Battery advise

[Cuppa]

Thanks Cuppa. At the moment I have a century 12 amp 9 stage charger I was going to use for recharging it.
I love the idea of the agm, especially as far as safety goes. How long does an agm roughly last? I know out of my all rounder I only got about two years before it was buggered.
The only thing putting me off the agm is the price at the moment. Usually I’d be all for it but I bought my first house last weekend and have just signed my mortgage papers haha.
Am I right in saying (very roughly) it’s around $220 vs about $380 for wet/agm in the 105ah range?

I think you will get an AGM for a fair bit less than that. I just did a quick Google Eg. Giant 110Ah @ $299. with free delivery. (Look around more & ask locally too, this was just a 30 sec Google, so you may well get cheaper) https://www.aussiebatteries.com.au/b...-cycle-battery

A better known quality brand like Ritar I saw for under $320 for 100Ah.

Weight is a good indicator of quality. Ritar 100Ah are 29kg .My 120Ah Ritars are 35kg each. The Giant ones in the link are 110AH & 28kg. I'd guess they would actually be closer to 100Ah than 110Ah, but that's ok if it suits.

The difference in lifespan between a battery properly charged by a multi stage charger like you have compared to one charged by the vehicle's alternator via a solenoid (Like the SBi12) will be chalk & cheese. (Which is why I consider dc to dc chargers to be superior as they too are smart chargers). The AGMs have a far lower self discharge rate so can sit without use for longer periods, provided you recharge them before leaving them (no lead based battery likes sitting discharged for any longer than necessary - that is the main cause of shortened lifespan). If you get an AGM, & recharge it on your charger asap after each use you will be able to then disconnect it from the charger & 2 or 3 months later it's rested voltage will only be marginally less than full charge. Used like this it should give you 6 to 10 years. (My AGM's are currently 8.5 years, & previous ones I had were still in service at 12.5 years). Lifespan also depends on how much use they get too of course , but 6 to 10 years is based on the assumption the boat wont be used more than weekly at most. So whilst a bit more expensive to buy they are far cheaper in the long run if 'looked after', & the looking after is far less than with wet batteries.