Small current "back" into my charger - unplugged

[tboydva]

OK, I've been beating my head against the wall (hull) on this one and I can't find it covered here (hard to search with multiple words). Anyway, my starting battery continues to be drawn down several days after unplugging my charger. I have a two battery charger system and a digital duo charge (http://www.balmar.net/page20-Duocharge.html) on my boat. I plug in the charger and several days after unplugging, it won't crank the engine. I thought something was maybe defective with the duocharge, but it seems to work soon after the batteries have a full charge. So, after re tightening and putting some fresh conductive grease on, I decided to check the currents. Sure enough, I have 136 ?A current flowing from my battery to the charger unit (which obviously is unplugged at this point). I'm not savvy enough to do the ?A.hr calculation, but after about 3-4 days, my battery can be drawn down enough to make starting difficult. So, my question is: 1) is this normal? 2) if not, do I need a new charger (and better quality as this thing has only 6 months of use? 3) can I put in a high current diode to make sure there is no trickling flow out of the battery.

Thanks for any help and as always, sorry if I missed this question on my searches.

TJB

 

[TerryMSU]

Re: Small current "back" into my charger - unplugged

TJB:

136 uA is not enough to pull down the battery in a week or likely even a month. Do you have a known good starting battery? Take it to a good parts store and get it tested. It should take at least 10 times that leakage current to cause an issue. Otherwise, do you have any corroded connections in the wiring? Maybe a bad section of wire... I had one that had that issue.

Good luck,
TerryMSU

 

[tx1961whaler]

Re: Small current "back" into my charger - unplugged

The charger already has diodes. They do have a reverse bias current in the micro-amp range. To make the math easy, if you had 100 uA reverse current, for 500 hours (~21 days) , that would be 0.05 Amp-Hrs. That's not enough to run down a lead acid starting battery on its own. Now if you measured 100 MILLIamps draw, then that would be 50 amp-hours, which would be a problem....

 

[Silvertip]

Re: Small current "back" into my charger - unplugged

You probably mean 136 ma (milliamps) which is .136 amps which is a more significant draw (basically a little under 1.5 amp every 10 hours or 3 amps per day. That would seem to indicate the charger has a diode issue. If your measurement was indeed 136 ua (micro amps) -- thats .000136 amps and it would take a long period of storage to pull the battery down to the point where it won't start the engine. Are you certain the battery is good (as in have you had it load tested). Just because it measures 12.6 volts it may not have enough a weak cell or two and the minute the charger is turned off it drops well below the threshold.

 

[tboydva]

Re: Small current "back" into my charger - unplugged

Wow, thanks for the replies... I'm pretty sure it's ?A (according to my meter). The battery is over a year old and sat for about that much time while I was refurbing my boat. I took it in to have it tested, they said it was taking and holding a charge... I figured they were just trying not to honor the warranty (sears). I think it must be the battery... I think I'm just going to have to charge it alone, then see how long it holds. I think it's toast. Thanks!!!

Tom

 

[pvanv]

Re: Small current "back" into my charger - unplugged

Yes, 100-200 uA is normal reverse leakage on blocking diodes for these types of chargers, and won't likely cause a problem with battery drainage for months.

If the battery loses power over time, either the battery is bad, or something is draining it. Period.

Is anything else connected to the battery when it is "resting"? If so that might be suspect. An easy way to check would be to swap in a spare, Known-Good, battery and see if it suffers from the same malady.

 

[tboydva]

Re: Small current "back" into my charger - unplugged

This is my cranking battery so I only have the charger and duo-charge hooked to it. The duo-charge is switched (and only runs while I'm on the water - motor running or starting or accessories on). It has no leakage current under "standing conditions" (or at least reads 0.000 ?A). I took this battery back to sears and they tested it and said it was good... I think their test was not thorough. Everything I've tried leads me to believe the battery is just no good. Time for another trip to sears (it's still under warranty). Thanks again for all the help. If nothing else, I got some ideas on normal current draws!

TJB

 

[Ridemywideglide]

Re: Small current "back" into my charger - unplugged

If you only have 2 things hooked to it, unhook 1 of them at a time and see if it dies in 3 or 4 days.. I'd suspect the duo-charge.

 

[KLINDWW]

Re: Small current "back" into my charger - unplugged

How about charging th battery and then disconnecting it completly. Come back in about 4 days and see if it is drained down. If it is, it's the battery if not look further. Also, was wondering what kind of tester you had. Not a real common item to messure microamps.

 

[tboydva]

Re: Small current "back" into my charger - unplugged

KLINDWW,

I put my ammeter between the battery and the duo-charge and didn't register any current at all. I keep the duo-charge off until I go to use the boat, so I think it's gotta be the battery itself. It's at Sears now getting tested. I need to check the status...

