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Am I doing any harm to my starter (or anything else) by not disconnecting the battery when charging? I've charged my battery a few times without turning the battery switch to "off". Now I'm noticing some flat spots when using the starter. Thanks for your input!

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I have been told before that jump starting the older motors or charging them could cause the power pack to blow, but I've never heard anyone mention the starter itself............Probably wouldn't be a bad idea though, so why take a chance

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I would disconnect the battery and open the battery vent's when charging (prevent's Hydrogen gas built up). Is your charging sys. working on the engine o.k. ? Battery O.K. ? Terminal's clean ?

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No, you do not have to disconnect your battery before charging.

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I don't disconnect batteries while charging. I loosen the caps if it has them.

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Hi, shouldn't make any differance while charging from an outside source, ie: portable charger. Think about it, the engine is running and the switch is on and the battery is being charged by the engine. Now if you turn the switch to the off position while the engine is running, you might damage the charging circuit.

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Disconnecting is a safety precaution. In the case of an electrical surge in the shore power or perhaps a failure of the charger, disconnecting the rest of the electrical system would limit potential damage.

Is it necessary? No. Is it good practice? I'd say it is if it can be done in a practical manner. Personally I'd never have a marine electrical system without a main disconnect switch no matter how simple the vessel.

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Thank you all for your help!

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I always remove the ground wire from the battery when charging, although I don`t know why, it just seems like a good thing.

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I've always left the terminals connected to the battery when charging or trickle charging. I've dome it on several outboards and an I/O too.

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I agree with the "No you don't have to" answers. Especially the logic of Thom's answer.

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The problem with not disconnecting isn't when everything goes as planned. Its when the unexpected happens. Lots of folks clean their guns while loaded and never have a problem. Every so often, one does.

Cant say I've always read every written word in the documentation with every charger I've ever purchased but I know I've stumbled on the information more than once that the battery should be disconnected from the electrical system when charging. But hey, if most folks don't have a problem not disconnecting the battery, then why should we heed the manufacturer's warnings? What do they know anyway... sheesh. Must be some lawyer mumbo jumbo.

Find the documentation for your charger rather than ask in an Internet forum.

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I never put much stock in the warning that battery charging can build up "Hydrogen" gas in it that can explode... Not until I saw someone hook up the terminal's (spark) and heard a loud "POP" as a chunk of the battery case blew across the room... "Hey, they "CAN" explode" !

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The problem is tha not everyone buys new and the documentation isn't always availabe.

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Don't discount the damage power spikes can do to electronics, not only the ones on the engine, but on the console too. You'll never have an issue if you disconnect one batt lead, or turn the selector switch to the off position before hooking up.

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That is understandable. But being without documentation, I would think the safe bet is to disconnect.

Something else to think about, with older chargers is, the high voltage spike generated by the charger itself when supply power is cut to the charger. As the magnetic field from the step-down transformer collapses, a very brief but high voltage spike is generated by the coil. Many chargers didn't adequately protect their output leads from that potential spike and it can be conducted back to the battery. Not a big deal for the battery but maybe not so good for any modern electronics still connected to it. Fortunately this particular issue isnt a concern with any decent modern charger.

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I can attest that a battery can and will explode............Had it happen on a car and it came close to taking my head off!