Batteries in parallel

jazzwannabe · Post by **jazzwannabe** » Thu Oct 28, 2010 5:23 pm

I have a 12v trolling motor on a 17-foot Tracker. A friend suggested I try wiring two 12v batteries in parallel to extend their draw on a long windy day at Isabella. Anyone have this in their boats? Does it make a noticeable difference? Any downside to it?

offduty · Post by **offduty** » Thu Oct 28, 2010 6:40 pm

Works fine, down side is weight.

Rich

Byron · Post by **Byron** » Thu Oct 28, 2010 8:42 pm

On my little Nitro 640LX with 52lb MG I swaped out the tray and put in a group 31. Runs all day at Casitas without slowing down. If you can fit the 31 it's lighter than 2 of the 24's and 27's.

Mitch · Post by **Mitch** » Wed Nov 03, 2010 6:15 pm

If you wire 2 12v in paralell be sure to use the + off one and the - off the other. Do not come off the same battery. You also could try 2 6v in series. Palalell connections will give you the same VOLTAGE, and DOULBE the AMPRAGE. Series connections will DOUBLE the VOLTAGE and the AMPRAGE will remain the same.

Andy Giannini · Post by **Andy Giannini** » Thu Nov 04, 2010 2:17 am

Mitch wrote:If you wire 2 12v in paralell be sure to use the + off one and the - off the other. Do not come off the same battery. You also could try 2 6v in series. Palalell connections will give you the same VOLTAGE, and DOULBE the AMPRAGE. Series connections will DOUBLE the VOLTAGE and the AMPRAGE will remain the same.

Mitch,

If you use the + off one battery, and the - off another that is going in series. That would be 24 volts with two 12s.

Or how am I misunderstanding your post?

A.G.

Bill K · Post by **Bill K** » Thu Nov 04, 2010 2:46 pm

To double your staying power, wire X to X and _ to _ and then your TM, You still have 12volt and will not burn up your TM, but will have longer staying power.
Do not wire X to Neg, etc as that is series and you turn it into a 24 Volt setup and that will toast your 12 volt TM.
Bill K

bryanmc · Post by **bryanmc** » Thu Nov 04, 2010 2:55 pm

Back in the day of the Mercury thruster 12v TMs we used to use 2 6v golf cart batteries in series. There was no 12v battery that would match the performance.

Bill K · Post by **Bill K** » Fri Nov 05, 2010 5:58 am

bryanmc wrote:Back in the day of the Mercury thruster 12v TMs we used to use 2 6v golf cart batteries in series. There was no 12v battery that would match the performance.

But Bryanmc, these young people, now days, are not as old as we fossils and the batterys are Sooo much better now, then in the dark ages.

Bill K

Garrettt · Post by **Garrettt** » Fri Nov 05, 2010 6:12 am

jazzwannabe wrote:I have a 12v trolling motor on a 17-foot Tracker. A friend suggested I try wiring two 12v batteries in parallel to extend their draw on a long windy day at Isabella. Anyone have this in their boats? Does it make a noticeable difference? Any downside to it?

If youre putting in another battery you should just make it 24v. I just upgraged my TM on my 17' tracker. 71lb 24volt is so awesome on my boat. All day long in high wind no problem. On 5 it will throw you out of the boat if you're not careful

Mitch · Post by **Mitch** » Fri Nov 05, 2010 7:21 am

Andy Giannini wrote:
Mitch wrote:If you wire 2 12v in paralell be sure to use the + off one and the - off the other. Do not come off the same battery. You also could try 2 6v in series. Palalell connections will give you the same VOLTAGE, and DOULBE the AMPRAGE. Series connections will DOUBLE the VOLTAGE and the AMPRAGE will remain the same.
Mitch,

If you use the + off one battery, and the - off another that is going in series. That would be 24 volts with two 12s.

Or how am I misunderstanding your post?

A.G.

Andy, You wire (+ to +) and ( - to - ) to get the 12v paralell, but the wire to your TM, go + off one battery and - off the other battery. This way youre using the full circuit of power and not pulling off one battery that is "boosted" by the second. If youre still confused semd me an IM and I'll give you my cell #

Leon Pugh · Post by **Leon Pugh** » Fri Nov 05, 2010 10:18 am

Mitch wrote:
Andy Giannini wrote:
Mitch wrote:If you wire 2 12v in paralell be sure to use the + off one and the - off the other. Do not come off the same battery. You also could try 2 6v in series. Palalell connections will give you the same VOLTAGE, and DOULBE the AMPRAGE. Series connections will DOUBLE the VOLTAGE and the AMPRAGE will remain the same.
Mitch,

If you use the + off one battery, and the - off another that is going in series. That would be 24 volts with two 12s.

