300 XS Battery woes

[90mph]

I have a new 300 XS on a 22 Sterling Flats boat. The factory installed an Optima 34M for the cranking battery. If this battery is discharged any at all (12.6v vs 12.8 at full charge), it won't start the motor. The motor turns over but will not fire until I jump it with a hot battery. This is a problem because this is a fishing boat with a lot of auxillaries, ie; pumps, aerators, etc. I'm told the ECM needs to see 12.3v before it will fire, is this true?

Any others having this issue?

[AwesomeBullet]

Batteries for Mercury Optimax motors must be a minimum of 1000CCA...

[DsturbD]

Check the voltage at the engine whilst cranking as compared to the battery i think mercury specifies 10.5v but i have seen opti's reluctantly start with as little as 7.6v at the engine. IMO the battery leads shipped with the engine are to small especially when a battery switch is added so if you have extended the battery leads make sure you have the appropriate sized cable and always connect the negative directly to the battery and use nylock nuts on the terminals and battery switch.

Good Luck


Cheers.

[90mph]

Good points, I have the nylocks, battery switch and the cables xtd to the center helm. I need to check the voltage at the motor. Will advise
1

[90mph]

It was the battery switch. I put the motor leads directly on the battery and she fires right up. Thanks for the help.

[DsturbD]

Cheers.

[WILDMAN]

Damn fish botes!

[j_martin]

Damn fish botes!

go jump inalake.