53 chevy truck with 12v system. Still has all stock gages. HEI setup. Voltage looks fine on the battery, but there just doesn't seem to be enough amperage to back it all up. If I let the truck sit for a day without it running the battery will not crank the engine. If it sits for more than a day then dead battery. If I drive it everyday (it is a daily driver) then usually no problem. When I put my Ammeter on it I see a .27A draw with nothing on, but I can't find where the draw is coming from. Battery is in the stock location under the floor and I bought the biggest one that would fit which is 750 cranking amps. Any clue what is causing this? It's driving me nuts!!
I assume you upgraded to an alternator, is it a one wire? When I converted the '57 to a 10SI GM one wire it did the same thing until I put a one way diode in it.
Pull the fuses and/or disconnect accessories one by one and check the draw after each one. When the draw disappears, bingo, the fuse you just pulled is the circuit that's draining the battery.
Try putting the meter between the battery B+ and the positive cable with the cable off. That will check the whole system for a draw.If you don't have a draw then consider the battery as a possibility.I've had even new batteries that would not hold a charge.
that's about a quarter of an amp. A typical car battery has at least 75 amp hour capacity, that means that if you run draw an amp for 37 hours it will discharge the battery only about half way. A quarter amp over 24 hours is only 6 amp hours, and it's killing the battery? somethings funny here. Have you fully charged the battery with a battery charger?
Check the specific gravity of the acid in the cells. That will give you a pretty good picture of the condition of the battery. See this link http://www.engineersedge.com/battery/specific_gravity_battery.htm
If you didn't find the draw on the fused circuits try the items that are not fused. Unplug the feed wires to your alternator and recheck, same with the starter. Also you can go to the positive power junction, where the positive cable from the battery feeds the elecrtical system. This is usually at the starter solenoid, remove each feed wire untill you identify the drawing circuit then the hunt is on to which component.
Is this a new thing, or has the system had recent work where immediately after that the battery started going down? Have you checked the battery?
Not a new thing. Has been happening for a while now and I've tried to track it down before with no luck. It is a new battery and the 2nd one I've tried.
In OP you said voltage looks fine on battery. What does the ammeter do?; right after cranking? Does it eventually come back all the way to zero? If it charges constantly, like somebody said, it could be the regulator is stuck.
Have the battery load tested, if it checks out take the alternator to auto zone and have it tested, if it checks out run through your whole set up and check all of your grounds. If that checks out take a hand held meter and find out if you have a draw, chase down each fuse circuit until you locate the one with the draw. Anything out of the ordinary or slightly suspect or non stock should be the first things checked.
Like Fleetliner said; Unplug the alternator. I had a IH Scout that we never did figure out what was wrong, so unplugging the alternator fixed the problem. Just had to lift the hood and do the drill. I had a nephew that was learning to drive about that time, he would lift the hood every day, imitating uncle.
A few more things that no one has mentioned. Dirty/damp top on battery. Take your multimeter and check for voltage across the top of the battery. Not post to post but post to top in various spots. In one case the drain across the top of the battery was enough to draw the battery down enough to keep the truck from starting. Bad diode in the alternator that will cause the battery to drain with the engine is off. Light staying on (dome, glove box------) not too likely in this case. Bad horn relay, This just happened on my ot truck. I unplugged the horn but the bad relay still caused a drain. Bad battery. As a couple of others said, just because it's new isn't a total indicator that the battery is good. You can check external drains by disconnecting the battery when you park the car. One cable should do. If it sets a couple of days and you hook it up an the vehicle starts it's in the vehicle. If it doesn't it's the battery. That might be something to try if you don't plan on driving it for a couple of days. And it might not be the vehicle or battery. I had one student who had trouble with his battery being down in the mornings when he got ready to go to school and we couldn't track down the problem. Battery checked good both with a meter and hydrometer. No drains on the system and no bad connections. After about three weeks of it his mom mentioned that his little brother and his friends were playing the sterio in the afternoons when he left the car at home and went to work.
Do you have a radio that has memory? 1/4 A. would be about right for that. And Squirrel is right about that little draw not killing a GOOD battery. I'd swap the battery if you have another to put in there and see what happens. And what's the system voltage when it's running?
That small draw won't kill a good battery. Probably self-discharging inside the battery. Do you have an alarm on this? That can draw hard if a little Bosch relay is set to disengage the starter circuit.
The radio does have memory, but I've put the meter across that and no draw. No alarm. Not lights staying on or anything. I have a spare alternator laying around I'll try swapping that in and I'll get the battery checked. My auto parts place is pretty good. They'll probably just warranty me a new one if I want.
I agree with the regulator in the alternator. I had it happen to my Hard Top this year. The same symptoms. I had a small load and saw a tiny spark when connecting the positive cable to the battery. Once I disconnected the alternator the spark was gone. It was the regulator and a diode. Had it rebuilt and all has been fine.
A simple check: pull the cable off the battery and leave em off for a couple days--then recheck battery--if OK,then battery ok,if not , I'd check the alternator--diodes are known to "leak" and pull the battery down.
I had that problem with my T. It was fine with no radio. When I hooked up the radio it would drain the battery quickly. Can't remember how long though. I tightened the clamp on the negative terminal. Problem went away. The nut was 12 mm. I was using a 1/2 inch socket. I figured it was tight but it was the socket slipping. Tried a 12 mm and the problem went away. I'm sure you checked but are the battery terminals clean and tight? Bill
This is how I find a power drain. Hook up a light bulb between the positive battery post and positive cable.If you have a drain the light will come on. Radio memory will make the bulb barely glow faintly. I will have to cup it in your hands to see. The higher the drain the brighter the bulb will get.. Unplug your fuses or any hard wired component one at a time. When the light goes out. You have found that electron eating bastard! Now you can kill it...Good luck....
if you have another alternator swap it out and see if your prob goes away sometime the diodes go bad they have a life of about 30 yrs i have had a few go bad on me its about 50 bucks for a new diode pack they need to be soldered in but is a DIY if you need to do it
Everyone has give you good advice so, I won't add to it. I find MR48chev post very funny that's little brothers for you. Good luck with the drain problem. CRUISER
The Jalopy Journal
