

What is your voltage with the motor running without these high draw accessories on? You may have to upgrade to a higher capacity alternator, or simply not use these devices at the same time.