What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

keep blowing coils ever since dual batterys were installed....?

down4thakrown

down4thakrown

1/2 ton status
 Premium
GMOTM Winner
Joined
Aug 5, 2003
Posts
1,981
Reaction score
342
Location
flagstaff,az
well ever since i put a 2nd battery in truck i have gone through 2 coils. i have a pac 200 battery isolator http://www.shipsound.com/product_info.php?products_id=102870 that just runs off a switch to switch off 2nd battery when truck is not runing. should i run a voltage regulator? talked to the summit tech guys and they say bad ground but i havnt touched the ground of primary battery since i buiilt truck and never had a problem til i installed 2nd batt. any ideas?
 
and whats wierd is when they go they dont tottally go to were the truck doesnt want to start at all. it will studder and sound like it almost wants to start. like the coil isnt producing a strong enuf spark?
 
How is the second battery grounded? Sounds to me like the coils are getting too much voltage. I can't think its getting the full 24Vs that a set of series batteries would put out, but if the alternator is losing its ground reference, it will put too much voltage.
 
Are you sure the battery that is being charged when the switch is thrown
is the original truck battery and not the new one ?



Second,, make sure the engine is grounded to the frame and I mean a GOOD LARGE GROUND CABLE FROM THE BLOCK TO THE FRAME,,,,not a piece of # 10 wire...to the fenderwell..


Third,,,make sure that there is no way voltage can backfeed thru the coils..
If you have a bad ground, the system maybe trying to find a ground path...and it could be right thru your coil...
 
I'm thinking, actually, that your alternator is on its way out and is not putting out ENOUGH voltage... but a DVM would tell you for sure.

I would wholeheartedly recommend a digital voltmeter, even a $10 cheapo from Harbor Freight.

You'd watch the voltage with the motor off, with the motor cranking, and if it runs, at running.

With the motor off you should see a smidge over 12V; even cranking it shouldn't go below 10V at lowest... and then running, you should see 12.5 to 13, maybe 13.5 tops. More than that, your alternator is on the fritz and you're gonna fry coils along with whatever else. Less than that, the alternator isn't doing its job and is undercharging.

You should also check voltages around the system, i.e. at the batteries, at the alternator (red lead on the output, black lead on various grounds), etc. If you get wildly different voltages with different grounds, then you can chase down those grounds as suspect. If you get wildly different voltages at the batteries than at the alternator output, then the isolator is suspect, etc.

If it's a diode-based isolator, you should see about half a volt difference from one side to the other; if it's relay-based, then you should see no material difference.

Hope this helps ... it's a start, as it were =))

-- A
 
its a brandnew altanator from summit racing 140 amp single wire altanator. but i do got a thin long ground cable goin to back of motor. but i painted motor too. i have the battery mounted behind pass. seat. and im sure the isolator is goin to the 2nd battery its inbetween the wire coming from the altanator and 2nd battery. and i noticed another thing when trying to adjust timing while truck was runing i got a good jolt when touch dist. cap with my other hand on fender and i felt it through my hand on fender so that makes me think bad ground too...what about you guys?
 
i forgot to add that the 2nd battery is only grounded to the body...if that makes a differance too..
 
down4thakrown said:
i forgot to add that the 2nd battery is only grounded to the body...if that makes a differance too..
Click to expand...


Um, not really the right way to do it. But if thats how you did it, make sure you have an extra ground cable from body to frame in the engine area that is at least as large as your 2nd bat cables. The factory ground strap to the body isn't large enough for this duty.
 
now that i think about it i dont think thers a ground cable at all comin from the body...would that be whats causin me to go through coils?
 
down4thakrown said:
now that i think about it i dont think thers a ground cable at all comin from the body...would that be whats causin me to go through coils?
Click to expand...

When someone said the battery might be grounding through the coil, this might be the cause.

Theres a factory ground strap (back of motor to passenger firewall on my 91), but if you grounded the battery to the body, this won't be sufficient.

Really, i woudl reground your 2nd battery to the frame, AND increase the body to frame/engine ground size. Short thick cables are cheap in teh walmart battery area, often called lawn and garden batt cables.

See if that solves your problem
 
down4thakrown said:
and i noticed another thing when trying to adjust timing while truck was runing i got a good jolt when touch dist. cap with my other hand on fender and i felt it through my hand on fender so that makes me think bad ground too...what about you guys?
Click to expand...
You need to figure out why your body was the path of least resistance for that shock. You should not get shocked touching any of the dist cap or wires. For some reason your ignition is working too hard. What else did you do when you installed the 2nd battery? Did you do any other upgrades? Did you remove or modify anything? Basically start by retracing your steps and see if you missed anything.

You're original battery still in the stock location?
Make sure the negative cable goes from the battery to the engine.
 
ive always had my primary battery behind pass. seat. then put 2nd batt. behind driver seat. the primary batt ground cable is really thin like 6 or 4 gauge the thinest one in the battery section at autozone. ground cable from my primary goes straight to the back of the block and bolted to head. then i have a thicker cable bolted to same spot that goes to the frame and is bolted on there. my power cable is -2 gauge. the 2nd battery ground only goes to the body where the seat bolts to. and a 8 gauge high quality wire goes to the isolator and then to altanator. im thinking its a bad ground and this mite be why my heater and every thing draws so much when i turn them on.cuz i have no ground cable connecting body to frame or engine.
 
Last edited:
down4thakrown said:
ive always had my primary battery behind pass. seat. then put 2nd batt. behind driver seat. the primary batt ground cable is really thin like 6 or 4 gauge the thinest one in the battery section at autozone. ground cable from my primary goes straight to the back of the block and bolted to head. then i have a thicker cable bolted to same spot that goes to the frame and is bolted on there. my power cable is -2 gauge. the 2nd battery ground only goes to the body where the seat bolts to. and a 8 gauge high quality wire goes to the isolator and then to altanator. im thinking its a bad ground and this mite be why my heater and every thing draws so much when i turn them on.cuz i have no ground cable connecting body to frame or engine.
Click to expand...


Yah, go buy a bunch of those walmart cables i talked about, and reground everything. Both batteries to frame, frame to body, frame to engine.
 
Just to be on the safe side, make sure the two batteries' grounds are either tied together or real close.
Split grounds in a truck are not as bad as split grounds in a house, but can still cause weird things to happen.

J.
 
You must log in or register to reply here.

Latest Posts

Top Bottom