what should my charging rate be?

[chdabren]

1974 Evinrude 85hp (model 85493-B). I installed a new rectifier on this engine. What should my charge rate be? I have standing voltage of 12.12 at the battery, engine off, key off. After starting engine and letting it run for 10 minutes....charging rate goes to a maximum of 12.45 volts. Is this normal? Should I be getting higher voltage readings? Again, being used to "alternators" putting out 85-140 amps, I'm thinking this engine is running low on voltage. I'm figuring this thing has a 6 amp stator. I just want to know what my charging rate should be. Battery is fully charged. I replaced the rectifier cause it failed the ohm's test. Anyone know what I should be seeing for #'s? so I can make sure I have a good stator or not. I do not have any accessories operating while engine is running. I know that it does take some time for the stator and rectifier to start charging but was just curious whether I was getting correct readings or not. Thanks

Chris

 

[Vic.S]

Re: what should my charging rate be?

Yes its 6amp stator according to the parts catalog HERE

You know from your experiences with proper alternators that it wont be charging at 12.45 volts but it wont deliver much of an output at low revs. In fact you'll only get decent charging at high revs but once the battery is fully recharged you should see the volts rise to quite a high figure because it is not regulated.

Give it a good run and monitor either the volts to see if they do come up or the amps to see if you are getting any charge. You'll only see anything like 6amps if the battery is down a bit and if you are at high revs.

 

[Faztbullet]

Re: what should my charging rate be?

Make sure you are not using a deep cycle or dual purpose battery as these will take longer and may even damage charging circuit.

 

[wilde1j]

Re: what should my charging rate be?

Something's whacked with your voltages. A fully charged battery should read ~ 12.68 VDC at rest. If you have a 6A rectifier, the voltage won't go up a lot (depending on the load), but another .5 to .75 would be reasonable. Are you measuring with a decent VOM, or a little panel gauge? A good sign is the voltage increases when running, however.

 

[chdabren]

Re: what should my charging rate be?

Thanks gang!! I'm using a Die Hard Marine Starting battery. I had the motor running for a bit on the bad rectifier (it was the one that failed the ohms test) so it probably dragged the battery down a bit. I had 12.22 volts standing voltage, key off, engine not running. Installed new rectifier and fired engine up, watched my DVOM slowly climb to 12.35....using my "fast idle", I brought it to about 2,000 rpm, DVOM showed fair increase to 12.45-48. I didn't "load" the motor (put it in gear and throttle it) and I had no accessories on. I can't use my dash gauge as it's not hooked up. Just seems to me that it's not charging, but it may just be me. I don't xpect to see 13.85+ volts as this isn't a 140 amp item but it does seem as tho it's not charging. The new rectifier is the exact same one I had (got it from iboats) and the wiring was set up a bit different but same color wiring. Instead of the wires being in a horizontal triangular fashion, they were in a 90' fashion exiting the new rectifier. I hooked it up (didn't redo the ohms test as I didn't figure I needed to), hooked up my DVOM (snap on type) and set it for "dc voltage"..fired engine up and watched. Like I said, the voltage isn't what I expected so perhaps I'm looking too hard for #'s that won't exist. Maybe I should test the stator. Anyone know how that's done?? I'm getting frustrated as I don't want to break down on the water some 10 miles out cuz my battery died. I run vhf @ 5 amps, am/fm cd @ 10 amps and humminbird depth/fish @ 1 amp. Plus my nav lights when needed, and my horn (5 amps) when needed for fog, etc.. I really don't have many electronics on board, just enuf for what's needed. And the only items that are hooked up right now are fish finder (and I take that out when not in use as it's detachable) vhf and nav lights. No draws either. Is there a way to test the stator to determine servicability?

Chris

 

[wilde1j]

Re: what should my charging rate be?

Chris, for a stator charging test, measure AC voltage ... make sure you're on the AC scale. I think it's across the yellow leads, but a shop manual can confirm and I think the voltage should be over 20 VAC, but I could be wrong on the voltage.

 

[chdabren]

Re: what should my charging rate be?

Are u talking about the leads off the rectifier? or the actual stator itself. Can someone please tell me what #'s I'm looking for on the DVOM that will tell me whether I AM getting sufficient charge to the battery? It's a 6 amp stator, that I know but I don't know exactly what #'s to look for or the actual procedure (rpm's,etc.) I need to follow or be at to determine whether the stator is any good. Is it possible that I hooked up the rectifier incorrectly? The only wires I wondered about were the yellow wires due to the configuration of wires exiting the rectifier. One red wire and 2 yellow wires (one yellow wire also has a red tracer on it. Stators, as I've discovered aren't cheap ($300.00+). I'd just like to be able to verify the stator's condition. Maybe I'm overloading it with electronics altho combined total of accessories is around 20 amps. Maybe I need to use the battery I have now only for starting and running the engine. It's a marine starting battery. Should I go to a deep cycle marine battery for accessories and run a seperate fuse block for accessories? Any help/advise would be great!! Thanks!!

