PDA

View Full Version : "High Starter Draw" & misc. elec.


Ben
07-06-2006, 07:21 PM
After some electrical troubleshooting to figure out some intermittent starting issues, I am curious to compare my starter draw. I think I have my issue solved as poor connections to battery, but wanted to check a few other items while I'm dug in...

REKTEK indicated that high starter draw could indicate faulty starter or mech. eng. issue. I am getting 29-35A on startup, then it slowly drops to about 1 or 2 A after maybe 10-15 seconds. Does anyone else have #"s for this, or know what "high" would be in this case.

Other thing I noticed was that my PP volts and dash guage don't agree with each other, or my voltmeters. For example, Voltmeter 1 (radio shack ~$30) reads 12.88 at the dash (lighter) while engine is off. Voltmeter 2 (craftsman voltmeter / ammeter) reads 12.83. PP tells me 11.3, and I estimate the dash guage at 10. When running, same readings (in order) are 14.36, 14.32, 12.4 and about 12.1. Anyone else ever see this? If I hadn't used 2 separate voltmeters, I'd suspect that, but they seem close. Need to check w/neighbors nice yellow Fluke to make sure I guess. Makes it hard to monitor voltage when you know dash gages are off..

Finally, my alternator is reading 10-12A at idle (~650rpm) and 13A at 1960rpm. Seem ok too?

Thanks for any comments / comparisons. Engine is a '94 LT1.

rektek
07-07-2006, 06:33 AM
Ben,
are you still having starting issues ? 29-35@mp for a starter draw is excellent, anything under a 100@mps and I wouldn't be worried, how are you measuring the amperage ? do you have a inductive clamp ?

[note: if you're checking amperage draw at the battery which is the easiest spot in my mind, if you have multiple wires coming off the positive terminal you'll have to grab all those wires inside your clamp, too many wires from stereo etc.. use the negative cable but you still have to grab all the wires inside your inductive clamp otherwise you will receive inaccurate readings.]

I'd consider 12.88vdc and 12.83vdc the same reading the difference in test leads and calibration etc... if you have access to a fluke try it, even flukes can be out of calibration, I send my flukes in every few years but I tend to trust them more than others. [FLuke is a awesome company btw, very professional ]

I'd say you still have a issue if PP and your dash gauge are that far off, any way to get behind there and check for terminal tightness on the gauges ? if you can get back there some simple voltage drop tests will track down your differences in short order.

charging:
10-12@mps at idle sounds about right, where was this measurement taken ? I normally check at both the battery and the back of the alternator B+, [again grabbing all the wires in your clamp] 12@mps at battery probably means 20 @mps at alternator the difference is being used by the boats electrical system, stereo etc, you can see why a boat with a massive stereo might need a alternator with a higher output. I'm seeing most boat alternators in the 60-80@mp range which is fine for a stock boat.
most modern cars now have 120 @mp and higher alternators.

by the end of this thread you'll be a expert on starting and charging diagnostics.

cheers
Jeff

Ben
07-07-2006, 07:33 AM
Thanks Jeff.

I believe the starting issues are gone, will confirm over the weekend. Embarrasingly enough, the battery connections weren't super tight. Boat uses the wingnut method, and the prop I just took off had some vibration, which I figure wasn't helping me. Anyway, I'm either replacing wingnuts w/regular nuts or going to swap to regular battery post clamps somehow. Anyway, I'm pretty confident that was it, especailly after taking all of the measurements I did... It started 4 or 5 times w/o issues while I was messing with it last night.

Anyway, my amp #'s are using a craftsman clamp over the wire ammerter / voltmeter combo unit.

I checked the current at the devices, starter where the big red fatty goes in the back and alternator at wire that connects to the + post on the back of it. So I olny should have measured what I was looking for I think. Didn't consider checking @ battery. Would I gain anything here?

Based on your recommendation from another thread, I checked drop from batt+ to starter+ and also loss of ground from batt to eng. block. Both were 0, so I figure thats good.

I agree something sounds fishy w/ the wires / connections behind the dash. Not hard to look at, just takes some time (very limited at the moment). Knowing that all is well between engine & battery for now, I may wait until fall for that one, we'll see.

Thanks for the confirmation on the starter draw. I plan to lube the starter for the 1st time (for me) this fall. Any special tricks there, and what kind of lube do I use? Thanks.

Ben

rektek
07-07-2006, 08:07 AM
Ben,

so someone actually read my voltage drop post and put it to use! awesome, I hate when people just start throwing parts [shotgun approach] at a problem in the hopes of a fix, it sounds like you have everything under control, the next step is to grab the family, put the boat in the water and enjoy a few man sodas !

leave the battery wing-nut connection in tact, put stainless steel lock washers under them if you think they are coming loose, home depot, lowes, OSH carry SS hardware now.

I always start making measurements at the battery, if something's up I start checking at the components.

great to hear you're using the clamp/combo meter, I keep one in my boat, they are cheap now a days, every boat owner should own and learn how to use one.

starter lube, automotive lithium grease is fine, get a small tube and ad it to your boat tool kit, don't over due it, just a light application is needed.

PP follow-up, check all the PP electrical connections, not just at the gauge.

can't think of anything else except for Ben Wallace to the Bulls oh no !

cheers
Jeff

Ben
07-10-2006, 11:51 AM
Simple, cheap trip to Depot for some washers, nuts & lock washers fixed the problem. Made for a happy weekend. Thanks for the tips.

JimN
07-10-2006, 12:12 PM
29A-35A for starter draw is very doubtful. More likely, the meter can't deal with the draw and shows what it can. Most hand-held meters are good to about 10A and have a fuse for this function. I see in your later post that you used a clamp type attachment for your meter. Was it set to the correct range? I have never seen a starter draw this little current, even when it was free spinning. Under load, these usually draw 150A-275A.

.05Vdc variance is not a big deal- 2Vdc is when comparing meters. It's possible that there is a bad or loose ground on the motor, the battery cables may need cleaning/tightening or the dash ground is bad. The Fluke probably won't show much difference from your other meters.

Ben
07-11-2006, 07:23 AM
Jim,
No range selection for clamp ammeter, auto. I will check again later when I can borrow my dad's meter which is better, and has a peak hold function. It may be peaking to high & quick for my meter to get it.
I'm fully suspecting that something is funny behind the dash, but everything works now, therefore putting the funny dash meter reading on the fall / winter list...
Cleaning / tightening batt. cables fixed problem.

Thanks.