What starting batteries do you recommend?

[coopec43]

The electrical system on my yacht is:

24V (starter, winch, bilge pumps, macerator) and

12V (through DC DC Converter 24V 12V) lighting. oscillating fans, freshwater pump, bilge bower, toilet blower, radio, DC outlets)

The HOUSE BANK and STARTING BANK are both (750CCA) (When I bought them there was a price war and I got them very cheap)


27X MF Century Dual Force AGM Battery

https://www.batteryworld.com.au › 27X-MF-Century-D...

Product Details

Suitable for use in both starting and cycling applications, Dual Force is a multi-purpose AGM battery designed and built specifically for use in a diverse range of applications where dependable starting power and cycling power is a must.
Unlike many competitor AGM products, Century’s new Dual Force is manufactured using advanced AGM technology and a specialist hard wearing Polypropylene case which makes it ideal for use in under bonnet applications where heat, fluids and other contaminants can damage products not built to the same specification.
The new Dual Force is supplied with twin terminals, a dual warranty and an array of advanced design features to ensure long lasting dependable power in a range of applications including 4x4 and light commercial starting systems, marine starting and dual battery systems, caravan, RV and recreational camping applications, and situations where dependable deep cycle power is required.
The key features of the new 27LX MF:

• Multi-Purpose AGM battery- Cycling & starting
• Reinforced polypropylene case making it suitable for under bonnet use
• Up to 20x greater vibration resistance for improved durability & longer life
• 4x more cycle life to handle increased electrical loads & power demands
• Maintenance free design
• Heat sealed double lid ensuring spill proof design for multi-angle fitments.

The 27X Dual Force is a multi-purpose AGM battery designed for use in a diverse range of applications where dependable starting power and cycling power is a ...

$409.00 · ‎In stock


NOW THE PROBLEM

Apparently I have destroyed one of the starting batteries as I can only charge it to 9V. I've just priced a replacement AGM battery at $409 but the guy behind the counter says both will have to be replaced as "you can't mix new with old AGM batteries".


Now I'm looking at X2 lead/acid batteries in series but do I really need two 750 CCA batteries? Maybe x2 much lighter batteries would be adequate? (They need to start a Perkins 4.108 diesel 1,7L)


In any case here is a 780CCA battery at $259 much, much cheaper than the $409 AGM battery.

https://www.bcf.com.au/p/century-mar...l?gclsrc=aw.ds


As I have little faith in the spiel given by the young guys behind the counter your guidance would be appreciated,

NOTE
There is no trouble running a 12V starter motor on 24V

[Bowdrie]

Jeepers, I was shocked at the price you guys have to pay for a battery down in Oz.
A friend of mine starts his 4-53 Detroit, (about double the displacement of your 4-108,) on 1 group 24 batt.
I would think a pair of them would easily start the Perkins, maybe go up to Group 27s if you're worried.
The CCA stays the same when you wire in series to double the voltage.

[Uncle Bob]

Originally Posted by Bowdrie

Jeepers, I was shocked at the price you guys have to pay for a battery down in Oz.
A friend of mine starts his 4-53 Detroit, (about double the displacement of your 4-108,) on 1 group 24 batt.
I would think a pair of them would easily start the Perkins, maybe go up to Group 27s if you're worried.
The CCA stays the same when you wire in series to double the voltage.

They are Aus dollars, but yeah, we have to pay through the nose.

[coopec43]

Originally Posted by Bowdrie

Jeepers, I was shocked at the price you guys have to pay for a battery down in Oz.
A friend of mine starts his 4-53 Detroit, (about double the displacement of your 4-108,) on 1 group 24 batt.
I would think a pair of them would easily start the Perkins, maybe go up to Group 27s if you're worried.
The CCA stays the same when you wire in series to double the voltage.

Now that you've said that I think I'll steer clear of Aust made/sold batteries. (I don't like being ripped off)

I haven't really thought about it but wouldn't two 500 CCA be equal to one battery 1000 CCA?

[Mickeyrouse]

I have ruined too many “ high quality” batteries to count by overcharging them. Now, unless I’m running the reefer, I charge at the lowest level my Xantrex will go. With this new approach, it’s been a year and a half since I last cooked the water out of the house bank, and the batteries are in the best shape I’ve seen in years.
I’ve made a life decision to go with Auto Zone or Walmart batteries. If I get two years out of them I’m ahead of the game. $100 every two years vs. $400 for six- whatcha think?

[Uncle Bob]

Originally Posted by coopec43

Now that you've said that I think I'll steer clear of Aust made/sold batteries. (I don't like being ripped off)


I haven't really thought about it but wouldn't two 500 CCA be equal to one battery 1000 CCA?

In series no, double the voltage, same amps, parallel then double the amps, same voltage.

[coopec43]

Originally Posted by Uncle Bob

They are Aus dollars, but yeah, we have to pay through the nose.

I'm starting to smell a rat.

Why wouldn't I buy two Exide batteries @ $185 ea? Quality Batteries are a local Western Australian crowd so I've contacted them to see what they have.

[coopec43]

Originally Posted by Uncle Bob

In series no, double the voltage, same amps, parallel then double the amps, same voltage.

Yes, I'll go along with that now that I've done some research.

But a 12V starter motor running on 24V will turn the diesel aux over much more quickly than a 12V starter motor running on 12V? (and if the diesel starts more quickly as a result less amps will be used)

[rslifkin]

Originally Posted by coopec43

Yes, I'll go along with that now that I've done some research.

But a 12V starter motor running on 24V will turn the diesel aux over much more quickly than a 12V starter motor running on 12V? (and if the diesel starts more quickly as a result less amps will be used)

I'd expect the starter to draw more amps (if the batteries and wiring can keep up) on 24v, however. So a bigger burst of power for a shorter time. A pair of group 24s or 27s should be plenty though.



Just don't forget that a starting battery isn't sized for a normal start under perfect conditions, it's sized for when you have to bleed air out of the fuel system and then get the thing started on the coldest day it'll encounter (which is fortunately not that cold for most boats).