Battery Switch Operation

[pmirenda]

Battery Switch Operation for Catalina 30s

BATTERY SWITCH


· Most Catalina 30 sailboats have 2 batteries on board which are isolated from each other. (Note: A third battery can also be wired into the house bank to extend amp hours. If this is the case, the battery switch for the house bank is used for both batteries on the house bank if the switch only has a 1 and 2 position.)
· Battery #1 (if wired as the starting battery) is used for starting the engine.
· Battery #2 (if wired as the house bank) is used to run the boats electrical system such as interior lights, navigation equipment, running lights, refrigeration, etc. (Note: If wired with 1 as house bank and 2 as starting, then change the battery designations for this writeup).
· Battery switch has the following positions: 1, 2, All, Off.
· When sailing, keep this switch in position #2 if 2 is the house battery so battery #2 only is being used to run the electrical system. This way if the battery runs down you can still start the engine by switching to battery #1.
When starting the engine the All Position will provide greater starting power.
· When running the engine you can select which battery to charge by using the battery switch. In position 1 or 2 you will charge only the battery selected. In the “All” position both batteries are charged. In “Off” position neither is charged.
· Recharge Battery #2 frequently since electrical system can easily drain a battery. Batteries should never be discharged past 50% to insure longer battery life. With diesel engines, battery #1 requires less charging since it is only used to start the engine and will only slightly discharge the battery. Gasoline engines require a constant power source so it is better keep the switch in the “All position” while motoring to insure both batteries remain charged.
· Be careful to insure the battery switch is not left in the “All” position while sailing since this will run down both batteries and you may not be able to start the engine. Always check the switch position whenever the engine is shut down and the vessel begins sailing.
· The battery switch is bypassed while charging on shore power so both batteries are charged regardless of switch position.
· Avoid changing battery switch position to off while the engine is running as this can damage the alternator.
Note: This post was entered under the Cat 30 Forum and was intended for the Catalina 30 only and does not apply to every sailboat. It has been my experience that this battery switch configuration was standard on the production Catalina 30's and was consistent through the MKIII models. If anyone has experienced a Cat 30 that doesn't have this battery switch configuration, please let me know. It is absolutely correct that this may not apply to every sailboat.

 

[centerline]

BATTERY SWITCH


· The Battery switch has the following positions: 1, 2, All, Off.
· When sailing, keep this switch in position #2 so battery #2 only is being used to run the electrical system. This way if the battery runs down you can still start the engine by switching to battery #1.

#2 frequently[/U][/I][/B] With diesel engines, battery #1 requires less charging since it is only used to start the engine and will only slightly discharge the battery. Gasoline engines require a constant power source so it is better keep the switch in the “All position” while motoring to insure both batteries remain charged.[/FONT][/COLOR]

there needs to be an adjustment to the wording...

sailboats as well as any other boats can have any number of batteries, but those having a 4-pos battery switch are usually divided in to 2 banks.

some boats are wired with 3 banks, and if so, this could all be different.

but for a 2 bank system, depending on how the switch is wired, switch position 2 could be for the house bank...and if so, then yes, position 2 would be the "normal" position.

the house bank and the start bank should be isolated from each other... with the switch in position 2, the house bank is the one that is likely to run down.
so with the isolation working as it does, that will leave the start battery fully charged and available for starting.

if for some reason the start bank has failed and is too dead to start, and if the house bank has not been run down by the demands of the house, then the switch can be set to "combine" to join forces between the 2 batts to hopefully combine enough power so that the engine can be started...

Position 1 on the switch only allows you to switch the house demand off of the house bank and on to the other bank, which in this case is the start battery...


AND... it makes little difference if its a gas engine or a diesel engine. the batteries are isolated from one another for current draw, but if the system was properly set up with a charge relay at the time of the switch install, both batteries should charge fine, so there should be no need to combine the batteries when motoring for charging purposes.

but if someone installed a switch simply so they could take one or the other of banks out of the system, then its possible that they wont charge together, and this is not desirable..

 

[Stu Jackson]

It all depends on how it is wired

This is a nice idea, but fraught with possible errors and inconsistencies for folks/skippers who don't know any better, and who may not understand electrical systems.

In preparing information like this, it is always helpful to involve a "teaching moment" rather than to distribute absolutes, rather than "usuallys." For example, batt #1 and #2 are rarely "usually" wired as start and house. I find having #1 be the house bank to be helpful, and also it is required if you're using a Link 2000 with a large house bank for programming purposes.

