Nevermind

This message has been edited. Last edited by: imakehp,

No need for a 2nd battery. Make the switch to 16V and never look back

Big Steve…knows!

Get a new battery switch as well....Losing half your available voltage tells me the contacts are toast.....should be little to no drop through it.....

Its your car, but you are adding 45lbs to it for no good reason

Again, Big Steve…knows and imakehp is clueless!

quote:

I have alot of computer and EFI stuff on the car, just bought a new 120 amp alternator and charger, so a 16V change over is NOT in my near future.

If you were loosing 1/2 volt across the disconnect at rest, that is a lot. It probably is even greater at cranking also.

When I added EFI and digital dash it did not reduce the battery voltage at idle from prior MFI.They draw little.

My voltage measures (rock solid) 14.2v at 1300 rpm idle with the water pump, cooling fan and transbrake On. My alternator will output over 100 amps at idle and 165 at wot. Pulleys are 2 to 1.

I never use my battery charger at the track. The charging cable size on the alternator is the same size as the one going to the battery. They terminate together at the starter solenoid.

Everything EFI and digital on my car is on a clean power bus and isolated from all the dirty power, relay board output to devices to include ignition. Not using CNP.

I didn't have great luck with optima batteries. I switched to a AutoZone group 34 Duralast AGM battery and a powermaster high speed starter on my 555. We always get it cranking before hitting the ignition.

If I remember right you have a hard tail? If so weight balance is critical in making that car work good.
If you need to add weight to the nose of the car and have room for it a second battery is a good way to do so. (12 or 16 volt) My Front Engine Dragster was a hard tail and it worked best with most of weight in back and very front. When I had a lot of weight in the middle it wanted to bounce or tire shake. Yours may be similar but with a hard tail chassis is more flexible so weight has to be in right location. Took some testing but I got my car working really well. Mine worked best with battery in the nose and an additional 30 Lbs up front. Did not have room up front for second battery. I even added some bars to chassis to make it stiffer and that helped. 4 link chassis is stiffer and more forgiving where the weight is.

As for 12 volt and 16 volt I have ran both and they are about same. 16 volt will spin over faster and 12 volt will spin it longer. Both have about same cold cranking amps total. CCA is basically total energy available and dual batteries will help there. Most do not need it but it does not hurt. (If you need the weight)
Right now one of my Altereds has 16 volt and the other is 12 volt system and both work good so I will not be changing them. Good grounds, good battery, wired right and alternator or charger and you are good. I prefer to run an alternator when possible.
To answer your other question about if the MUST be same type and brand. I do not THINK so but I would still try to make them both same, brand type and age. Once again I would not add a second battery unless you needed the weight.

Speedwire has a solenoid for battery shut off that is rated way higher than the ones most of us use. Rather expensive but when I need to replace mine that is probably direction I would go. Being higher rated it should last longer than the others. I have had some of the Cole Hersee ones fail. Typically I do not fall into that More Expensive so it must be better but in this case with all the failures of the Cole Hersee this one is worth trying IMHO.

quote:

Originally posted by imakehp:
I want to put a 2nd battery in my dragster. I have an Optima 800cca in it right now. Do you think it's a must, or at least a good idea, to only use the same brand?

Dave,

If you're going to add a second battery & it sounds like that's what you are going to do. You need to replace them at the same time & I would run the same brand for both batteries. Curly mentioned "I would still try to make them both same, brand type and age." in his post.

Adding the alternator is a good thing.

2BKing

If you are losing .5 voltage across the switch while at rest, something is wrong. You should have no more than 0.3 voltage drop across a switch.
This is where doing a simple voltage drop test will save you a bunch of time and money.


Joe

quote:

Originally posted by imakehp:Are you using a 16v system or 12v ?

As I wrote, my battery voltage is 14.2v at idle with the water pump, cooling fan and transbrake On. I am using a 12v system.

quote:

You should have no more than 0.3 voltage drop across a switch.

That is excessive and on its way to failure imho. Across a disconnect switch when activated, I want to read 0.0X v or less on the meter. Preferably 0.00 v.

If you need a 2nd battery, you have a chitty battery to start with. ABSOLUTELY NO reason for 2 unless your band aiding something else.

Agree with most on 16V, makes any 12V system look/seem inadequate. Even 14.2 on 12V is weak in comparison to 18.1 on 16V with alternator. This is from experience not guessing.

Nevermind carrying unnecessary weight...

quote:

Originally posted by imakehp:
I want to put a 2nd battery in my dragster. I have an Optima 800cca in it right now. Do you think it's a must, or at least a good idea, to only use the same brand?

I also lose 1/2 volt through my battery switch....normal or F no?

You`re way old school. You need to get with the times. 16V FTW.

quote:

I have alot of computer and EFI stuff on the car, just bought a new 120 amp alternator and charger, so a 16V change over is NOT in my near future.

I run one 16V battery, no alt, Fast EFI W/data, Race Pak and with the Olds engine, i drove to and from the the lanes. You`re making excuses not to buy one. You`ll spend $$$ on two 12V battery`s but you wont buy one 16V. I get it, you`re from California. Makes seance.

quote:

Originally posted by imakehp:
I want to put a 2nd battery in my dragster. I have an Optima 800cca in it right now. Do you think it's a must, or at least a good idea, to only use the same brand?

I also lose 1/2 volt through my battery switch....normal or F no?

I do think it is a good idea to run same batteries. I do not know if it a MUST.

Weight is always a consideration and if you have a hard tail and need more weight in the front another battery is a good way to do so. I had to add weight to front of my Front Engine Dragster so I moved the battery up to the nose and added a few weights. Then car worked perfectly in that case a second battery would have also worked if I had room for it.

I would not put another battery in there unless you need the weight to make chassis work good. Then I guess a second battery is better than just adding lead weights.

12 volt system is just fine when right. If you are having starting issues then you have some sort of problem that needs to be resolved.
Most of the battery switches and solenoids are cheap junk. Just replace it with a new one if you are least bit concerned about it.

16 volt systems are also okay if you want to run them but you still need to resolve any electrical issues you have or you will have same problem.

Difference between 12 volt and 16 volt is how fast the energy is dumped. Your car will not be any faster, will not be any more consistent and if you have issues before you will still have issues until you fix them.

So brings up a question. WHY DO YOU WANT TO ADD A SECOND BATTERY? Is it because you need the weight or because you have an electrical issue?

The OP never implied or stated he was considering an extra battery for the purpose of adding weight to his car to make it work. Infact he implied the extra battery would be an attempt to counter the loss of available cranking amps. That said, there is no reason for him or anyone else to run a second full size 12v battery in a dragster.

Which is exactly why I asked "WHY DO YOU WANT TO ADD A SECOND BATTERY?"

I believe his car is a hard tail which is why I asked about if it was because of weight?