big black master switch ... any good?

[Kesh]

Our old perko masterswitch was broken (actually cracked, and one battery position does not work) and had to be replaced. The owner of a nautic shop where I use to buy stuff, a gentleman and ponderated person, showed me three masterswitch models when I told him I needed to replace it: the same perko model (expensive), another red model very similar (almost identical) to the perko model but chinese I think, and a big black masterswitch korean made. The last one looked to me very robust and well constructed. The case is made of phenolic resin (like black plastic, but with a surface harder than plastic, the same material used in old Simpsom multimeters). The control knob is big and has a red latch you have to press to change position. The posts on the back are copper, very robust. The back of the case has SS screws on the perimeter (6 to 8, dont remember exactly) so you can open and clean or eventually try to repair. This gentleman told me that he installed one of those korean masterswitches and it works perfectly; told me to buy it with "closed eyes". At the first glance it looked to me that the black switch was the most expensive, because of the size and robustness, but resulted to be a bit cheaper.<br /><br />I made the purchase, as the man is a trustable person in my opinion.<br /><br />I will install the switch saturday morning.<br /><br />Would like to know if you have used one of those.<br /><br />thanks in advance,

 

[Kesh]

Re: big black master switch ... any good?

^bump^

 

[Boatist]

Re: big black master switch ... any good?

Kesh<br />I know nothing about the switch. What the switch looks like mean nothing to me. What is important is how it works. Does the second battery make before the first battery breaks connection? If it does not then if you turn it with the engine running you will need a new alternator. Does it have a alternator field disconect circuit?<br /><br />I would not buy any switch that is not make before break and has a alternator field disconnect circuit. Sure they cost $10 to $15 more but cheaper than a new alternator every time your turn the switch.

 

[Kesh]

Re: big black master switch ... any good?

it says specifically to ONLY TURN WHEN ENGINE OFF, so I guess it is a simple switch and it lacks any make before disconnect or alternator field disconnect features.

 

[Kesh]

Re: big black master switch ... any good?

if I follow the ONLY TURN WHEN ENGINE OFF rule do you think there will be situations when I need to turn when the engine is running???

 

[Kesh]

Re: big black master switch ... any good?

well, I've been thinking that I do pay attention to how things are done and look, because that tells a lot about the quality. I'm very dissapointed with many perko marine accesories; for example, stern lights corrode easily, the plastic cover of the ligth is not UV resistant so it gets cracky and fragile with sun, the masterswitch is made of a not robust plastic, etc. I guess they do it on purpose to continue selling the same accesory very frequently.

 

[Boatist]

Re: big black master switch ... any good?

Kesh<br />all I can tell you is people turn them all the time and blow the alternator. What if your starting battery is dead and you want to start off your house battery. You turn the switch and start and charge your house battery but how do you charge your starting battery??<br /><br />I use a battery isolator to charge both batteries and keep a load on the alternator at all times. Use a switch just in case starting battery fails. Test the switch once a year just to make sure it works but the rest of the time it stays on # 1.

 

[cp]

Re: big black master switch ... any good?

Kesh - With that switch it seems your engine will only be able to charge the battery you started it with. That might not be a problem if both your batteries are the same so you can alternate using them. But if one of your batteries is a deep cycle type, or one battery dies on you, you won't start the engine with that battery hence can't charge it. Of course you could still charge that battery using pierside shore power or at home.<br /><br />Especially in your case, with that switch, having a battery isolator, like Boatist says, sounds like a good idea because then your engine could charge both batteries no matter which one you used to start. Just be sure you know how your engine's alternator regulator senses voltage. The regulator senses voltage somewhere along the output circuit and controls the field excitation to regulate the alternator's output. You've got to take that into account when connecting an isolator.<br /><br />The problem with a battery switch without the make-before-break feature is that if the battery is disconnected from the alternator there is no load on the alternator so its output voltage will spike high, possibly blowing the windings and/or diodes. Likewise if the regulator sense wire is disconnected or connected incorrectly the regulator may drive the alternator output high enough to blow the windings and/or diodes or fry your connected battery. A battery switch field disconnect feature would keep excitation from the regulator from driving up alternator output. The below link gives some info about isolators and regulators:<br /><br />Battery Isolators

 

[Kesh]

Re: big black master switch ... any good?

