Number 2 battery no power when selected Chaparral 1930 SS

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1999Chap

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Hey All,
I purchased a Chaparral 1930 SS Sport 5.0L last year and while getting it ready for spring I found out that the number 2 battery doesn't power anything when selected. The batteries are fully charged, I replaced the Perko dual battery switch even the old one tests good, the cables are correctly installed and getting continuity and I'm stumped. Battery select 1 and both works just fine but in the number 2 position I get crickets at the ignition switch and no power to anything. I also have a question about something on the wiring diagram that I cannot identify and it's a box labeled "A" with a 1 & 2 in it and then a single wire goes to the alternator. See image below and any help would be greatly appreciated.
 

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"A" its a battery isolator ,allows both battteries to charge no matter what battery is selected.
As far as #2 battery, check to make sure the negatives are connected together
 
Bt Doctur said:
"A" its a battery isolator ,allows both battteries to charge no matter what battery is selected.
As far as #2 battery, check to make sure the negatives are connected together
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Thanks for the info on "A". Yes, the negative is connected between #2 and #1 and both batteries are being charged when engine is running. I have switched the batteries and get the same result and all dash switches and gauges work on battery #1 and both but not battery #2. I thought maybe that "A" box had a fuse in it that may be blown on the #2 side but since both batteries take a charge I have no idea. I think I broke my brain going around in circles with this because this is pretty simple and it makes no sense why it's not working.
 
Ok, so I’m an idiot for connecting the cables like the previous owner. They had the bat 1 cable on the common and vise versa. Now that I’ve got that squared away is the red box the isolator and can I put a bat 2 cable on it over the bat 1 cable? Right now there is only a bat 1 cable attached and I’m assuming that bat 2 will only charge if the selector is set to both since bat 2 has no cable attached like shown in the wiring diagram?
 

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So I answered my own question about the isolator but what I don’t know is why they would have ran the bat 1 cable on the common post? Was it just a mistake or another reason because bat 2 was just along for the ride and not used for anything.
 
I had an isolator that went bad. The company that I had purchased it from warranted it. So through talking with them and my battery people I got an education. The purpose of an isolator is to segregate batteries. Mine has 3+terminals. There is 1 input terminal which is power coming in from either my alternator or my A/C tender /charger, and 2 output terminals that are labeled battery #1 and battery #2. For me battery #1 is my start battery, battery #2 is my house battery. I took off all my wires and one by one I touched them to my house battery and labeled it and then put it on the battery that I wanted to be on. Then I added a switch on my +wire that I could throw and join my 2 batteries together if one was low and needed a boost.
Also I learned that your alternator and A/C charger when hooked through an isolator will only charge the battery they are hooked to. If I want to charge both batteries, I have to throw my switch. My alternator is hooked up to my battery #1. If I have been draining my house battery, I have to throw the switch to charge it using my alternator. My batteries are hooked up in parallel. You said that you have an isolator, check the voltage coming out of each terminal. Find out where each wire goes and label it. Old School : If you have an issue first look where someone has worked on it. Hope this helps.
 
Denny said:
I had an isolator that went bad. The company that I had purchased it from warranted it. So through talking with them and my battery people I got an education. The purpose of an isolator is to segregate batteries. Mine has 3+terminals. There is 1 input terminal which is power coming in from either my alternator or my A/C tender /charger, and 2 output terminals that are labeled battery #1 and battery #2. For me battery #1 is my start battery, battery #2 is my house battery. I took off all my wires and one by one I touched them to my house battery and labeled it and then put it on the battery that I wanted to be on. Then I added a switch on my +wire that I could throw and join my 2 batteries together if one was low and needed a boost.
Also I learned that your alternator and A/C charger when hooked through an isolator will only charge the battery they are hooked to. If I want to charge both batteries, I have to throw my switch. My alternator is hooked up to my battery #1. If I have been draining my house battery, I have to throw the switch to charge it using my alternator. My batteries are hooked up in parallel. You said that you have an isolator, check the voltage coming out of each terminal. Find out where each wire goes and label it. Old School : If you have an issue first look where someone has worked on it. Hope this helps.
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Thanks for the in-depth response and I wish I had the time to do all of that right now but my HOA doesn’t like the boat in the driveway. I wired the batteries as shown in the diagram and will only use bat 2 as a house battery as you suggest.

I requested the original build for my boat from Chaparral so I can get the exact wiring diagram if possible to see how it was originally set up so I can restore it back to factory specs plus some upgrades like the isolator. As I dig in more I see wires that go nowhere and wires just hanging here and there and I’m not sure I trust all of that and I can’t imagine it came that way from the factory. The downloadable diagrams are pretty generic and don’t show all of the component's so that’s why I contacted Chaparral. Hopefully they get back with me soon.
 
I stand corrected. I did some more research because I was not sure and found this:
But what exactly is a battery isolator? In simple terms, it is a device that separates or isolates the batteries in a multi-battery system, allowing each battery to charge separately. It acts as a gatekeeper, controlling the flow of electrical current between the batteries and making sure they receive the proper amount of energy without draining each other.
So being that the alternator's energy is controlled by the isolator you do not tie the start and the house batteries together while using the boat.
But when using an A/C tender / charger you do need to tie them together, because the tender / charger regulates the energy, and thinks that there is only 1 battery so that is why they have to be tied together in parallel. I learned that 1st hand.
 
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Personally, I would not use an isolator. Not all, but most have a 0.6V drop. Which means the battery only comes close to be fully charged.

I would use an ARC. Automatic Charging Relay between the two batteries. Than when leaving the slip, use battery #one to start. On return, use #two to restart the engine. By doing it this way you always know ether battery can start the engine. The ARC, will charge the other battery that is not being used. Than disconnect when there is no charge voltage.
 
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Iggy said:
Personally, I would not use an isolator. Not all, but most have a 0.6V drop. Which means the battery only comes close to be fully charged.

I would use an ARC. Automatic Charging Relay between the two batteries. Than when leaving the slip, use battery #one to start. On return, use #two to restart the engine. By doing it this way you always know ether battery can start the engine. The ARC, will charge the other battery that is not being used. Than disconnect when there is no charge voltage.
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Thanks for the suggestion and I will look in to that as I move along with putting this electrical system back together correctly.
 
Do the math. Load and distance to the size wire needed. I always go up a size to be safe.
 
Iggy said:
Personally, I would not use an isolator. Not all, but most have a 0.6V drop. Which means the battery only comes close to be fully charged.

I would use an ARC. Automatic Charging Relay between the two batteries. Than when leaving the slip, use battery #one to start. On return, use #two to restart the engine. By doing it this way you always know ether battery can start the engine. The ARC, will charge the other battery that is not being used. Than disconnect when there is no charge voltage.
Click to expand...
Thanks Iggy, I will start a log / checklist and compare voltage before I go out after I take the batteries off from the A/C charger I will let them rest for a little while before I check them. When I come back, I will take a reading and compare.
 
I don't know if this helps. The battery switch will isolate the two batteries or banks. With the ARC connected between them and if the voltage goes over or about 14V the rely inside the ARC will close. So both batteries will be charging. Charge voltage stops, than the relay opens.
 
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