Dual battery necessary, AT what point is better to have 2?

B

bleucharm

New member
Currently using a single battery, thinking about re-wiring the whole electrical system. And wanting a dual battery setup.

The battery is currently sitting on the port side inside the cabin right below the steering cable and electrical panel.


I have a 92 19' Angler. Where do you guys have your dual battery setup?
 
In my opinion every power boat should have two batteries. One for house, the other for engine start. Why two batteries? If you run down one, it is difficult, but not totally impossible to "hand start" a 70 to 90 hp outboard! Your batter won't run down? It happens to the best of us.

I prefer the old fashion-1/2/off/combine switch. I then like a voltage sensitive relay, where it combines the two batteries (which should be the same type, capacity, age and capacity) when the engine is charging the batteries. They comb one when the battery reaches about 13.7 volts, and separate batteries when the voltage drops below 12.7 volts. (may be slight variations. )
 
The point at which it is best to have two batteries on a boat is when you want to leave the dock.

1/2/Both switch is a must ($28.50). Digital LED battery monitors are now a ridiculous $1.49 on Ebay. Walmart is now the cheapest provider of brand name serviceable batteries ($60 without the brand name). Tractor Supply has inexpensive cable, solid copper lugs, silicon sealant heat seal shrink tubing from which you can make your own "marine grade" cables. You could be in to second battery security land for under $150.

Now, where to put that second battery.

Mark
 
I purchase batteries from Wal Mart which were flooded cell type and now I only see maintenance free units and use solar charger when the boat is in storage. I do use the Battery Minder battery charger and feel it does help but there is a lot of hype to weed through just like fuel additives. To save time, I dont read the testimonials any longer

Works fine for now

I prefer to upgrade to larger batteries. Attwood battery tray bc the posts are threaded into the base , very convenient when swapping out , add a Blue Seas VSR instead of a Perko, battery charger probably NICO and Victron battery meter in the dash or go move to solar charger unit at dock and on the boat bc we boat in Florida and it is sunny most days.

Attwood battery tray see
http://www.attwoodmarine.com/store/product/Battery-Tray

Good luck,,, lots of options, ideas and equipment
 
I also agree that two batteries is a great idea especially if you run more than a very basic set of electronics. We run a regular size group 24 between the gas tanks, next to the bilge for starting the motor only.

In our case (lots of accessories), we put two AGM batteries up front under the berth area to run everything else.

http://www.c-brats.com/modules.php?set_ ... _photo.php

I like the approach of sizing your starting battery to be just big enough to provide reliable starting service then scale your house battery up or down depending on your estimated needs plus choosing the type based on where you will mount it.

Greg
 
Question, with a 1/2/off/combine switch you must manually switch between 1 and 2 after starting and back to 1 before starting again? Assuming 1 is the start battery.

Jake
 
Typically #1 is the starter battery.
see
http://www.marine-j.com/pdf/8501DP.pdf

Have you decided on the switch? some are dumb - you can damage the outboard charging system diodes when making switch setting with the outboard running. If you have this type then turn off outboard when making battery switch (1, 2 , All, Off) changes

some mechanical switches have protection builtin to avoid diodes damage

or consider the advantage of installing a VSR which costs more but has more features m2cw
see
https://www.keoghsmarine.com.au/BEP-Mar ... -140A-DVSR
 
I want to get this kit

Blue Sea 7650 Add-A-Battery Kit 120A Battery Switch Automatic Charging Relay

According to the diagram, it seems simple and straight forward.

Another question just comes to mind. Is it better to connect my 2 electric Scotty DR to the switch panel, or directly to battery, with fuse connector?

I understand the bilge should on the 24hrs circuit panel.
 
I have an '03 19. I have the starter battery in the starboard gunnel battery box and the house battery in the port box. The switch and combiner unit are mounted below transom box, near the fuel tanks.

