Battery problem

[smitty1994]

I recently bought a 2010 RZ2. When I bought it in Dec the guy put two new batteries in it. Couple of weeks ago I went to turn on stereo and nothing. Took it in and they said the cranking battery had gone bad, put a new one in and it started fine. I took it home and turned the switch off. Took it to the lake this weekend and it started, but was a little weak. Kept getting a low voltage warning the whole time I was on the water, so I never turned it off. I watched the voltage meter the whole time and it slowly went from 11.6 to 11.2. I ran the stereo the whole time and played with the ballast for 15 mins or so with the engine running. I was expecting the engine to charge it up a little as long as I ran it (about an hour), but that didn't happen. After I got it on the trailer, I turned it off and recranked, it started but was weak.
Everytime I put it away I turn the isolator switch off and that turns everything off from both batteries, but it seems I'm still getting some drain from somewhere. Any ideas?
Also am I expecting too much out of the alternator or could there be a problem there too?
Thanks for the help.

[IDBoating]

Do you have a voltmeter? You can get a cheap but functional digital multimeter from Harbor Freight for ~$5. Put that on the battery with the engine off, then start the engine and see if the voltage pops up to something over 13VDC. If so, your alternator and charging circuit are working fine.

As for the battery, it must be a national curse or something. I have a similar mystery going on with my loader/backhoe. After using its existing commercial size (Group 31 IIRC) battery that is probably 15+ years old, I replaced it with a high end, very expensive battery about a year ago. (I use this machine to plow snow in the winter so it needs to start reliably in really cold weather, and I feared a 15+ year old battery was probably getting weak.) The new battery has been working fine for the last year or so. Then, a few days ago, I went to start up the machine so I could remove its snow chains, and the new battery was basically dead (?!?). I checked the charging voltage as described above and it was fine, so it's not that the battery wasn't getting charged by the engine. I put it on a standalone charger, then figured the problem must be some sort of unintentional drain when the machine is off - so I removed one battery cable and measured the current when the key was off. Result: Zero, just as it should be. There is NO load on the battery, yet it completely self-discharged in 30-60 days (from the last time I started it). Weird.

Anyway, get a cheap multimeter and see what your engine on/engine off battery terminal voltages are and report back!

[smitty1994]

Do you have a voltmeter? You can get a cheap but functional digital multimeter from Harbor Freight for ~$5. Put that on the battery with the engine off, then start the engine and see if the voltage pops up to something over 13VDC. If so, your alternator and charging circuit are working fine.

As for the battery, it must be a national curse or something. I have a similar mystery going on with my loader/backhoe. After using its existing commercial size (Group 31 IIRC) battery that is probably 15+ years old, I replaced it with a high end, very expensive battery about a year ago. (I use this machine to plow snow in the winter so it needs to start reliably in really cold weather, and I feared a 15+ year old battery was probably getting weak.) The new battery has been working fine for the last year or so. Then, a few days ago, I went to start up the machine so I could remove its snow chains, and the new battery was basically dead (?!?). I checked the charging voltage as described above and it was fine, so it's not that the battery wasn't getting charged by the engine. I put it on a standalone charger, then figured the problem must be some sort of unintentional drain when the machine is off - so I removed one battery cable and measured the current when the key was off. Result: Zero, just as it should be. There is NO load on the battery, yet it completely self-discharged in 30-60 days (from the last time I started it). Weird.

Anyway, get a cheap multimeter and see what your engine on/engine off battery terminal voltages are and report back!

Thanks WABoating,
I got a voltmeter and will take it with me next time I put her in the water.

[chpthril]

Its not a red and black RZ that came NC is it?

Describe the switch...is it a simple ON/OFF or is is OFF/ON/Combine? When the cranking battery was replaced a couple of weeks ago, did the tech test the voltage/condition of the house battery? This is typically the one that sounds the low voltage alarm on the TT.

[Ewok]

If you have the simple on/off switch it only cuts power to the cranking battery, not the house battery. I added a second blue sea battery switch so both batteries are disconnected in case I leave something on by accident and for when I plug in my on board battery charger.

[smitty1994]

Its not a red and black RZ that came NC is it?

Describe the switch...is it a simple ON/OFF or is is OFF/ON/Combine? When the cranking battery was replaced a couple of weeks ago, did the tech test the voltage/condition of the house battery? This is typically the one that sounds the low voltage alarm on the TT.

