Double Pole Battery Switch

[GordMay]

Blue Sea Systems new ‘Dual Circuit’ and ‘Dual Circuit Plus’ Battery Switches.
http://www.bluesea.com/product.asp?Product_id=174086
https://resources.myeporia.com/company_57/E_Series.pdf
https://resources.myeporia.com/compa...rcuit_Plus.pdf

Basically a Double Pole Battery Switch, that switches the Start & House Batteries (“on-off-combined”) at the same time, while maintaining isolation between banks (except when switched to “Combine”).

See also “CL-Series BatteryLink ACR*”: http://www.bluesea.com/product.asp?Product_id=53476

*Automatic Charge Relay

[BC Mike]

The good switches ( more money ) will allow you to switch from 1 to 2 to both with the engine running.
The cheap switches might cause the alternator problems.
Doing a test by turning on a cabin light and then switching may not be a reliable test.
Read the info about the switch. I have been switching with the engine running for 25 years with no problem so I guess ( note the pun ) my switch is okay.
Michael

[GordMay]

Alternator Field Disconnect (AFD) is available from all reputable manufacturers, including these.

[Rick]

Read the footnote on the Bluesea data sheets and note that the current ratings are valid ONLY when using 4/0 cable. In their comparison with the competitor ratings you might discern that the Cole Hersey switch, for example, might equal or exceed the Bluesea swich ratings for 1/0 and 2/0 cable.

Keep in mind that the current ratings largely (not entirely, of course) are time dependent and that the size of the connecting cable determines just how fast the heat is drawn away from the switch contact resistance.

In addition, the Bluesea switch is touted as taking 4/0 cable with only the footprint of a Perko switch and I can tell you that you had better mount that baby on a very secure panel else the mounting screws can be torn from a basic plywood structure with such heavy cable. The Cole Hersey, on the other hand, WILL support 4/0 cable (I have done this) with sufficient spacers beneath the switch.

Now I am neither for or against the Bluesea products I am merely pointing out that one must take such marketing info with some skepticism and make an informed investigative check in order to understand the limits of claims.

Another example of a marketing claim in comparison with the Cole Hersey switch (and others) is that the cable terminal bolts might be inferior. I have worked on a lot of boats with various switches with many failures. The only "bad" Cole Hersey switch that I found was one that I purposefully destroyed with 2000A for a long time. One other in an old power boat was intermittent and I was able to dissasemble the switch and clean the contacts from a contamination of some grease which had been too liberally applied to the axle of the switch and had migrated to the contacts. After reassembly I measured the contact resistance which was as "new".

On the other hand, the switch that I observed that had the greatest number of failures are the Perko switches which have, in my opinion, cheap design and construction and, therefore, are a bad buy at any price.

[GordMay]

The Blue Sea intermittent switch rating is specified as 450 Amps, and 350A continuous.
Depending upon the ambient temperature, 4/0 Cu. cable (105 F. insulation) is rated: 378 A @ 122 Deg. F, and 445 A at 86 deg F ambient - whereas 2/0 cable is only rated 280/330 A, and 1/0 is rated 242/285 A. Clearly, a 2/0 cable (or less) would be an inappropriate choice for a 350 A application.
Note that the Blue Sea terminals are tin plated Cu, whereas the C-H are bare Cu.
Notwithstanding, I also like the Cole-Hersey switches (tho’ only rated 310 A cont.), and don’t like the Perko nor Guest.

[Rick]

The current ratings of any switch have little to do with cable current ratings. Comparing the two is like comparing apples with oranges.

Cable ratings for continuous current are for safety concerns so that the jacket material will be rated to survive at some specified temperature due to both the copper loss of the cable internal as well as the external temperature, assuming a standard air pressure and humidity.

Switch contact ratings depend upon connecting cable thermal mass and thermal conductivity to achieve a steady-state contact temperature which will not "run away" with normal contact resistance variations due to vibration, contact area, and contamination.

Please note, again, that the current ratings of the switch are DEPENDENT upon the existence of externally connectec copper cables. The cable current ratings are NOT dependent upon any externally connected devices. Note, in conjunction with that, that the switch continuous current rating is LESS than the continuous 4/0 cable rating (almost regardless of jacket material) which one may deduce that as the external cable rating decreases so does the switch rating. Without measuring the new Blueseas switches (I have measured others in the past) I think that I will be in the ball park by stating that the Cole Hersey switch would fair at least as well as the Blueseas switch when tested with 4/0 cable.

Here is the problem: One does NOT know if the Blueseas switch will carry as much current as does the Cole Hersey switch (or others) because Blueseas does NOT give us that information and, therefore, their competitive comparisons are apples to oranges and not valid due to the fact that the other switches are not specified for the same test conditions.

BTW, a copper jacketed cable rated at 378 A continuous can carry more than 200,000 A without necessarily destroying itself (obviously for a very short period of time) yet a switch rated at 278 A CANNOT.

[GordMay]

Battery Switches are rated under UL standard 1107*, which defines two important switch ratings (current being common to both):

* There is an equivalent CE certification.

Continuous Duty Rating: Amperage that can be conducted for 1 hour without raising the terminal temperature more than 100 degrees C or the housing temperature more than 65 degrees C.

Intermittent Duty Rating: Amperage that can be conducted for 5 minutes without raising the terminal temperature more than 100 degrees C or the housing temperature more than 65 degrees C.

Current carrying capacity, measured in amps, is the maximum load that a switch will carry, with the contacts in a closed position. When you switch between positions (make or break), an electrical arc occurs, which causes contact wear. A switch with the contacts closed has no arc, and the carrying capacity is higher.

Make & Break Arcing:
Make is when the switch is turned On (the circuit is 'made'), and break is when the switch is turned Off (the circuit is 'broken'). Arcing is greater on Break than on Make, and greater on Direct Current (DC) than Alternating Current (AC). The arc produced by a DC voltage will be greater and last longer than an AC voltage because DC current has a constant value in relation to ground and zero. AC current has a value that is always rising or falling in relation to zero. Whenever it reaches zero (120 times a second) in cannot produce an arc. Quick Make Quick Break (QMQB) switches are designed to make or break circuits in less than 5 milliseconds, as recommended for use on DC circuits. For this reason, any switch used in a dc circuit should be specifically rated for dc operation**. Battery switches are “Make before Break” type (connects the new circuit before disconnecting the old), in order to avoid an open circuit for the engine alternator, which can cause extreme voltages that can damage the alternator and accessory electronics.

** According to Eaton, a 120VAC switch current rating will be roughly equivalent to the 28VDC current rating.
Eaton Switch Training Module:
http://www.eatonelectrical.com/unsec...NINGMANUAL.PDF

Cole Hersey, Blue Sea Systems, & others rate their switches under UL Standard 1107.
I suspect that the only difference between Blue Sea & Cole Hersey is that Blue Sea notes the conditions under which their switch meets the standard (with 4/0 cables connected) and Cole Hersey appears not to. I don’t have the standard, but I’m fairly certain that the testing is performed under defined installation conditions, which would include cable sizes.

Blue Sea also offers an “Engine Starting Standard”.

See
Battery Switch Ratings Explained: http://www.bluesea.com/Article_detai...n_ID=145&id=96
and
Blue Sea Systems Engine Starting Standard:
http://www.bluesea.com/Article_detai...n_ID=145&id=97