Finally had my slant breathing life again, unfortunately it was rather briefly. My ignition/electrical consists of two optima batteries separated by an isolator, 100 amp alternator, and an MSD 6A and blaster2 coil. All stock accesories run off the "stock" battery (driver side batt) and the MSD, radio, and a host of other things run off my auxillary battery (pass side batt) When I finally got her running, after about 5 minutes the auxillary battery began boiling battery acid out of it's vents. Shut down, tried to find a short, restarted (no short found). This time she would not fire, and smoke began billowing out of the MSD Yes, I know the ignition is likely toast. The only explanation I can think of is when I primed the oil pump & bearings by turning the engine over w/ no plugs, I saw the coil arc from the output to the negative terminal a few times. As the coil negative wire goes to the MSD, and the MSD is grounded directly to the aux battery, I figure this arcing current from the coil fried the MSD and boiled the battery. Does this sound like a plausible explanation or is there something I missed? Aux batt has 12.3 volts by itself, stock batt has 11.8 volts by itself (it did a lot of cranking and has not had a chance to charge yet) Both batteries read 13.5 volts when the engine was running.



-S/6

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The "Silver Bullet"
87 Ram D150

If you are charging both batteries with same alternator and you are using batteries separately, You have problems. Stock battery seems to need more charging and auxillary battery is full, that makes alternator charging too much auxillary battery and it's boiling. Difficult to explain with my poor english. Mayby You should put batteries together, positive to positive and negative to negative.

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Sorry, my english is not very good

Hmm, your explanation is possible but not sure if its likely. Make sure you have the polarity of the wires to the coil right and not swapped. Thats your first cuplrit.

I wouldn't worry about the alternator charging what battery. As long as the isolator is doing its job its fine. However one thing you do want to make sure of is both batteries have the same ground. Either run a heavy ground wire between the two, or at least make sure each one is grounded directly to the body. Ground loops caused by uncommon grounds can do this sort of thing. I would check "the host of other things" running off the secondary battery to make sure nothing popped there as well when you get things going.

stock battery grounds to both the block and the frame. Aux battery grounds to frame. Block has two grounds, one from firewall to head, one from block to frame. Body is also grounded to frame in three places (bed, cab, and engine compartment).

Isolator checked out OK (ohmeter)

"host of other accesories" includes driving lights, stereo, amp, and MSD. Lights, stereo and amp all go thru the breaker AND have their own fuses...none of them blown. They also all have good continuity (no shorts)

Joug Fin- My starter runs off the 'stock' battery only, and the isolator prevents this battery from draining the auxillary battery. That is why the 'stock' battery is reading low voltage at the moment--the isolator is doing what it is intended to. If I get her running it will charge both batteries, but only if they need it. I still may try wiring the batteries in parallel.

I just find it odd that my batteries are identical, are hooked up thru the isolator to the alternator identically with the same amperage breaker, and the one that boiled is hooked up to the MSD. Unfortunately, I neglected to put a breaker/fuse on the MSD when I installed it (I thought I ran it through the main breaker, but did not. I have already fixed this situation so it does not happen to my new ignition)

I will take a picture of the coil and post it. The plastic 'neck' is almost completely gone directly adjacent to the coil negative terminal (coil wires are hooked up properly)

Incidentally, before this happened I tried a spare 'el-cheapo' coil I had in the tool box (known working) and the MSD did not like it. Truck started but was mis-firing badly. Checked spark and it was weak (dull yellow/white) With the MSD coil spark was very bright blue....

I appreciate all the suggestions. As you can see I have already done quite a bit of electrical debugging and cannot find anything wrong. I am usually pretty adept at finding electrical problems, but this one is going to drive me nuts. The only other thing I can think of at this point is the aux optima may be a defective unit---but I doubt it.

BTW--aren't optima's gel-filled? Where did the liquid acid come from?

-S/6

I overcharged an optima once and it sure wasn't pretty. You could smell the sulphur quite distinctly and it was sputtering its inards out of those two little circular vents. When its inards heat up and it boils everything turns to mush.

