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Old 10-09-2015, 00:39   #1
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Battery selector switch

After a night on the hook, I'm wondering how to properly recharge my set of house batteries. I've been told not to switch the battery selector switch while the main engine is running. Is this true?

I am aware that the selector switch should NEVER be turned to the off position while the engine is running but not sure about switching between the starting battery and house batteries.

I've tried starting the main with the starting battery and then switching to the house batteries or both. That resulted in the motor lugging as it seemed the alternator was working to recharge the house bank. As the Yanmar 3cyl 28hp was upgraded from a 35 to a 55 amp alternator, I thought the motor lugging made sense. However, as I've been told that the charger charges both starter and house bank regardless of selector position, I am a bit nervous that the engine lugging was potentially damaging to the charging system.

Would appreciate some guidance.
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Old 10-09-2015, 01:31   #2
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Battery selector switch

A lot to learn.

Let's start with the switch. You should, if it is at looking like like a red switch with three positions and off - be able able to cycle through everything but off. Some switches even allow off by breaking the field wire on the alternator as they go there. Let presume you don't have that - never got the off position while engine is running.

Charging, probably not doing enough of it, or your batteries are toasted, especially given the lugging (full alternator output) of the engine. Any idea how many amp hours you used? If still on incidence the lights, with no other load this could be close to having drained batteries, and 60 amp alternator, running for an hour would be hard pressed to accomplish recharge...




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Old 10-09-2015, 02:09   #3
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Re: Battery selector switch

Batteries are fine. They were full when I dropped the anchor the afternoon before. I used 35 amp hours over night out of 245 total....two 6 volt 245's linked in a series. Batteries were still showing almost 13 volts in the morning.
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Old 10-09-2015, 02:13   #4
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Re: Battery selector switch

Is it possible that some lugging would be expected when charging batteries? It would make sense that the motor did not lug when running on the starting battery as I only use it for starting and motoring and presume it to be fully charged.
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Old 10-09-2015, 05:28   #5
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Re: Battery selector switch

It depends upon the switch. Most Batt Sel Switches are "make before break”, in which case you can safely switch between 1 & 2 &/or both with the engine running.

Make-before-break switches are those that will complete a new circuit before breaking an old one. With this type of function, the next contact is made or closed before the previous contact is broken or opened.
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Old 10-09-2015, 05:43   #6
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Battery selector switch

Quote:
Originally Posted by SanJuanTruant View Post
Batteries are fine. They were full when I dropped the anchor the afternoon before. I used 35 amp hours over night out of 245 total....two 6 volt 245's linked in a series. Batteries were still showing almost 13 volts in the morning.

So yes batteries need about a full hour from the 55 amp alt to recover, and will load up the alt at the beginning and then taper off. Not sure what kind of upgrade that is, normally you go from manufacturer alt to something over 100amp...



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Old 10-09-2015, 06:10   #7
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Re: Battery selector switch

Lugging is normal, it takes horsepower to make electricity. At idle you don't have much horsepower available, so turning the alternator takes a larger percentage of the available power.
If I'm going to run the engine to charge batteries (something I only do if we're below 60%), then I need to increase the idle speed to prevent the engine shaking the boat apart!!


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Old 10-09-2015, 10:01   #8
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Re: Battery selector switch

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Originally Posted by SanJuanTruant View Post
Is it possible that some lugging would be expected when charging batteries? It would make sense that the motor did not lug when running on the starting battery as I only use it for starting and motoring and presume it to be fully charged.

yes your engine battery is always full. your alt is proably only running at 5amp when connected to the start battery.

when you move to both and the house battery is low your alt is jumping from 5a to 55a which is a big load change.
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Old 10-09-2015, 10:14   #9
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Re: Battery selector switch

Do not turn OFF a battery to an engine with its alternator charging unless you have a battery switch that will disconnect the field voltage to the alternator. The type of battery switches that do that are available but I have seen very few actually wired up to do so correctly. There has to be a separate (small) terminal to route the alternator field current wire from the alternator regulator to the switch and then to the alternator. I bet you do not have that, so in general do not turn off ALL your batteries that the alternator is hooked to.

As far as switching from one battery bank to another, there are battery switches that "make before break" which will make it OK to do so. There are also MANY switches that do not do this. Sometimes the switch is labeled that it is "make before break". If it does not say that, then look up the specs for your specific battery switch model and see if it does, or not. If it does not, then you are risking your alternator diodes to switch between batteries, because you will switch OFF the ON battery before switching ON the new battery. This is assuming that you have a 1-2-all type switch. If you have a separate parallel switch then it should be ON before you turn off one of the other batteries. One battery has to be connected to the alternator at all times.

