Wiring set-up for battery switch.

pehrst · #1 04-16-2002

I have a perko 1,2,all and off switch in my boat and (2) deep cycle batteries. My question is, shouldn''t the #1 battery be high AMP starting battery and #2 a deep cycle (house battery). If so how should the wiring be made so that the starter always gets its power from the starting battery and all other requirements will draw from the house?

Thanks,

SailorMitch · #2 04-16-2002

While waiting for the electrical experts to chime in, I''ll give you my simpleton view of things electrical. I think you''re making this too hard. Assuming you have a "normal" boat, meaning nothing with a huge engine that might require all kinds of amps to start,a deep cycle marine battery will do just fine to start the engine. What most folks do with your same (basic) set up, including me on my boat, is to rotate the use of the batteries. Battery 1 is the starting battery one day, and the house battery the next. Battery 2 is the opposite of course. The theory is you''ll always have a good battery to start the engine.

The main thing to do is to make sure you keep them both charged up as much as possible. Wet cell batteries like to stay charged, so invest in an onboard battery charger that will go to a trickle charge level when the batteries are topped off and won''t cook them by over-charging. Also invest in a digital meter so that you know the charge state of each battery.

Last thing -- don''t use that "All" or "Both" setting on the Perko switch as a matter of course while at anchor. Putting it on "All" and running your lights, the stereo, the water pump, etc. while at anchor will only lead to angst the next morning when you have two dead batteries that won''t turn over the engine. Always leave one charged battery to start the engine!

Oh...one more last thing: depending on where and how you want to sail/anchor out, etc., and how good you are at maintaining your batteries, you may want to invest in one of those emergency starter deals, like the Vector that''s in the West catalog (page 573.) For $60 you can always (well, as long as you keep this gizmo charged up!) start your engine even if your deep cycles are dead. I have one, which I mainly use to jump start my garden tractor when that battery goes dead. But I still have it for the boat if I need it.

pehrst · #3 04-16-2002

Here are some more details, engine is a Yanmar 2GM from 1986 with a re-built starter and new solenoid in 2000. The main wiring for batteries, alternator, panel and starter was replaced in 1988. The altenator output is 13.5 volts. The boats electric requirements are light, instruments, Vhf, Gps stereo and lights.

From time to time, the starter would not kick in and I have been forced to jump the terminals on the starter. I am a novice when it comes to electrical work. I thought maybe that the cranking amps are too low to force the solenoid to kick in and hence my questtion concerning battery type and wiring.

SailorMitch · #4 04-16-2002

I''m no expert at this either, but I doubt the battery is the problem if you can start the engine by jumping the starter. Sounds more like a starter/solenoid problem. (This from a liberal arts major.)

Do buy a digital multi-meter and check the charge level of the batteries. As a guide, at 80 degrees F, a lead acid battery will show around 12.73 volts when 100 percent charged. The volts drop to about 12.1 when 50 percent charged. You don''t want the battery to drop below 50 percent charge for very long, and expect the battery to last. In other words, you aren''t dealing with a wide range of available voltage in a battery to start with. That fact alone will save you some grief down the road. You also can get a decent charger for about $100 that won''t fry your batteries. Overcharging them is as bad as undercharging.

I used to get 2 years out of a battery and think I was doing well. Now I get double that, basically because I have learned more about the care and feeding of batteries -- at least enough to be dangerous.

fer@fer · #5 04-16-2002

Hi pehrst,

Depending upon the electrical equipment you have on the house load, you don´t want the starting battery to draw the voltage being supplied to your radar or Gps, or whatever. Even if you have a high amp rated starter battery, with the kind of 1,2,both, off Perko switch, by the time you connect the #1 starter battery, you do also supply voltage to the house load. When you start the engine, you will find a huge voltage drop in the electric supply to the house load. The more old the battery higher voltage drop. The inmediate result in some equipment is the reset or restart, case in Radars or 12v GPS. Some other equipment may harm.

In addition, nothing happens at the departure on dock. But when you are negotiating the access to certain ports, with bad weather, and decide to star the motor, the last thing you would probably like is to reset your instruments.
For that reason, some people hardly recommend having two off-on switches and a third one to paralel both batteries just in case. With this arrangement you can isolate completely the starting and house load systems.

In the case of your Yanmar, as SailorMitch suggets, you would´nt need a high amp starter battery. Probably a standard one is enough. Particularly considering that the engine has decompressors that will allow the starter motor to run even with very low battery. However, the theory for always having a good battery to start the engine, is to use the starter battery only as starter battery, and the other one for house loads.

If you find from time to time, the starter would not kick in you should check tightness & cleaneness of connections first. But more important, is to be sure that no water is inside the engine. Sometimes, the flowbak or siphoning might let water inside the cilinders. Particularly is an exhaust design problem. If that might be the case, you should decompress the engine at the ignition, and after a couple of turns, put down again the compression handles. This will allow any water in, out the exhaust.

Lastly, you did measure the altenator output as 13.5 volts, where, at the batteries or at the alt output. In any case, at 2.000 RPM the figure should be greater, at least 13.8 v.

You might want to review some introduction on electricity matters in th Westmarine page :

http://www.westmarine.com/webapp/commerce/command/ExecMacro/west_advisor.d2w/advisors

Regards

Fernando

chud · #6 06-18-2002

I''m looking for the proper wiring diagramfor a Perko 3 way battery switch. I have a 20 singe outboard boat. Ib just bought it used and need to figure out all the wires. Thanks

windship · #7 06-18-2002

While some people do use their house batts for starting, it''s not a good practice to be in.Deep cycle batts(to put it simply) have thick plates to allow a long discharge time. Starting batts have thin plates to release large amounts of amperage in a short period of time.Batts that are meant for deep cycle that are constantly used to start your engine (especialy a diesel) will loose eficency quicker and batt life will be greatly decreased.People in this practice will find that their batts might only last a couple of years, unless you have a huge bank.Think about adding a batt that is only meant for starting,you''ll be better off.And also charging voltage for a flooded batt should be no less than fourteen and no more than fourteen point two. Incorrect charging voltage will also decrease batt performance and life.

Dennis