'76 115 Charging/Cranking voltage issue

[Cricket Too]

Hey guys, have the above engine, and noticed at the end of last season the dash voltage gauge was reading very high, what looked like 16 or 17 volts at WOT. Never got a chance to actually check it with a voltmeter, until another problem popped up.<br /><br />Went to start it up after winter storage this year, and after putting a good charge on the battery, it would barely crank the engine, cranked good and strong for about 2 or 3 seconds and then would slow down hard and barely turn the engine, and couldn't get the engine started. Battery was brand new last year, and got a good charge this year, but it's a Deep Cycle battery and I don't usually like those.<br /><br />Took a look at the cable ends and saw a decent amount of corrosion on the battery side ends. Decided to just cut all of the + and - connections off and cut the cables back to where I saw good copper(couple of inches on each). Cut them all back to nice clean copper, put brand new connections on, with dielectric grease on the cable, and then put marine shrinkwrap over all connections. Hooked everything back up, and same problem, cranked good and hard for 2 or 3 seconds and then dies down, until it completely stops. Checked all the lugs and none of them were hot to the touch, which I've seen before with bad cables(higher resistance).<br /><br />Kept trying to start it and it finally kicked over and ran great. Decided to put a meter on the battery while it was running and it started out at about 13.5 and just kept going up. Ran the engine at about 3,000 RPM for a couple of seconds with the meter on, and it went up to about 15.3, then dropped back down at idle to about 14.6. I can only assume it goes up higher at WOT, but couldn't check that on the hose.<br /><br />So could this be charging more, due to bad cables and higher resistance, or could this be a bad regulator/rectifier and this higher charging voltage damaged the battery, which is why I now have a cranking problem? I know all of the cable ends are good, because they're brand new, and I didn't see any spots on the length of the cables that could have gotten corrosion in them, but I guess it's always a possibility. Just don't want to replace all the cables if I don't have to, since they are expensive, about $4.00 a foot and I need about 15ft of both + and -, probably $150 all said and done.<br /><br />Any hints would be a big help. I had no cranking issues last season, just noticed that high charging voltage at the end of the season, and now I have a cranking problem, with the same battery, and brand new cable ends.<br /><br />I appreciate any help, need to get on the water, weather is getting nice. Thanks again, Mike.

 

[ezeke]

Re: '76 115 Charging/Cranking voltage issue

Others will have different ideas, here is mine.<br /><br />I think that you should take your battery to a dealer and have it checked. Almost all of the marine batteries are warrantied on a pro rata basis.<br /><br />BTW, what size cable are you using on your battery?

 

[Cricket Too]

Re: '76 115 Charging/Cranking voltage issue

Thanks ezeke, I was thinking it was a battery issue, I charged it and tested the electrolyte on each cell with a hrydometer, and it tests good, but I don't have a load tester, so I will have to bring it somewhere to have it load tested. It just didn't seem like a cable issue, since I replaced all of the connections and the wire underneath all of the connections was bright, clean copper. Also, it would seem that I would have a constant resistance problem when cranking if it were bad cables or connections, but this thing rips for 2 or 3 seconds, and then dies out fast.<br /><br />I got the battery from a local shop, which I have since become on bad terms with, due to them scamming out a friend, so if it turns out to be a bad battery, I'll eat the $70 I paid and just buy another one. But that charging voltage worries me. Am I supposed to be seeing anything over 14v or so, even at WOT? Could this have killed the battery, or could it be that that voltage is being put out, because of the extra resisitance that a bad battery is causing??<br /><br />Also I am using the #4 Gauge cables that were in the boat already when I bought it. I would prefer #2, but like I said, it's expensive, and I never had a problem with these #4 cables before.<br /><br />Thanks.

 

[ezeke]

Re: '76 115 Charging/Cranking voltage issue

I don't think that the cables are the problem now. I think you could well have had some serious damage to the battery when the cables were corroded because then it was not being recharged properly. Winter storage is really hard on the batteries, too, if you don't charge them up periodically. I've taken to bringing them inside and using a trickle charger monthly.<br /><br />If you get another battery try to monitor the voltage on your meter when you are not running. Try to keep it at least above 12.5 volts all of the time.<br /><br />On the charging voltage, it is unregulated, keeps trying to do the best that it can to charge the battery. If it gets too high it will start injuring the rest of the electronics including the stator. Ideal policy with the unregulated rectifier is to start each trip with a fully charged battery.

