Battery switch setup - House vs Starting?

Kenneth Pfaff · Mar 31, 2003

What the BOOK recommends is 3 on / off switches

One switch for Starting Bank, one for house bank and a third to switch the house to start the engine.

Frank Walker · Mar 31, 2003

On the right track

Jim, I think that you are on the right track. Some might argue that the house bank side be split up with another switch which on my boat is always in the both position. Normally the engine battery is kept in reserve for emergency starting with the house bank covering all bases. Just be sure to keep the starting bank off line else you will wake some morning to dead everything. The new Freedom chargers make provisions for this setup with an auxiliary charge connection (mirror charge)for the engine starting battery. Be sure to fuse the 12v going to the inverter as recommended.

Paul Akers · Mar 31, 2003

I think you are OK

Jim. I currently have a Perko Off,1,2, both switch installed and don't see the need for a separate switch. I had an isolator installed to prevent the higher bank from draining into the lower level bank. When the engine runs, and the switch is set to "Both", then both banks charge. When stopped the switch is set to 2 (house, in my case). I have one starting battery and 3 house batteries. All are about 100 amps. I rotate them all each year (a different start battery each year) to keep them balanced. As a final backup, I keep a portable battery pack under the Nav station for emergencies. I've never had to use it except on a friend's dinghy that needed a jump start.

Dan · Mar 31, 2003

Battery Set-up

Jim,It really is a question of control. With 450ah it seems that you may have several batteries in parellel, unless we are talking two good 4d or 8d batteries, and that seems a little steep to reserve for starting.In our 356 we modified the charging and battery system during commissioning. We did the following:Group 27 AGM battery for a dedicated starting battery. It is seperately switched (on/off) and can be manually parelled with either or both house batteries in a pinch. It also is hooked to a Pathmaker combiner and can be parelleled there remotely.We have two Group 4d AGM house batteries. One hooked to battery switch one, the other to battery switch two. These are also hooked to the Pathmaker combiner. We installed a Balmar 100 amp alternator and regulate same with an MC-612. We have a 100 amp charger in the Freedom Marine Inverter/charger and we keep track of the house side with a Link 2000.In our case, we can switch in or out any individual battery. We have 400ah on the house side, and the Group 27 is plenty for the starter battery. We also have charging going to everything when there is any charging source.Dan Jonas (S/V Fieje II)

Stu Jackson · Mar 31, 2003

Switches

Try looking at the West Marine Advisor on the link. This explains the multiple switch idea in detail, and what your firend was saying. They recommend three switches, but it seems to me the idea is for brain-dead folks who can't remember to switch the switch. What you have is just fine, and doesn't require any more wiring or connections. We've used a dymo labeler to put a little number "2" on our engine kill switch as a reminder to make sure that only the house bank is on when the engine is shut down.Depending on how you wire your other charging sources, it might be helpful to install a combiner or echo charger so that you can leave the switch on the house bank and still charge the starting battery without moving the switch. You'll need to completely understand how your incoming wiring from the alternator is run. The inverter/charger should just go to the house bank.We have the alternator, inverter/charger (Freedom 15) and the solar panel hooked up to a positive distribution post to the house bank with a battery combiner which charges the starting battery without ever having to move the switch.

Jeff · Mar 31, 2003

Get Calder's book

I don't have enough knowledge to answer the question but do recommend Nigel Calder's book "Boatowners Mechanical and Electrical Manual". It has great detail and is relatively easy to digest. No pat answers as every situation is different.Jeff

Brent Headberg · Mar 31, 2003

Battery Switch

Jim,I have studied all the available and confusing information about multiple battery systems on a sailboat and I found the one from Blue Sea Systems to be the easiest to understand, and I beleive it's the safest way to isolate your starting battery from your house batteries. Especially if you're going to run an inverter, you don't want to run the chance of a dead starting battery. See photo.This switch provides separate switches for starting and house banks and also provides an emergency parallel switch in case one bank or the other needs to be temporarily connected.Somewhere in the archives I provided a diagram...you'll probably find it in the 33.5 photo forum. If not, send me email and I'll return a copy of it.Good Luck,Capn' BrentS/V Elena Lua1990 Hunter 33.5http://www.elenalua.homestead.com

Nelson Windsor · Apr 3, 2003

I think you are OK

I have been running this setup for several years with no problems. The only difference is our house batteries are four 6 volt golf cart batteries. I would suggest you have a big alternator and you might invest in a Link 10 battery monitoring system. It is really nice to see your battery condition at a glance and know how much you have left and how much you are drawing. We run 12 volt refrigeration and during a hot summer that knocks the amps down pretty fast.

Geoff Kloster · Apr 3, 2003

Some sites to look at

Try some of these sites. The BEP site has some nice diagrams and some very nice switches. If you really want to know what to do and why go to the Ample Power site and get Smead's book, "Living on Twelve Volts with Ample Power". It's written by the guy that manufactures/distributes/sells Ample Power products, but it has a great deal of objective data.Geoffhttp://www.amplepower.com/http://www.bepmarine.com/http://www.victronenergy.com/http://www.adverc.co.uk/http://www.newmarpower.com/productinformation.html

Capt Jerry · Apr 3, 2003

Simple is good

I have 4 golf cart batteries and have had them for three years. i also have a single starting battery, high output alternator, isolator and three 75 watt solar panels. With this set up the high output alternator is not necessary. the isolator is good so I don't have to remember to change the switch, I have two. Our last 6 week trip to the Bahamas on three year old batteries we were at anchor for a week and a half under rainy cloudy conditions and ran the engine a total of 2 hours for battery charging. Without the solar panels we would have had to run the engine about 2 hours every third day or so.When deciding on your battery size and charging system, especially high output alternators, consider how much your batteries will take and how much your alternator will give and how long you will use your engine. There are times, in my case most of the time, my batteries are unable to acdcept all that my alternator is capable of giving.

sCOTT · Apr 3, 2003

Make sure your Batteries are isolated!

The problem with using the both swich on a battery is they are connected, meaning they share power as one gradually discharges the other battery also does! By installing an isolator you can effectively isolate the batteries when you want them for seperate duties and yet still have the ability to use both when needed and not have to worry about a dead or low battery dragging down the other.Just thought you might like to know.

Derek Rowell · Apr 4, 2003

BEP Marine switches

In a post below, Geoff mentioned the BEP Marine web site as a resource. They are a New Zealand company, and when I was down there at Xmas I was so impressed with their electrical gear I bought $NZ1500 worth to rewire all my 12v system this spring. I gotta say that as an electrical engineer I am very impressed with the design and construction of everything that I purchased.I bought a 200 amp combiner, a 60 amp combiner (to use as an automatic refrigerator switch), a remotely controlled battery switch, DC system monitor, propane gas detector, and sundry bits and pieces. I had a technical question and emailed their customer support. They not only emailed back an answer immediately but also left a very long and detailed answer on my voice-mail - an international call! I'm impressed. They do have an agent in the USA, and I notice that Jack Rabbit Marine is starting to offer their stuff. I have absolutely nothing to do with the company...Derek

Battery switch setup - House vs Starting?

Jim Seamans

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Kenneth Pfaff

Frank Walker

Paul Akers

Dan

Stu Jackson

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Jeff

Brent Headberg

Nelson Windsor

Geoff Kloster

Capt Jerry

sCOTT

Derek Rowell