2 Optima D31T Commercial Yellow Tops

About three months ago, I purchased two of the new Yellow Top Commerical Deep Cycle Batteries.

The batteries are hard wired in parallel, I was previously running 2 Memphis Mojo, 2 Memphis 16-MC3004 4 channel amps, 17" monitor, 2 7" monitors, av switch box, RF headphones, 400w invertor and PS/2, Pioneer AVIC-N1, 6 disc dvd changer, and a second indash DVD/Tuner for 2nd source for kids. I wasnt really having any problems, until I scrapped the AVIC-n1 for a DC-DC powered Windows XP computer. I have a 250watt Ohio alt for the vehicle, but havent put it into the car yet. The power requirments for the Opus are listed at the end of this message.

On the carputer forums, I'm getting told that my batteries are not big enough. (yeah right) and that my voltage is dropping down below the specs that power supply needs, unlike the car audio equipment, the computer is very regulated on the power being fed to it. So I went and grabed my fluke and checked the voltage at the rear optima (remember they are wired parallel with 0/1 wire and 250amp RF circuit breakers between the +12v poles). With all my amps and accessories powered on, and the car engine running, the voltage at the rear battery is like 11.90 or so, although I seem to remember it was like 14.50volts when I first added the batteries. I never have any problems starting the truck, EVER. 11.50 or so with the engine not running.

SO what have I fried? and any reason why this would have happened since during the last 2 months, the remote turn on has been disconnected so the amps or any of the accessories have not been "turned" on although they have been connected to the batteries? This is a 98 Ford Expedition, before I put the 250amp Ohio ALt in place, I dont want to fry this new altenator if its the original altenator I screwed up, is the voltage regualtion seperate or is there a voltage regulator in the altenators? If it is a fried Altenator was it the strain of the 2 batteries that has handicapped or killed this stock  altenator? Any suggestions would be apperciated. Have I damaged my Optimas? Tomorrow I am going to throw a chanrge on them with the 10/40/200 amp charger at 40amp setting. See how the batteries take a charge and hold it, and how the whole "carputer with amps on" thing goes. The carputer powers on and stays on with the remote on disabled (and all my accessories/amps not powered on), with the engine running and off, but what good is that?

The DC-DC power supply is a Opus 150W, the technical specs are at http://www.mp3car.com/products/SFX_DC-DC_User_Guide-Rev_C.pdf and posted below for your understanding in helping me out here. Thanks

Input 12V

BTW, thanks to everyone in advance...

SD

Im going to get it tested.

I charged the batterys today with a shop charger, 40 amps

Engine running at front 13.9, at rear 12.8 after CHARGING

No isolater, basically wanted the "massive" amount of reserve time.

Driving habits are short 10 mile loops m-f (college) and occasional 40-60 mile weekends, with 1 or 2 200 mile weekends to mother in laws in LA from SD.

I JUST got the carputer in the car, so music has been NONE for the last 3 months. But usually, loud, 2 Memphis Mojo 2400's running 4 Rockford Fosgate Power HX2 (the big ones) in a 10cuft ported enclosure, 2 Memphis 16-MC3004 runing 8" mid bas, 6.5 mids, 1" tweets in each of 4 doors.

It seemed today, after I charged the system manually, that with everything on (it finally all stayed on) that the vehicle was able to barley "keep" up with the draw.  With the engine running, and everything on, the rear battery DMM reading was 13.40 or so, once the engine was turned off, that number droped to 12.5-12.6 or so. Then started slowly dropping, once I let it drop to 12.0 and fired up the engine, it charged at like 12.2 with everything on, once I turned off all the stereo, it jumped back up to 14.05

Its all over the place, I've got the 250 amp Ohio, so I am going to install it Saturday, basically everything I complained about the day before was GONE once the truck batteries were fully charged via external charger, seemed once they were charged, they managed to stay charged, its only after they are drained for some time that the system seems to NOT be able to recover fast enough?

Im going to go at it again, Ill keep details posted. Thanks for your help? Any more comments? Thanks

So, connecting everything to the 2nd battery and issolate the front one for starting purposes? Or are you talking about using a issolator that will allow each battery to run the system but never at the same time? I've seen users add a battery isolator to there systems so the sound system could not drain the front battery and so that the charging system charges each battery seperate. Care to offer some suggestions on method, as well as products that could help here.

Not trying to steal limelight on this thread, but I have an interest in what you have stated Teken, not for any doubtful reasons, just questioning of my own knowledge now, lol.

Yellow Tops are a deep cycle battery, which in turn are not made to be charged by an alternator, The purpose of a deep cycle battery is to be drained and recharged, and not a constant current pull and quick recharge, which can damage the cells in a deep cycle, as where your standard car battery is designed for this situation.

This is reasoning for us dealing strictly Red Tops for vehicles and Yellow and Blue Tops for marine applications. Optima will not warrant any Yellow or Blue tops in an alternator charging system. We have had a situation where we used a yellow top in a car and they would not warrant it. 

Now, lol, with that having been said as my understanding, where am I off basis in your knowledge of the design of these batteries? I am just going by what our Optima representative has informed us, though not saying that he is 100% correct, this is why I am questioning.