First I have to thanks for the advices. Second I have to confess that I need to read a lot because got confused. I don't know any details about the charging system except that it is basically an alternator plus some sort of rectifier and regulator. I don't know about the regulator sense wire or the field disconnect wire.<br /><br />Makes a lot of sense the issue about how will I switch to a discharged battery if I start with the one that is charged. I will read about the isolators to see if I understand the purpose and how it is connected and combined with the masterswitch and also considering the regulator sense.

 

[Kesh]

Re: big black master switch ... any good?

hmmm... I've read the page about the isolators... but one doubt remains:<br /><br />point No. 7 mentions the shortcomings of having just one sense wire which is connected only to one of the batteries. Then point No.8 says that you can solve that using a switch to make the sense wire capable of sensing one battery or the other. It also says that during cruising you keep monitoring the swicth (the switch recommended there has a digital volts readout) and keep the switch in the battery which shows the lower volts reading (so the regulator keeps sending charge). My question is: in my view, the problem stays the same, that is, the regulator also charges the other battery, risking an overcharge... what am I missing in their solution for the shortcomming???? I see no difference, the only good thing about the switch is that it allows you to TURN ON the regulator again by means of sensing the battery with the lower volts.<br /><br />Boatist, could you please describe your wiring of the isolator and the two batteries ? (I hope you have one outboard same as the tai-tai...so I can follow the same)

 

[cp]

Re: big black master switch ... any good?

Kesh - Scenario 7.A will normally not result in detrimental overcharging of BATT 2 because when it's fully charged its built-up voltage will reverse bias the diodes in the isolator and stop amps from flowing in. For example, if the alternator is putting out 14.2 volts based on sensing BATT 1 at 12 volts, but BATT 2 is charged up to 13.6 volts, the 0.7 volt drop across the diodes will result in no current going into BATT 2 while there will still be 1.5 volts worth of amps being pushed into BATT 1. Scenario 7.B is the greater concern since it will leave BATT 2 undercharged. Bottom line is that the switch they discuss in paragraph 8. is a viable resolution if your alternator regulator sensing is suitable for use with such a switch. Hopefully you and Boatist do have the same engine so you can duplicate his set-up . Good luck.

 

[Boatist]

Re: big black master switch ... any good?

