Dual Battery setup - proposed

gigy · 1st November 2009, 20:05

Hi all,
I am planning to put in a second battery in to my baleno for two purpose.
i have just now downgraded the battery to default capacity from the large one previously installed. with my modest ice setup there was no issue previously but with new one the car lights also thump along with music, this was not there previously. so i guess need more reserve capacity. ideally the second one needs to be near the amplifier but i am putting into the stock tray itself as of now.
Second reason i can use this as a emergency backup built in. in case the primary battery drains of due any reason (since it always remains connected) i can use the second anytime to start the car.( it connects to car only when powered)
One of my friend is running a dual setup with complicated electronic control and voltage indication and all but i want to keep the system simple. there is no issue in his car due to doubling of battery capacity .
Please suggest improvements
i got some free time now, thats why this time pass.
A diagram of setup below.

low_bass_makker · 1st November 2009, 20:29

What size of contactor or relay you plan to use ?

gigy · 1st November 2009, 20:58

I have this contactor/relay lying around for sometime without use. plan to use it.
Its specification
Mobile Audio Relay and Battery Isolator
Great for isolating a second batter making it dedicated to the stereo system
Does not create a voltage drop to the second battery like conventional isolators
80 Amps at 12V Continuous Power Handling
150 Amps Surge Power Handling
Switching Power: 10 - 16 VDC
Draws Less Than 1 Amp When On
Dimensions: 2-11/16" L x 3-5/16" W x 4" H.

I hope it can take few starting current cycles in its life time.

BaCkSeAtDrIVeR · 1st November 2009, 21:12

You may need to upgrade the alternator so that the 2nd battery is charged properly.

gigy · 1st November 2009, 21:39

We have another baleno running for ,more than 2 years now with two batteries and there is no issue till date regarding his car electrical system.
Even he has a basic ice setup like mine and his dual battery did save him few time from being stranded on road.
Basically the second one will always be in a charged state from day one. it will be the primary one which will have a larger charge/discharge graph, so don't expect trouble.

karankapoor · 1st November 2009, 21:50

For the reason stated by you i don't think one needs 2 batteries in a car for at least a normal ICE with 1/2 amplifiers which require 60/80 amp current and for the second reason i personally dint faced any problem in the past 17/18 years of my driving, But if you want 2 off them in your car go ahead but be sure you are clear with every thing before you install the second battery.

gigy · 1st November 2009, 22:26

Even i didn't expect any change coming when i was replacing the previous 48 one with this 35amph one, but the thing is the power fluctuation now exists. nothing else has changed, its the same amp, wiring player, groundings etc. so what could be the issue. Even i dont know if this is going to help

karankapoor · 1st November 2009, 22:48

Why had you changed the battery with a 35 ampere battery this is actually a downgrade any particular reason, I think this is causing dimming.

Baleno needs a 45 amp battery or a 35 amp battery ?

gigy · 1st November 2009, 23:03

The stock one is 35amp battery. i had installed the 48 amp one earlier.

Ravveendrra · 1st November 2009, 23:18

Why did you shift back to 35A from 48A? It will be much easier, cheaper and uncomplicated to upgrade your battery and use only one battery.

Cheers,

gigy · 1st November 2009, 23:29

When we were replacing batteries, i took one large battery and my friend put in two smaller batteries. in due course of use i had problems regarding total voltage in car, had to replace alternator, his setup is running fine till date with 70amph in total. so the dual battery had bitten me long ago and i was waiting for present one to go bad. with this big one there was no place to put in a second one. didn't want to put it in boot. when time came i have gone for stock one as two sit in tray easily with minor modification.

