Question about alternator/batteries

[95Prober 10+ year member]

Hi

I have an Optima D34 under my hood connected parallel to a second gel cell battery in the trunk. My alternator is stock so I was wondering, is there a lot of extra stress on the alternator to keep both gel cells charged? Or does the Optima get charged the most and the second battery gets juice just when needed?

Both batteries had optimum voltage readouts when installed

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[smoka 10+ year member]

Since there is no isolator installed, both batts get charged/discharged at the same time. They will also charge/discharge each other if for some reason their voltages were different.

 

[95Prober 10+ year member]

Since there is no isolator installed, both batts get charged/discharged at the same time. They will also charge/discharge each other if for some reason their voltages were different.

So is an isolator recommended ?

and since the alt. is charging both at the same time, does that mean the alt. can burn out faster/easier?

 

[loopkiller 10+ year member]

You have to be very careful with gel batteries. They are very fragile when compared to other battery technologies. And to be absolutely clear here, Optima is an AGM battery, not gel.

Now to answer your question directly, yes adding additional batteries is an additional load for your alt. Is it a small addition or a large addition is the real question that you should ask.

Two Optima batteries would have a relatively small ESR compared to a single flooded battery. So in that sense, the two AGMs would present a smaller load. But, if you drained both of the Optima batteries with the key off, then started the car, they would for sure draw much more than your single flooded battery. So in this case, yes they would be a much larger load.

Sometimes questions are not as simple as you would like them to be. It is not a black/white question. It depends on many other factors.

 

[TnT_Sounds 10+ year member]

I know guys who used to run 6 AGM batteries off the stock alternator for years with no problems..

They always told me more batteries is better than no batteries on a stock alternator. Its actually easier on your entire electrical cuz your not constantly pulling current from one battery but from multiple.. And daisy chained altogether one battery discharges another and the alternator charges up the one which charges up the rest.

I'm sure you'll be fine until you start needing to meet high current demands from your alternator.

 

[loopkiller 10+ year member]

I know guys who used to run 6 AGM batteries off the stock alternator for years with no problems..
They always told me more batteries is better than no batteries on a stock alternator. Its actually easier on your entire electrical cuz your not constantly pulling current from one battery but from multiple.. And daisy chained altogether one battery discharges another and the alternator charges up the one which charges up the rest.

I'm sure you'll be fine until you start needing to meet high current demands from your alternator.

That is true to an extent. Your current demands of your electrical devices determine your load for the most part, but batteries in general also self discharge as well. So the more batteries you have self discharging, the more load you will see at the alt as well. It is a minor thing, but if you want to talk exacts, there you go.

 

[TnT_Sounds 10+ year member]

Of course.

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[badvlvo 10+ year member]

I know guys who used to run 6 AGM batteries off the stock alternator for years with no problems..
They always told me more batteries is better than no batteries on a stock alternator. Its actually easier on your entire electrical cuz your not constantly pulling current from one battery but from multiple.. And daisy chained altogether one battery discharges another and the alternator charges up the one which charges up the rest.

I'm sure you'll be fine until you start needing to meet high current demands from your alternator.

This has been my experience as well.

Then it was time for a bigger alternator.

 

[95Prober 10+ year member]

So Kinetiks are also "AGM batteries"?

 

[loopkiller 10+ year member]

So Kinetiks are also "AGM batteries"?

Yep. Every car audio marketed battery is AGM.

 

[TnT_Sounds 10+ year member]

Northstar - FTW