Would like to hear some general thoughts, pros, or cons on dual battery set ups.  I'm currently running two light bars and have considered a sound system. The operating voltage on my front bar is 10-30 volts and 10-20 on the rear if I remember right.  Haven't  decided on a sound system yet... Am I approaching territory in which I should run a dual battery set up if the sounds are added?

[2015 Z Force 800 53/Trail EPS]

It's when you approach or exceed 15 amps of draw when you need to consider...something. Your stator only has that 15 amp extra after all other factory draws are being used. After that your draw or load exceeds what the stator can put out at 3-5K RPM. Having a dual battery then only slows the pull-down...and also slows the recharge. I found that LED light bars don't pull as many amps as one would think so keep that in mind. I would suggest getting a meter that can actually show the DC amp draw being used by your accessories and just total them up....and stay under 15 amps. Also keep in mind if you don't use stuff like the OE headlights, that 6 amps or so can be used elsewhere or added to that 15.  One other thing to consider is voltage. You have some components such as the ECU that needs stable voltages. If it swings from 11-14 all the time you are asking for failures of some expensive equipment also consider the stresses on a charging system that is maxed-out most of the time. So, its to your benefit to watch what you add on and don't over do it.

Good food for thought! My knee jerk reaction would be that sounds like a great idea, however you're right. They are only made to recharge the OE and 15A worth of extras. Sounds like to run a dual battery setup you'd need a larger generator/alternator, voltage regulator and probably a capacitor if running the batteries in parallel.

[2015 Z Force 800 53/Trail EPS]

Well, nothing wrong with having a dual-battery setup. Gives twice the storage capacity but won't side-step an over-load issue, only takes longer to drain two batteries over one. If you think of it like a 5 gallon bucket with a 2" valve on the bottom and a garden hose on top filling it. The 2" will let water out way faster wide open then the hose can fill.. but don't exceed the rate of filling and the level can be maintained. Now do the same for a 10 gallon bucket...same 2" valve and same hose. Same thing happens it just takes longer to drain-off 10 gallons of water then 5...it also takes longer to re-fill the 10 gallon bucket then the 5 as well. What the charging system..or garden hose.. can put out doesn't change, only what is stored with two batteries.

Well, nothing wrong with having a dual-battery setup. Gives twice the storage capacity but won't side-step an over-load issue, only takes longer to drain two batteries over one. If you think of it like a 5 gallon bucket with a 2" valve on the bottom and a garden hose on top filling it. The 2" will let water out way faster wide open then the hose can fill.. but don't exceed the rate of filling and the level can be maintained. Now do the same for a 10 gallon bucket...same 2" valve and same hose. Same thing happens it just takes longer to drain-off 10 gallons of water then 5...it also takes longer to re-fill the 10 gallon bucket then the 5 as well. What the charging system..or garden hose.. can put out doesn't change, only what is stored with two batteries.

amps/volts is not my thing; now those 5/10 gallon buckets I can understand Thanks for the simple/stupid..helped me!

Well, nothing wrong with having a dual-battery setup. Gives twice the storage capacity but won't side-step an over-load issue, only takes longer to drain two batteries over one. If you think of it like a 5 gallon bucket with a 2" valve on the bottom and a garden hose on top filling it. The 2" will let water out way faster wide open then the hose can fill.. but don't exceed the rate of filling and the level can be maintained. Now do the same for a 10 gallon bucket...same 2" valve and same hose. Same thing happens it just takes longer to drain-off 10 gallons of water then 5...it also takes longer to re-fill the 10 gallon bucket then the 5 as well. What the charging system..or garden hose.. can put out doesn't change, only what is stored with two batteries.

I HAVE IN MY Z8 , SOUND SYSTEM , 2 LED BAR , STROBOS, AND MARINE RADIO , SO I HAVE PROBLEMS WHEN I STOP  FOR A WHILE , I CAN'T RUNNING THE Z8 AGAIN I NEED POWER FROM ANOTHER CAR, SO MY QUESTION IS CAN I GET A LARGE GENERATOR/ALTERNATOR, OR I NEED TO REDUCE THE ACCESORIES. LESS AMP.

