Battery life

[BogMonster]

Thanks. Still looking for an answer to the point about battery chemistries before I order.

[jwalker]

Originally Posted by BogMonster

Thanks. Still looking for an answer to the point about battery chemistries before I order.

I think there is an issue, especially in confined spaces, if the salt water and the sulphuric acid mix.

Just don't mix them and put your head in the box!

[jeffstevens763@g]

Some disscssion

https://www.boatdesign.net/threads/b...t-water.25678/

I would buy a gel battery as I have if its above tube height should be ok if water gets to it there you have more problems than a small amount of noxious gas it may produce

[Pete7]

I think you are on the right track with an AGM battery which have many advantages but you may not be able to make best use of all of them.

They can be charged faster than flooded lead acid, if you have a high.c charging option.

They can be discharged more quickly at a higher .c rate.

They discharge more slowly when left unattended.

They are sealed.

There are some downsides, they must not be charged above the max voltage each manufacturer states. If this information isn't available don't buy the battery. Check the engine charging voltage at fast idle doesn't exceed this value.

Since you have done quite well with the existing battery, if it's an AGM type then I would replace like for like.

If you want to dig deeper into batteries then this forum has a wealth of information which should keep you occupied for some months:


Electrical: Batteries, Generators & Solar - Cruisers & Sailing Forums

[Limecc]

I recently needed to buy a new battery charger and although initially skeptical about so called battery desulphators or reconditioners it appears they really do work. I looked at models from Ctek but eventually decided on one from Ring who are the market leaders in the UK.
I am on holiday at the moment so have had little time to try it out before we left but it revived two 7ah sealed lead acid batteries which had been at 9v for several years. I charged them in parallel because 2 amps was the lowest setting I could select.

Here's some useful info:
Car and Deep Cycle Battery Frequently Asked Questions (FAQ) Section 16

[Erin]

I believe the issue with any form of lead acid battery is that it will give off chlorine if the acid is mixed with seawater. Was a problem on electric submarines in the early days. When they started to sink, if you didn't drown the chlorine gas would kill you instead.

I've found batteries in my cars have generally lasted about 6 years so I work on a 6 year replacement cycle on my boats too.