But going beyond that and addressing anything else, you really need to detail diagram your battery wiring to/from the batteries, switches and and the alternator. But I wouldn't expect a large lugging with full batteries (if I understood you correctly). But what smac999 says is true if you are turning on the house bank and they need a charge. Your engine will have to work harder then to charge those batteries.
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Old 10-09-2015, 10:16   #10
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Re: Battery selector switch

As mentioned, no problem switching while running. (quickly!) Another solution is adding a device that always allows charging the start battery even though the switch is on the house batteries. Plenty of those out there and cheap.
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Old 10-09-2015, 10:21   #11
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Re: Battery selector switch

Quote:
Originally Posted by SanJuanTruant View Post

I've been told not to switch the battery selector switch while the main engine is running. Is this true?

As the Yanmar 3cyl 28hp was upgraded from a 35 to a 55 amp alternator, I thought the motor lugging made sense. However, as I've been told that the charger charges both starter and house bank regardless of selector position, I am a bit nervous that the engine lugging was potentially damaging to the charging system.

Would appreciate some guidance.
SJT,

"I've been told..." is a very good reason to caution you to do some more research and homework about this entire charging subject. It indicates that you need to understand what you have and how it works.

Here are some links and a discussion about Hitachi alternators that should get you started.

Basically, once you read these, you'll understand WHY you need to make a wiring diagram of YOUR boat and then begin to understand the workings and the MANAGEMENT of the system.

Good luck.

OEM 1-2-B Switch Wiring History Alternator/Batteries & "The Basic" 1-2-B Switch BEST Wiring Diagrams

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: Basic Battery Wiring Diagrams

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
1/BOTH/2/OFF Switches Thoughts & Musings - SailboatOwners.com

Hitachi Alternators 101 Alternator upgrade - SailboatOwners.com This comes up so often on other boating forums...

Those are starters. Here's one for long term reading (and where those came from)

Electrical Systems 101 Electrical Systems 101

Good luck.
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Old 10-09-2015, 10:32   #12
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Re: Battery selector switch

Thank you all for your suggestions. I've got a little research to do.
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Old 10-09-2015, 10:50   #13
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Re: Battery selector switch

to many places to start but..

1. If the engine is "lugging" then i assume you have the engine at idle.. this is not good. the engine cannot provide sizeable torque, nor is the alternator spinning fast enough to provide rated output... eg Balmar require (iirc) 3000rpm alternator, which is 1300rpm engine on my W38.
2. your 55A alternator could well produce 30A or less.. such was the case on my stock 50A alternator (23A max)
3. Battery charging with a fixed regulator takes several hours.. an hour may dump plenty AH but the battery will not be fully charged.
4. Consider a battery monitor system that measures current.. looking at the voltage is an inaccurate means of assessing battery condition.
5. Also consider a product such as the Balmar duocharge.. this will give preference to the houses battery for charging purposes and only charge the start battery once the house bank is >13V.... Simple lower cost diode packs do a similar function..at the expense of voltage drop and reduced charging efficiency... something like this would eliminate the need/use of a battery selector switch while charging.

faced with 2 battery 2 bank system and stock (crap) alternator, I ..
1. Organised batteries to house plus start having 3 batteries in one bank (house), and single engine start battery.
2. Upgraded to Balmar 100A alternator
3. Bought external 3 stage regulator (xantrex).. and given this alternator would deliver 110A, reduced max output to 80A (measured).
4. Added Balmar duocharge for two bank charging
5. added Xantrex link lite battery monitor for 100% visibility to battery state and consumption.

Sure this cost a bit, but I have not touched the battery selector switch in 7 years, it charges quickly and I have full visibility to consumption, state and charging current...worth every penny
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Old 10-09-2015, 10:52   #14
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Re: Battery selector switch

Quote:
Originally Posted by GordMay View Post
It depends upon the switch. Most Batt Sel Switches are "make before break”, in which case you can safely switch between 1 & 2 &/or both with the engine running.

Make-before-break switches are those that will complete a new circuit before breaking an old one. With this type of function, the next contact is made or closed before the previous contact is broken or opened.
If the "both" position is in between the 1 (starter) and 2 (house), would that be make-before-break?
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Old 10-09-2015, 11:16   #15
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Re: Battery selector switch

I found this from a licensed marine electrician. His thoughts on make-before-break:

On many older boats, the big 1-2-BOTH battery switch can be either a make-before-break switch or a break-before-make switch. Engineering speak! What it really means is a description of what happens when you turn the switch knob/handle/etc.:
Make-Before-Break
Nowadays, all switches are make-before-break., As you turn the handle from 1 to BOTH to 2, the battery voltage to the boat will never go to zero, i.e., there is never a voltage interruption. If you had a light on while turning the switch, you would see that it doesn't blink, though the light brightness might change, depending on your battery voltages. If this is your switch type, you can switch it while the engine is running.
Break-Before-Make
As you turn the handle from 1 to BOTH to 2, the battery voltage gets disconnected before each new switch position. If you had a light on while turning the switch, you would see it blink off then on. If this is your switch type, don't ever switch it while the engine is running or you could blow out your alternator!
Never switch off the battery switch with the engine running. Doing so will destroy your alternator!

It seems that a simple test of turning the selector switch between 1, all, and 2 while the lights are on, engine off, and shore power off would answer my question by telling me if power is briefly interrupted or continuous.

Does this sound correct?
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