Or how am I misunderstanding your post?

A.G.

Andy, You wire (+ to +) and ( - to - ) to get the 12v paralell, but the wire to your TM, go + off one battery and - off the other battery. This way youre using the full circuit of power and not pulling off one battery that is "boosted" by the second. If youre still confused semd me an IM and I'll give you my cell #

Mitch, it does not work like that. The battery with the greatest potential will flow the most amps regardless of how many batteries are connected in parallel. As the potential becomes equal they will begin flowing equal amps. Does not matter which batteries you connect to. If the batteries are perfectly matched they will draw down at the same rates, the state of charge will always be exactly the same in both batteries with matched batteries.

Mitch · Post by **Mitch** » Fri Nov 05, 2010 6:31 pm

Sorry Leon, but I strongly disagree with you. I've worked with batterys on cars boats, ships, motorhomes, and Big Trucks for over 45 yrs. I also have a 1st phone license (electronics), and it DOES make a difference. I run 4-12v batts in my Peterbuilt and the best case senero is to come off the first and last battery. It also makes a BIG difference in CHARGING. You can run YOURS anyway you want,

Leon Pugh · Post by **Leon Pugh** » Fri Nov 05, 2010 10:08 pm

Mitch wrote:Sorry Leon, but I strongly disagree with you. I've worked with batterys on cars boats, ships, motorhomes, and Big Trucks for over 45 yrs. I also have a 1st phone license (electronics), and it DOES make a difference. I run 4-12v batts in my Peterbuilt and the best case senero is to come off the first and last battery. It also makes a BIG difference in CHARGING. You can run YOURS anyway you want,

Mitch that is another old mechanics tale that set right beside the one that says you can not charge a battery that is setting on cement.

What you saying won't hurt a thing, as long as the cables and connectors are in good shape that connect the batteries together. With the method you describe you do have four more connectors and two short cables that can cause resistance issues under some conditions, just does not matter that much where you connect. When they are charging buy the way the most amps will go to the battery with the least electrical resistance regardless of how they are connected. You seem to be forgetting one of the fundamentals of current flow in that it always takes the path of least resistance which is not the same as the shortest distance. Try running one battery down a little and put a inductive amp meter on each battery, start it up and watch the meters, you will see that I am right. I am not trying to make you look bad, just trying to help you out. You really don't want to compare credentials with me on this subject.

Mitch · Post by **Mitch** » Sat Nov 06, 2010 7:46 am

As I said " You can run your anyway you want". I know the law of least resistance and also understand that a weak batterey in the mix will cause a breakdown of the system either way you hook em up. However, I'm not understanding the part about needing more cables to connect them together. Never intended to start an "electrical" war. Other than that.................you do it your way and I'll do it mine. C-ya

bryanmc · Post by **bryanmc** » Sat Nov 06, 2010 4:01 pm

Bill K wrote:
bryanmc wrote:Back in the day of the Mercury thruster 12v TMs we used to use 2 6v golf cart batteries in series. There was no 12v battery that would match the performance.
But Bryanmc, these young people, now days, are not as old as we fossils and the batterys are Sooo much better now, then in the dark ages. Bill K

Fossil? I'm crushed Bill

Bill K · Post by **Bill K** » Sun Nov 07, 2010 5:57 am

bryanmc wrote:
Bill K wrote:
bryanmc wrote:Back in the day of the Mercury thruster 12v TMs we used to use 2 6v golf cart batteries in series. There was no 12v battery that would match the performance.
But Bryanmc, these young people, now days, are not as old as we fossils and the batterys are Sooo much better now, then in the dark ages. Bill K
Fossil? I'm crushed Bill

OOOOh, so sorry Bryan.. I was refering to myself.. Bill K

Bill K · Post by **Bill K** » Sun Nov 07, 2010 6:00 am

As a side note, hate to tell some of you this, but right now the s/m are hitting spoons around 30 ft at Almanor, if you can hold up with the cold/rain and maybe snow.. They have not started working on the damn ramp (yet) but you can launch at Prattville, if they do start. I think it was you, Bryanmc and a couple others asking a few weeks back. Bill K