adding a 2nd starting battery

[jopes]

you can use a marine rated isolator on the second battery which will allow all your electronics to be ran off of it and not drain your starting battery.

http://www.iboats.com/Volvo-Penta-Is...view_id.271021

[oldschooltiller]

I guess I'm in the minority here.

Add another battery. Hook up your accessories to one, engine to the other. Attach a two bank charger to them. You are done. No switches, isolators none of that.

[scott.keeley]

Originally Posted by oldschooltiller

I guess I'm in the minority here.

Add another battery. Hook up your accessories to one, engine to the other. Attach a two bank charger to them. You are done. No switches, isolators none of that.

I'm even more simple. I just hooked up an additional battery in parallel. IS there some significant risk to this? 2 x interstate group 29's...

[perchjerker]

Originally Posted by scott.keeley

I'm even more simple. I just hooked up an additional battery in parallel. IS there some significant risk to this? 2 x interstate group 29's...

no but it really defeats the idea of having a spare battery.

You have created one huge battery, but if it happens to go flat you still have no spare.

[scott.keeley]

I was looking for combined reserve capacity to run 3-4 graphs and pumps all day and still have the required cranking power. Jumper cables along "just in case" but haven't used them. Yet... Just keep an eye on the voltage display on the graph. After about 5 or 6 hours I will drop to 11.8 - 12 volts if I haven't started the outboard. Cranks right up.

[perchjerker]

Originally Posted by scott.keeley

I was looking for combined reserve capacity to run 3-4 graphs and pumps all day and still have the required cranking power. Jumper cables along "just in case" but haven't used them. Yet... Just keep an eye on the voltage display on the graph. After about 5 or 6 hours I will drop to 11.8 - 12 volts if I haven't started the outboard. Cranks right up.

yeah I understand but its still not a spare battery as the original question was about. If one of those batteries happens to take a dump it will take the other one down with it.

[Slabomania]

I have a Ranger 680 so I only have room for 2 batteries. I have a 24 volt Terrova 80 lb. trolling motor so all I can do is get the largest batteries (Group 31) and carry jumper cables, which I have had to use a few times, but haven't been left stranded yet.

[walleye.bill]

I went with the blue sea star add a battery pack. Comes with automatic charging relay and battery switch. Really not as difficult as it sounds and for $100 and piece of mind it was well worth it.