Different Types of Batteries in a Dual Battery System?

[coax]

Hi All,
I am getting ready to install a dual battery system, and in the planning/research stage. I am going to go with the Blue Sea 7622 as it will provide a good deal of functionality for the price, fairly straight forward installation, and I can leave my winch set up as-is. However, one thing this Blue Sea ACR doesn't do is charge the batteries separately. They are either isolated or in parallel.

Given this, I am wondering what my options are for the type of second (house) battery. I already have a Diehard platinum as the starting battery. A better type for the house battery would be a deep cycle, but do I need to worry about a constant charge/discharge between the two batteries when in parallel? Or will the higher charge voltage coming off the Alt. negate that?

Basically just wondering if it is a "better/more reliable" setup to go with two identical batteries and the downside of running a starting battery as a house battery that has the potential to be deeply discharged and thereby reducing its life?

Sorry if this has been discussed before.

Thanks
Corey

Edit: after some more reading, it seems that some are of the oppinion that the DHP auto and marine batteries are the same internally. Sears even lists the Auto batteries as a deep cycle. In that case, it might be much simpler to just go with the same Auto DHP??

 

[4x4junkie]

A recent similar thread here

Having two different types/sizes/age batteries shouldn't be an issue during charging, it's when leaving them permanently in parallel all the time where issues could arise.
As long as both are 12V lead-acid types (flooded, AGM, both) you should be fine with whatever you want to get.

 

[dwh]

Edit: after some more reading, it seems that some are of the oppinion that the DHP auto and marine batteries are the same internally. Sears even lists the Auto batteries as a deep cycle. In that case, it might be much simpler to just go with the same Auto DHP??

IIRC, the DHP is actually a re-badged EnerSys Odyssey:

http://www.odysseybattery.com/

The Odyssey is a bit of a strange beast. It is apparently made with a bunch of thin plates, which would normally be considered a cranking battery design and definitely not recommended for any sort of deep discharging, but it seems Odyssey batteries can be used for deep discharge (deep cycle) even though they are made with thin plates.

On the surface, the thin plate design would make it appear that they might not last as long under true deep cycle use as a battery designed for deep cycle (thick plates). From this page:

http://www.odysseybattery.com/batteries.html

"And they can handle 400 charge-discharge cycles to 80% depth of discharge."

But in fact, 400 cycles to 80% DoD is very close to the published numbers for Lifeline deep cycle batteries:

http://www.bdbatteries.com/images/lifelinelifecycles.jpg



So yea, go ahead and use the DHP/Odyssey for deep cycle. It's made for it.


EDIT: But in general, it's a bad idea to deeply discharge any cranking (thin plate) battery other than the Odyssey.