I took MB out on the harbour today for a short run. Unfurled the heady and engaged the tiller pilot which worked very hard as we were only doing a couple of knots. I was on Battery 2, the house batteries.
After 10 minutes I went to start the engine and the house batteries were flat. They were replaced in 2010 so a pretty good life.
I was just looking on ebay and it seems to me that battery technology has come a long way.
When I bought these 105ah batteries they were the highest amp/hour batteries I could get to fit in the space for them and they were $290ea.
I might get 160ah ones now for $250ea in 2019 $$.

Road Tech Marine and Tackle World have Century Marine 780s on sale at $229 ($50 off) at the moment.

They are a bit of a hybrid start/deep cycle which my great mate said he got a good service life out of.

I went to my local Battery Barn and asked if he could match the price. He looked up his price list and said he retails them for $234, so yeah he could match it. I started writing out the checque putting in $229 and he said Yeah I can do them for......pause while he saw me write in the figure.......$229 no problem.

If I had been smart enough I might have got it for $184 ($50 off).

Had a phone conversation with a guy recently who said that with batteries "You get what you pay for as with most things." He highly recommended the American made Optima brand deep cycle units. They will have more than enough CCA to start a yacht engine and the deep cycle capability to run house requirements, particularly fridges.

Battery technology is going ahead in leaps and bounds at the moment.

I have got mine from batteries direct at peakhurst .
They have a dual 130 and high crank AGM battery at a good price have a look at them.

Hi, I have used Online Batteries, excellent prices and service, batteries are lasting very well. Matt is the owners name, located at Picnic Point and delivers of course.
Cheers.

Purely my opinions below - no facts to substantiate.
I used to like AGMs because they can accept and deliver high currents, but I don't anymore because I gained the impression from reading online blogs and forums that they fail more frequently than Flooded and Gel type batteries in the same price bracket. I had an AGM by Deka that died after two years despite being treated well.

I also don't like super large batteries (like 12v 280AH in one unit) because of the weight and bulk - difficult to handle and it's more difficult to properly secure 30kg than a smaller 18kg. I would prefer to get two lower AH 12v batteries or 2 x 6V batteries (golfcart style). More flexibility in emergencies, can be carried in a dinghy, and if one cell fails offshore there are more options than with a single, large battery.

Sectorsteve said..
I've been buying 140ah deep cycles from a warehouse in lane cove. Light weight and have last well the last 2 years.

Can you give me contact details please Steve.

I have had great service from used UPS batteries sourced through Gumtree, costing about a dollar per Amphour. Although they are fine for starting small diesels, beware of prolonged heavy drain (like windlass, speaking from experience) as they're not built for that service.

I've used them for nearly ten years and get about 5 years out of them, but of course that will vary according to your use (day vs cruising) and Ah capacity vs your daily usage and charging. At those prices you can oversize to give some reserve to allow for the inevitable decline.

Cheers, Graeme