Chris

 

[wilde1j]

Re: what should my charging rate be?

The AC leads are from the stator to the rectifier.

 

[patrick4266]

Re: what should my charging rate be?

I have a 1972-85hp rude and your numbers are similar to mine except i believe I get around 13.45 at idle with my om meter , the actual votage gage on the dash goes just a little past charge

 

[chdabren]

Re: what should my charging rate be?

Thanks for the varied input guys!! As I said before, I'm using a Die Hard Marine Starting battery. I'm going to install a deep cycle battery and seperate fuse block to run my accessories as I don't think my stator will provide enuf power to run my electronics. I run a 1 amp Humminbird Fish/Depth finder, a 5 amp West Marine dsc vhf, and my am/fm/cd player has a self contained 10 amp fuse. I believe the combined amperage for these items will far exceed what my stator and rectifier will be able to put out, even at the high rpm's. I'm just looking for ways to determine if my stator is any good. The rectifier is new (from iboats). Maybe I have it hooked up to my power strip wrong but I doubt it. How can I test the stator w/out removing it? I'd have to take off my flywheel to access it. Is there a way to test it at the power strip? It's a '74 Evinrude 85hp (model 85493-b). Do I test it with an ohm meter or DVOM and what setting for the DVOM? I'm kind of lost here and confused as to the #'s I should see. What rpm's? The boat is not in the water nor, at this time, registered, so everything is being tested in the driveway, muffs on. Do I need to just use fast idle or do I need it in gear and engine loaded (in gear at certain rpm)? I'm trying to come to terms with the fact that I'm NOT gonna find #'s like I would in a car, so please bear with me. With family on board, it's not a good idea to run the battery down trying to get to the fishing spots and suddenly have no power to get back home.
Thanks again..you guys are great!! P.S...my dash gauge isn't hooked up so I can't use it anyway.

Chris

 

[jimg984]

Re: what should my charging rate be?

chris i sure you have ohm thur the stator with 2 yellow wires loose should read closed circuit thru yellow wires and stator. should have open circuit from each yellow wire to ground,, i thinking you have done this

 

[wilde1j]

Re: what should my charging rate be?

Chris, fast (1200 rpm) idling on the muffs is fine. Just measure the AC voltage (don't remove ANY leads) across the yellow pair from the stator. You should get an AC voltage above 15 VAC (I don't know the specific value, you really need an OEM shop manual BC I don't have one for your motor). The shop manual will give ohms for a non-running test as well.

 

[Vic.S]

Re: what should my charging rate be?

Things you can do

1. Disconnect the AC wires going to the rectifier from the terminal block (that's the two yellows) leaving the wires from the stator . Connect your voltmeter selected to AC volts (20 volts range) to the wires from the stator. Start the engine and observe the meter reading. It may be below 12 at idle but when you increase the revs it should rise way above 12. Perhaps getting up to 16, 18 maybe towards 20 at max revs. If you get good readings like this the stator is probably OK.

2. EITHER:-

Properly charge your battery on a decent mains charger. If its a basic non-regulated charger monitor the volts and keep charging until the Volts have read at least 14.4 volts for a couple of hours. Let the battery rest for 12 hours and check the volts. If its 12.7 or above its charged. If it isn't charge it some more until you do get that reading after a 12 hour rest. Then reconnect the rectifier, refit the battery to the boat and start the motor. Check the DC volts at the battery. If all is well with the battery freshly charged you should soon see the volts rise from what ever they fell to while starting to something like 13 to 14 volts but you will need the engine running at a good speed not just idling. If that happens it is bound to be charging the battery.
It would be sensible to also check the volts at the red wire leaving the rectifier you should get the same here as at the battery. If it is higher (by more than a tiny bit) then you have a bad connection somewhere between there and the battery.


OR (better perhaps)

Disconnect the battery.
Reconnect the yellows, disconnect the red wire that comes from the rectifier from the terminal block and reconnect it via a DC ammeter with a range of at least 6 amps. (That's the red wire to the positive terminal of the ammeter and another wire from the negative terminal to the terminal block. Presumably the wire leading way from there is also red) Make sure your temporary connections are insulated because they will have the full battery volts on them and if they touch the motor anywhere you will short the whole darn thing out.
Reconnect the battery and start the motor and increase the revs. You should see a good current reading, several amps initially, maybe near the full 6 amps, but it will fall as the battery charges.
This really is the best test because it is actually measuring the charging current which is after all what you are most interested in.
Also try putting some load on, what ever takes the most current, nav lights perhaps. you should see the reading on the ammeter increase again .

(remember that your VHF only takes much current when you are transmitting)

When you have done disconnect the battery while you remove the ammeter and reconnect the red.

Whenever you connect the battery make absolutely sure you never get the connections reversed. Your rectifier is instant toast if you do. You may burn out the stator coils as well.