 

[Cricket Too]

Re: '76 115 Charging/Cranking voltage issue

Thanks ezeke. I did charge the battery up with a 10amp charger, periodically throughout the winter, but not too often, maybe only twice between September and April, so I guess not too much at all, and if it wasn't being properly charged by the engine, then it could be shot. I guess I'll really just have to start with getting this battery load tested.<br /><br />So as far as charging voltage, are you saying that this particluar engine's charging voltage is unregulated or that all charging voltage is unregulated? I guess if this battery is bad, that would explain why I was getting these higher voltages, if it's trying to charge up a battery that won't take a charge or has high resistance in it. <br /><br />I will get that battery load tested and post back, but I really hope it's the problem.<br /><br />Thanks again, Mike.

 

[ezeke]

Re: '76 115 Charging/Cranking voltage issue

This series of motors had unregulated rectifiers which were 6 or 10 amps. The motors with the 10 amps had tilt and trim. They used such a small amp rectifier because it usually could not overcharge the battery. You should expect to continue to see the higher voltage that you have seen in the past.<br /><br />You can regulate the rectifier on your motor if you wish to. You can also install the regulated rectifier used in later models if you want.<br /><br />I have the same motor that you have and it only has a 6 amp rectifier. I use a 650 cca Die-Hard Marine Deep Cycle for a starting battery. This will be its 5th year of service. I have an on-board trickle charger that I use on it whenever it is in the yard.<br /><br />Here is a link to a thread on this subject that I liked: More battery stuff<br /><br />I think you will find that the relationship between unregulated rectifiers and deep cycle marine batteries is good.

 

[Cricket Too]

Re: '76 115 Charging/Cranking voltage issue

Great, thanks for all of that info ezeke, very, very helpful. I was almost certain that I had a reg/rectifier problem when I saw that higher voltage, got really nervous when I was out on the water at WOT and saw my volt gauge showing right below 18v, probably around 16.8 or so. Headed in just because of that. This is the oldest engine I have ever owned, so I was used to seeing nothing higher than 14v on that gauge.<br /><br />I have to wait until the weekend to get that battery load tested, since I'm in the city all week. But I will post back when I find out if it tests bad, I really hope it does, and think it will, just seems that it wouldn't crank hard and fast for a couple of seconds if I had a high resistance problem in the cables, seems more like the battery not holding up under a load after 2 or 3 seconds.<br /><br />Anyway, I'm gonna check out that link above and read up. I'll let you know what happens. Thanks again for the help, I really appreciate your knowledge on this. Helps me out a lot.<br /><br />Mike

 

[Cricket Too]

Re: '76 115 Charging/Cranking voltage issue

OK ezeke, or anyone else out there, I got my battery load tested, actually did it myself at Auto Zone, tested great, didn't fall below 11.10 volts under load, tested it twice and it performed the same on both tests. <br /><br />Now I'm stumped. I re-did all of the connections (lugs), cut the cables back to nice clean pure copper, checked the whole length of both cables and found no crack or bad insulation that would let water(corrosion) in and add resistance, and it would have to be pretty extensive to give this kind of resistance. The engine cranks hard and fast for about 3-5 seconds and then dies down quick and then stops altogether, leaving the bendix stuck up on the flywheel, wait about 30 seconds and it cranks hard and fast again for another 3-5 seconds and dies. The cable lugs are not heating up on either the battery or engine side when this happens. I just don't see how this could be a cable problem, it just seems that I would have a constant resistance problem if it were the cables, rather than a fast crank and then slowly dying.<br /><br />At this point I guess the only thing left to do is replace the cables. Is there anyway to measure the resistance in the cables?? One thing I did notice is that the cable strands are a decent amount thicker than what I see in the new cable in the store. I know thicker strands have higher resistance and vice versa, so is it possible that these cables are just poor quality and should be replaced anyway??<br /><br />I bought the boat at the end of last season, so I don't know if this has been a problem on this thing for a while. I did notice it a little the 2 times I was out in it last year, but knew the battery in it was old, so I just replaced the battery and figured that was the problem....obviously not.<br /><br />Not sure where to go from here, thanks.

 

[Tom Scully]

Re: '76 115 Charging/Cranking voltage issue

Check to see if the wire from the rectifier is the cause of the excess resistance. I am not sure where it connects to the battery but I think it is at the starter solenoid. Before you replace the cables check the starter solenoid for excessive voltage drop during cranking, this is usaully caused by bad contacts in the solenoid. Put your volt meter across the large studs on the solenoid, any voltage dropped across the contacts is that much less making it to the starter.<br />If voltage drop is low enough check the starter.