OP : It's good that you're adding another battery and re wiring. A reliable battery system is important. I actually keep a portable battery charger on board too. Ya never know.... lol
 
There are a number of reasons you should have the same type, capacity and age of battery. Basically, there can be an imbalance in charging.

Most mechanical 1/2/on/off switches, do have "make before break"--that is there is always a battery (resistance) attached to the "alternator".

My son's "new" 25 cruise ship--has had several modifications--and it is taking some time to sort thru what has been done. It has the off, one and combine, So far I have not found the wiring diagram--there are some ? wiring issues, and it its taking time to sort it out. (The VCR is supposed to automatically switch, one battery for start and one for house).

Many folks will have two identical batteries. On the even days they run on #2 and on the odd days, #1. This way each battery is used equally (?)> In any case, it is best to put the batteries on a "smart" charter when you are thru using the boat each night if possible.
 
Hey thataway,

It sounds like your son may have Blue Seas Systems, Add-A-Battery. I installed the Mini Add-A-Battery system on my CD 16, it more than meets our modest requirements

If it is Blue Sea Systems they have wiring diagrams on their website, www.bluesea.com. I have found they will respond to any technical questions reasonably fast.

Be safe.
Spuncopper
 
thataway":vevzf5xp said:
Many folks will have two identical batteries. On the even days they run on #2 and on the odd days, #1. This way each battery is used equally (?)
Click to expand...

No need to go into details for me but wouldn't this setup eliminate the advantage of having all the electronics connected to a battery separate from the battery used to start the boat?
Thanks,
Jake
 
I just installed a second battery via mini ACR. I put a post up on here and got some good advice not too long ago.

I never had any problem, spent many nights on my boat, use an electric windlass, and didn't even have a battery switch, just my panel. I am installing an electric line puller as soon as it arrives, and felt like I had to add the second battery, and the charging relay, despite the trouble-free life I was living.

While I do agree that it is a very smart, and cost effective upgrade that any boater should take advantage of in a boat with electric start and some kind of electric component that is on while the engine is off, I didn't install mine for that reason. I just wasn't enjoying my boat as much because the IDEA of a single battery bothered me so much.

I did have some longer time on the anchor with my sounder and stereo going where I realized that I had to check my voltage and found it had slipped below 12v, but the engine always fired right up. These moments of tension break up a relaxing and nice time, and sort of ruin the whole purpose of the boat.

So if you are at all concerned, or if life with a single battery causes you to enjoy your boat less, install the second.

I had a bona fide START battery in hand, so I don't have a matched pair, but when I get new batteries I'll run a redundant pair.
 
Jake":38eo9eia said:
thataway":38eo9eia said:
Many folks will have two identical batteries. On the even days they run on #2 and on the odd days, #1. This way each battery is used equally (?)
Click to expand...

No need to go into details for me but wouldn't this setup eliminate the advantage of having all the electronics connected to a battery separate from the battery used to start the boat?
Thanks,
Jake
Click to expand...

Nope. You just swap the wires on the battery and battery A becomes your start and B becomes your house. Tomorrow swap again and A is house and B is start. Then one doesn't spend it's whole life doing duty as a cranking (high amp, short duration use) and the other electronics (low amp, long duration use) and they both wear out and get replaced around the same time.

Alternately you can have two types of battery, a start battery and a house battery, each purpose built for what they do, and they remain in those roles.

The advantage of the redundant pair (especially in a small boat that doesn't need a huge amp output to crank like ours) is that if one dies prematurely at sea, your remaining battery is fine to do the rest of the work, versus having your start battery run your electronics all day, or your deep cycle house battery cranking your engine.

It's all tradeoffs. But regardless of whether your pair of batteries are a redundant pair or house/start, your add-a-battery system will keep one battery isolated from current draw at all times, until you start the engine. You can run down your house battery all the way and the start battery will be ready to roll. And if your start battery dies on you at sea, you can flip a switch and use the house battery to start your motor.
 
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