Over the weekend, the battery drained down to 5.6VDC.

Charged it up via slow charge, 12.65VDC, cool. Checked the simplest of things, cables good, battery is new in April of 2010, good. Start the 914, 13.4 at idle, 12.6 at idle with everything on, jumps up to 13.5+ as soon as you go past 1000rpms.

Lights always nice and bright, even at idle etc. So probably not the charging system....well, not at first glance.

So two days in a row, the car will sit overnight and loose quite a bit of charge.

12.65VDC down to 12.2VDC or so last two days.

I tried to read the parasitic draw, but keep getting 0.000?

I removed both cables and checked the omatic value between + and -, it was .003 with meter set at 20.



That seems high? Do I have a major short?

The parasitic draw I could be doing wrong. I put the meter wires with + disconnected between the cable and the battery. I have to plug into a different socket and may not be using the correct one. Should be the 10amp setting as well?

Using a "wish I was a Fluke" Radio Shack meter.

Does anyone have a stock 914-4 they could remove the battery cables and check the omatic value on? I'd be interested to see if it's similar to mine or if I have bigger issues to look into?

I would start by removing all of the fuses except one or two and leave it over night to see if it dies. If not you know it is not those two circuts and add two more the next night. Eventualy you will figure out which circut is the problem and you can trace it from there!!

Dan,
Try shorting your ohmmeter leads together and see what you read. Most ohmmeters will read something with the leads installed and shorted together. Always do that whenever taking very low readings and then subtract your shorted leads readings from any new readings you take.
Also, disconnect the battery for a couple of days and see what happens. It could be discharging itself very slowly.
By the way, .003 ohms at 12 volts = .00024 amps. Almost nothing! 240 micro amps, if my caculations are correct and memory is not gone! Your meter may not read that low. I would suspect that battery.
Tom

check the fuses & battery
(if you haven't already)

I'm using one of the Odessy 680's so there isn't a ton of storage. But since April, it's always worked like a charm.

I know there's a draw somewhere more than it should be.

fuses are a good idea, isolate the system to just those components.

I'll double check my meter when I get home tonight. Maybe post up some pics.

Thanks for the advice guys.

Tom,

That omatic reading was just the cables with no battery. So ground cable to poss cable disconnected from the battery. The resistance in the chassis electrical - no battery.

Does that same value still sound reasonable? .003?

the ohm reading is not of much use, what yoiu need to do is get a current draw reading wih the battery connected and ALL acessories off, the current reading (amps) will be very sensitive to small milliamp flows of current (milliamp is 1/1000 amp) make sure you know how to use the amp meter and its limitations (easy to fry one with too much current so dont turn on a heavey use thing like a light when testing (make sure the door activated interior light is off)

if you find current draw wiht all things off then you got a current leak, (note pull the fuse on your radio as many new modern radios draw a small current to retain memory presets)

once you determine current flow is happening, try pulling one fuse at a time form teh fuse panels and see if the current stops, if so, you found the path thru the fuse and can start to isolate its location

Note not all circuits are fused, so if you puyll all the fuses and stillsee current then you look up the items that are not fused, the highbeam flash cicuit from teh turn signal lever is one such circuit that is not fused the wire wears away in the steering column assembly tillit starts to short, small short gives mystry battery drains, a bigger short (ie more wire exposed to ground) means the wire will melt and you'll then need to get a new turn signal switch!!!!

good luck, post results

Make sure you set your multimeter to the highest amp setting. If you set it too low and the current draw is higher than that range, you will blow a fuse in the mulitmeter - several times if you are like me . Get a few extra fuses in case you happen to leave a door open that turns on the interior light!

warrenoliver

Dan,
I wasn't thinking right before. .003 ohms between the positive and negative battery cables is indicating a nearly direct short. Not possible or you would have different symptoms - IE; a fire or explosion.
You need to just try disconnecting the battery, take a reading with voltmeter, let sit 48 hours, take another voltmeter reading. They should be very close of your battery is self discharging somehow. Do you have a console clock? That is always powered up.
If your problem persiste, I have a Fluke 189 that you are welcome to use to trouble shoot your problem. It is a very good meter!
Tom

No new theroey, just is the amp meter test is driven by teh cars own 12 Volt power source, that can push a lot thru high resistance wires to teh short, the ohm meter uses an internal maybe 9 volts lvery limited power source to sence the short. that is why the amp meter method is a bit more sensitive becuase it uses the actual higher volts condition that the car see's.

Good thoughts!

Thanks Tom, the .003 ohm reading explanation helps. There is the smallest little spark and tick when you connect the battery. I do have a CDR220, so there has to be some current draw with that.

That was my plan for tonight.

Yesterday it was fully charged @ 12.65VDC and in the morning, it was 12.2VDC.

Today when I get home, I'll disconnect the battery assuming the drive home will get it up to 12.6+VDC (Sure it will) and take a reading in the morning. If it still drops, that'd most likely be the battery.

