Adding An Extra Battery

**suysuy** · January 17th, 2010 04:12 PM

Im planning to add an extra battery in my trunk. syempre in parallel. but i read somewhere if you use different kinds/ratings of battery, dapat merong isolator. pag same type naman hindi na kailangan.

ang tanong, saan ba may bentang isolator? or can it be DIYed? im planning to add an extra battery. meron kasi dito brand new Motolite Excel N70 ata ito malaki. extra battery dito sa amin. honda city 2006 ang ride na lalagyan ko. it is for my sound system tsaka para longer running ako with accessories with the engine off. i dont have time to buy a deep cycle battery. kasi meron naman dito extra battery

ang iniisip ko lang pag walang isolator eh baka ma overcharge ang original battery ko which is only an NS40. kasi when putting a battery in parallel, iisang load siya para alternator

can you please clarify things for me? hehe thanks!

**jick.cejoco** · January 17th, 2010 04:58 PM

Originally Posted by suysuy

Im planning to add an extra battery in my trunk. syempre in parallel. but i read somewhere if you use different kinds/ratings of battery, dapat merong isolator. pag same type naman hindi na kailangan.

ang tanong, saan ba may bentang isolator? or can it be DIYed? im planning to add an extra battery. meron kasi dito brand new Motolite Excel N70 ata ito malaki. extra battery dito sa amin. honda city 2006 ang ride na lalagyan ko. it is for my sound system tsaka para longer running ako with accessories with the engine off. i dont have time to buy a deep cycle battery. kasi meron naman dito extra battery

ang iniisip ko lang pag walang isolator eh baka ma overcharge ang original battery ko which is only an NS40. kasi when putting a battery in parallel, iisang load siya para alternator

can you please clarify things for me? hehe thanks!

if you have two different size batteries being charged by one alternator, the voltage will be the same. if suppose the N70 is at 14.5 volts with the engine running, the N40 will have the same voltage. if they start out that the auxilliary battery N70 is 11 volts and the main battery N40 is 12.6 volts, they will be charged at the same rate with using the average voltage. but you have to isolate the aux battery to prevent a no start with the main battery by using either an isolator or in its absence, a normally open relay to the current of the alternator. it has to be wired that it will disconnect the aux from the main battery through the alternator

**ghosthunter** · January 17th, 2010 05:54 PM

Why do you need a 2nd battery? Having a bigger one would pretty much solve power problems.

Do you have an aftermarket AV setup in your car or something that draws a lot of power?

**suysuy** · January 17th, 2010 06:45 PM

yes i do have an aftermarket AV setup hehe

Having a bigger one would pretty much solve power problems.

i cant find a higher speced battery aside sa normal NS40 niya. anything bigger than the NS40 wont fit. that is my dilemma. that is why since meron spare battery dito. i might as well wire it in parallel.

*jick
so pwede siya isabay? hindi ma overcharge yung NS40 ko?

**suysuy** · January 17th, 2010 06:46 PM

yes i do have an aftermarket AV setup hehe

Having a bigger one would pretty much solve power problems.

i cant find a higher speced battery aside sa normal NS40 niya. anything bigger than the NS40 wont fit. that is my dilemma. that is why since meron spare battery dito. i might as well wire it in parallel.

*jick
so pwede siya isabay? hindi ma overcharge yung NS40 ko?

--

edit

madali nalang mag wire ng extra battery sa trunk kasi meron nang existing connections sa likod. ang iniisip ko lang baka ma overcharge aking battery sa harap (NS40)

**jick.cejoco** · January 17th, 2010 07:15 PM

Originally Posted by suysuy

yes i do have an aftermarket AV setup hehe

i cant find a higher speced battery aside sa normal NS40 niya. anything bigger than the NS40 wont fit. that is my dilemma. that is why since meron spare battery dito. i might as well wire it in parallel.

*jick
so pwede siya isabay? hindi ma overcharge yung NS40 ko?

--

edit

madali nalang mag wire ng extra battery sa trunk kasi meron nang existing connections sa likod. ang iniisip ko lang baka ma overcharge aking battery sa harap (NS40)

you can experiment on two D cell batteries of different state of charge to confirm the voltage averaging effect. i have a set up of two batteries in one of my vans. the alternator had to be beefed up for the auxilliary battery that is running a 1000 watt power inverter that runs a chest freezer inside the van. the isolation was made with an 80 amp relay to control the charging of the aux battery. isolators are available on ebay from $7.00 and up depending on model

**ghosthunter** · January 17th, 2010 10:11 PM

Originally Posted by suysuy

yes i do have an aftermarket AV setup hehe

i cant find a higher speced battery aside sa normal NS40 niya. anything bigger than the NS40 wont fit. that is my dilemma. that is why since meron spare battery dito. i might as well wire it in parallel.

*jick
so pwede siya isabay? hindi ma overcharge yung NS40 ko?

--

edit

madali nalang mag wire ng extra battery sa trunk kasi meron nang existing connections sa likod. ang iniisip ko lang baka ma overcharge aking battery sa harap (NS40)

You don't need a bigger battery. What you need is a more powerful alternator.

**suysuy** · January 18th, 2010 12:28 AM

You don't need a bigger battery. What you need is a more powerful alternator.

i think you dont understand me sir. kaya nga gusto ko more reserve power kasi i dont want to turn the engine on while listening something while waiting for someone/something while parked. na experience ko na kasi muntik ayaw na mag start kasi na lowbat yung ride hehe

isipin mo, kung naka park ka isang oras nakaandar makina mo jusko, ubos gas mo.

**oj88** · January 18th, 2010 02:40 AM

Here's a simple circuit I made that will isolate the secondary battery from the primary battery when the ignition key is off or set to Acc. In this state, your sound system (load), will operate off of the secondary battery exclusively, without discharging your primary battery.

But when you set the ignition key to ON or while the engine is running, both batteries are connected in parallel as the alternator charges both.

Needless to say, you must have a good understanding of your car's electrics as far as the thickness of the wires to use, the value of the fuses, and where exactly to tap on the alternator (pre or post OEM fuse - not included in the drawing). If you choose pre-OEM fuse, you must install your own fuse with the correct rating.

You can probably also implement a 555 timer chip to delay the relay (ie. 30-60 secs.) to give you time to start the car with the secondary battery still offline.

Finally, you can put a "master safety switch" to cut off power to the relay in case of a malfunction or if you need to work on something in which there's a need for the 2nd battery to remain offline.

Good luck!