How do I add a 3rd battery?

[TheOtherLine]

I have two batteries currently and they supply power to the engine and electronics.

I am thinking about adding a 3rd battery, just for the electronics like the chartplotter, FF, windlass, spot lights, etc.,

Is it as simple as just re routing those electronics to a bus bar and then to the 3rd battery? How would I charge the 3rd battery while running but not allow it to draw down the other 2 batteries?

Am I missing anything? Anything I should be thinking about that I've missed?

 

[BayRat166]

I have the same question.

 

[tara11]

Check this site out, depending on your motor set up, change the bat switch and add the battery and wire correctly, and you are good to go, one for each motor and one for house, or what ever motor set up you have, search for battery, you will find all the info and many different ways, but i can tell you from doing it my self, if you just add the battery and loop into your current two batterys, after about a year or two, all your batterys will be shot, I did it, so i am speaking from exp, i just redid all my switches and had to get new batterys


http://www.bepmarine.com/

 

[DaleH]

I am thinking about adding a 3rd battery, just for the electronics like the chartplotter, FF, windlass, spot lights, etc.,

I don't get it ... Why mix low-amp CRITICAL items (GPS & FF, ~1-amp each) on the same battery as a high-amp NON-SAFETY (windlass, 60+) item? I mean, even the spotlight is likely to draw less than 5-amps or so.

What does that gain you? Also, the wiring for the windlass needs to be sized appropriately from the battery source to the windlass. As proposed, running the windlass could draw down that circuit for sensitive items like GPSs and FFs, some that shut-off when they sense a low circuit. Many on this board see that phenomenon when they start up.

FWIW I went another route, rather than batteries, I focused on circuits. I have 2 circuits to my helm, 1 for critical items like nav lights, GPS, storm pumps, spotlight, radar, FF, etc ... and the other for 'normal' non-safety items like trim tabs, house lights, livewell, rain bilge pump, stereo etc. Now I did the wiring and each main run is sized to handle the entire load if needed, so in an emergency I can simply run panel #1 from panel #1, in the event I have a breakdown of a main.

I simply run 2 batteries from the Off-1-Both-2 switch and use battery #1 on odd days of the week and battery #2 on even days. If on long weekend trips on the boat, while cruising out and away for a few hours, I'll run the battery on Both, but will switch to the selector for the odd/even day of the week once there (I leave the port over my selector switch off as a reminder to do so). Note that leaving a switch on Both will draw both batteries down to the same level.

Personally, I believe most battery/circuit-related issues are caused by poor wiring designs from the start and poor maintenance of the batteries themselves. Keep the tops clean and top off with water every month. Allowing a plate to sulfate is the surest way to kill a battery.

I can honestly say I haven't had a wiring or battery or circuit related issued ever ...

 

[tara11]

See the post in this section about new switches, this is what I did with only 2 batterys, took out 3, works perfect, like Dale said, you just have to work out a system for switching the batterys !
Craig

 

[DaleH]

I will say a few friends have recently re-wired their boats using the wiring 101 article I prepared, but they also added those BEP Marine Switches that Tara11 talks about.

It seems like such a no-brainer upgrade that I may do that sometime, as it appears to combine the best features of charging where/when needed, battery isolation, and battery management in a simple-to-use item.

 

[BradV]

I just added a house only battery. got one of those auto charging units that allows the house to charge off of the engine batteries. it also allows you to pull some power off the engine batteries up until a predetermined voltage. That way you arent constantly pulling all power from 1 battery and you also cant run down your engine batteries where you cant start the boat. I also have a switch to turn on and off the house battery. So 3 switches 3 batteries and 1 auto charger.

 

[DaleH]

That way you arent constantly pulling all power from 1 battery and you also cant run down your engine batteries where you cant start the boat.

When your motor is running, that doesn't really apply, since you're really running off your OB's alternator, and not the battery per se.

You can only run down your battery when the motor is off. And if the selector switch is only on 1 battery, you leave the 2nd in reserve for starting. Works for me!

 

[TheOtherLine]

I am thinking about adding a 3rd battery, just for the electronics like the chartplotter, FF, windlass, spot lights, etc.,

I don't get it ... Why mix low-amp CRITICAL items (GPS & FF, ~1-amp each) on the same battery as a high-amp NON-SAFETY (windlass, 60+) item? I mean, even the spotlight is likely to draw less than 5-amps or so.