I'll post more tomorrow!

Realred,
Agree, but we were not thinking right. .003 ohms is almost a direct short = smoke and fire. Dan needs to check with another meter that is better quality and then he can can read a lower amp draw. I must be getting rusty brain from my 914 .
Tom

Dan,
Looked up your battery and it only has a 17A/H rating. What this means is that your battery can only handle 1 amp draw for 17 hours to be virtually dead. Google "battery amp hour" and you will see what I mean. So, if you have a 1/4 amp draw, the battery would only be slowly discharging for 68 hours or so before being at such a low voltage as to be dead. I'm thinking these type batteries are good for A/X or race, but not so good for daily drivers with constant current draws such as clocks and sterios, etc. So, your battery is probably not bad, just not a best choice for the application.
I used to have a Radio shack meter and threw it away! Kept getting funny readings.
Tom

I just looked at your battery spec. I agree, the battery is your problem. Most new vehicles have about 1/2 amp draw. This level is considered acceptible. The drain is the ECU, clock, radio, etc... Your battery is for racing or lawn mowers. Not designed to have constant drain. I would suggest installing a battery disconnect or using a larger battery.

I would also argue that your battery is too small to get optimum spark from the ignition system. In a vehicle electrical system the battery does most of the electrical work while the alternator keeps it charged. The battery discharge can react much quicker than the alternator. every time the coil fires, a dip in voltage is caused by the current spike. The smaller the battery gets, the faster it can react but with less capacity. The larger, the slower it will react to a current spike but with a higher capacity. This can be calculated based on L.C. time constants (totally different discussion). The Starter uses massive amounts of current at a slow rate. The alternator can not force a charge into the battery at the same discharge rate. Every time you stsrt your car, it takes at least 15 minutes over 1500rpm to gain the charge back. That estimate is for a normal capacity battery. Yours being smaller, you have less energy storage left after starting the engine. The coil reacts quickly, but since it is firing over an over so quickly, the circuit reaches a saturation and becomes pulsating DC current. This pulsating DC acts like a constant load on the charging system.

If it were my car, I would put a full size battery in it. The added security of starting all the time far out weighs the weight savings of the little battery. Keep the little one for track days.

It's your car, do as you feel best.

Mike

1. Get a bigger battery
2. These batteries really do not like deep cycles. Draining to the level you did could have easily damaged it.
3. Charging is also special. They do not like real fast charge. I think 14.25 is the highest voltage that they tolerate. Fast charger push higher currents by raising the voltage (ohms law).
4. Forget the ohm meter!
5. Current draw should be less than 100ma. That's .1 amp.

I suspect that your battery has an internal short and is draining itself. You may have a current draw in the car that started this process damaging the battery.

Pretty much confirmed, the battery is fine. I have a short somewhere in the system I need to track down. I found all this out just this morning:

Last night got home and disconnected the battery @ 12.61VDC after 30 minute rest and one restart to put it back in the garage. Another good baseline to start with.

This morning it read 12.54VDC, not enough I would think the battery is an issue.

Yup, it is a small battery with not that much storage, but it's always worked perfectly. Even when I converted from carbs to FI, I had plenty of trial and error cranking power for days. Never had to put a charger on it. Car always spins over fast and fires right off. Everything is always bright and clean, no flashlight headlights etc.

Tom is correct, I poked around a little more this morning and there is a short somewhere. I need to track it down. Something has happened, something has rubbed through, I F'd up and didn't grommet a loom or wire maybe? Not sure, but I'll track it down.

Not the battery, something I did, I'm sure.

Another thing I did this morning was the layman's test mentioned earlier in the thread. Is there any spark or noise when the cables are re-connected to the battery? This morning I pretty much put my face on top of the battery post to see and hear what happened.

No visible spark.

I could barely hear the faint 'tic' when the cable touched the post.

I wonder if I should unplug my CDR220 and see if it does the same thing?

Also, I want to get a good clamp on meter so I can measure true draw.

This battery might just be too small for this application? I've always used a 925 in the past, even on 914-6's and one Fiero V8. This is my first 680. Maybe it's just not up to the job?

With one battery connection removed, connect the amp meter between the open battery connection and the disconnected lead. This is in series. Make sure you are on the highest amp setting on the meter. There will be different plug locations on the meter. Make sure all lights are off. If you get zero amps, the meter is either not connect / setup correctly or you blew an internal fuse in the meter. This is very easy to do. Most small meters will only measure up to 2 amps. If you measure less than 100ma then your problem is the battery. Make sure your radio is connected properly. There is one constant hot wire and one is switched. If both are connected to an unswitched wire, the radio could draw more current even with the radio turned off. I had one that did this. You should only have the radio standby current (channel memory etc) and your clock pulling current.

How old is the battery?

Battery was new in April (Well, purchased in April) of this year.

You know, I read nothing but 0.00.