TJB

 

[tboydva]

Re: Small current "back" into my charger - unplugged

OK, here's my update (still having issues). Maybe someone has something I haven't tried. I finally got tired of taking my battery back (it tested fine 3 times) and got a new one. Same problem. Runs like crazy some of the time. Won't hardly crank the engine others. I can take it right off the charger and get the same intermittent behavior. I've removed the power cables from the battery and cleaned (again!). I use carbon conductive grease on all my connections (http://www.mgchemicals.com/products/846.html). I worked with a guy who built ocean sensor moorings and he swore by this stuff for making good, corrosion-resistant connections. I can say over the years, I have never had an electrical failure where I used this grease.... SO, I think my connections are all good. I'm getting a solid 12V at the solenoid (greased), When I manually "short" the solenoid, I get the same issue (sometimes cranks like a champ, other times, slow and sickly). The cable to the solenoid seems serviceable and I've cleaned and greased the connections. From experiences with trailer lights, I've always found intermittent problems the result of faulty grounding. I removed, cleaned and greased all my grounding points (including the starter mount). So now, I'm really starting to get flumuxed!

Here's one anomaly. Twice, I had the battery indicating full charge (and the charger still on). I went to crank the engine, and it was completely dead - I couldn't even get the choke to engage. After unplugging from the charger, the choke functioned and it was able to crank (slowly this time).

I don't know how I can check the resistance of the master cable (service from cranking battery to engine). I put on a multimeter and got 0 ohms, but if there's some "internal" corrosion (which I tried to look for), I can't really tell. I can't find a replacement cable part (maybe you just have to make them?) for my model ('83 Johnson 60HP). A colleague suggested maybe the rectifier was faulty (he had issues with charging and would have trouble starting after running for a while). I'm guessing this isn't the problem - 'cause I put mine on the charger while it's in the garage. I was thinking perhaps my solenoid might have some corrosion on the contacts? I don't know if the solenoid(s) in my vintage engine are solid state or mechanical, but I figured I could use a spare (for $30).

My next thought is to take my battery out, and hook it up directly to the solenoid using jumper cables. Anyone agree with this test? This would let me know if my main service cables have too much resistance (perhaps). What's killing me is that the problem is so intermittent. It'll crank like gang-busters one try, then the next, just chug and labor (too slow to start).

Anyone have any other ideas???? Thanks!
Tom

 

[Silvertip]

Re: Small current "back" into my charger - unplugged

Did you disconnect and clean both ends of the cables (as in the ends at the engine)? If not, you only did half the job. Use a single jumper cable and connect one end to the POS terminal on the battery. Touch the other end to the large terminal directly on the starter. If it spins, the starter is ok. If not, you have a starter issue. You can use the second jumper cable connecting it to the negative post and the engine block (no paint area) and repeat the test. If it now cranks, you have cable or solenoid issues. Starters can and do become balky. Bad brushes, bad commutators, worn end plate bushngs cause armature drag, and bad solenoids all can affect starter performance.

 

[tboydva]

Re: Small current "back" into my charger - unplugged

Dear Silvertip,

Aye, I did clean, grease and re-seat both ends. I like your idea of hitting the starter motor directly (w/out the solenoid). I'll give that a go tomorrow. I didn't figure the starter motor into my troubleshooting - seems like it should fire or not (then again, a solenoid should function thus too...). Come to think of it, I did run the starter without the plugs in one time and it spun like crazy (no compression state). Maybe it just can't handle a load?

Thanks!
Tom

 

[pvanv]

Re: Small current "back" into my charger - unplugged

Silvertip's test sounds perfect.

In electrical troubleshooting, one effective approach is to bypass "half" of the circuit, and see whether the problem persists or has been bypassed. In his test, you bypass the boat wiring, testing the motor wiring. Still, intermittent problems are the hardest to find.

Yes, starter motors can act this way for all the reasons mentioned.

Battery cables are available pre-made in various lengths and gauges, but not typically by application for older motors. We also custom-make them to length for our customers. Good marine-grade cables will have adhesive-lined shrink tubing covering the joint between the lug and the wire insulation, keeping the internal wire dry.

I have found some older (non-marine-grade) cables that look good, yet have mild corrosion at the crimp point where the wire joins the lug. Almost impossible to see. A high-sensitivity micro-amp-driven ohm meter often will not detect this resistance, but pumping 40 amps through it to crank can cause a significant voltage drop there. Scratched my head for quite a few minutes on a similar issue once.

