OX66 charging second battery

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I've got a single 2003 Yamaha 200 hp OX66 with 2 Batteries wired thru a Perko selector switch (bat1 - bat 2 -or both).
I have found the second charge wire from the motor and there is a yamaha wiring kit to hook the second battery up so they are both charging without having to remember to change from bat1 to bat2 for charging.
My question is......Has anyone done this and if so are there any drawbacks to this over an aftermarket ACR?
Just seems like it is a cleaner installation over all the extra wiring of the ACR.
 
This is an interesting question and I don't know the answer. My concern is that the secondary charge current is not isolated from travelling to the primary charge path and visa versa. An isolator or ACR might be a safer installation.
 
The ACR wiring is pretty straight forward... probably a whole bunch easier because you don't have to snake the 2nd charging wire through the rigging tube!

But either way is perfectly good.

Seasick... can you expand on your concern? I think there must be more to your reason for saying that since the two charge wires are isolated (unless the battery switch is on both)... but even then, it doesn't really matter if they do combine - it's just voltage - and it's not like the V doubles or anything.
 
:)
I am not sure what my concern is exactly so let me ask a question:
Suppose you have two batteries, one when isolated(disconnected) stands at 12,4 volts and the second when isolated stands at 11.4 volts. When you switch to both what is the combined battery voltage? Remember I was and in theory still am an electrical engineer and the answer might not be simple.
It's OK to assume both batteries are the same type and age. (for now....)
 
I did exactly that with the previous boat. The aux charging lead from your voltage regulator on the engine will keep that number two battery charged up when it is not selected. I was also concerned that when it was selected providing two charge leads to the same battery might be an issue, checked with a Yamaha technician and they said should not be a problem. I’m not sure that having two charge leads when “both” are selected would be a good idea, however. I would only select “both” if it was required for a low battery start. And my previous boat I used that to charge a deep cycle backup battery also used for a trolling motor. I could use that deep cycle for a start if my number one battery went dead. Worked good for years.
 
seasick said:
:)
I am not sure what my concern is exactly so let me ask a question:
Suppose you have two batteries, one when isolated(disconnected) stands at 12,4 volts and the second when isolated stands at 11.4 volts. When you switch to both what is the combined battery voltage? Remember I was and in theory still am an electrical engineer and the answer might not be simple.
It's OK to assume both batteries are the same type and age. (for now....)
Click to expand...
I was an aeronautical engineer, but here’s my theory. If one battery is higher voltage than the other, current should flow to the lower voltage in an amount, dependent on the internal resistance of the lower voltage battery. The actual voltage delta is typically very small so the current flow would also be very small depending on the resistance of the lower voltage battery. I believe those internal resistance numbers are available, but probably vary significantly depending on age and condition of the battery. This theory is probably excessively simplistic and doesn’t account for inductance, etc. However, I believe it’s probably a pretty good estimate. Anytime you select “both” that process occurs. I have not heard of any significant problems with selecting “both” and it is essentially the same as paralleling two batteries in a single bank.
 
seasick said:
:)
I am not sure what my concern is exactly so let me ask a question:
Suppose you have two batteries, one when isolated(disconnected) stands at 12,4 volts and the second when isolated stands at 11.4 volts. When you switch to both what is the combined battery voltage? Remember I was and in theory still am an electrical engineer and the answer might not be simple.
It's OK to assume both batteries are the same type and age. (for now....)
Click to expand...
:)

The combined V of the two batteries will be somewhere in the middle. I honestly don't know if we can simply state the V would be dead in the middle given there are other factors at play here regarding health of a battery (you eliminated type and age as variables). BUT, I've also never actually combined two batteries and took a reading after first measuring individually as I never found a need to... nor thought about it ;)

Best to figure this out (although it's really just for fun/informational purposes only)... measure them and try it! :)

But, regardless, it won't affect the battery health nor the engine charging supply in any negative way when/if the battery switch is turned to "both".

This isn't a perfect example, but it's roughly accurate... Take two glasses of water, connected at the bottom with a tube and a shut-off valve. Fill the glasses unequally. Open the shut-off valve and the glass' water level will equalize. Now, when you add water to either one glass or both at the same time, they will fill up.

I believe that wire length and wire health would come into play (along with the other variables)... but that's going down a road that isn't really what this thread/question is about. It's simply "Is it OK to do that"... and the answer is "yes" :)
 
That is a pretty good explanation by both Dennis and wspliter. I agree the voltage reading when both batteries would be somewhere in between. Whether it's in the middle or not I can't say.
. When the two different voltage batteries batteries are being charged, one is being charged a little less than it normally would be and the other is being charged a little more than it would be. We can probably agree on that premise. I do understand that a ton of parallel wired batteries are wired that way. My issue is when the secondary charge feed is connected to the main power feed from the motor and how the two charging circuits interact with each other. I do not know how the secondary lead is designed. Are there two regulators? I don't think so. If that is true the secondary lead must be connected to the single regulator. Perhaps the secondary charge feed has an isolation diode to prevent the two circuits fighting each other ( one charge lead trying to charge the motor in effect.
Maybe someone has a diagram of how the secondary charge lead is configured..
If it weren't so nasty outside these days, I might be fussing with my new to me boat and not dwelling on a practice that appears to be common:)
 
"Agree on that premise"... Yes, agree. Typically what happens is the lesser charged battery will take most of the charging current. So what happens is once the two batteries equalize, the charging current bounces back and forth between the two... give or take.