It's been a while since I used a multimeter, but I thought I was doing it correctly, just as you stated. I have a seperate plug for the 10amp, I used the + cable, so one lead attached to that, the other to the battery +. 0.00.

I'll pull my meter cover off. Maybe I have a blown fuse? I can't remember the last time I used it for anything but ohms or simple continuity testing.

This is how I used my meter for the draw test:

Having a 0.000 current reading means you fuse in the meter is blown. When you fix it and connect like you picture' If you have less then 0.4mA your system is OK. any higher would indicate too much idle load.

The red wire goes in the 10 amp plug. Some meter need 2 buttons pressed at the same time. Don't worry about polarity. If backwards you will read minus numbers. Current readings are voltage readings measured over a very low ohm resistor. The resistor can handle only so much current or it will burn out (hence the fuse) also the heat generated by high currents would melt the case.

After posting I see the meter is a dial switch. No 2 buttons to press. Just select the highest ma setting.

Dan,
Your radio shack meter is definitely better than the one I threw away and should be good enough for what you are doing. Does the switch have a ma and amp position? Usually meters like that have a seperate plug for amp versus ma and you have to have both switch and plug correct to get a reading. I sent you a PM also.
I think Mike in his last post means 0.4 amp, not 0.4 ma. I measured 5 ma and I have never had any battery problems. Besides he mentioned modern cars usually can have up to 1/2 amp when idle ( meaning I'm sure, at rest with key off), and that sounds very reasonable to me.
Tom

**** True ,unless you have a analog meter.

A reverse polarity will can burn out an analog.

in old analog meter days we was trained to flash the test probe on the terminal to be tested quickly, just brush it fast across it, We was trained to do this while observing the meter, if the needle twitched the wrong way, or if it was on too low a range and started to peg, if you were fast, you could save the fuse, or meter, some times not


most all new digital meters can handle the reserve polarity with a minus sign on the display,


most all analog meters can not be reveresed with out damage or fuse blow

(some funky old analog meters had the needle at rest in the middle of the gage, so it could swing either way negitive or positive)

and always use a fast blow fuse in ALL meters digital and analog.

Just a quick note one of the diodes can go bad in the trio and it try to charge ok but will cause a drain if the car is not running.

Got home and found another meter to test the fuse in the meter I was using......things are just getting weird!

Fuse was bad, I don't think I hooked anything up wrong before though. Either way, I had another (better) meter and found this, DOH!

Testing, isolating, testing.

First was fuses, one at a time while watching the meter.

Nada

Then back to the engine bay relay board, fuses, one a time, relays etc.

Head under car, everything looking perfect, nada, nada, nada.

Still pulling the same draw.

Start trying to think what has changed recently. Nothing other than converting from carbs back to FI......Hmm?

Head straight for the double relay, becuase we all know it's connected directly to the battery and found this:

Kinda bad picture, little poss lead from the large poss wire was rubbed through touching the yellow wire. Pulled it and put heat-shrink on it.

TADDA!

Everything back together, CDR220 plugged back in etc.

No draw!

I turned the dome light on for a test and it jumped to what I established as a control test earlier.

Fixed!

Hopefully this becomes a good searchable thread for future issues.

YaHOO!

Great work Dan! I have used that logic many times to find faults, it is so easy to think, hey, I just worked on that, so it must be OK. When in fact, that is where the problem is.
Tom

Since my last post my drain came back!

Shocked by this, I new I missed something. Turns out the exposed wire on the double relay harnes may or may not actually have been causing the drain. Or it could have caused the drain and also damaged the relay?

Story:

Saturday morning go to run errands, 914 drags to start.

Knowing why, I decide to drive it, charge up the battery, grab the multi-meter and the wife and I head out.

Get a couple of errands ran, 914 if lighting right off, so battery is charged back up.

Using the same methods as before I test for parasitic drain in a parking lot. Yup, same old drain is back.



I look and check the double relay harnes since I know 100% it is coming from there. I leave the meter hooked up so I can watch it draw amps...... I tap the double relay lightly with a box wrench, drain goes to 0.00!



So I don't know if the harnes damaged the relay or if the relay was always the drain? The relay hasn't "stuck" on like that since, but I'll source a new one.

Dan i'm sorry i missed this thread until now i could have helped you out with this and had this fingered out long ago!

next time just gimme a call!

I seriously doubt the harness damaged the relay. Probably just a sticky relay. I have taken relays apart and found that rust had formed inside. These loose particles get in the wrong place. They are still magnetic and the relay is a magnet device. It is easy to see them cause relays to be intermittent. Time for a new relay.

Yup!

got one on order....Bosch is pretty proud of that little device!

Got the new relay the other day, one of my block plugs isn't correct, so I had to source another plug:

Here is a shot of the new relay and one I picked up from a 411 in a local bone yard.

I was able to switch the block to the correct style:

I can say I really like how the white plugs fit only one way into the new relay. You can't put them in wrong.

Hopefully this closes the battery drain adventure!