 

[tboydva]

Re: Small current "back" into my charger - unplugged

OK, the plot thickens (molasses consistency). Was on travel and didn't get a chance to test until today. So... I tried using jumper cables to go from my fully-charged battery to the starter. Seemed to lug quite a bit - so I guess I've got some starter issues (at the very least). Now, however, I can't get any start at all from my key switch. It's completely dead? I'm trying to check resistances and my manual has a b/w diagram. For some reason, I'm not getting an "on" when I turn the key - and I'd like to see if if my on/off switch is shorting. The b/w diagram has a short between the A and B terminal in the "on" condition. My cheapy Seloc manual shows the wire from A going to the big red connector - but not coming out? It doesn't offer a color? I think my "ignition" isn't getting turned on. According to the diagram I have, there are 8 wires going into the main red connector from the control box - but only 7 coming out. When I activate the choke, it shorts properly (with ohm meter). I'm confused (and probably too frustrated to think clearly). It seems like the switch shorts the black-yellow wire when off, then opens it when on. The on position seems to only "activate" the temperature sensor (from the way I read the diagram). Is this right? Also - any advise on "refreshing the starter motor? Perhaps a link to a relevant thread (I can't search on multiple words)? It seems to be the reason for the chugging-dragging starts...

Thanks all again. If I figure this out, I'm going to offer all a 'virtual' toast!

Tom

 

[tboydva]

Re: Small current "back" into my charger - unplugged

Well - here's a preemptive strike. I've been testing everything possible with my multimeter. I seem to have an intermittent problem with the ignition switch. Been searching here most of the morning, but can't seem to find similar issues. I took apart the control box - and by the time I got it apart, the switch started working. I jiggled and jostled and it seemed to be functioning fine (tested by activating the choke). Then, I put it all back together and nothing! So, based on the considerable experience represented here, do I have a wire that's grounding out somewhere, or is my switch really going bad? I'll probably loose patience before the end of the day and disassemble it again, checking each lead wire for fray. However, if I don't get to it, I'd like to know if I should order another switch! Any experiences out there?

BTW, I pulled off the starter motor and am dropping it off for a rebuild tomorrow!

Tom

 

[tboydva]

Re: Small current "back" into my charger - unplugged

OK, now I'm convinced the laws of Ohm, Kirchoff (and probably Thevenin) fail to apply on my boat! I'm totally flabbergasted now and would really appreciate any comments. Here's the series of tests

1) I took apart my control box. Suddenly, the key "worked" as I had power to the starter and I was able to engage the choke. I re-assembled - nothing.

2) Took out the switch and tested the resistance based on the manual shorting(s) under different conditions:
2a) on "removed" the short between the M posts on the switch
2b) pushing in the choke shorted between B and C
2c) pushing the starter shorted between B and S

3) I thought there might be something grounding out all signals (like the kill switch). They all seemed to work.

4) Then, I went to the engine and tested jumpering the 12V service to purple/white wire at the choke. Choke engaged.

5) So, I took a wire from the choke (purple/white) to the switch and tested the resistance at the switch (0 Ohms). So, I know that there is
no short between the switch and the point on the motor where the choke wire is located.

6) Now, I get 12 V (12.35V) at the B terminal in the switch. I can remove the fuse and I get 0V. I'm confident I'm getting 12V at the switch.

7) At the terminal on the motor, I get 12.38V and jumpering to the purple/white on the engine engages the choke. Now, at the switch (reading 12.35 V), I jumper to the choke wire and get nothing! I jumper between the 12.35V at the switch and a 12 ga wire jumpered to the choke on the engine and get nothing. I take the exact same wire back to the engine and the 12.38V post and it fires! I can't believe it needs the extra 0.03V?

8) check the resistance again to the choke (0 Ohms)...

9) getting more frustrated - perhaps the switch/control box isn't properly grounded and it's floating! Checked and the ground is common - 0 V difference between ground on engine and on the switch /control box.

10) WTF? How can this be? Has anyone else had such a weird set of observations? Doesn't seem that the wire is shorted. Could it be grounding out somewhere along my conduit? I'm so confused. Any help would of course be welcome!!!

 

[tboydva]

Re: Small current "back" into my charger - unplugged

Well, since I'm auto-posting - I'll share my resolution. I'm glad to say that Ohms law is alive and well on my boat. My conclusion: somewhere within my conduit or elsewhere between the motor and control box, there is an intermittent break. Not a complete break, mind you, but a break no less. There's enough current flowing to allow a potential of 12.36 V to develop at the end of the wire. Short it to solenoid, and only about 300 uA can flow (and it drops to 0.02V). So, sometimes the break doesn't produce enough resistance and current can flow. Dang hard to troubleshoot.

The solution - run a "hot" wire into the control box outside the ganged cable. Now she runs. Doesn't look spectacular - but it's an '83 motor so if I ever repower, I can worry it about it then. Hope my travails help others.

TJB