 

[Cricket Too]

Re: '76 115 Charging/Cranking voltage issue

Thanks Tom, I will check that out. This is a brand new starter, and it doesn't bind at all or have any other issue, the solenoid could be older, like I said I only bought the boat at the end of last season, so it could have been in there for a while. The only reason I haven't checked that out yet is that it cranks fast and hard for 3-5 seconds and then starts to die down, before completely stopping. <br /><br />I figured if I had a resistance problem anywhere, that it would not be able to crank at normal speed at all, but I guess I could be wrong. The other thing I don't understand, is how it eventually stops cranking altogether, I mean it's not just like it starts to slow down and cranks slow, it stops dead and won't move at all, like I had a dead battery, except this is with a good battery that's fully charged. It's like whatever is causing the resistance, is actually putting more resistance into the circuit as the thing cranks. That's what's really throwing me off.

 

[ezeke]

Re: '76 115 Charging/Cranking voltage issue

You have a good battery and a new starter and all the wires have been removed, cleaned, and reinstalled, the only thing left is the solenoid.<br /><br />If you have a thought that the rectifier wire may be shorting it, disconnect it (the rectifier) at the terminal block. You don't need it right now.

 

[ezeke]

Re: '76 115 Charging/Cranking voltage issue

BTW Solenoid replacement cost: <br />Sierra part #18-5808 around $22.<br />MES #1938-M around $13. Solenoid<br /><br />I'm glad your battery is OK

 

[Cricket Too]

Re: '76 115 Charging/Cranking voltage issue

Thanks guys, I guess I'll have to take a look at that solenoid. <br /><br />Ezeke, would the solenoid cause the resistance to increase while cranking or could it just be possible that even a good battery can only overcome the resistance for 3-5 seconds and then starts to weaken as it fights the resistance and cranks? I don't think it's the rectifier, it's not like anything is shorting, it's still trying to turn the flywheel, it just has no power at all to do so, it's not shorted and dead altogether, just so weak it can't turn the flywheel, should have worded that better.<br /><br />Do you think the actually strands of the cables being thicker would have anything to do with it?

 

[Silvertip]

Re: '76 115 Charging/Cranking voltage issue

Next time it acts up, connect one end of a single jumper cable to the POS battery terminal. Touch the other end directly to the large post on the starter. Be prepared for a spark. If the engine spins normally, you have a bad soleniod. If it still spins a bit and begins to die you have a bad-new starter or bad ground connection.

 

[Tom Scully]

Re: '76 115 Charging/Cranking voltage issue

Two separate issues. Charging voltage, and cranking speed.<br />The over-voltage while running indicates excess resistance in the charging circuit, ie: not enough of a load on the rectifier. This can be caused by a bad connection between the rectifier and the battery or the improper type of battery.<br /><br />With what you have posted considered, the cranking speed problem indicates bad contacts either to or in the solenoid. Check the terminals on the solenoid. Bad contacts in the solenoid can cause the problem with the cranking speed being normal for a brief time and then slowing or stopping.

 

[Cricket Too]

Re: '76 115 Charging/Cranking voltage issue

I'll definitely check it out this weekend Tom. I originally thought the charging voltage was a problem, but as ezeke says above these engines have an un-regulated charging system that charges at low amperage(6 amps). So I don't think I have a problem with the charging voltage anymore, at least I hope I don't. <br /><br />I will take a look at the solenoid this weekend though. I just remembered that I have a pair of short battery cables that I used to run on my smaller boat that had the battery in the stern. I know these cables are good, so I will put the battery in the back of the boat this weekend and crank it with these cables, if I still get the problem, my next step is the solenoid, if not, well then I guess I'm putting new cables in the boat. <br /><br />Probably would have been a lot easier if I would have remembered those cables from the start....must be too many weekends of too many beers. I'll let you guys know how it goes. Just for my information, if I do end up replacing the cables, should I use #2 or #4 gauge cable? I have #4 in it right now, and #2 isn't all that much more expensive, might be worth it to put the thicker gauge in.

 

[Seasport]

