Moderated Discussion Areas
  ContinuousWave: Small Boat Electrical
  Mixing battery types

Post New Topic  Post Reply
search | FAQ | profile | register | author help

Author Topic:   Mixing battery types
Riptide23WA posted 05-03-2006 09:57 PM ET (US)   Profile for Riptide23WA   Send Email to Riptide23WA  
First, I DID try the search button, but didn't find anything exactly pertaining to my setup...

My 1992 23 Walkaround has two batteries; identical West Marine starting batteries, 1000 CCA, Group 24s, bought new last year. Each cell starts its respective engine (twin Yamahas). In addition, the starboard cell carries all house loads. There is an onboard charger, factory installed, that charges both cells.

While working on the boat this spring, I must have run the starboard cell down, over the course of two days. I was surprised, I guess, that it ran down so fast, as I was mainly listening to the radio, although I did use the cockpit floodlight for a few hours one night.

Seeing as how the starboard cell carries the house loads, should I switch that one out for a dual-purpose or deep cycle type? Any problem mixing battery types on board? What's the highest capacity Group 24 out there?


towboater posted 05-04-2006 10:53 AM ET (US)     Profile for towboater  Send Email to towboater     
Before you buy a new bat, a one year old bat should come back. Leave it on a 40 amp charger for 24 hrs.

Im not an electrician, but, a dual charging system and using aux power off one bat doesnt seem right. You should probably have a pro look it over.

Long as Im here...
Ive used several twin eng dual battery schemes. To be brief, Ive had better luck isolating each battery to each engine and sort of splitting up the aux loads to both batteries equally. This example is a twin I/O. The engine room stuff (blower/bilge pumps/trim) comes off of one bat, the helm electronics come off the other.

Each bat has its own on/off switch & buse bar.
There is a on/off switch between them in case I need a jump but I never run with both bats connected to eachother although I could if I lost a alternator or eng.
This system also allows you to mix battery capabilities/size as long as it has enough cranking amps recomended to start the engine.

Again, because of your dual charger, I recommend you see a pro before you mix battery sizes.

ratherwhalering posted 05-04-2006 12:16 PM ET (US)     Profile for ratherwhalering  Send Email to ratherwhalering     
Perkos makes a switch called an "emergency parallel" that allows you to isolate the port start battery from the starboard start/house battery. If you have space for it, you can also install a third, house only battery. Basically, you run the engine cables to the starboard battery, then jumpers to house battery, with a Automatic Current Limiter (ACL) on the positive feed from the starboard battery to the house battery. This way, when the starboard start battery is fully charged, the ACL will trip, and begin charging the house battery. The only drawback is that if the house battery runs low, it will not draw from the starboard battery.


ratherwhalering posted 05-04-2006 12:22 PM ET (US)     Profile for ratherwhalering  Send Email to ratherwhalering     
Oops, I meant Automatic Charging Relay (ACR)
towboater posted 05-04-2006 01:23 PM ET (US)     Profile for towboater  Send Email to towboater     
I dont want to debate rathers suggestion, but, as I mentioned, Ive had problems with the isolator systems that I havent had with the simple independent battery setup.
Again, I defer to the new high tech engine specs but 12v is 12v no matter how you try to spin it.

Actually, the independant setup was installed BECAUSE a isolator switch quit working, none was avail so I just separated everything to get going (different boat).
AGain, No probs since.

Adding a house battery is great. Using the independant setup, you can install the 3rd battery anywhere and connect to each battery with a simple 3 pole 1/2/off switch.
1 goes to stbd bat...the alt will charge both bats.
2 goes to port bat...""
OFF kills the likelyhood of draining the main bats while you are using the house bat to power different things while the engines arent running (charging). After you start the engines & select which eng you want to charge the house battery, the alternator will feel it just like turning on your headlights (you dont need a separate amp gauge). Still, you should get into a habit of turning off anything that is drawing a lot of amps (floods, radar) before you switch the house battery to the charging system to prevent blowing a diode. Wait til the amp gauge is showing a charge, then turn things back on.
Basically, all the main bats are doing now is starting the engines. IF you leave a flood light on...which I often do when I start early & end my day mid afternoon & forget...only the house/aux bat goes dead.

As long as you are at it, install a volt meter. This time, you can run each bat thru a 3 way switch on/on/on using small gauge wires. Whenever you read 12v or less, its time to start an engine to charge.

Use 6 gauge soldered lugs on the primary ground loops.
You can get by with 8 ga. These connections are just as important as the batteries themselves.


Bulldog posted 05-04-2006 04:28 PM ET (US)     Profile for Bulldog  Send Email to Bulldog     
Pat, check out the reference section under "Dual battery", then go down to the "New dual battery configuration", that is a nice setup and I am an electrician! The wiring setup, I'm referring to allows you to select which battery the house loads are put on , plus it also allows you to tie the battery systems together in a low battery sitaution. You can get higher then 1000CCA but a dual use battery will probably be fine, as long as you stay with the same type of lead acid battery , not going to optima or AGM. Unless you plan on draining down the batteries a lot , I would charge it up and not worry about it. My 1987 Yamaha engines seem to run a little hot on voltage up to almost 15 volts, the AGM batteries at Cabela's have a sticker that says using in a system that allows over 14 volts voids warranty. You have a twin engine setup , keep it separate and keep it simple! I replaced both batteries last year and went with dual use batteries, but I'm cranking twin 70 hp engines......Jack
jimh posted 05-04-2006 09:02 PM ET (US)     Profile for jimh  Send Email to jimh     
Riptide23WA posted 05-04-2006 10:10 PM ET (US)     Profile for Riptide23WA  Send Email to Riptide23WA     
Thanks for all the tips. I had forgotten about the Reference section. Nice work on that article, jimh.

I am going to hand-over-hand my system, as it kind of looks like the factory scheme shown in the Reference article. I like the idea of the "new" system in it's simplicity though.

Thanks once again everyone. Pat h

Post New Topic  Post Reply
Hop to:

Contact Us | RETURN to ContinuousWave Top Page

Powered by: Ultimate Bulletin Board, Freeware Version 2000
Purchase our Licensed Version- which adds many more features!
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.