...

I don't get it either. Electronics, that is...

I was just trying to figure out a way to minimize the risk of draining my startup battery after extended use of electronics.

What got me thinking about this was an overnight fishing trip where I had the two flood lights that light up the cockpit "on". After about 10 minutes, my fishing buddy suggested I turn them off as they would totally drain down the battery if left on for 30 minutes or so. :shock:

I wasn't sure if those lights were hooked up to the start battery or not. So when I got back I thought, why run the risk. Just hook them up to a 3rd battery. If it dies, it dies. No big deal.

Your idea sounds more practical. I just have to think about how to re rig the wires and switches.

 

[DaleH]

I was just trying to figure out a way to minimize the risk of draining my startup battery after extended use of electronics.

Ahhh, now that's a GREAT question and I have the answer for you via 'Dry Doc'. Of course, where is ol' Dry Doc now ... he used to hang out with many of 'us' from the old Pilothouses.org forums that pre-date even the old Parker boards.

What you want is an ACTIVE battery monitor gauge, like the Link 10 model by Heart as shown above. It actively monitors the amp draw/status while the motor is Off and it acts like a battery fuel gauge and tells you HOW LONG you can run that battery at the given amp draw.

Now mind you, you can do this yourself too. If you battery has a 100-amp/hour reserve, theoretically, it can last a 100-amp load for 1-hour, or a 10-amp load for 10-hours, or a 1-amp load for 100-hours. Determine your rough amp load and you can get a good idea.

Small voltage items like GPS and FFs draw 1-amp or less, VHF 1-amp on standby and ~8 when communicating. Stereos depend on how much 'power' your pushing through the speakers. If you get a rating in watts, dvide that by 12.6volts for the amp value.

Simple !

That said, ... here you go ...

Heart Link 10 Battery Monitor

Single Bank Monitor

Provides Battery Status Information At-A-Glance

The Link 10 (part#84-2016-01) uses sophisticated microprocessor technology to provide complete battery status information for one battery bank. Simple and easy-to-use multicolour display show volts, amps h ours consumed, and operating time remaining. The Link 10 and 20 allow you to select Automatic, Sleep and Scanning modes an automatically calculate and dislay charging efficiency. By adding an optional prescaler, Link 10 can monitor single battery banks up to 500 volts.

Product Features

Digital Numeric Display - LED display shows numerical of volts, amps, amp-hours and time remaining
Easy to read multi-color LED bar graph
Splash proof panels allow for outdoor mounting and hands free operation
Displays key historical battery information such as charge efficiency, deepest discharge, and average discharge
Compatible with 12 and 24 volt DC systems
Works with any battery type
Includes DC shunt (part#84-2010-00)
Low battery alarm contacts
One year warranty

Specifications
Voltage Measurement
(standard model auto range) 0-19.95 VDC (0.05 V resolution)
20.0-50.0 VDC (0.1 V resolution)
Voltage Measurement
(optional prescalers) 0-100 V (used with standard models)
0-500 V (used with standard models)
Amperage Measurement Low range +/- 0-40 A (0.1 A resolution) High range +/- 500 A (1.0 A resolution)
Amp-hour Measurement Low range +/- 0-199 Ah (0.1 hour resolution) High range +/- 200-1, 999 Ah (1 hour resolution)
Time Remaining Measurement Low range 0-199.9 hours (0.1 hour resolution) High range 0-255 hours (1 hour resolution)
Power Requirements 9.5-40 VDC (DC power supply voltage)
Power Consumption 50-225 mA (display auto dims with ambient light) 28 mA (sleep mode - bar graph display only)
Shunt Type 500 A/50 mV (included)
Accuracy Voltage +/- 0.6% of reading + 1 least count of resolution Amperage +/- 0.8% of reading + 1 least count of resolution

General Specifications
Installation Flush mount
Front Panel Splash resistant
Outer bezel diameter (face) 2.5" (63.5 cm)
Barrel diameter 1.95" (50 mm)
Depth 3.15" (80 mm)
Hole cut size 2.25" (52 mm) diameter
Weight (not including shunt) 4.6 oz (130.4 g)
Warranty 1 year

 

[TheOtherLine]

I was just trying to figure out a way to minimize the risk of draining my startup battery after extended use of electronics.