Haha, yep this is that Tige! Do you know what the problem is with this boat?
It's a simple on/off switch not a combine.
After replacing the cranking battery, the house battery worked fine when the key was turned to acc. After I pulled it out of the water Saturday, I checked the voltage on both and they were the same.

[smitty1994]

If you have the simple on/off switch it only cuts power to the cranking battery, not the house battery. I added a second blue sea battery switch so both batteries are disconnected in case I leave something on by accident and for when I plug in my on board battery charger.

I figured the switch just turned them both off because when the switch is off and you turn the key either way there is no power.
Am I wrong?

[chpthril]

before I get into too details, lets make sure its indeed the same one. Was it being brokered by the Charlotte Mastercraft? If so, I sea trialed this boat for someone else interested in it. At the time, the shop had just put new batteries in it. When I met the lot-boy at the ramp, nothing would power up. First, I found the main helm BUSS B+ cable left off. Reconnected. Next, the main breaker was turned off, reset. Last thing I discovered was that the shop wired the POS of both batteries together, thus defeating the diode isolator. Pulled that cable and returned the boat to its OEM configuration. At this point, the helm powered up and every thing seemed normal. Backed the boat back down the ramp and fired it up. We backed it off the trailer and took it for a spin. During the entire ride, we had a low voltage alarm and the volt readout indicated that there was no alternator charge.

I suggested that their tech recheck with a volt meter. I informed the interested buyer of my findings and never heard back from him.

[Ewok]

I figured the switch just turned them both off because when the switch is off and you turn the key either way there is no power.
Am I wrong?

If its wired properly from the factory, the battery switch only disconnects the starting battery. You can test this by
Trying to turn on some accessories, such as the nav lights or courtesy lights. Whether the key is on or off, if its wired stock those lights will sti work. That is the reason I put in the second switch so I wouldn't drain the house battery accidentally.

[smitty1994]

If its wired properly from the factory, the battery switch only disconnects the starting battery. You can test this by
Trying to turn on some accessories, such as the nav lights or courtesy lights. Whether the key is on or off, if its wired stock those lights will sti work. That is the reason I put in the second switch so I wouldn't drain the house battery accidentally.

I'll check that out.
Thanks Ewok

[smitty1994]

So I checked the voltage across the batteries with the motor running and with it off. The battery on the left (has more cables and fuses on some of the cables) stayed the same but the battery on the right (less cables) jumped from 12.6 to 14.2. Unfortunately I have two cranking batteries instead of a cranking and deep cycle. I'm guessing that the alternator is fine, the battery on the left is the cranking battery and is not connected properly to the alternator and the battery on the right is the house and is working properly and should be a deep cycle battery. Any suggestions?
I also did what Ewok suggested and the courtesy lights stayed on with the battery switch off, I'm guessing only one battery is connected to the switch and it is for the most part properly wired.
Thanks

[chpthril]

Sounds like the dipchits as the MC dealer disconnected more then what I was able to see. Having 2 cranking is not an issue, so ignore that for now. 14.2 with engine running is a good indicator that the alt is functioning ok. Sounds like the B+ lead from the diode isolator that should go to the battery on the left has been left off and is floating loose back there somewhere. The isolator will look something like this. The center post is where the alternator cable goes. The left and right posts go to each batteries B+ post. The Iso is typically bolted to the transom or the front wall of the engine bay, with is the back of the back seat. Find it and fallow the cables to make sure they are connected as they should. Once you get alternator charge back to both batteries, then you can worry about the battery types.

yes, the simple ON/OFF switch does work that way. it only interrupts the main cranking battery from the engine controls.

Well, how do you attach pics like we could before??? well, see if this link works

http://www.spidermarine.com/UserData...rge/113428.jpg

[Ewok]

If all the cables are installed properly, could the diode be bad and only giving power to one battery?

[chpthril]

That sure is a possibility, Ewok, but seems slim. Easy check though with a DVM. test center post then test each outer post. regardless of the outer cables being connected at the batteries, the diode will still pass voltage.

[IDBoating]

If all the cables are installed properly, could the diode be bad and only giving power to one battery?

Sure, and I was wondering the same thing, but those isolators are tough. Built to handle a whole lot of amps, and if it's just a simple diode isolator you can't hurt it by wiring it backwards because the reverse breakdown voltage of the diodes will be more than the batteries can produce.

I share ChpThril's opinion that there's a dis/misconnected cable somewhere. I suggest he start at the alternator and work along its output cable until he finds the isolator, then work along the two battery cables to confirm they're actually connected to the positive terminal of the respective battery. Once we know the wiring is correct, we can suggest further tests.