[2015 Z Force 800 53/Trail EPS]

Well, nothing wrong with having a dual-battery setup. Gives twice the storage capacity but won't side-step an over-load issue, only takes longer to drain two batteries over one. If you think of it like a 5 gallon bucket with a 2" valve on the bottom and a garden hose on top filling it. The 2" will let water out way faster wide open then the hose can fill.. but don't exceed the rate of filling and the level can be maintained. Now do the same for a 10 gallon bucket...same 2" valve and same hose. Same thing happens it just takes longer to drain-off 10 gallons of water then 5...it also takes longer to re-fill the 10 gallon bucket then the 5 as well. What the charging system..or garden hose.. can put out doesn't change, only what is stored with two batteries.

I HAVE IN MY Z8 , SOUND SYSTEM , 2 LED BAR , STROBOS, AND MARINE RADIO , SO I HAVE PROBLEMS WHEN I STOP  FOR A WHILE , I CAN'T RUNNING THE Z8 AGAIN I NEED POWER FROM ANOTHER CAR, SO MY QUESTION IS CAN I GET A LARGE GENERATOR/ALTERNATOR, OR I NEED TO REDUCE THE ACCESORIES. LESS AMP.

If your Z8 is a non-power steering model, you can replace the 350watt stator and rectifier with the 500 watt system. If your Z8 has power steering, then you already have the 500 watt stator and that extra is needed for the power steering so...you will need to reduce your extra accessories to less then 15 amps. Even then without running any power usage will drain the battery over time...like leaving the lights on.

Well, nothing wrong with having a dual-battery setup. Gives twice the storage capacity but won't side-step an over-load issue, only takes longer to drain two batteries over one. If you think of it like a 5 gallon bucket with a 2" valve on the bottom and a garden hose on top filling it. The 2" will let water out way faster wide open then the hose can fill.. but don't exceed the rate of filling and the level can be maintained. Now do the same for a 10 gallon bucket...same 2" valve and same hose. Same thing happens it just takes longer to drain-off 10 gallons of water then 5...it also takes longer to re-fill the 10 gallon bucket then the 5 as well. What the charging system..or garden hose.. can put out doesn't change, only what is stored with two batteries.

I HAVE IN MY Z8 , SOUND SYSTEM , 2 LED BAR , STROBOS, AND MARINE RADIO , SO I HAVE PROBLEMS WHEN I STOP  FOR A WHILE , I CAN'T RUNNING THE Z8 AGAIN I NEED POWER FROM ANOTHER CAR, SO MY QUESTION IS CAN I GET A LARGE GENERATOR/ALTERNATOR, OR I NEED TO REDUCE THE ACCESORIES. LESS AMP.

If your Z8 is a non-power steering model, you can replace the 350watt stator and rectifier with the 500 watt system. If your Z8 has power steering, then you already have the 500 watt stator and that extra is needed for the power steering so...you will need to reduce your extra accessories to less then 15 amps. Even then without running any power usage will drain the battery over time...like leaving the lights on.

thanks for your quick answer.

The reality is if you are going to run dual batteries you NEED a battery separator.  I have run them for YEARS and when i put a second battery in the CF moto it will get one also.  What it does is when the main battery is at 13.2v it will then connect the aux battery to the main.  If the voltage of the aux battery drops below 12.8v then it will disconnect the aux from the main battery.  This protects your charging system and the main battery.  You connect ALL of your accessories to the aux battery only.  This ENSURES you will always have a good battery to start your rig and get you home no matter what.  They are only about $55 and worth every penny.  Plus they have a feature (if you hook it up this way) that when cranking it connects the batteries to give you the max power for starting.  Here is a link to part.  IMO if your running ANYTHING off road or away from help/a shop with dual batteries you need one of these.

http://www.allbatterysalesandservice.com/browse.cfm/4,2706.html