Now earlier plan was to stagger purchase of second one by a year so that both don't loose service life together but with dimming of lights in night i have changed plans to put in same or higher life one but of same capacity,same or different brand.

pranava999 · 2nd November 2009, 00:32

Have you considered the big 3 upgrade? Do look into it. I think the upgrade could be an alternative to having another battery on-board.

low_bass_makker · 2nd November 2009, 00:38

I am using two batteries for quite sometime now. First of all you will need to watch the voltage as the alternator will have to work double for charging the two batteries. Rest no need to put the contactor or any thing if both the batteries are same and new there will be no issue. And yes with one battery close to the amps make them play better.

gigy · 2nd November 2009, 08:41

Contactor is actually to see that only one battery is involved in the starting of car and dont get discharged along with the main one in case i forget switching off headlights in parking.(it happened twice with me). This will also ensure that alternator will have to charge back only one battery at higher current. the second is doing a job more like a capacitor. To place it in boot i will have to put in a fuse which will have to take the starting current load also, so its not practically safe i suppose. if it was to support the amplifier only a 60amp fuse would have done the job.
I have left with two wires to be replaced/supported( battery to ground, alternator to battery, it was to happen with the install. Will do this first and see if it is making a difference before buying the second battery.

DerAlte · 2nd November 2009, 13:04

Perhaps you could consider a diode in parallel with the contactor main contacts. Anode to main battery +, hence it will charge when the main battery charges. Cathode to the +ive of the 2nd battery. The contactor contact will be, at this time in Open position. Because of the diode, no current will be drawn from the 2nd battery during cranking.

Now, when you want to use the 2nd battery for cranking, 'make' the contact and it will short the diode and bypass it. In this state, the 2nd battery will supply the juice to crank the engine.

Anyhow, if the alternator (due to to poor current regulation) & 2nd battery combo cannot supply the current needed by you ICE dynamically, the lights will still dim in sync with large current demands.

1st November 2009, 20:29	#2
low_bass_makker Senior - BHPian Join Date: Mar 2006 Location: Faridabad Posts: 6,813 Thanked: 306 Times View My Garage	What size of contactor or relay you plan to use ?
	() Thanks

1st November 2009, 20:58	#3
gigy Senior - BHPian Join Date: Jul 2006 Location: mumbai Posts: 1,321 Thanked: 47 Times	I have this contactor/relay lying around for sometime without use. plan to use it. Its specification Mobile Audio Relay and Battery Isolator Great for isolating a second batter making it dedicated to the stereo system Does not create a voltage drop to the second battery like conventional isolators 80 Amps at 12V Continuous Power Handling 150 Amps Surge Power Handling Switching Power: 10 - 16 VDC Draws Less Than 1 Amp When On Dimensions: 2-11/16" L x 3-5/16" W x 4" H. I hope it can take few starting current cycles in its life time. Attached Thumbnails
	() Thanks

1st November 2009, 21:12	#4
BaCkSeAtDrIVeR Senior - BHPian Join Date: Jun 2007 Location: Kochi Posts: 2,540 Thanked: 758 Times	You may need to upgrade the alternator so that the 2nd battery is charged properly.
	() Thanks

1st November 2009, 21:39	#5
gigy Senior - BHPian Join Date: Jul 2006 Location: mumbai Posts: 1,321 Thanked: 47 Times	We have another baleno running for ,more than 2 years now with two batteries and there is no issue till date regarding his car electrical system. Even he has a basic ice setup like mine and his dual battery did save him few time from being stranded on road. Basically the second one will always be in a charged state from day one. it will be the primary one which will have a larger charge/discharge graph, so don't expect trouble.
	() Thanks

1st November 2009, 21:50	#6
karankapoor Senior - BHPian Join Date: Apr 2008 Location: in the car!!! Posts: 1,674 Thanked: 6 Times	For the reason stated by you i don't think one needs 2 batteries in a car for at least a normal ICE with 1/2 amplifiers which require 60/80 amp current and for the second reason i personally dint faced any problem in the past 17/18 years of my driving, But if you want 2 off them in your car go ahead but be sure you are clear with every thing before you install the second battery. Last edited by karankapoor : 1st November 2009 at 21:52.
	(1) Thanks

1st November 2009, 22:26	#7
gigy Senior - BHPian Join Date: Jul 2006 Location: mumbai Posts: 1,321 Thanked: 47 Times	Even i didn't expect any change coming when i was replacing the previous 48 one with this 35amph one, but the thing is the power fluctuation now exists. nothing else has changed, its the same amp, wiring player, groundings etc. so what could be the issue. Even i dont know if this is going to help
	() Thanks