kesh<br />It is really not that hard or important. To start with when you start your motor with one battery discharged and one charged. The alternator will put out a voltage from 13.8 to 15 volts depending on the alternator and voltage regulator. This voltage will be supplied to both batteries thru the isolator. If the battery is fully charged it will take very little amps. If the battery is dead it will take a lot of amps maybe 30 amps and tapper to 0 amps as it reaches full charge. The isolator is really just two big diodes to allow current in one direction only. It stops a discharged battery from draining the other battery. <br /><br />Only a few problems a isolator might cause. <br />If your have a small alternator and a big discharged battery then the discharged battery voltage may be so low it take all the current from the small alternator and the starting battery may not get any charge until the discharged battery has charged up some. Any alternator 15 amps or more it is not a problem unless you have totally shorted battery, in which case you would have to disconnect the bad battery. In my case I have I/O with a 40 amp alternator so no problem at all.<br /><br />As far as voltage sensing not a big deal unless your voltage regulator is set for a low voltage like 13.7 volts. The isolator will have some voltage drop acrossed the diodes. Some say .7 volts but I have tried to messure mine with a digital voltage and never seen over .3 volts. If your alternator voltage is 13.7 and the diode drops .7 then your charge voltage would be 13.0. Batteries would charge slower and may never reach full charge. In this case then alternator would need to since battery voltage on the battery side of the isolator to adjust the voltage back up. Another way would be to add a diode to the sense line going to the regulator. This would also drop voltage acrossed diode and cause the voltage regulator to raise the voltage back up. <br /><br />I tried two isolators and never seen any problem. First one I made out of some old power supply diodes for a old mainframe computer I worked on. It worked great and never had a problem but looked home made so I replaced with a 70 amp comerial one. I tried to messure the voltage drop but really did not see much so I figured would jumper accrossed isolator with a jumper cable I made for the boat and messure battery voltage. Did not see any change in battery voltage and have not checked since 1981. Batteries last about 6 years so it must be working.<br /><br />Wireing on my boat really easy. Took the Alternator output wire to the isolator input wire. I cut the wire and installed a heavy connector. The other end of the cut wire that goes to boat starting battery I installed a heavy connector and connected to the number one output of the isolator. Then I took another wire and connected to the #2 output of the isolator. Ran that wire to the number 2 battery. Just that simple. I use the same size wire, 10 guage but the wire to the #2 battery is longer so if for some reason both batteries were completely dead the number one battery would get a little more current in the begining.<br /><br />One last thing I did was run a 12-2 guage wire from a plug at the front of the boat to the isolator input and the ground wire to the engine block. This lets me do two thing, Plug in my battery charger in the off season to charge both the batteries or to charge before a trip when it has been sitting for some time. I use to hate getting in the boat to hook up a battery charger once a month in the winter. This wire also let me charge the battery from my trucks charging system while going down the road. I have a 12 volt line going to the trailer. So to charge I have short power cord from the trailer 12 volt line to the boat. Really do not use this much but if I need it just have to plug in the cord.<br /><br />Hope it all makes sence because it works great.

 

[Kesh]

Re: big black master switch ... any good?

hey guys, I really appreciate your detailed comments. I will read them carefully again this evening. In my first pass through them one question came to mind: how can I know the amps of my alternator ??? our engine is a 1994, 225HP evinrude

 

[Boatist]

Re: big black master switch ... any good?

Need to find a spec sheet for your motor. Would be in your shop manual. Todays Evinrude 225 is a 60 amp.

 

[Kesh]

Re: big black master switch ... any good?

well, I have to wait until I buy manuals, as I don't have them... goverment has just started to authorize dollars for individuals (we live under a cubanized rigid exchange control and dollars are not available to everybody; the goverment exercises total control of the dollars; I have to go through a registration process to get an authorization to spend $3,000 using my credit card, and that is a total limit per year; that is only granted if you demonstrate you have air tickets to travel abroad; otherwise, you can only ask for $1,500 for internet purchases, also a one year limit).

 

[Kesh]

Re: big black master switch ... any good?

Boatist,<br />I re-read your wiring description, thanks again. Now it is clear to me.<br /><br />I also read this page http://www.boatfix.com/how/Ele2.html <br /><br />and I think that diagram "G" is a good one for the Tai-Tai. What do you think guys?

 

[cp]

Re: big black master switch ... any good?

Kesh - I brought up the regulator sensing because I'm the cautious type who wants to account for everything so I don't co$t myself lot$ of buck$ when I do something. I don't know your regulator sensing setup, so I can't tell you for sure, but I'd think most outboards would have the sensing internal to the cowling, with the ECU perhaps serving as the regulator. Since the isolator would be external to the cowling, the odds are that installing an isolator and charger per the "G" diagram you refer to won't affect the sensing and will result in satisfactory operation. The regulator will likely not sense actual battery voltage, but it will be close enough (0.3 to 0.7 volt difference) that you'll never really notice it. Sounds like Boatist has had no problems with that . Again, I can't tell you for sure that it will work, so the final call is yours. Good luck.

 

[Kesh]

Re: big black master switch ... any good?

hey pchonda, thanks for all the advice. My next step is to go to the boat and inspect how the cabling from the alternator is, etc.