Mixing Batts on Dual Battery setup

[Harrison256]

I've got a dual battery setup on my tahoe and one of the AC delcos from the factory just went rotten egg on me. I'm looking at replacing the batteries and wanted to see first, if I can run an Optima Yellow top and an AC delco battery (im guessing not), and second if I can run an Optima Yellow Top and an Optima Red Top together.

 

[DCT]

I don't think the batteries have to be identical. I can't think of a reason why they need to be. How would the electrical system know the difference?

 

[sparks]

for safety, ALWAYS use identical batteries when doing a multiple battery setup. when they are mismatched, they could have different amp out put capabilities, as well as different discharge rates and things like that cause really bad things to happen. theres a lot of technical things that come into play here but the bottom line is that its a big NO NO.

---------- Post added at 09:57 PM ---------- Previous post was at 09:52 PM ----------

a more technical link to reinforce what I stated earlier:

http://www.caraudio.com/forums/wiri.../398527-dual-battery-wiring-tutorial-why.html

 

[DCT]

I meant they don't have to be identical brands. As long as both batteries have proper specs, it should not make a difference. I don't recall identical brands being referenced in the owners manual. Definitely don't use a GM spec battery and one from a Honda Civic.

 

[08grey]

Ideal senario is to be the exact same battery made within the same run as the other. You can see the run code on the battery. This will ensure the long life of this install. Anything else will die prematurely.

If you already have a optima put it up for sale on Craigslist or something and take that money and get two diehard battery's. or the green ones ever state or something. They will last you forever

Remember same battery same run.

Energy will always follow the path of least resistance. You want to have a level playing field. In every race there is a desire for the faster lane.

 

[Sub]

It depends on how the dual batteries are wired.

Are they paralleled always? Or are they separated at times?

If separated, is the second battery hot in crank? Or only hot in run?

Is the second battery for running auxiliary loads while the engine is off? (big stereo?)

If so, and if both batteries are hot in crank, then there could be a problem. But that problem would exist anyway if you discharged the second battery (even if an identical battery) all the way down to 11 volts during a tailgate party.

Bottom line: You CAN run two entirely different type of 12 volt batteries if wired correctly.

1. Use an automotive grade, continuous duty, high current rated, diode suppressed solenoid, not those isolators they sell at stereo shops.

2. Wire the solenoid so that it parallels the batteries only in RUN.

3. Do NOT wire the solenoid so that it parallels the batteries in Start.


If the second battery is severely run down, then your main battery won't try to instantaneously equalize it's own charged potential with the uncharged potential of the drained battery (huge current rush) while at that same time trying to start the engine.

Get the engine started first, then while the alternator is spinning, bring the second battery back online to get charged. (This all happens instantaneously).

GM offered dual batteries in some gasoline powered Tahoes... like the PPV police Tahoe. GM used two different sized batteries in that package in 2003-2006 (the only years I know about). GM wired them to avoid problems with using two different sized batteries.

It is not a problem using two different size batteries. OEM's do this all the time. Look at motorhomes with deep cycle "house" battery banks, and then a separate, differently sized engine starting battery. The problem is not having two different sized batteries. The problem is the installation practices in the aftermarket.

The diesel pickups need two batteries to start the engine in cold weather, and those two batteries are paralleled in start, because they are needed at START, and thus are exactly the same size, and should be about the same age, same chemistry, and same ampacity.

People that add second batteries to their gasoline vehicles following the diesel installations as a pattern for the wiring are not doing themselves any favors. If the gas engine doesn't need two batteries to start (it doesn't), then why wire it in such a way that you can't take full advantage of being able to deplete the auxiliary battery without worrying about bringing down the main battery at start?

 

[DCT]

Dropping knowledge. I learned something today. I've been wanting to add the OEM dual battery set up in the Suburban. Thank you.

 

[Harrison256]

It depends on how the dual batteries are wired.

Are they paralleled always? Or are they separated at times?

If separated, is the second battery hot in crank? Or only hot in run?

Is the second battery for running auxiliary loads while the engine is off? (big stereo?)

If so, and if both batteries are hot in crank, then there could be a problem. But that problem would exist anyway if you discharged the second battery (even if an identical battery) all the way down to 11 volts during a tailgate party.

Bottom line: You CAN run two entirely different type of 12 volt batteries if wired correctly.

1. Use an automotive grade, continuous duty, high current rated, diode suppressed solenoid, not those isolators they sell at stereo shops.

2. Wire the solenoid so that it parallels the batteries only in RUN.

3. Do NOT wire the solenoid so that it parallels the batteries in Start.


If the second battery is severely run down, then your main battery won't try to instantaneously equalize it's own charged potential with the uncharged potential of the drained battery (huge current rush) while at that same time trying to start the engine.

Get the engine started first, then while the alternator is spinning, bring the second battery back online to get charged. (This all happens instantaneously).

GM offered dual batteries in some gasoline powered Tahoes... like the PPV police Tahoe. GM used two different sized batteries in that package in 2003-2006 (the only years I know about). GM wired them to avoid problems with using two different sized batteries.

It is not a problem using two different size batteries. OEM's do this all the time. Look at motorhomes with deep cycle "house" battery banks, and then a separate, differently sized engine starting battery. The problem is not having two different sized batteries. The problem is the installation practices in the aftermarket.

The diesel pickups need two batteries to start the engine in cold weather, and those two batteries are paralleled in start, because they are needed at START, and thus are exactly the same size, and should be about the same age, same chemistry, and same ampacity.

People that add second batteries to their gasoline vehicles following the diesel installations as a pattern for the wiring are not doing themselves any favors. If the gas engine doesn't need two batteries to start (it doesn't), then why wire it in such a way that you can't take full advantage of being able to deplete the auxiliary battery without worrying about bringing down the main battery at start?

Perfect! That answered any question I could ever have regarding my battery setup/setups in general. I actually have the Tahoe SSV so it sounds like I have the setup that GM did accommodating for different voltages so should be good to run the cranking and deepcyle together then after I verify. Thanks for the knowledge