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rivcokid 10-06-2018 05:18 PM

Battery keeps depleting

Hi all - I've had my '31 roadster for a couple of weeks now. All of a sudden, the battery is being depleted. I left the car in storage for a week and it was completely dead. I removed the battery, had it charged, reinstalled it, and it was fine. Went the next day to use the car, and it was dead again. The battery was said to be good and it took/held the charge from the charging station to the car, so I'm reluctant to say it's the battery itself, but I'm at a loss. Any ideas? Thanks in advance.

I should add that I've never used the lights beyond a quick check to see that they work, and have only used the horn once or twice.

Marshall V. Daut 10-06-2018 05:24 PM

Re: Battery keeps depleting

Two possibilities:
(1) The points inside the cutout are sticking, which drains the battery in a short time;
(2) the brake light is staying on because the brake pedal is not returning to the full top position.
'Could be something else, but these are the two most usual culprits.

2manycars 10-06-2018 05:26 PM

Re: Battery keeps depleting

Could be the stop switch sticking. Does the ammeter show a discharge when the car is off? Does the car have an alternator? If it has a generator, is the cutout sticking? Could be a lot of things.
Disconnect the battery cable, and put a test light in series from the cable to the battery post. If it lights, you have a draw somewhere, so keep disconnecting things until the light goes out.

monto 10-06-2018 06:04 PM

Re: Battery keeps depleting

Don't give up until you find the culprit, but also consider installing a good quality battery kill switch to isolate it when the car is shut down.

frank55a 10-06-2018 06:31 PM

Re: Battery keeps depleting

Last year I had a new battery that kept going dead also. Took it out and had it checked at the place I bought it from, they said it was good, charged it, and I reinstalled it. After a day it went dead again. I figured that I must have some wiring problem, so charged the battery and checked all the normal stuff, could not find a problem. The next day the battery was dead again, so charged it again and figured I would isolate the battery from the electrical system I disconnected the power supply at the starter switch. Once again the battery was dead the next day. I reasoned that either there was a problem with the starter or the battery. At this point I was more suspect of the battery than the starter. So I once again pulled the battery and took it back to the store, this time they did a more comprehensive test on the battery and found a bad cell. It was a new battery so the store replaced the battery and I have not had a problem since.

eagle 10-06-2018 08:09 PM

Re: Battery keeps depleting

Get a good DVOM and check for a current draw. When using an ammeter it goes in series with the battery cable.

J Franklin 10-06-2018 10:32 PM

Re: Battery keeps depleting

charge the battery and don't connect it for a day and see if it dumps the charge. If so it is definitely the battery.

Marshall V. Daut 10-06-2018 10:56 PM

Re: Battery keeps depleting

After charging the battery AGAIN - but with the negative cable disconnected - touch the end of that cable to the negative battery terminal post. If you hear or see a spark, there is definitely a drain somewhere in the electrical system. It's just a process of elimination until you find which component is drawing current. In addition to the two I suggested above as likely suspects, check the wiring behind the reflectors in the headlights. If one of the wires is frayed or loose and possibly touching metal inside the headlight shell or the light bulb socket, that will draw current, too.
If, however, there is no spark (it won't be big, so listen closely for the "snap"), then I'd suspect the battery itself. Batteries these days just aren't the same quality that they were a couple years ago and stories about defective batteries right out of the box abound.

J Franklin 10-07-2018 12:36 AM

Re: Battery keeps depleting

A spark at the battery could trigger an explosion (messy & dangerous). Lift the cable from the starter if you need to try a spark test. I had a battery explode once starting a car, there was a loose cable on the battery terminal that sparked when I stepped on the starter.

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