Alternator not charging properly

Clinton

Have a 2000 242 fiesta vee. 5.0 mercruiser. The alternator is not charging as it is supposed to. It seems to be the original as it looks very old. I took it off and cleaned up the post on the back of it and re-installed. Was a pretty good improvement for a short period of time. Seems that it doesn't want to charge at all. Only made it off the water this weekend due to the second battery. It is a 55 amp alternator and I have found another one at the parts store but I would like to know if it is possible to put a larger amp alternator or would it over charge batteries. I was thinking somewhere in the 75 to 85 amp range. Really don't want to get stuck on the water. currently when engine is running it is barely showing 12 volts. I didn't run any of my electric components all weekend except nav lights only due to requirements at night. Batteries are 2 brand new deep cycle Interstate. Thanks in advance to any answers.

Black_Diamond

I would take it in and get it tested, remember to NOT use an automotive replacement.  Check your grounds too, esp off the batteries. 

Clinton

I took it to autozone and they crossed referenced the number and came back with an exact match. I seen several photos they use to verify. If it showed up and wasn't an exact match I won't except it. But I'm just curious if I could go larger. What is an esp?  I looked at all the cables on the battery and they were all tight. look farely new as well.

Black_Diamond

Esp = especially. Sorry for the shorthand. Do not accept a non-marine replacement as it is flat out dangerous. 

Clinton

I don't understand. Why is it dangerous. When they entered the part number off of my alternator it came up as an alternator for an mercury. Not sure what model as they didn't enter it that why. It was the exact match to what I brought into the store. What is the difference?

bluto

Yes, you can install a higher output alternator with no problems.

Marine alternators are "ignition protected", meaning they will not ignite gasoline vapors. Automotive types are not ignition protected.

JC290

Clinton upgrade the alternator, but make sure it is for marine use as others have stated. The factory one on that model is not enough from my experience with my old 242. double check all connections batteries and alternator. Make sure when you are not running the boat and are just sitting around listening to radio and such you move the batter switch from both to one or two, that way you will not drain both batteries. The fridge on that model will drain a battery quickly around 6 hours if the fridge is turned up to it's coldest setting. I will leave mine turned up while motors are running than turn the knob half back. Good Luck 

Clinton

Ok. Good to know. Is there a Rinker site you can order parts from? Also, I don't use the fridge at all yet seeing since I have been having this problem. Didn't want to leave me self hanging. I have only been using battery 1, but I haven't been using any electronics because of slow starts due to weak battery. When we stop I just turn the batteries off and we swim. Nothing has been running when we are not running the engine. But it still drained so low it almost didn't start Sun morning when we got up. When the engine is running and were  moving down the river around 2300 rpm it's only showing 12 volts if I'm lucky. It typically stayed just below 12 volts. Both of my batteries are "deep cycle" does that matter or should I have a normal battery for the starting of the engine?

Dream_Inn

When I owned a 240, I used deep cycle for both of my batteries.  I think you should be ok with that, even if it is not ideal (Ideal would probably be the batteries that are both for cranking and deep cycle).  I believe an alternator should solve your problems.  Hopefully you have not drained your batteries far enough that they do not make full recovery.  Does it charge ok on shore power with the inboard charger?

rasbury

also, there are companies that will rebuild- I have a local shop here in Fl. that is their only business-rebuilding alternators and starters as I had to get my starter rebuilt as it got wet. The new starter cost was going to be like 500 bucks or something and I rebuilt for $135.....

Clinton

Just double checked and both batteries are cranking batteries. I did not see "deep cycle" any where on them. Sorry for the miss information. Does that make a difference. Pics coming soon. May help in the aid of this situation. Rasbury, there is a shop right down the road that rebuilds starters and alternators I am going to give them a call today. Thanks for the advice.

Handymans342

Ras, did you have your alt upgraded? 

rasbury

no- alt was not the issue, the starter was- I was just saying that the guy that did my starter also did the alt's but so far that has not been a problem...and I don't seem to be having any charging issues, now using the fridge all the time so seems like the factory set up is working ok for me.

rasbury

and Clinton- I'm not sure other than by description what the difference is between the marine and the auto but make sure the guy that rebuilds will rebuild to a a marine spec!

rasbury

does your diesel alternator work better? lol Don't diesel run a lower RPM thus making you upgrade your alt perhaps???

rasbury

and the company that did mine marine is their only business!

Clinton

Ok, 1) Picture 1 is of battery 1 and it's connections. Not much going on.

2) Picture 2 is of some sort of what looks to me as a relay post.

3) Picture 3 is of battery 2. The 2 small wires go to the setup in picture 2.