1st November 2009, 22:48	#8
karankapoor Senior - BHPian Join Date: Apr 2008 Location: in the car!!! Posts: 1,674 Thanked: 6 Times	Why had you changed the battery with a 35 ampere battery this is actually a downgrade any particular reason, I think this is causing dimming. Baleno needs a 45 amp battery or a 35 amp battery ?
	() Thanks

1st November 2009, 23:03	#9
gigy Senior - BHPian Join Date: Jul 2006 Location: mumbai Posts: 1,321 Thanked: 47 Times	The stock one is 35amp battery. i had installed the 48 amp one earlier.
	() Thanks

1st November 2009, 23:18	#10
Ravveendrra Senior - BHPian Join Date: Jan 2008 Location: Hyderabad Posts: 1,390 Thanked: 447 Times View My Garage	Why did you shift back to 35A from 48A? It will be much easier, cheaper and uncomplicated to upgrade your battery and use only one battery. Cheers,
	() Thanks

1st November 2009, 23:29	#11
gigy Senior - BHPian Join Date: Jul 2006 Location: mumbai Posts: 1,321 Thanked: 47 Times	When we were replacing batteries, i took one large battery and my friend put in two smaller batteries. in due course of use i had problems regarding total voltage in car, had to replace alternator, his setup is running fine till date with 70amph in total. so the dual battery had bitten me long ago and i was waiting for present one to go bad. with this big one there was no place to put in a second one. didn't want to put it in boot. when time came i have gone for stock one as two sit in tray easily with minor modification. Now earlier plan was to stagger purchase of second one by a year so that both don't loose service life together but with dimming of lights in night i have changed plans to put in same or higher life one but of same capacity,same or different brand.
	() Thanks

2nd November 2009, 00:32	#12
pranava999 BHPian Join Date: Aug 2006 Location: BANGALORE Posts: 845 Thanked: 23 Times View My Garage	Have you considered the big 3 upgrade? Do look into it. I think the upgrade could be an alternative to having another battery on-board. Last edited by pranava999 : 2nd November 2009 at 00:33.
	() Thanks

2nd November 2009, 00:38	#13
low_bass_makker Senior - BHPian Join Date: Mar 2006 Location: Faridabad Posts: 6,813 Thanked: 306 Times View My Garage	I am using two batteries for quite sometime now. First of all you will need to watch the voltage as the alternator will have to work double for charging the two batteries. Rest no need to put the contactor or any thing if both the batteries are same and new there will be no issue. And yes with one battery close to the amps make them play better.
	() Thanks

2nd November 2009, 08:41	#14
gigy Senior - BHPian Join Date: Jul 2006 Location: mumbai Posts: 1,321 Thanked: 47 Times	Contactor is actually to see that only one battery is involved in the starting of car and dont get discharged along with the main one in case i forget switching off headlights in parking.(it happened twice with me). This will also ensure that alternator will have to charge back only one battery at higher current. the second is doing a job more like a capacitor. To place it in boot i will have to put in a fuse which will have to take the starting current load also, so its not practically safe i suppose. if it was to support the amplifier only a 60amp fuse would have done the job. I have left with two wires to be replaced/supported( battery to ground, alternator to battery, it was to happen with the install. Will do this first and see if it is making a difference before buying the second battery.
	() Thanks

2nd November 2009, 13:04	#15
DerAlte Senior - BHPian Join Date: Mar 2007 Location: Bangalore Posts: 8,035 Thanked: 2,920 Times	Perhaps you could consider a diode in parallel with the contactor main contacts. Anode to main battery +, hence it will charge when the main battery charges. Cathode to the +ive of the 2nd battery. The contactor contact will be, at this time in Open position. Because of the diode, no current will be drawn from the 2nd battery during cranking. Now, when you want to use the 2nd battery for cranking, 'make' the contact and it will short the diode and bypass it. In this state, the 2nd battery will supply the juice to crank the engine. Anyhow, if the alternator (due to to poor current regulation) & 2nd battery combo cannot supply the current needed by you ICE dynamically, the lights will still dim in sync with large current demands.
	() Thanks