Regarding your concern about "charging the motor"... while a fair thought, I think you're overthinking it. Just like a battery charger (generally speaking), there's absolutely no issues. They are outputs. You could just as easily put both charging leads on a single battery.
 
It works. Use it. Thats what its there for. Don't overthink it.

Switching between 1 & 2 is stupid.

I had twin ox66. Ran both aux chargining leads to a House bank. Worked perfectly for years.

I have Zukes now. Same thing.


Its just a diode connected to the same wire that goes to the main battery (the "starter" wire).
The charging is "split" to two wires. Current only flows to second battery thru aux wire. No current flows back to motor or other battery.
It is ISOLATED.
Drawback--- The diode has a voltage drop (.6-.7v) and loses some efficiency due to heat.(the diode is in the regulator housing and is cooled)
Pro- It is FREE! It can also be used to separate the HOUSE from the Start battery


ACR uses the "starter" wire. It is btween batteries and has a sensor circuit to control a relay to choose which battery gets the charge.
The relay is minimally more efficient than the Isolator diode.
The ACR does not isolate the batteries
It costs money.
 
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thanks greatly for all the replies.
I've been sitting back and reading all the replies. Great stuff to ponder.
It even raised the question I was actually wondering but didn't voice.
are the two outputs isolated from each other and/or do they actually work like an ACR and regulate charging as needed.
Or is this (simplified example) just another wire tapped off the charging wire where if one bat is 12 v and the other is 6 v is the regulator seeing 9v and charges equally to both?
I've got the Yamaha cable on order, when it comes in I'll try to get some more information from the tech on how the motor is wired.
Might even put a couple of ammeters on the batteries to see what is actually happening.
Wire will not be in until next week. boats covered in the back yard and the weather is not supposed to cooperate for a few days but I'll let you know what I find
Again Thanks for the input
Larry
 
SkunkBoat said:
It works. Use it. Thats what its there for. Don't overthink it.

Switching between 1 & 2 is stupid.

I had twin ox66. Ran both aux chargining leads to a House bank. Worked perfectly for years.

I have Zukes now. Same thing.


Its just a diode connected to the same wire that goes to the main battery (the "starter" wire).
The charging is "split" to two wires. Current only flows to second battery thru aux wire. No current flows back to motor or other battery.
It is ISOLATED.
Drawback--- The diode has a voltage drop (.6-.7v) and loses some efficiency due to heat.(the diode is in the regulator housing and is cooled)
Pro- It is FREE! It can also be used to separate the HOUSE from the Start battery


ACR uses the "starter" wire. It is btween batteries and has a sensor circuit to control a relay to choose which battery gets the charge.
The relay is minimally more efficient than the Isolator diode.
The ACR does not isolate the batteries
It costs money.
Click to expand...
Overthinking is and has been my cross to bear:)
Your explanation of how the secondary feed is derived, using a diode makes perfect sense to me.
An ACR solution would be quite a lot more expensive but does offer some advantages. One that comes to mind is overvoltage protection should the alternator/regulator run amok . Without over voltage the battery could be boiled.

I had my 208 for almost 20 years and would do the 'select which battery' to run on and on occasion do my return trip on BOTH. I never had an issue and in fact for some unknown reason, I got 7 years out of a set of batteries three times:)
 
seasick said:
That is a pretty good explanation by both Dennis and wspliter. I agree the voltage reading when both batteries would be somewhere in between. Whether it's in the middle or not I can't say.
. When the two different voltage batteries batteries are being charged, one is being charged a little less than it normally would be and the other is being charged a little more than it would be. We can probably agree on that premise. I do understand that a ton of parallel wired batteries are wired that way. My issue is when the secondary charge feed is connected to the main power feed from the motor and how the two charging circuits interact with each other. I do not know how the secondary lead is designed. Are there two regulators? I don't think so. If that is true the secondary lead must be connected to the single regulator. Perhaps the secondary charge feed has an isolation diode to prevent the two circuits fighting each other ( one charge lead trying to charge the motor in effect.
Maybe someone has a diagram of how the secondary charge lead is configured..
If it weren't so nasty outside these days, I might be fussing with my new to me boat and not dwelling on a practice that appears to be common:)
Click to expand...
Now I’m confused. I did a little reading on this subject, and if I understand what I read connecting two dissimilar voltage batteries in parallel can lead to massive current flow as the higher voltage battery tries to charge the lower. It can lead to shorts and battery explosions. Hmmm. Isn’t it a tribal practice to put the battery switch in the “both” position to start the engine when neither battery has sufficient charge? The explanation I have read is that this combines the remaining potential and can lead to a successful start. Doesn’t that assume both batteries have exactly the same remaining voltage because otherwise there could be a a potential fire? Am I missing something?
My OX66 also has this extra charging lead so this thread interests me. I haven’t hooked it up and not sure I will until I understand all this.
 