Re: '76 115 Charging/Cranking voltage issue

Hey Cricket<br />Your problem could well be the solenoid where the contacts fail as they heat up.<br /><br />You should be able to isolate the problem using a voltmeter.<br /><br />Here's some instructions I have given others in case they are of any use.<br /><br />Starter problems can be hard to diagnose. It doesn't take much voltage drop to upset correct operation.<br /><br />During cranking the starter motor current flows from the battery +ve terminal through the battery switch, solenoid (& connecting cables obviously) to the starter motor and then back to the battery –ve terminal through the ground connections and –ve battery cable. There is a lot of current flowing so any poor connection in the whole circuit will lead to excessive voltage drop there (& heat build up) and poor starter motor performance. This includes the ground connections from the starter motor body back to the -ve battery terminal. You will get voltage drop here too which takes away volts from the starter motor.<br /><br />I assume you have access to a voltmeter. If so, I suggest you start by measuring the DC voltage directly across the starter motor during cranking under load, i.e. with the red probe of the meter on the starter motor +ve terminal and the black probe on the case of the starter motor. If this reading is greater than about 9.5V suspect a starter motor problem. Easiest if you have someone else to turn the starter motor over for you while you take the measurements.<br /><br />If the voltage is less than 9.5V you are dropping volts somewhere else. Check and clean all of the connections from the +ve battery terminal to the starter solenoid (including the battery switch if fitted) and from the solenoid to the starter motor. (As a clue, any bad connection should get warm when cranking).<br /><br />Check & clean also the -ve battery terminal & powerhead ground connection and also the ground connection from the starter motor to the engine. On some motors the -ve battery terminal is connected directly to the starter motor body and on others it is bolted elsewhere to the powerhead.<br /><br />If this doesn't fix the problem, you may have bad cables or a bad solenoid. If you have access to a voltmeter you can use the following tests to isolate the problem. You need to measure the voltage drop across each part of the circuit while cranking the motor. Start by measuring the voltage from the battery +ve terminal to the battery side of the starter solenoid (large terminal), i.e. meter red probe to +ve battery terminal and meter black probe to the large solenoid terminal that is connected back to the battery. This voltage should not be more than about 0.3V – 0.5V. If it is suspect a bad cable or connection here somewhere.<br /><br />Next measure the voltage directly across the solenoid when the starter motor is cranking (or trying to crank), i.e. meter red probe to battery side of the solenoid and meter black probe to the starter motor side. This voltage should not be more than about 0.2V.<br /><br />Next measure the voltage between the solenoid (starter motor side) and starter motor +ve terminal. This should not be more than about 0.3V. If it is too high check the cables and connections here.<br /><br />Finally measure the voltage between the starter motor case and the battery –ve terminal. This shouldn’t be more than about 0.3V. If it is check for a good solid and clean ground connection between the battery –ve cable and powerhead or –ve battery cable problems.<br /><br />Make sure your battery is in good shape. Battery voltage when cranking will also vary with condition of the battery. The battery voltage shouldn't drop below about 10V when cranking.<br /><br />The voltages mentioned above are indicative. They will vary a bit with starting system. What you are looking for is an excessive voltage drop. The voltage readings may well go up and down a bit as the motor turns over slowly but just try to choose a consistent set of readings. The key is that the starter motor needs at least 9.5V to operate properly.

 

[Tom Scully]

Re: '76 115 Charging/Cranking voltage issue

Well said SeaSport!<br /><br />The voltage of the charging system should not go much above 13.5-14 volts, 16-18 volts is too high.<br />The system uses the battery as a sort of voltage regulator.<br /><br />Follow Seasports directions and you will find your cranking speed problem.<br /><br />Good luck.

 

[Cricket Too]

Re: '76 115 Charging/Cranking voltage issue

Seasport, wow thanks for taking the time to run me through that, that will definitely help me get to the bottom of this problem.<br /><br />Tom, I was always under the impression that charging voltage should never go any higher than 14v also, but was told by ezeke above that this particular engine or series of engine, has unregulated charging voltage and that seeing higher charging voltages is normal.<br /><br />Now I don't want to step on any toes here, you guys have been more than helpful, but these are two totally opposite points of view, and I'm a little confused. <br /><br />When I originally saw the high charging voltage, when I was running WOT out on the water, I was concerned and decided to come in, then I started to have the cranking problem and figured they were related, ie. too much resistance in the circuit equaled slow cranking and higher charge voltage to over come this resistance.<br /><br />Ezeke explained that this was normal, and I felt better, and decided to concentrate on the cranking problem, he seems to be very knowledgeable about this particular engine, as he has the same exact one, and has the same higher charging voltage. This is the oldest engine I have owned and was not usd to seeing this higher voltage, and while I tend to believe what he says about it, it goes against everything I've ever known about charging voltage. So not really sure what to think about that now.

 

[ezeke]

Re: '76 115 Charging/Cranking voltage issue

I agree with Tom Scully<br /><br />I don't have the problem of high voltage readings on my system, Cricket Too. <br /><br />You have the problem. Are these fellows saying that you did not see the voltage readings that you reported? I don't think so. <br /><br />You should expect to continue to see high voltage readings until you fix your system and/or can keep your batteries charged. You could be having those same readings just because you are running too many accessories.