Batteries for adult toy.

[LaunchnRetrieve]

I've set up my boat for 2 batteries, one for starting and one for running the anchor light and radio when not underway. Since you are battery geniuses I thought I ask for opinions.

It's time for new batteries so I'm wondering what would be better overall. Two starting/cranking batteries, using the second for the light/radio or 1 starting/cranking and 1 deep cycle rv/marine?

The idea for the backup battery was to be sure I could start the boat after extended light/radio use. So that makes me lean toward the backup actually being another cranking/starting battery.

Thoughts?
Thanks

[SoundGuy]

red31 wrote:
temp comp Deka Flooded
http://africanenergy.com/new/wp-content/uploads/2012/08/Renewable-Energy-Charging-Parameters.pdf

The point is a flooded battery can be re-watered, an AGM can't - if an AGM is overcharged because temperature compensated charging wasn't used the AGM will vent out acid as vapour, with no way to restore it. Deka AGMs are LABELED to this effect, warning that these AGM batteries MUST be temperature compensated charged ...



You can bet if Deka required temperature compensated charging for their flooded line those batteries would also be labeled with this warning ... they're NOT. 😉

[LaunchnRetrieve]

First, I do not have temperature compensation ability as is.
Second, let me twist the question a little bit.
If I have one cranking battery and one deep cycle and my switch is set to both, is there a charging issue since they are different battery types?

[red31]

temp comp Rolls flooded
http://rollsbattery.com/wp-content/plugins/rollsbatteries/pdfs/Rolls_Battery_Manual.pdf

temp comp Trojan Flooded
http://www.trojanbattery.com/tech-support/faq/#Temperature

temp comp Deka Flooded
http://africanenergy.com/new/wp-content/uploads/2012/08/Renewable-Energy-Charging-Parameters.pdf

temp comp us battery flooded
http://usbattery.com/wp-content/uploads/2014/05/usb-charging-recommendations.pdf

[Canadian_Rainbi]

It would depend somewhat on the demands of both. How big an engine are you starting? I have had a couple of old cruisers in the old days; a 24' Bellbuoy with the "Volvo" engine--really a GM 350, and a 28' Chriscraft similarly powered. I ran a pair of group 27 "Marine Deep Cycle" batteries using a manual battery switch. 1, 2, , BOTH and OFF. Battery one was the engine battery, 2 for all the 12V loads (power anchor windlass on the Chriscraft). Batteries lasted me about three years due to the difficulty of staying on top of the charging during the off season.

[SoundGuy]

GordonThree wrote:
A pair of Duracell AGM deep cycle, also sold as the DEKA Intimidator at boat supply stores.

And which for maximum life expectancy require temperature compensated charging ... which the OP likely doesn't have. The only batteries I'd personally invest in are those I can properly recharge. Good ol' flooded don't have this requirement. 😉

[Bumpyroad]

I would do/have done one deepcycle for trolling motor, etc., and a cranking battery. no reason for two deep cycles unless you are running a 24 volt trolling motor and use them in parallel. lights and radio should not be that big a draw however, unless you have multi floods for bow hunting.
bumpy

[GordonThree]

A pair of Duracell AGM deep cycle, also sold as the DEKA Intimidator at boat supply stores.

If you have the room for two batteries go for it.

They're pretty cheap at Sam's Club