My Motomaster Group 24 boat battery is dead. I have disconnected it and taken it out of the boat. I have a small motomaster 1A - 12V battery charger. Can I use this to charge the boat battery?

These machines always suffer with neglect and failing internal batteries. Try charging it up.

Now people use capacitive smart boosters that have no batteries, just a capacitor. The voltage in the battery is stored up in the unit over the space of about 5 minutes and then boosted back to the battery when you turn the key.

It is supposed to have a Lithium battery and they aren't supposed to drain, but my guess is that the control circuit monitors the battery and depletes it very slowly. When was it last charged? I trickle charge my boat batteries for 24 hours once a month. The same should apply for the booster.

https://www.google.com/search?q=Motomaster+Eliminator+Booster%2FJump+Pack+750

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It sounds like you just have water spraying somewhere it shouldn't. Do you have the protective panels in the wheel arches and under the engine. Some people take them off.

The squeaking noise might be the serpentine belt slipping. You can get a spray called 'Belt Conditioner'. It softens it and makes it grip. It often needs two treatments a week apart.

MotoMaster Belt-Dressing, 170-g - Canadian Tire

https://www.canadiantire.ca > pdp > motomaster-belt-dr...

Aug 16, 2022 - MotoMaster Belt-Dressing stops belt slippage and squealing, For use on automotive, marine, industrial and home,
Size: 170 g.
Rating: 3.3 · ‎47 reviews · ‎US$7.99

Remove all the screws in the handle and any more that hold the front and back case halves together. Gently separate enough to expose the wires going to the battery. Disconnect the negative wire first to stop any chance of tools touching the positive connection.The battery can be lifted out and replaced.

positive to positive and negative to negative --yes

its the safest and correct way to charge it but you can charge it also in vehicle

You are in the wrong category.

You do not need to remove the battery to charge the battery. When you connect the charger you MUST be careful to connect the charger's positive lead to the positive terminal to the battery and the negative lead to the negative lead to the battery before you turn on the battery charger. Connecting the charger leads the wrong way around most likely damage the vehicle's electronics.
When you finish charging the battery turn off the charger before you disconnect the charger leads. This will prevent arcing between the leads and the battery.

You should be able to get adapters where you bought the battery. Hope this helps.

Any battery unless you have upgraded equipment/electronics. I can tell you what battery NOT to get, Motomaster or Eliminator. I have replaced more of these than I can count. Go with one that has a good warranty and/or Roadside assist

Its quite ez to replace. The big question is with what brand. It all depends how much u want to spend. Optima Batteries are the best but a little pricey. Interstate, Die Hard & similar brand are a bit less but still durable. Look for warranty & roadside assistance. I would stay away from Motomaster or Eliminator batteries. I have replaced many of these! If they didnt have warranty, Id never get another one!