well all i can give you is my experience so take it as you may. I am currently running 3 XS Power XP950 batteries isolated from the stock gel battery in my Highlifter and it works great. I am using a TRU Isolator and it functions absolutely perfect.
I personally have the winch connected to my starting battery along with all of the stock stuff that comes with it and all aftermarket lights and stereo stuff is running on the other 3 batts.

Maybe your isolator isn't up to snuff.

Also the reason I chose to leave the winch on the starting battery is because I don't use the winch all the time and the starting battery is always being charged unlike the other 3 that only charge when the starting battery is past a certain voltage.

 

Go with a TrueAM isolator they are the best you can buy. The kit we sell below has 2 gauges so you can monitor the voltage in ea battery. So if you are having a problem with 1 of them you will be able to see it before its too late.

TrueAm TRUE UTV-SBI-15 Isolator kit

 

I kept my winch on the primary battery and have my light bar and audio system running off the second. As mentioned twice already, the True isolator is the real deal. Mine has been underwater many times and works like a charm. I talked to the owner of the company and he said if it ever messes up, even after the 1yr warranty, call him and he'll replace it.

 

I intend to run dual batteries on my 570LE. The OEM battery is still working fine and I was considering the Deka ETX30L as the second battery. I plan to run all accessories off of the Second battery which will be isolated from the First battery by the TrueAM isolater. My OEM is a 30aH but is 3 years old. I'm considering making the OEM battery the Second one and using the Deka ETX30L as the main/starting battery.

Does anybody think this a good plan or should I use the Deka as the second battery? How do these batteries handle constant discharging before they are charged up again when operating the RZR? I'm planning to hook up a front light bar and 2 rear LED lights, a horn, and AUX for things like a phone or GPS or even a small sound system. I doubt I'll run the accessories much when the machine is turned off but I don't want a drained starting battery.

Sorry for all of the questions but I'd like some observations from those of you who have been down this road before.

 

I really prefer to match battery's I've got two 30's in my rzr 800 but mine are in parallel so matching is more important cause a older weaker battery will drag down a new battery

With dual 30 ' s I've got close to 800 cca and when I pull with my winch it's much stronger pulling an no more bogging down

 

Finally going to upgrade to dual batteries as my stock one kicked the bucket. Any suggestions on which two batteries to use with the isolator? Putting one in the stock location and the other in the empty slot next to in in an XP1000. Have always switched to AGM when replacing, but the lithium ones have come down in price, just don't seem to offer the deep cycle characteristics.