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Old    kschroeder            03-09-2003, 5:19 PM Reply   
Hey all, I recently installed a system in my '02 SAN. I took it out for the first time this weekend and got stuck with a starter battery below 12volts. It was real strange I wjust got done with my first run, came in and told the driver to turn off the engine. About 10 minutes later we went to start it up and no dice. We had the stereo playing at a moderate volume the whole time while I was getting in and while trying to start the first time. I thought I had taken all the neccessary precautions to prevent this but apparently I am missing something. I am using the cheap $15 stinger isolator to prevent starter battery drain, which could be part of the problem. I'd read in other posts about how solid state isolators drop your voltage. Anyway Here is a power diagram of wiring. I'd appreciate any input from someone who know what they are talking about or has any good suggestions. Thanks...
Power Diagram
Old    tabiggs            03-10-2003, 8:31 AM Reply   
Isolators are funny, I have experienced the same thing you have in my truck, You might want to go with a switch, position 1,2, and all. They sell these at marine stores, This way you control the power and charging arrangement..

I have 7 dry cells that power and stereo system with a high current alternator and this setup works the best..

Hope this helps
Old    wakeman456            03-10-2003, 11:33 AM Reply   
I agree with Tom, use two batteries and install all the stereo equip. only to one battery, that way you'll have one batery always with power to start the engine and to recharge the drain one (the one for the stereo)
Old    kschroeder            03-10-2003, 11:39 AM Reply   
I think I need a more sophisticated isolator is the problem. The relay type I have still bridges the two batteries when the ignition is started. That initial cutover I believe put all my load on one circuit between the two batteries, i.e. stereo and iginition all in one burst and it drained put my starter below 12v. So I think if I get an isolator that always keeps the batteries seperate wether it is in ignition or not that should solve my problem. Although the switches would be effective I dislike the idea as human error is beyond my control.
Old     (salty87)      Join Date: Jul 2002       03-10-2003, 3:28 PM Reply   
did you splice into the switched wire off the alternator for the isolator? if you didn't get the right one, the isolator might not charge either battery.

got multi-meter?
Old     (csquared)      Join Date: Jan 2002       03-10-2003, 4:05 PM Reply   
I don't mean to question the obvious, but were the batteries new and/or fully charged before your went out? If it was the first run of the year, it just may have been a low battery that didn't have time to charge during your first run, especially if you did some testing with the stereo before hitting the water...just a thought
Old     (bob)      Join Date: Feb 2001       03-10-2003, 4:43 PM Reply   
dont most of the cheaper isolators just have 1 input (hot+) and two outputs(+) to the batterys?
Oh also if you wired into the ignition circuit AND NOT AN ACCESORY CIRCUIT then yes both batterys were probably coupled and you were draining both BUT surely you dont think you drained two fully charged batterys with a 550 and 750 watt amps in only 10 minutes?
Old     (sdub)      Join Date: Jan 2003       03-10-2003, 4:49 PM Reply   

