Understanding Alternator Charging Circuit and Battery Switch Position

Willhound

Yep, here comes a new-to-be owner with a post on something that I'm sure has been covered many times. I did search around and this post was wonderful in explaining, in fact I think I've seen this text somewhere before:
https://rinkerboats.vanillaforums.com/discussion/comment/28632#Comment_28632
I think I have this figured out, just checking if I am correct or am I misunderstanding anything? 

The Rinker FV270 has an on board charger with two circuits that will charge both starting and house batteries simultaneously when hooked to shore power, that is to say, they charge independently, not in parrallel so that the charge controller doesn't read the "stronger" battery and shuts down before both fully charged, correct?

The battery switch dictates which battery is being utilized for starting, providing power to circuits and also being charged by the alternator, for example at battery switch position 1, battery 1 is on line, battery 2 is totally isolated and vice versa. In a situation where both batteries are low, the "both" position can be used to start by putting both bateries into a parallel circuit, correct?

Here's where I start getting a little hazy. I know that it's bad to switch between batteries with engine running and alternator charging, bad for batteries and alternator, etc. So in an example where you use "Both" to start I would presume that both batteries will then be charging by the alternator. But in parallel, the charging circuit will read the "stronger" battery and shut down once at capacity, leaving the other battery at less than full charge. Is the proper method then to shut down, switch to the battery that has been discharged, restart and let it then fully charge?
And the second part of this is, let's say I've run the house battery down, no problem, I fire up on the starting battery but then how do I switch over to the house battery while under power so that it will charge as the engine runs?

Or is the answer as per the post above "The arrangement of the contacts of the typical OFF-1-2-BOTH permits the operation of the switch in the range of 1-2-BOTH without ever disconnecting the batteries from the load or the outboard charging circuit. This is important, as it is possible to cause damage to the charging circuit if the battery is disconnected while the engine is running. By choosing the path of rotation of the switch, it is possible to change from 1 to 2 without moving through the OFF position."
This doesn't make sense to me. Whether or not you move through the OFF position, simply by switching from 1 to 2 or both while under charge, does this not cause an issue? Or is there something I'm not getting?

Finally, for overnighters on the hook, I may want to install a second house battery in parallel for more capacity. Any issues with the stock on-board charger, or alternator/charging circuit I should take into account?

reneechris14

depending on the year and set up you have and issolator  will charge both batteries when engine is running.no matter where the switch is at. Issolator is mounted between the alternator and batteries like a check valve power can only go one way,so one battery can not discharge other.And is not effected by shore power.As far as the 1 2 switch going thru the off could make a surge.but no reason to switch because you are charging the low battery.  I did over night a lot on my 270 would kill battery in about 30 hoursish because of refrigerator switch to 1(start battery)start up and go on my way.two group 27s  should get you 48 hour i think.

Stodge

The battery charger on shore power should be smart enough to manage the banks individually.  Normally the connection goes directly from the bank output to the battery bank (can be more than 1 battery in parallel).  So if your charger has 2 banks, it should be able to fast charge the house while it trickle charges the starters, then switch to all trickle when the house it up enough.

If you have an older charger it may be worth looking at a newer one down the road.  I had a friend with an older (90's era) charger that had one charge level, which was high.  It cooked a couple of his batteries dry before he figured out he had to manually turn the thing off when it was not needed.  

Stodge

I believe you are correct on the isolator.  

I'd look at the charger, get the make and model, and look it up on-line to verify what it can do.  You may see something on the output side that indicates banks, but it may not tell you how "smart" the charger is.  

Cableguy Greg

Willhound said:

So if I have this straight, as long as I have the isolator mounted between alternator and batteries, both batteries will charge while under way, regardless of switch position?

Yes, you are correct. The output of the alternator goes to the isolator, then each output leg of the isolator goes to each of the batteries. Switch position doesn't matter when charging the batteries.

Willhound

Thanks once again folks. Have to say that Rinker should be proud of not only the support and loyalty they get from owners, but also how the community supports and helps one another.
So if I have this straight, as long as I have the isolator mounted between alternator and batteries, both batteries will charge while under way, regardless of switch position?
And newer model on-board chargers will be dual circuit, I get that, my other boat had that set-up for the two trolling batteries I had. I have a pic somewhere of the charger, so I'll do some research on that.
I did get a few pics of the battery area also, not sure if I saw an isolator/controller there or not, I'll go back through and check. Otherwise I'll just have to wait until delivery to do some more investigating.
Thanks again!

MikeSeas

Hello everyone, I'm new to the forum. I purchased a 1996 270 Fiesta Vee last year and I have two batteries and a switch to switch to battery 1, 2 or both.  Which one of the two batteries is the starting battery?
One is sitting aft and the other close to the bulkhead.
The reason I ask is because I would like to add a third battery in parallel with the house battery.

randy56

You will have to follow the wire's, cable's can be switched back and forth, from either battrie. There is no set arrangement. 

