Two batteries, different ratings

[zeitgeist]

I am buying a Catalina 270LE and was inspecting it when I discovered the two batteries in the bank are rated differently. I've read before that batteries shouldn't be different ratings or ages, but how different is bad? They are very similar, they both look new, and bottom line is I would hate to have to toss them out and buy two brand new batteries... but then again, I would hate even more to be damaging them or other systems on the vessel.

The specs, battery #1 (WestMarine): Model 15020316, MCA@32F = 615, RC 130, Ah@ 20hr = 75

#2: Model 15020183, MCA = 675, RC = 120, Ah = 65

I don't know if these are significant differences, if there is a solution that doesn't require tossing both batteries or if I can keep one or both? Maybe I could transfer one to a different purpose and separate them?

[donradcliffe]

The operative word is "shouldn't", not "can't". Combining the two batteries you have will not damage anything. People who tell you otherwise are simply misinformed.

If the battery bank gets too weak to meet your needs, you "should" replace it with batteries of similar characteristics.

[ranger58sb]

Originally Posted by zeitgeist

I am buying a Catalina 270LE and was inspecting it when I discovered the two batteries in the bank are rated differently.

Are they really in "the bank" (the same bank)?

Would have expected the boat would have a start bank and a house bank... and it's not impossible a "bank" is made up of only one battery.

-Chris

[Stu Jackson]

ranger could be right. Have you looked in their catalog? One could be deep cycle and the other start technology.

[PommyDave]

Starting batteries are usually rated in Cold-Cranking Amps, while deep-cycle batteries are rated in Amp/hours.

Cold Cranking Amps (CCA) CCA is a rating used in the battery industry to define a battery's ability to start an engine in cold temperatures. ... The rating refers to the number of amps a 12-volt battery can deliver at 0°F for 30 seconds while maintaining a voltage of at least 7.2 volts.

The normal storage battery rating is the AMP-HOUR RATING. This is a unit of measurement for battery capacity, obtained by multiplying a current flow in amperes by the time in hours of discharge. (Example: A battery which delivers 5 amperes for 20 hours delivers 5 amperes times 20 hours, or 100 ampere-hours.)

[zeitgeist]

Thanks for all the input so far, I am less worried about them now. I also need to buy a new battery charger and it seems that the new models have a feature that monitors individual battery levels and maintains them individually. (such as This one

The first is listed as a "Deep Cycle Flooded Marine Battery", the second is listed as a "Deep Cycle Dual Purpose Marine Battery"

I did not verify if the batteries were connected in series, parallel, or separately; they are located next to each other in the same forward compartment, underneath a bench seat.

[ranger58sb]

Originally Posted by zeitgeist

I also need to buy a new battery charger and it seems that the new models have a feature that monitors individual battery levels and maintains them individually.

The first is listed as a "Deep Cycle Flooded Marine Battery", the second is listed as a "Deep Cycle Dual Purpose Marine Battery"

I did not verify if the batteries were connected in series, parallel, or separately; they are located next to each other in the same forward compartment, underneath a bench seat.

You'll want to understand wiring before deciding how to proceed.

And if they're connected... you'll want to understand whether it means you've got a single combined start/house bank... or whether you haven't found the start (or house) battery yet.

You might be better served by the ProNautic line of chargers, if you choose to stay with the ProMariner brand. (FWIW, Sterling mostly sells the same products, slightly different names.)

-Chris

[thomm225]

When I first bought my boat, I wanted to get the engine started first so I ran over to Walmart and got a car battery ($75.00) to start the old diesel.

This in 2011.

The diesel failed a month or so later as did another junker diesel I installed.

I then installed a new outboard on a bracket with pull start and no alternator.

I then installed a 100 Watt Solar Panel with controller and bought an Interstate Deep Cycle Flooded Battery.

I hooked the Deep Cycle Battery in parallel with the Walmart Car Battery. This served as my "House Bank." The solar charged the batteries.

The Interstate Deep Cycle Battery failed after 5 years. The Walmart battery is still installed along with a Deep Cycle Battery I got from Advanced Auto.

My goal is two deep cycle batteries in parallel of the same type, but I hate to get rid of something (the Walmart Car Battery) that's working.

[LLizzard]

Is there a battery red switch with "1", "2", and "All" or "Both"? If so you have 2 banks, one for starting and one for house. That's why there are 2 different types of batteries, one a starting/ deep cycle and one a true deep cycle. Don't overthink it, if the charger works keep it.

[thomm225]

Originally Posted by LLizzard

Is there a battery red switch with "1", "2", and "All" or "Both"? If so you have 2 banks, one for starting and one for house. That's why there are 2 different types of batteries, one a starting/ deep cycle and one a true deep cycle. Don't overthink it, if the charger works keep it.

The switch means absolutely nothing.

It's all about how it's hooked up.

Now I'm getting worried about folks that have zero knowledge of electricity or electronics especially on a boat.

[Doug4bass]

Originally Posted by thomm225

The switch means absolutely nothing.

It's all about how it's hooked up.

Now I'm getting worried about folks that have zero knowledge of electricity or electronics especially on a boat.

Meooooow........

[thomm225]

Originally Posted by Doug4bass

Meooooow........

Ruff-Ruff, ruff, ruff, ruff.............