I been looking at your diagram. Shouldn't the alt. positive go directly to the isolator, and the starter feed go directly to starting battery? In your diagram, those are reversed.
Old    kschroeder            03-11-2003, 3:49 PM Reply   
My accessory battery is new my starter is only a year old. We rode around from probably 20-30 minutes before I took a run. The isolator I have is merely a relay so there is no one in and two out. It is merely a bridge of my positive channels between the two batteries, which is what I think caused my problem. The alternator positive goes to my starter battery, my starter to isolator Pos #1 then out Pos #2 on the isolator to my secondary battery positive. The ignition wire is merely a signal we spliced from one of my guages that get power when the igntion is turned on.
Old     (joesell)      Join Date: Apr 2001       03-11-2003, 5:25 PM Reply   
Ken, I have the exact same set-up that you have. I don't think it's the isolater. Just because a battery is new doesn't mean it's good. If you have a multi-meter check the voltage at each batt. You might have a bad or dead batt. The only difference in how we ran our isolaters is the ignition wire. I'm running off a wire at the key. You have to check what wire is hot when the key is on. Hope this helps, Joe
Old    kschroeder            03-12-2003, 1:37 PM Reply   
Yes I have a multi-meter. I have tested both batteries and they are both fine. The isolator turns on and off properly when the key is on or off.
Old     (cyclonecj)      Join Date: Jul 2001       03-12-2003, 2:53 PM Reply   
It sounds as if you were running everything including the ignition off battery power and the alternator was not charging either battery. It would only take 30 min or so to drain both batteries. The isolator should be on and voltage at each battery should be roughly 14.4 vdc -.7 vdc (13.7vdc or so) when running. When not running, they should be 12.7 vdc or so with no drain. Check the output from the alternator when running to get a reference voltage, ideally it should be 14.4 VDC. Make sure that the terminal to the isolator on input is hot when the key is in the RUN position, not the START position. Got to be something simple.
Old     (bob)      Join Date: Feb 2001       03-12-2003, 4:32 PM Reply   
Psyclone?? so let me get this clear two batterys will only power the two amps for 30 minutes so?? Ive run my system, 600.4 @ 600 watts rms and 400.4 @ 200 watts rms for over two hours and probably closer to 3 hours without charging the ONE batt back up and it was up loud, it was july 4th and there was a small party goin on. Of course this was with a red top.

(Message edited by bob on March 12, 2003)
Old     (cyclonecj)      Join Date: Jul 2001       03-12-2003, 9:16 PM Reply   
I was looking at the symptoms and thinking that the alternator may not have been connected to the batteries during run condition, so both batteries, or possibly only one, were powering the amps AND the ignition and everything else for as long as they could. Just the amps, probably a heck of a lot longer than 30 min, but fuel injectors and computers and spark plugs and all those damn sensors and servo driven gauges and electric fuel pumps, ballast pumps, etc. hair dryers, tube blower uppers, dvd players on the tower, etc. use a lot of amps. He said that he took the boat out for a run, (how long?) and then parked the boat and ran the stereo for ten minutes. After that, it wouldn't crank. If the batteries were combined via the isolator and weren't getting charged the whole time, they could both have been drained. If the relay isolator was energized while running with or even without an alternator charge input, and one battery was dead, the good one could have discharged into the dead one, resulting in two mostly flat batteries relatively quickly, that's why diode isolators can be useful, they wouldn't allow that cross charge to take place, they are one way switches. Relay isolators and mechanical switches are cheap and work well but should't be used when combining dissimilar batteries, i.e. deep cell and starting battery. If the stereo was running when the boat was parked, was the isolator powered up and combining the batteries? The isolator should turn off when the engine is not running, and not be energized in the "accessory" position if the aux battery is supposed to be isolated.

Easy to troubleshoot, start the boat, check the voltage on each battery, should be pretty close to equal to the alternator output and more than 13vdc. If one battery is not, charge it for a while with the engine or a charger, and check again. Turn on a load like a ballast pump or stereo amp, the voltage should drop a little but not below 12vdc or so, both batteries. Check the voltage drop across the contacts of the relay, it should be virtually nothing, way less than .1 volt under load. Kill the engine and the isolator should deenergize, disconnecting the starting battery. Measure the voltage from common to each side of the isolator. The voltage on the aux battery should drop a bit when you turn on pumps, etc. The voltage on the starting battery should stay the same, and remain higher than that of the aux battery. That means that the isolator is doing it's job. Relays will still allow bad stuff to happen when one battery or the alternator fails. Diode isolators will cause batteries to fail over time due to undercharge, and use up a lot of voltage to turn on and off.
HellRoaring isolators use a solid state relay, they combine the best features of both types of isolators, one way energy transfer and very low voltage drop, so no battery damage. They are expensive (140$) but so are my weekends! I don't sell 'em or anything, I paid retail for mine. Heard about them here on Wakeworld.


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