Ahhh, now that's a GREAT question and I have the answer for you via 'Dry Doc'. Of course, where is ol' Dry Doc now ... he used to hang out with many of 'us' from the old Pilothouses.org forums that pre-date even the old Parker boards.

Oooh. I like that idea. At least I would have a pretty good clue as to my battery status.

Am I correct in assuming that if I start the engines, that the batteries will begin charging? If so, any idea how long you have to run the motor to charge up the batteries by, say, 50% ?

 

[steve j]

On my new 2520 I had the rigger add two AGM batteries to the pilothouse under the companion seat on the starboard side as house batteries. All of my electronics are bussed to those two batteries. My cranking circuit, bilge float switches and anchor windlass are still fed from the cranking batteries. The manual bilge switches, livewell and washdown pumps, and high-water alarm are fed from the house batteries. I had the aux charging circuit from one of my F150s wired to the house batteries for charging. I had them install a 1-2-Both-Off switch and a voltmeter to the house batteries (also a 12V outlet so I can make coffee). I can operate from either battery at will. I will alternate their use as I have always done on my previous boats. The last set of Optimas I had lasted over 4 yrs and never had anything charging them but my single Yamaha 225. If it doesn't work, I'll change it....but I think it will be sufficient for my needs. Oh, and I also had Hella LED deck lights installed, which should reduce my power requirements a lot if I choose to fish from or work on my boat at night.
Good fishing.

 

[tara11]

SteveJ
Got any pictures of that setup, that sounds cool, like to see how it looks

 

[BradV]

i meant more when you get to a fishing spot and run the fishfinder and radio and stuff it will pull power from all 3 batteries until the starting batteries get down to a certain volt. then it goes back to the house only battery. then it will charge the starting batteries first all the way then work on the house battery again.

 

[BradV]

here is the picture of my switches and the charging system that i have that is hooked up to the engine batteries.

 

[Marty D]

Were are you putting this 3rd. battery ?

 

[BradV]

In my 2530 i have room to add up to 4 batteries in the rear hatch in front of the transom where the two were from the factory.

 

[TheOtherLine]

Were are you putting this 3rd. battery ?

On my 2520 model year, there is a space, just forward of the transom fish box where the bilge and filter are. There's room for another battery down there.

 

[offshoreguy]

When I got my boat 1997 2520 5.7l i/o volvo, it had 2 group 24 batts, knowing how much juice i use I shoe-horned 2 group 31's in there. On my last boat I installed the blue seas batt isolator system, soon to be installed on the parker.

http://bluesea.com/category/2/productline/overview/329
They call it the add a batt system, It isolates the house and starting batt, so you can run your house batt down to nothing, and still start with no prob, there is also a remote led you can intall on the dash so you know the system is working. I also had 2 group 31 on the old boat and would run lights (4 floods and running), all elec, livewell, washdown, stero, and this unit was not in a nice dry parker bilge it was constantly gettin soaked by water draing from the deck into the bilge, and it never had a prob. Cant say enough about it it made me a believer, I even let my house batt drain down to nothing by leavin my flood lights on all night to test it, a few times, no probs. And auto zone sells the water proof circuit breaker you need for the system install for like a third of the price of west, its the same product just doesnt have the expensive name. Anyone worried about batt power should definately look into these, I dont know why every new boat doesnt have one. I actually think you can download more info on the blue seas web site, but there is a good write up on them in last yrs west marine catalog.

Just a thought hope this helps
Wade

 

[J V]

I HAVE A VOLT METER ON MY GARMIN FISH FINDER. IT WILL SOUND A ALARM IF THE BATTERY DROP BELOW 11AMPS. WHEN MY BOAT WAS NEW IT ONLY HAD ONE BATTERY. THE ALARM WENT OFF ONE DAY. I WAS ABLE TO START MY MOTOR. THE NEXT DAY I HAD A SECOND BATTERY PUT IN.I START MY MOTOR ON BATTERY ONE. BEFORE I LEAVE THE DOCK I SWITCH TO BATTERY TWO ON THE WAY HOME I SWITCH BACK TO BATTERY ONE. WORKS GREAT.