This is really becoming maddening. I have tried a new alternator, new voltage regulator, new ignition, new coil, different batteries, new battery isolator, and running the batteries in parallel. Even with the new isolator the aux battery still boils after about 4 minutes of running. I get a voltage spike at the battery around 20 volts or so the voltage drops to 11.5-12 through the entire electrical system, and it will creep back up to 14 volts. (the spike only shows on my analog volt meter at the battery, the gauge in the truck shows a straight drop from 14 to 12 volts) This spike & drop in voltage is not related to engine rpm as it has happened at anywhere between 2000 rpm and idle. The drop in voltage is also very noticable to the ignition as the slant will die if I dont feather the pedal for 2-3 seconds, then everything will resume being fine.

So, ideas on what would cause this volt spike/drop after 4 to 5 minutes of running, and then about every 30 seconds after that? I have fused every positive lead coming off both batteries and have not blown any fuses, nor can I find any shorts.

The only thing that has really changed wiring wise in this truck is the addition of an electric choke....could this somehow be the source of the problem? Is there a test procedure for electric chokes? I have never had one before so I am not even sure how they work, I am guessing an electr-thermostatic coil of some sort.

Any and all help is, as always, greatly appreciated. My slant is just dying to get back on the road She sounds great and actually starts better than my '00 Ram...1 second of cranking, tops, even stone-cold.

-S/6

_________________
The "Silver Bullet"
87 Ram D150

My opinion is still that your only problem is that you are loading differently batteries.

Example: If you have two batteries put serial. So you 24v. and you are using 24v charger. Then you put 12v radio between one battery. That radio, you know, is not using much power. Result is that the other battery is overcharged and other is undercharged. This is real situation and I have found that few times at my work. Mayby it is same situation when You have batteris put parallel. And when I suggested that I was wrong.

I don't know what is best way, put mayby you have to use own regulator for both batteries.

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Sorry, my english is not very good

If you have both batteries in parallel (or with an isolator between the two) you don't need seperate alternators or regulators for each battery. Assuming both batteries are of the same brand/type/age, you are fine. In theory you have double the availible reserve. And when charging, it will take roughly twice as long.

Joug, its a completely different situation then two batteries in series. The issue there is, in your situation, charging two series batteries with one bigger charger.... the ammount of current flow is dictated by the battery of most charge. As the battery that is "fuller" gets to 100% charged, it can't absorb any more current, and current flow essentially stops, leaving the "lesser" battery with less then 100% charged. The only way you can overcharge the "fuller" battery is if you have a "dumb" type charger that tryes to brute-force push as much current as it can through the batteries its charging. Commonly, these type of chargers just force the series batteries to a certain voltage. Let's say the "lesser" battery is only at 11v, for a total of 23. The charger wants 24v, so it keeps forcing current through the loop, eventually overcharging the fuller battery. That is why when charging batteries in series they are supposed to be in equally discharged states, otherwise you are supposed to charge them seperately.

Now for parallel batteries, its a bit different. Lets say you have two batteries in parallel, one fuller and one lesser. Even if you have a brute force type 12v charger, both batteries will be charged at the same time. Although, they will be charged at varying rates because the lesser battery will absorb a bigger fraction of the chargers current. The fuller one will reach 100%, and stop absorbing current. The lesser one will eventually catch up, and everything is fine. If you apply 12v to a battery that is already at 12v, nothing is going to happen becasue there is no current flow. Thats why small 1 A chargers are ok to leave on car batteries indeffinately, and even recomended when storing an unused battery for a long time.

Whew, sorry for the long winded explanation.

Super6, does this spike only occur on the auxillary (battery after the isolator) or do you see it across both batteries? If it is only on the auxillary battery, then the suspects are any load on the auxillary battery or the isolator.

Also, I would recomend on putting anything vital to car operation (you mentioned msd box was on auxillary battery) related on the primary battery incase for some reason the auxillary craps out on you so you can still start your car.

If I were in your shoes, I would move the msd box to the primary battery, disconnect any loads from the secondary, and run the car to see how things go. Let the isolator do its job, watch the voltage at both batteries, and let them charge up. If all is well, then one by one add the accessories back to the auxillary and see what happens.

Btw, when you said new ignition, did you get the msd box replaced or did you revert back to stock (points or mopar electronic) ? I would be quite suspect of an msd box that went up in smoke

That's true Pierre. After I wrote that I thought it also. I was just woken up and not thinking it.

Joug

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Sorry, my english is not very good

Pierre-

Will try moving MSD power to main battery. I have always had the MSD hooked up to the aux, and the truck would still start with the aux battery dead before (alt put out enough to trigger the MSD during cranking) But I think I have exhausted other options.

