Battery switch (AFD) questions

[FLboy3]

OK guys, been doing some research today for the purchase of a battery switch for adding a second battery to the boat. Ran into a couple of things that I didnt understand so I started calling around and still am not real clear on which switch to get.
1. AFD- Alternator Field Disconnect. Didn't know what that was and didn't know if I should get the switch with it or without it. So I called chatlees and spoke to the service dept. The person that answered didn't know what it was, but gave me the perko switch that they have used for years he said. Perko-8501. I looked it up and it doesn't have the AFD. Called a couple of the local dealers and one said get the switch with and one said without it. Called suzuki costomer service and they didn't know and told me to call chatlees. Why is this so complicated? I pulled up the perko switchs on westmarine website and they say that they recommend the AFD because what it does is protect the alternator in the event someone switches the battery switch by accident with motor running. Which means I would want to get one with AFD to protect my alternator. Why didn't any of the suzuki dealers now this?
2. According to Basspro website you should make sure your engine's cold cranking amperage is lower than the intermittent rating of the switch. The CCA on my battery from chatlees on my boat is 550. The one chatlees use's Perko-8501 intermittent rating is 360A as with most all that I found. The only one I found that had a higher intermittent rating was the blueSea 9001e and 9002e. The 9002e has the AFD and intermittent rating of 600A.
Does anyone have any additional or better info on this subject?

[FLboy3]

OK guys, been doing some research today for the purchase of a battery switch for adding a second battery to the boat. Ran into a couple of things that I didnt understand so I started calling around and still am not real clear on which switch to get.
1. AFD- Alternator Field Disconnect. Didn't know what that was and didn't know if I should get the switch with it or without it. So I called chatlees and spoke to the service dept. The person that answered didn't know what it was, but gave me the perko switch that they have used for years he said. Perko-8501. I looked it up and it doesn't have the AFD. Called a couple of the local dealers and one said get the switch with and one said without it. Called suzuki costomer service and they didn't know and told me to call chatlees. Why is this so complicated? I pulled up the perko switchs on westmarine website and they say that they recommend the AFD because what it does is protect the alternator in the event someone switches the battery switch by accident with motor running. Which means I would want to get one with AFD to protect my alternator. Why didn't any of the suzuki dealers now this?
2. According to Basspro website you should make sure your engine's cold cranking amperage is lower than the intermittent rating of the switch. The CCA on my battery from chatlees on my boat is 550. The one chatlees use's Perko-8501 intermittent rating is 360A as with most all that I found. The only one I found that had a higher intermittent rating was the blueSea 9001e and 9002e. The 9002e has the AFD and intermittent rating of 600A.
Does anyone have any additional or better info on this subject?
Just read this on Basspro also about AFD. When using a switch with alternators with internal voltage regulators, be sure to choose a switch without AFD. I don't know what that means. Help.......D

[Shakespeare]

What it means is that you never want to disconnect your alternator (starter wiring) while switching from one batt to the next. Most of the switches are "late break/early make" meaning that during the transition from one selection to another both batteries will be momentarily engaged while making the switchover, thus leaving the alternator a path to a battery.

Total isolation of the alternator can fry your regulator. So, I don't believe you'll be wanting the alternator field disconnect.

Mike C.

[Shakespeare]

Item #2... the switch needs to be rated for the motor's cold cranking amps... not the battery's CCA. You should be fine with the 360 amp switch unless you have some bohemoth motor on there.

Mike C.

[NOTHING ELSE MATTERS]

Flboy3, ditto on Shakespeare's both answers.I had the same swithch(w/o AFD) on my 225 optimax with no problems.
And i have the same switch on the skiff.

[Willie]

just a bump.....

[FLboy3]

Shake, I just read the part of my thread about the CCA. You are right about it being the engine CCA, not the battery. That clears that up. Thanks. I can stop looking for the Heavy Duty one.LOL. I am still thinking about going with the bluesea due to the size of the switch and I'm limited as to where to place it under my rear deck. Want to keep it close to the batterys as possible. Anyone use the bluesea and is it a good switch. The perko seems to be the popular one. As far as the AFD, I don't plan on changing the switch to Off position while motor running so it shouldn't be an issue.

[redfish74]

flboy3 You never want to switch to the off pos. while eng is running!!!!! but if you think you may need to go from 1 to 2 batteries get the switch that has the make before break. That will keep the alt field in contact with a battery at all times. Shakespeare is right on the money with what he said.