MikeSeas

Thanks Randy.

MarkB

There's no guarantees on the position. On mine the aft battery is the crank, and the foreward is the house. Just disconnect one and see if the engine still starts.

MikeSeas

Thanks for the good advice Mark!
I suspect the aft battery is the starting one as it is closest to the rear of the engine where I assume the starter is.
I’m going to try your suggestion. I've already tried finding the starter following the cables from the battery but the engine compartment is very small and in addition to the tight quarters there are a half a dozen cables to follow at the positive posts of my batteries.
Disconnecting one battery and trying to start the engine as you suggest will be a much easier way to discern which battery is cranking and which is my house battery.  

MikeSeas

I disconnected from shore power and my forward battery (the one on Guest switch #1) and left aft battery #2 connected. When I switch the Guest battery selector switch to #1 I get no power at all. The engine won’t start and no 12V DC anywhere. I switch to Guest number two or to both and my engine will start and the boat has 12V DC to run my lights and appliances.

I then reconnected the forward battery and disconnected the aft battery. Now the boat has 12V DC power to crank the engine and my house appliances in all the guest switch positions (1, 2 and both).
I’m confused; why would I have power to start the engine and run my appliances regardless of my Guest switch selection with Battery number two disconnected?
In this scenario which is my crank battery and which is the house battery?

Thanks for your help.

MarkB

Hold on, I'm trying to understand, please confirm if this is correct.

• Position 1, Forward batter disconnected, Rear battery connected - no power anywhere.
• Position 2, Forward batter disconnected, Rear battery connected - boat starts and DC everywhere.
• Position Both, Forward batter disconnected, Rear battery connected - boat starts and DC everywhere.
• Position 1, Forward battery hooked up, Rear battery disconnect - boat starts and DC everywhere.
• Position 2, Forward battery hooked up, Rear battery disconnect - boat starts and DC everywhere.
• Position Both, Forward battery hooked up, Rear battery disconnect - boat starts and DC everywhere.

Can you check with forward battery hooked up, rear disconnected and battery switch in OFF position, whether you have still have power everywhere and can turn engine.

What it seems is that your forward battery is not connected through the switch and is somehow wire to both the engine and the house, while your aft battery is also connected to both engine and house but goes through the switch.  If you confirm that the forward battery still powers the boat even with the switch in OFF, that confirms the setup as I suspect.

If that is the case, you do not have a dedicated house and crank battery, both batteries are doing both duties. It seems the previous owner had it set to use the forward battery always, and turn on the after battery via the switch only if the forward battery was dry. Or he/she added the forward battery and didn't bother to wire it via the switch and just runs both batteries in parallel.

Basically if you want to have dedicated batteries you need to put the aft battery on Battery 1 of the switch, and then disconnect it from either the house or engine (check what kind of batteries they are and pick one that is truly a crank battery for the engine). Then you need to remove the forward battery (battery 2) from the opposite (either the engine or house).

The only time then that both batteries will crank the engine, is if the battery switch is in both.

MikeSeas

Thanks For your reply Mark. I will check on that and get back to you.

MikeSeas

I checked with forward battery hooked up, rear battery disconnected and battery switch in OFF position and there is no power and I cannot turn the engine on.

MarkB

Wow, I'm confused.

It seems that the house circuit and crank circuit are combined, because you have no option where the engine cranks but there's no DC to the house circuit, or vice versa.

It also seems battery 1 works no matter what position that switch is in, unless it's off.

What you want is the following, pick one battery to be a dedicated one for the engine. For this example, say we pick Batt2.

Batt2 should be wired to the engine via the switch.

Batt1 should be wired to the house circuit via the switch.

Both should bridge the batteries so they run the engine crank and house together.

Can you pull the switch off and look at how it's wired?

MikeSeas

Thanks Mark for all your help.
I'm puzzled too. I tried following the wires but they are bunched up together and tied with zip ties every couple of inches or so; this makes it hard to trace individual wires. I will desist my attempt to discern which battery is for cranking and which is my house battery for now. Both crank the engine when selected via the Guest switch.
I will select #2 when at anchor to run my appliances and reserve #1 for starting.

Thanks!

MarkB

It sounds like Battery 2 is the emergency battery. So if you leave the switch on 1, you can crank from Battery 1 and run house. Battery 2 is only needed and used, if you have an emergency and Battery 1 is dead.

Might be the safer thing to do ... keep battery 2 as a back up, and only use it if you have a problem with battery 1.

MikeSeas

Thanks again Mark. 

MikeSeas

I traced all the wires from the batteries to the switch and to the isolator and it makes even less sense now.
Here is a picture.