how do i get more amps/volts.....volts drop hard when heater is on

[down4thakrown]

i have a 81 blazer i just set up with dual batterys and with nuthin but just stock headlites and the heater, the volts would still drop to 12 and keep droping......anything i can do to fix this? all kc lites are ran to 2nd battery i got 140amp altanator. i have 2 6'' kc daylighters with 100watt bulbs and 2 5'' on road driving kc lights with 55watt bulbs, and 4 stock headlights/hi beams...i have the pac 200 battery isolator and relays for kc lites....it would hold steady at 13 volts when all lights are on including hi beams. but when i put the radio on it will slowly drop. its only a 200 watt deck with 2, 6 1/2's and 2, 6x9s...

 

[Fordum]

Sounds like a bad alternator or voltage regulator. Unless you are just pulling more than the alternator is rated for. And from your description you aren't. Bear in mind, the heater fan can pull a lot more than people think.
First thing you need to check for is a slipping belt.
Crank it up, turn everything on and run it at fast idle or faster for a couple of minutes.
Then, switch the engine off, and carefully feel the alt. pulley.
If its warm, ok, but if it raises a blister, then the belt is slipping.

If not, then grab your voltmeter. With everything on, and the engine running at fast idle or above, check the voltage at the output of the alt.
If it is low there, then you need to get it checked. If not, then you need to find where you are losing it.
Check across both batteries. If one is normal or above and the other is low, then the isolator is suspect.
And fwiw, 13 volts is low anyway.

If the output of the alt is low, then you need a DC clamp-on ammeter. Not a lot of folks have one, so you may wind up going to Pep Boys or somewhere to get it checked.

J.

 

[95stroked1500]

how's your connections? and your wires to various places?.... like engine to frame, frame to batteries, body to frame (or battery), alt to batteries? make sure you have at least 2 gage at a minimum and not skimpy thin end connectors.

electricity is only going to flow as good as its weakest link.

 

[down4thakrown]

fixed it put a 10ga wire straight from altenator to #1 battery and it helped alot. and realized that i had relays for lights hooked up wrong.....now i can have all lights goin, radio and wipers....or i jus turn off 1 pair of lights even stock lights i can have heater goin with radio and wipers...

 

[95stroked1500]

see how warm that wire gets when you have big electrical draws. 10 ga is small for 140 amps. short run i wouldn't go smaller than 4 ga. i always like to build a little on the stout side, if it needs 4 ga to 2 ga..

 

[down4thakrown]

ya i think im guna upgrade to 4 ga goin to both batterys and the fuse block where all the lights are hooked up at...ive been doin a lot of researching and thats what alot of people suggest..

 

[4X4HIGH]

You can never go too large when it comes to wiring but too small can be a disaster.

Make sure that each battery is grounded to the engine, then make sure there is a large ground from the engine to the frame, and then a minimum of either a woven ground strap or 10ga wire from the engine to the firewall.

 

[nsxxtreme]

10 guage wire is to small.

I would install 4 guage from the alternator to the battery. And from the battery to ground.

The voltage drop you are getting could be from the increased resistance of using to small of wire for that current load.