Also remeber that if you leave your battery even partly discharged you will reduce its useful life. Always recharge it as soon as possible.

 

[chdabren]

Re: what should my charging rate be?

Ok...first of all, thanks for the responses. Second...I'm confused as hell. Should I have my rectifier disconnected during the charging process? I don't know what wires are coming from my stator. They are hidden under brittle plastic and I don't have a clue what color the wires are. Are you telling me that my accessories consume too much power for that charging system to handle? I haven't even included my bilge pump draw into the equation nor my navigation lights? This sounds like it's gonna be one big friggin' nightmare. The other thing to is, it seems that if my engine sits tilted long enough (2 days or more) that my float bowls drain out. Many is the time that I've had to spray my fuel mixture directly into the air box to get this motor to start. It aggravates the **** out of me. I can picture sitting at the dock, having just launched, and I go to start the motor and it just cranks and cranks, so I take off the engine cover, the airbox cover, shoot fuel into the intake and start it up, then put everything back together and go about my boating. This engine has a bad habit of pissing me off but it's a dam good, solid running motor. Once it's running...it's awesome!!! Lots of power and torque!! I'm just confused about this charging issue and it's aggravating me!! My fuel pump is new, carbs rebuilt, etc.. No leaks anywhere, needles are all free moving, etc.. I'm about ready to throw my hands in the air and say "f**k it all"...lol. Someone please motivate me!!!

Chris

 

[wilde1j]

Re: what should my charging rate be?

There's no reason at all to disconnect anything to read AC voltage from stator, Believe me, if you have AC voltage above 13 v to the rectifier, you have current for charging ... it's impossible not to and if you don't have more than 12.7 VDC across the battery terminals at a fast idle, you are clearly not charging the battery. If you have the AC voltage, but not the DC level, the rectifier may be smoked or the wiring isn't right (broken, high resistance, etc.).

1. Set VOM to measure AC voltage, say up to 50 VAC and measure voltage across yellows from stator. Needs to be above 13 VAC for sure with engine running. Advise what you get here.

2. Set VOM to measure 15-25 VDC. Measure DC voltage across battery terminals with engine running. If less than 13 VDC, not charging. Start looking for cause ... incorrect termination, bad wiring, smoked rectifier, etc.

This is just not that complicated.

 

[chdabren]

Re: what should my charging rate be?

Thank you. I'm not suggesting it to be complicated. All I'm saying is that I needed to know what voltage I'm needing to see on my battery terminals, at a specified rpm (load) to determine if my charging system is working. Reminding you that I'm used to seeing 13.75+ volts across the terminals and 140 amps (or whatever the charging system is designed for). In this case, 6 amps and I want to make sure I"m not missing anything or not doing my testing right. Sorry if I made it seem complicated. The NEW rectifier I bought from right here (iboats) did have a slightly different setup on the wiring but same color wires and I hooked them up EXACTLY how the old ones were, and had the same #'s as before (with the old rectifier) which is why I THINK the stator is bad. Thank you all for your help!

Chris

 

[Gary H NC]

Re: what should my charging rate be?

I would fully charge the battery and get the boat in the water and give it a good fast run.
My cross flow does not charge good until i get over 3000 rpm then it will push the volt meter up to 15 volts until the battery fully charges then the volt meter will drop back to 12.8 to about 13.6..

 

[chdabren]

Re: what should my charging rate be?

That's my problem...lol. I can't get the boat up to 3,000 rpm "on the water" as it's not registered yet. This is why I was asking about testing it in the driveway. No problem. I'll do the tests that everyone has suggested and see what happens. Thanks everyone!

Chris

 

[Vic.S]

Re: what should my charging rate be?

There's no reason at all to disconnect anything to read AC voltage from stator

the reason I suggested doing that was to see the no load reading. What was in the back of my mind was the possibility that the battery is fairly well down so the volts just are not rising yet. If thats the case the AC volts will be pretty low as well if the stator is connected up.

 

[chdabren]

Re: what should my charging rate be?

Ok..so, fully charged battery....12.7 volts. I did my ohms test again for the rectifier. I actually got readings on BOTH directions on a NEW rectifier hooked up exactly by the book (shop manual specifically for my engine). I ignored that and tested the stator. I got a reading of 2.5 mega ohms (spec. is .8-1.2 ohms- I didn't do the conversion). Anyway, I fired the engine up, DVOM still connected to battery, and "fast idled" motor to about 1,500 rpm....ish. Watched DVOM climb rather quickly to max out at 15.01 volts at battery. I'm assuming this means my stator and rectifier are working properly together. Starting out at 12.7 volts, key on, engine off, volts drop to 11.2 during cranking, back up to 12.7 almost immediately, raise fast idle to 1500 rpm, watch DVOM and *poof*, 15.01 volts within 30 seconds. I think that means I'm good on charging. Anyone have any input? Thanks

Chris