I replaced the 6A that went up in smoke with a 6AL ignition and new coil.

After speaking with my helper last night I discovered that my voltage "spike" was more of a "plateau" (sp) He said the voltage jumped to 20+ Volts at the aux battery for 2-3 seconds and dropped back down to 12 Volts right before I shut off the ignition. The voltmeter in my truck shows a straight drop from 14 to 12 volts. The only way I can see getting more than 20 volts at the battery is if the batteries were going inot series somehow, but I simply cannot see how this would be possible. Any ideas here? (it did this when the batteries were in parallel too )

Besides possibly having a faulty electric choke, the only other quirk I can find in my wiring diagram is the MSD "on" wire (small red wire that hooks to ignition wire) is hooked up between the alt and the voltage regulator. In theory this should not matter, as the ignition wire (blue) originally had several items hooked up to this wire between the alt and voltage regulator (e.g. computer, sensors, coil) Now all it has is the elec choke and the MSD.

I just do not get it

Sorry for the length of my posts.

-S/6

Length of your posts? Heh, don't worry bout it, mines not much better

I would not trust in dash anything at the moment, rely on your external instruments. Also, for the time being, put the msd turn-on wire directly to battery via a switch. If your that worried about the choke, you can temporarily remove it as well.

Sounds like you are using the stock charging wiring, I would connect a wire directly from output As to the 20v... if the alternator/regulator went belly up this can happen, but it will continue to happen and not be a single occurance. Or, when the msd box / coil went poof that might of been the cause. In a typical (yes I'm aware of the 16v batteries but thats not applicable here) healthy charging system, voltage should never reach higher then 14.. maybe 14.5.

And an fyi, red tops are sensitive to a severe discharge. They will outlast a typical liquid lead acid, but once you drop it below 11v (maybe less, this is just a guestimate) or so you've probably lost a significant ammount capacity. My brake lights stayed on for a few hours because I removed my master cylinder and forgot to prop up the brake pedal, I came back and it was sitting at about 10.6v. Wouldn't start the car, subsequent attempts at charging it and driving it for several miles yeilding nothing, still went back down to under 11v. And yes, my alternator is working just fine. VAT-40 verified to 275A and thats when the belt started slipping, could of went for more probably.

Oh and one more thing, compare the two optimas carefully. Look at the top of one that you think got messed up, and see if you can feel a round dome at the top of each cylinder. If you can, consider it needing replacment. It should be at 12.6v with no load on it fully charged.

No domes on the boiled optima, and I took it down to the parts store for a load test, and it checked out OK (1118 CCA ) I am not going solely by the dash voltmeter, I refuse to run it right now w/o someone testing the battery & alternator output with the multimeter. I am confident that the dash gauge is reading correctly, but either 1) it cannot react fast enough to show the 2-3 sec 'spike' or 2) the ignition wire is not getting the spike and it is contained within the alternator-regulator-battery loop. (2) does not make sense to me as the ignition wire runs between the VR and the alt....

I think I will also try my old batteries tonight (champion and an ooold Atlas) I have tried using one old battery, but not both yet. More later.

-S/6

This just keeps getting stranger and stranger.....

Last night I hooked up one of my old batteries as the auxillary on the isolator. Other than that the only change I made was to put a 15 amp blade fuse on the electric choke....ran the truck for about an hour, even drove it around the block a few times. No electrical problems.....spikes, discharge, nothing. Digital multimeter (got it working) read 14.5 volts at the alternator and 13.7 at both batteries at first. Just before I shut down she was getting 14.2 volts at the alt and 13.5 at the batteries, and both batteries now test at 12.6 volts. I know the old battery I hooked back up will not pass a load test, but it will power accesories well.

Once again I do not get it. Bad battery = electrical system works ????

While I should probably leave it alone because it works now, I am going to lose the isolator this weekend and hook the optimas up in parallel. If everything is "hunky doory" then, I will leave it alone.

Thx everyone. Feel free to voice your opinion on my latest electrical adventure

-S/6

Define load test? Just because a battery can't maintain a certain voltage across a load or its capacity is diminished doesn't mean its absolutely useless. I keep spare car batteries around that can't turn over a starter for smaller projects around the house. This works well.