4) Picture 4 is of the back of my battery switch knob. My finger is pointing to battery 1 position, the terminal on the right with the wire loom around the positive wire is the battery 2 position. And the middle wire is the both position. The off position is hidden behind all of the wires at the top of the dial. I hope this setup is correct.

I did test to see what battery ran what and  as long as I have the selector knob to the a battery that is connected it runs EVERYTHING that is not 110 volt. ALL the lights inside and out, all the dash gauges, radio, pumps, etc. Ether battery will run EVERYTHING so long as the selector knob is turn to the battery and the battery cables are connected to the battery. Is this normal?

Clinton

I unhooked the switch to see the writing on the back. The position with the label "feeder" had battery 2 connected to it and went to the starter.

The position labeled Bat1 had battery 1 connected to it.

The position labeled Bat 2 says both on the opposite

Clinton

I have a Guest 2111 model switch. I haven't found info on this specific switch but the 2111A. It says the 2111A  is a make before break switch and from what I read it means I can switch to any position except off while engine is running. I switched it to both and from 1 to 2 a couple of times and was worried I fried something.

Clinton

I also found this. From some diagrams of dual battery installation I found on-line this seems to be an isolator. Is that a bonus to the whole setup?

Cableguy Greg

If you only have cranking batteries, they will drain fast. When I had a 232, I used 2 deep cycle batteries and it worked out fine. I know that you get better cranking power with a starting battery, but the DC's worked. I would seriously consider changing the batteries to DC's or dual purpose batteries.

Stodge

An isolator allows for a different number of batteries versus alternators.  If you have 1 alternator and 2 batteries the isolator will allow the charge from the alternator to be split and is supposed to keep one battery from drawing from the other.

Clinton

This is the diagram I found. Is the battery charger it refers to what the 110 volts uses to charge the batteries? If so how do I find the battery charger wires?

Clinton

And if it is an isolator, does that mean the only way to charge both batteries at once is to be on the both selector on the battery switch?

Stodge

No, each battery and the output of the charger go to a post on the switch.  The charger or alternator should always charge both batteries regardless what position the switch is in.  The switch should only control which battery feeds the starter/DC circuit.

Dream_Inn

Yes, the battery charger it refers to is using AC shore power for charging.  The charger wires should come directly out of the charger.  Just follow them to see where they go (from the pic, it looks like they are going into your isolator).

I believe with an isolator, the alternator will charge both batteries no matter where the switch is.  You can check it with a voltmeter while running right at the batteries.

Clinton

Ok, I feel really good about all the info being given. I've went and looked at the isolator and it's wired properly. No here is the big mystery confusing me about the switch, according to the diagram the batteries should be connected to the terminals that match (1 on 1-2 on 2) and the starter to the feeder post on the switch. What confuses me is that the post on the switch's back that says battery 2 is labeled BOTH on the face side and the post on the back that says feeder is labeled 1 on the face side. Can anyone explain why that is and should I be connecting battery 2 on the back to the post that is labeled 2 even though the face of the switch in that position says BOTH.

Dream_Inn

Clinton, I've been wondering that all along here as well.  It sure doesn't sound right, but it is hard for me to say without being right there looking at it.  Maybe you can ohm out the switch to see which is correct.

MarkB

You have a different switch. In fact you have the switch I have. Your starter (crank) battery should be connected to battery 1. I believe (but you need to confirm) that battery 2 goes to the both.  My switch works as follows:

Off - both batteries are offline.
1 - battery 1 is on starter position, battery 2 is on house position
Both - battery 1 and battery 2 are bridged for emergency start.

Alternatively, there are switches that have off, 1, 2 and both.  I believe the way that works is setting 1 or 2 just decides which battery is the starter battery and by default the other is the house circuit.  Both will bridge the batteries together.

Clinton

This is a guest 2111 switch. It has 1,2,both, and off. It took several hours but the diagram was right on. I final traced all the wires and found them all to be in the correct position. With a little ingenuity was able to test my isolator as well all is working fine. Only issue comes back to the alternator not charging enough. The dealership is going to give me a replacement as I offered to install it since I don't trust their handy work. I will keep everyone posted. You guys are a great group and couldn't have figured this out without you all. Thanks!!!

youstolemybeer

Couple questions.    Are you reading the voltage directly off the batteries or are you just using the dash gauge. When you say you made it back to the dock thanks to the second battery was that because the boat wouldn't start or because of low battery voltage and you were concerned it wouldn't start?  
The reason I ask is if your reading off the dash volt gauge it will always read low because it is reading voltage at the dash, not at the batteries.  Using a dvm start the boat and check the voltage at the batteries.  It should be 13.5 or better  if the boat starts and you have low battery voltage, turn off the engine and check the water level in each battery.  If the water level is low, that will cause lower volt readings