"another" dual batteries question
Submitted: Sunday, Dec 14, 2008 at 08:29
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brentos
hi there eveyone i just have a question as i dont know that much about electrics.
my LC105 has all the wiring there for dual batteries,i only found this the other day,it is all tucked away cause it is not in use,hence the second battery is not there.
anyway it has the switch there,the type with the red handle for the battery switch over,also the red handle was not there either.
so i found an old one that was laying around and put it in.
so when i turn the switch all the ignition and electrics still work even know there is no second battery hooked up i thought there would have been no power at all,so does this mean when i put the second battery in my fridge is going to run off both batteries
even know i have switched them over not sure how all this works.
also it looks like the negative cable for the second battery earths on the motor and not run back to the neg on the main battery,is this ok i hope i explained all this ok
so could someone please enlighten me on how all this works
cheers
brentos
Reply By: Dunaruna - Sunday, Dec 14, 2008 at 08:56
Sunday, Dec 14, 2008 at 08:56
From your description it sounds like you have a simple on/off battery switch, they are often used in boats to isolate a second battery or to completely turn of the battery circuit while the boat is in storage. These switches can be 1, 2, 3 or 4 position, what type do you have?
If it is a single position switch (on/off), when it is on, the second battery is directly parallel with the main battery. With the switch off, the second battery is isolated.
Motors are often used as a battery earth, it is known as a common earth. No problem.
AnswerID:
339614
Follow Up By: brentos - Sunday, Dec 14, 2008 at 09:19
Sunday, Dec 14, 2008 at 09:19
hi dunaruna
its a single switch just on/off.if when on the second battery is running directly parallel with the main battery,i take it that means it is recieving power from both batteries at the same time and when it is off the second battery is isolated,shouldnt it be the other way around,when it is off the second battery is isolated
so the main battery is not being used.
is this system ok to use,when i go away it usually only for a about a week tops and i can just start the car every now and then and charge the batteries
regards
brentos
FollowupID:
607149
Follow Up By: Dunaruna - Sunday, Dec 14, 2008 at 09:38
Sunday, Dec 14, 2008 at 09:38
The fridge should be connected directly to the second battery (through a fuse or CB). It will have juice 24/7 as long as the battery has charge.
The switch is there simply to connect/disconnect the two batteries. When the switch is turned on, the alternator will begin to recharge the second battery AND the batteries will begin to equalise.
This type of setup is not ideal, but it will work short term. The longevity of both batteries will be affected.
FollowupID:
607157
Reply By: Member - Phil G (SA) - Sunday, Dec 14, 2008 at 09:36
Sunday, Dec 14, 2008 at 09:36
You have a system that cost all of $15! If you want to keep this system, then you'll need to have two identical batteries because they will be running together most of the time (they will crank together, charge together, and discharge together). You could leave them connected for overnight camps but if running a fridge for longer, then you'll want to flick the switch and isolate the batteries.
Can I suggest that if you install a second battery, then get a normal electronic isolator put in (like a Redarc, Rotronics, Sidewinder etc) and then you won't be lifting the bonnet every time you want to flick the switch, and you'll spend more time relaxing than worrying about your batteries.
Second battery neg needs to go to the motor (and body) because it gets recharged from the alternator.
AnswerID:
339619
Follow Up By: brentos - Sunday, Dec 14, 2008 at 10:00
Sunday, Dec 14, 2008 at 10:00
hi phil g
is the redarc thing the same as the switch but just automatic.
how do they work
regards
brentos
FollowupID:
607163
Follow Up By: Member - Phil G (SA) - Sunday, Dec 14, 2008 at 13:01
Sunday, Dec 14, 2008 at 13:01
Brentos,
Yep, they are an automatic electronic switch - switches the batteries together when driving (so they both get charged) and then switches off to isolate them when stopped (so your fridge only drains the second battery. So you don't have to do anything - just enjoy the coldies.
Derek's diagram below shows you where all the wires should go.
FollowupID:
607184
Reply By: ABR - SIDEWINDER - Sunday, Dec 14, 2008 at 11:35
Sunday, Dec 14, 2008 at 11:35
Hi Brentos
If you could post some photos it would help.
Here is a typical diagram of how it should look and work.
Regards
Derek from ABR
AnswerID:
339648
Reply By: brentos - Sunday, Dec 14, 2008 at 13:19
Sunday, Dec 14, 2008 at 13:19
hey guys
thanks for your replies i have it worked out now
from what i can see the i have the same setup is the same as the diagram exept for the isolator switch.
the only other question i have do i have to use an identical battery as the main or can i use a bigger deep cycle battery
thanks guys
brentos
AnswerID:
339665
Follow Up By: Member - Phil G (SA) - Sunday, Dec 14, 2008 at 16:55
Sunday, Dec 14, 2008 at 16:55
Brentos,
If the batteries are getting on a bit, take the opportunity to buy a pair of N70-size cranking batteries. Can usually get the Exide Extremes or similar for about $180 each. You can leave them connected all the time, unless staying camped for more than one night.
The downside of this setup, is that if one battery fails, it will pull down the other battery, so you might end up with two flat batteries. Thats why its best to buy in pairs, so you'll be sure to get a few years good use from them.
FollowupID:
607215