Perko Battery Swtich Needs replacing

[pred02]

My mechanic informs me my 210 VENTURA battery switch, PERKO model 8501 needs replacing.

Sue Lodel recommended Model 8503 as the replacement for the 8501. I understand that the difference is that the 8503 has the alternator field disconnect.

Q1: Is it worth paying extra for the 8503 (its cost about double the 8501 in Europe). The boat is Ventura 210 with twin batteries, onboard charger, and quite a bit of electronics.

[jimh]

A marine battery switch with an alternator field disconnect switch built into the assembly would typically be used with a field-excited alternator. The use of the alternator field disconnect switch is to add a circuit to the alternator wiring. The field current will be routed through the battery switch field disconnect switch. In this way, the battery switch can also control the alternator field current.

The purpose for doing this is to avoid a possible risk of damage to the alternator if the battery switch were to be moved to the OFF position while the engine was still running. The risk is that without a load on the alternator to absorb the output current being created, the alternator voltage would rise, possibly rising so high as to cause damage to the internal diode rectifiers in the alternator. The arrangement of the alternator field disconnect switch is done so that it will open BEFORE the main battery switch contacts open, thus shutting off the alternator just before the battery will be disconnected by the other contacts in the battery switch. The field current controls the alternator output current, but the field current is much lower than the output current.

If the OEM battery switch in your boat did not have the alternator field disconnect switch, you have been operating the battery switch with this inherent risk all the time you have been using the boat.

I am curious:

Q2: did your mechanic explain why he has recommended replacing the battery switch?

Q3: what fault is there in the present switch?

Q4: did Sue Lodel explain her recommendation to replace the original switch with the field disconnect option?

I wonder if Boston Whaler or Mercury are suggesting this change.

I strongly recommend contacting Boston Whaler customer support, or speaking with a Mercury engine service technician before making a change to original battery switch wiring. Unless there has been a recommendation from either Boston Whaler or from Mercury to modify the battery switch model, I would hesitate to make the change.

On the other hand, Sue is usually VERY well informed. I tried to reach her by telephone today (Monday), but she was away until July 25 (tomorrow). I will ask her about this.

If you were to change to a field disconnect switch, you will have to install the necessary new circuit to run to the battery switch from the engine and then back to the engine. This means the alternator must make that circuit available for external wiring. An alternator of the “unitized” type may not even provide access to the field winding circuit.

For more discussion about marine battery switches with alternator field disconnect switches, see

https://shop.pkys.com/What-is-the-alternator-field-disconnect-terminal-on-a-battery-switch-for_b_26.html

[pred02]

Thanks Jim for taking your time to provide a detailed explanation, it is very helpful.

The boat has two batteries which are in good condition (load tested by the mechanic) however we have an problem starting the engine when the switch is on 2 (versus on 1). Electrics run fine off the second battery and the voltage is good (no low voltage alarms on the Verado) it's just the cranking. Our Verado certified mechanic (in Croatia) has diagnosed it to a faulty Perko switch.

Fig. 1 Extreme close up of OEM PERKO battery switch showing model designator 8501.

batterySwitchCrop.jpg (28.85 KiB) Viewed 2308 times

I've emailed Sue as she is always helpful in sourcing parts for us and mentioned that the 8503D switch is used however I asked my dad to take picture of the switch to be replaced and saw its actually 8501. Sue is probably reading through the Boston Whaler manual and the books says its 8501. I will send her a picture and ask her again.

[jimh]

I looked at the Boston Whaler electrical diagram for a 2009 210 VENTURA in order to see it there was any addition circuit connected to the battery switch, such as an alternator field disconnect circuit. None was shown.

In your initial narrative you seemed to say it was Sue who recommended using the battery switch with the alternator field disconnect circuit, but now it seems she might have done that based on what you (incorrectly) told her about the battery switch that was already installed on your boat

Now that the OEM switch is clearly seen as the model 8051, I see no reason to change to a different model with an alternator field disconnect switch which costs twice as much as the original switch.

[Phil T]

George - Just replace with another 8501 or a Blue Seas 9001E or a BEP.

PERKO 8501DP
https://www.perko.com/catalog/battery_s ... or_switch/

BLUE SEA SYSTEMS 9001e
https://www.bluesea.com/products/9001e/ ... ery_Switch

BEP 701S-B
https://www.bepmarine.com/en/p/701S-B/M ... witch-200A

[Jefecinco]

BEP is not famous for reliability.

[jimh]

The BLUE SEA SYSTEMS products are very good in my experience.'

I doubt the BEP 701 will be a drop-in fit for the mounting holes, but I could not find any drawing for it. (ASIDE: The BEP website was very awkward to use and find information. Loading new pages was awfully slow and reloading them very erratic.) BEP are better known for the individual switches and clusters of them. Compare at

https://www.bepmarine.com/en/Products/B ... n-Clusters