Changing batteries

MJWB

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Folks question from someone who knows little about boat electrics. Please be kind.
I think the house battery may be leaking. Fluid coming from somehere on it. Going to remove to properly inspect. I'l disconnect shore power but do I disconnect live or neutral terminals first please?
Assume I reconnect in reverse order?
 

ChromeDome

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I don't think it is crucial on a boat but car people recommend the NEG off first - and ON last when refitting. Also keep an eye on where the cable wants to go when off as it def. should not reach anything else electric/metal.

To get a good indication of a battery's status, charge it fully with a known good charger (so called Smart or Intelligent types are best).
The charger should deliver no less than 10% of the battery Ah capacity (so a 100 Ah battery needs a 10 A charger). Then connect the charger for 10 hours, disconnect and leave it for at least 1 hour, then measure voltage. At fully charged a 12 v nominal battery should be 12.65 v or more.

1713891807378.png

A load test will show the stamina of a battery. A simple load tester isn't very expensive but you could bring the battery to a workshop also.

1713892120161.png

A different point to consider if your batteries seem not to perform is the alternator.
 

MJWB

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I don't think it is crucial on a boat but car people recommend the NEG off first - and ON last when refitting. Also keep an eye on where the cable wants to go when off as it def. should not reach anything else electric/metal.

To get a good indication of a battery's status, charge it fully with a known good charger (so called Smart or Intelligent types are best).
The charger should deliver no less than 10% of the battery Ah capacity (so a 100 Ah battery needs a 10 A charger). Then connect the charger for 10 hours, disconnect and leave it for at least 1 hour, then measure voltage. At fully charged a 12 v nominal battery should be 12.65 v or more.

View attachment 175876

A load test will show the stamina of a battery. A simple load tester isn't very expensive but you could bring the battery to a workshop also.

View attachment 175877

A different point to consider if your batteries seem not to perform is the alternator.
Many thanks
 

ChromeDome

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When you have access to the individual cells you can refill until the plates are covered. If curious and research-minded, you can test the gravity of each to tell if any is weak before adding fluid.
Interesting but not very valuable as if the battery is weak, you're going to replace it regardless of which cell(s) are bad.

1713946308824.png
 
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