Chinookie said:
Now I’m confused. I did a little reading on this subject, and if I understand what I read connecting two dissimilar voltage batteries in parallel can lead to massive current flow as the higher voltage battery tries to charge the lower. It can lead to shorts and battery explosions. Hmmm. Isn’t it a tribal practice to put the battery switch in the “both” position to start the engine when neither battery has sufficient charge? The explanation I have read is that this combines the remaining potential and can lead to a successful start. Doesn’t that assume both batteries have exactly the same remaining voltage because otherwise there could be a a potential fire? Am I missing something?
My OX66 also has this extra charging lead so this thread interests me. I haven’t hooked it up and not sure I will until I understand all this.
Click to expand...
I'm not sure where that info came from about (2) 12V batteries of unequal voltage creating a fire if connected together in parallel. I suspect you either misinterpreted what you read or that what you read is simple internet gossip/lore.

If you're still unsure, copy and paste what you read.
 
SkunkBoat said:
It works. Use it. Thats what its there for. Don't overthink it.

Switching between 1 & 2 is stupid.

I had twin ox66. Ran both aux chargining leads to a House bank. Worked perfectly for years.

I have Zukes now. Same thing.


Its just a diode connected to the same wire that goes to the main battery (the "starter" wire).
The charging is "split" to two wires. Current only flows to second battery thru aux wire. No current flows back to motor or other battery.
It is ISOLATED.
Drawback--- The diode has a voltage drop (.6-.7v) and loses some efficiency due to heat.(the diode is in the regulator housing and is cooled)
Pro- It is FREE! It can also be used to separate the HOUSE from the Start battery


ACR uses the "starter" wire. It is btween batteries and has a sensor circuit to control a relay to choose which battery gets the charge.
The relay is minimally more efficient than the Isolator diode.
The ACR
Click to expand...

DennisG01 said:
I'm not sure where that info came from about (2) 12V batteries of unequal voltage creating a fire if connected together in parallel. I suspect you either misinterpreted what you read or that what you read is simple internet gossip/lore.

If you're still unsure, copy and paste what you read.
Click to expand...
https://www.reddit.com/r/AskElectronics/comments/10kteeg/what_will_happen_if_we_parallel_two_different
 
I don't see any info in the reddit thing.

Skunk is not talking about it being a problem - just a waste of time given he has other means that work better for him.
 
As has always been the recommendation for parallel battery banks, it is important that the same type, model and age batteries be paired together.
Not only is the voltage of the batteries important but more so is the internal resistance/impedance of the batteries. That parameter can differ for different battery technologies.
I am not certain but the article may have been referring to paralleling different voltage batteries like a 12v and a 6 volt together as opposed to a 12v at 12.5 volts and another 12 v at 11.2 volts
 
But... to better state the answer to your question... connecting two 12V in parallel (even with different V) is done ALL the time and for MANY years. I'll take history's and personal experience's answer over internet stuff any day of the week! :)
 
seasick said:
As has always been the recommendation for parallel battery banks, it is important that the same type, model and age batteries be paired together.
Click to expand...
To expand on this for Chinookie - the reason for this stems primarily on preserving battery life (in years) as long as possible. Yes, different types/model/age CAN be safely combined - but lifespan may be affected.
 
If you have a severely discharged or damaged battery and you parallel it with a good charged one, it will "try to charge" the bad battery. In extremes, it can move a lot of current and not be pretty.
It will definitely discharge the good battery, possibly leaving you screwed.

For that reason, BOTH position is supposed to be a last resort.
I know many people use it as a "charging" position. Many people doing the wrong thing doesn't make it right. Some dealers even tell people to do that.
Using BOTH defeats the point of having two batteries and a switch. Many people forget to take it off BOTH.

You have a one motor, one battery switch, 2 battery setup. Lets call them 1 & 2.
Neither is technically the "primary" battery. Whichever position the switch is on connects that battery to start and charge ...AND the House 12V to the dash.
The point of that setup is to always have one battery that is fully charged in reserve, in case the one you are using won't start your motor.
If 1 doesn't start, switch to 2 (not BOTH). If neither will start you are already screwed so try BOTH.

Often the auto-bilge pump, and possibly stereo memory, is directly connected to the "1" battery. A second autobilge may be on the "2" battery.

Ideally, you would use the batteries equally. Switching the one that you use each trip. That is a pain. Nobody remembers. Its stupid.
Use the Aux charging cable...
 
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