Here are some explanations of WHY & HOW things work for further investigation by skippers:

OEM 1-2-B Switch Wiring History http://c34.org/bbs/index.php/topic,4949.msg30101.html#msg30101


Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: http://c34.org/bbs/index.php/topic,6604.0.html

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)
http://forums.catalina.sailboatowners.com/showthread.php?t=137615

 

[Maine Sail]

BATTERY SWITCH


· Most sailboats have 2 batteries on board which are isolated from each other.
· Battery #1 is normally used solely for starting the engine.
· Battery #2 is normally used to run the boats electrical system such as interior lights, navigation equipment, running lights, refrigeration, etc.

Most typical coastal cruisers have two banks a HOUSE bank and a STARTING or STARTING/RESERVE BANK depending upon how it is configured & used.....

We should remember that #1 is not necessarily "normally used for the engine"... In about 70% - 75% of the boats I work on #1 is dedicated as the HOUSE bank. This is a left over convention from the old Trace/Heart Interface days where HOUSE was always the #1 bank.. Most marine installers I know will use #1 as the primary or house bank.... Some owners still prefer #2 as house, and that is fine, but we really should not just guess/assume that #2 will normally be HOUSE, as I see most often, the HOUSE in on #1.......

The Battery switch has the following positions: 1, 2, All, Off.

· When sailing, keep this switch in position #2 so battery #2 only is being used to run the electrical system. This way if the battery runs down you can still start the engine by switching to battery #1.

Best just to keep it on which ever position is the HOUSE bank because we have no clue that #2 is HOUSE or not, unless we physically check this.....

When running the engine you can select which battery to charge by using the battery switch. In position 1 or 2 you will charge only the battery selected. In the “All” position both batteries are charged. In “Off” position neither is charged.

In today's day and age there are a high percentage of boats using automated charge directing devices such as ACR/Combiners or Echo type battery to battery chargers. This requires no switching on the owners part other than simply turning the switch ON to the HOUSE bank position.. Also many boats are set up so the switch is no longer a charge directing switch but rather a bank selection/use switch only.

Recharge Battery #2 frequently since electrical system can easily drain a battery. Batteries should never be discharged past 50% to insure longer battery life. With diesel engines, battery #1 requires less charging since it is only used to start the engine and will only slightly discharge the battery. Gasoline engines require a constant power source so it is better keep the switch in the “All position” while motoring to insure both batteries remain charged.

Again many ways to skin that cat and many boats today are using automated charge directing devices, Echo Chargers, Duo Chargers, ACR's, Combiners, Isolators etc. to avoid manual switching. In these installations the charge sources, all of them, are very often led to the HOUSE bank...

Be careful to insure the battery switch is not left in the “All” position while sailing since this will run down both batteries and you may not be able to start the engine. Always check the switch position whenever the engine is shut down and the vessel begins sailing.

This is why so many boats today use fully automated charge directing devices so that they can't forget..

The battery switch is bypassed while charging on shore power so both batteries are charged regardless of switch position.

In a perfect world would this be the case but sadly we don't live in a perfect world.... I see many boats where the charger has been fed directly to the "C" post of the battery switch just as the alternator is. If the switch is set to OFF no charging. Owners must really know how their own system is actually wired rather than to assume how it is wired. I had one owner who "assumed" his battery charger was working because when he flipped the breaker on the AC panel a red light came on. All this told him was that the breaker was on. He assumed the charger was on... Long and short the boat did not even have a battery charger....... After destroying two banks he called me who had to tell him he did not have a charger.......

Avoid changing battery switch position to off while the engine is running as this can damage the alternator.

Another reason why so many boats today are wired with all charge sources feeding the HOUSE bank directly. No possibility of a load dump that could blow diodes... You can still use ALL if needed to charge but ACR's and Echo's and such are extremely reliable so owners rarely if ever need it once this easy conversion is done.


There are many ways to make the 1/2/BOTH a better switch than how it shipped from the factory. This might be of interest to some...

Musings Regarding The 1/BOTH/2/OFF Switch

 

[JK_Boston_Catalina310]

In addition to what Maine Sail and Stu added, I am wondering if your batteries are in need of replacement or maintenance.

How long are you sailing that you are afraid that the house load will kill your batteries while sailing? Most Catalina 30s I have seen have either had group 27 or group 31 batteries. Unless you have an exceptionally large house load, you should have no problem with the battery having enough charge to start the engine, go out sailing all day and then start the engine to motor back to port. I would make sure you read the stuff Stu posted about electrical systems 101.

Good luck,

Jesse