FLH battery drain

[otis71]

My 1974 FLH is draining the battery. I repaired the factory connections under the dash and that helped reduce it. I then cleaned the light sockets in the dash and it is now but undetectable but will still drain down over several days. I get no continuity reading between unhooked positive and negative battery leads. Also with the positive hooked I get no amperage drain shown between the negative terminal and the negative lead. It is very slight and undetectable. With the negative unhooked it doesn't drain. Any ideas are appreciated.

[wideglide38]

otis71,
Sounds like you may have an open cell or almost open cell within the battery. What type is the battery and how old? A dry cell/charged with electrolyte or a Sealed/AGM type battery? If dry type, are all the lead plates covered with electrolyte/water inside each cell? If plates are not covered, add “distilled water” to battery and charge (not tap water, well water, filtered water or city water with chlorine - this can cause a loss of capacity in both plates, greater losses in positive plates). Have you check the specific gravity of the electrolyte with a hydrometer? Does the bike sit for long periods between rides? Use a battery tender? Continuity cannot be checked across a battery – the DC voltage may damage the VOM. I have a cheap Battery Load Tester (Harbor Freight has them) that I use to internally test the battery with a resistive load. Auto parts store typically have a battery tester and will check/test a battery - usually for free. Sorry for all the questions - batteries are quirky animals.
William

[otis71]

It's not the battery. The new battery that came with the recently purchased bike is totally trashed from me not knowing and it being left hooked up in the bike. I bought a new one which holds its charge if I unhook the ground but discharges if I don't. I checked the bike's wiring for continuity with the battery removed and it showed no signs of a closed circuit. Also shows no amperage draw with the battery in the bike but it discharges so something is shorted somewhere. Probably will be a process of elimination but hoping someone had the same issue and could tell their cause of the short.

[Lyle Manheimer]

Otis,
You are dealing with a very low current draw. You should be using a digital ammeter not an analog. I would check the positive lead for current draw. The meter must be hooked up with the proper polarity. Red lead goes to the battery +, black lead to the + wire to the bike. Good meters will be fuse protected if you have hooked it up wrong and blown the meter fuse it will not read or worse it may have damaged the meter if no fuse. You must be sure the equipment you are using is in good operating condition. A good meter should detect a milliamp draw. Don't forget to check the lead going to the rectifier/regulator as well, it too is landed on the battery positive and you could have a problem there as well. I do not have a wiring diagram/schematic in front of me but keep in mind this is happening with the key in the off position so lighting circuits, ignition circuits really should not come into play with the bike sitting and the key off. It could however be drawing down through a faulty ignition switch. The ignition switch has a live wire to it even when in the off position. Can't think of anything else off of the top of my head. Good luck.

[otis71]

I have done all you said. Even checked on the lowest milliamperes setting and it not detected but the battery still slowly drains if left hooked up. I am well versed in dc electrics and I'm stumped. Unless someone has experienced similiar situation and gives me a clue where to look first all I can do is unhook one thing at a time and see if I stops. Thanks.

[kval]

Otis
I had a friend with a similar problem, while tracing the problem he found a hair line of green fungus from the batt post on the key switch to ground. simply wiped it clean and problem was solved

[wideglide38]

Kevin's comment reminded me of acid traces on the outside of wet cell batteries (in stationary battery systems for Uninterruptible Power Supplies or UPSs). It didn’t take much acid to create a track down the side of a battery and form a ground path.

[otis71]

Thanks for the last 2 answers. That's the stuff I need to hear. It's ever so slight. Anymore ideas bring them on!

[motorhead1]

A common cause for this problem is usually the regulator, even if it is operating properly. Diodes go bad and when they do, voltage bleeds back through the regulator body ground and even through the stator plug. Remove the regulator from the bracket and with the voltmeter black lead grounded touch the regulator body with the red. Any reading is a problem. Also probe the stator plug terminals. They should also read nothing. Happy hunting.

[otis71]

I think you were spot on Kevin. With the regulator loose 1/2v was being read on the meter. With the regulator mounted it showed nothing because it was going to ground. This bike was fitted with a later model 1977- 2 prong rectifier/regulator so when I get a new one time will tell. Thanks.

[motorhead1]

You're welcome. And it's Dan.

[duffeycycles]

lights & things after the ignition switch dont get power without switch on[unless switch problem]..usually switch,charging system,wire to switch short,or battery problem..Battery drains from charging system are easily checked by unhooking the wire from reg to batt.

[T. Cotten]

Otis71!

I found that it takes an analog milli-amp meter to be sensitive to detect really small leakage from the disconnected negative battery terminal to the frame while the ignition is off.
Those are expensive, but a VU meter scrounged from an old stereo works just as well.

....Cotten

[wideglide38]

...it takes an analog milli-amp meter to be sensitive to detect really small leakage....

Cotten,
Good call with analog milli-amp meter. I've had one parasitic drain in a cycle electric generator-end regulator that I chased my tail on. I've used an old Simpson Mod. 375 DC Amp meter for checking current draw & charging rates.
William

[T. Cotten]

William!

Are you sure that a milli-amp will bump the needle?

That's why I scrounge from dumpsters.
But I do have a couple of old ebonite-cased ohmmeters similar, and the really, really big mystery is why they still work as if the batteries last forever!

(I'm afraid to open them up and let the genie out.)

....Cotten