Stutter On Start

[AustinV]

3B429907

2024 Pro XS 250

Last few times out after the boat has been sitting for at least a week, the first crank of the day has a bit of a stutter.

previously it would crank, kind of hiccup, and then fire up. Not the normal smooth, crank & fire.

yesterday, I hit the key and it sounded weak, barely turning the flywheel, then took off and started up. When it starts it almost hits like it’s going to fire, but then needs another revolution to really get it going.

This only happens on the first start of the day after the boat has been sitting. Currently have an X2 Size 31 Cranking battery, and it’s showing good on my battery charger. Merc monitor shows no issues, and I’m getting the normal one beep when keying on.

Initial thoughts are the battery is failing under load, but is still good enough after starting and running through the day so the issue doesn’t pop up. Will get the battery load tested when I get a chance to bring the boat home.

Anybody see this before?

[thommo59]

Battery would be the first point to check, most of the pro Xs v8’s will give like any extra cough on the first start then fine the rest of the day. I had a similar issue years ago and it was my battery isolation switch not carrying the load, I put a better quality one in and solved.

[catdude28]

I’m also thinking battery. How old is the X2 and what charger do you have? I would not rely on the charger to tell me health of the battery, but would use a voltmeter to measure.

[AustinV]

I was looking at my emails, I think it might be 2018. I may of gotten a replacement under warranty around 2020 though. So it’s probably on its last leg. Need to get a lithium anyway. Minn kota 460pc charger

[catdude28]

You will be be able to charge a lithium battery with your MK PC 460 if you put it on AGM mode.

[alli ss]

Can you even use a lithium battery on a mercury yet? I know a ReLion lifepo4 cranking battery is the only one approved for use. You put a big agm31 in there, hook your engine battery cables directly to the battery, and you wont have any more issues.

[mactlman]

Can you even use a lithium battery on a mercury yet? I know a ReLion lifepo4 cranking battery is the only one approved for use. You put a big agm31 in there, hook your engine battery cables directly to the battery, and you wont have any more issues.

some lifepo4 cranking batteries are approved by merc

[EuropeanAM]

There are a few out there now that meet the absolute BARE MINIMUM requirement for the engine alone. I strongly recommend a hybrid setup if you want to run a lithium on the cranking position (hybrid parallel an AGM).

Check your cables and battery switch- and make sure you're using clamp-style terminals for the engine cables, clean power and charger. Everything else goes on the built-in threaded lugs.

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