Battery Questions

[Andyfender]

My battery is :
Energizer Deep Cycle
Model E24DC-N
Cranking Amps 675
RC Minutes 140
Cold Cranking Amps 550
Age of Battery 5 Months Old

I know this is a Group 24 battery, it is good enough to power a 12 v 55lb thrust Trolling motor? Should I replace it with a Grp 27 Battery?

Thanks

AF

 

[halas]

Re: Battery Questions

It might be good enough for a bow mount motor that is used only to position the boat for casting in small to medium sized lakes.
But if you want to fish all electric lakes all day I would get a second same size battery and connect them in parallel.

 

[Silvertip]

Re: Battery Questions

Since you already have it, there is no need to buy a battery until you determine if it will work for you. If it doesn't then you have two options: 1) buy a bigger one, or 2) buy another of the same type. No need to connect them in parallel. Just switch batteries when one gets low.

 

[halas]

Re: Battery Questions

Connect them in parallel will give you a battery that is equivalent to a real nice sized one, much bigger then the 27 class. Try spreading the load by putting one in the bow and the second into the stern. No need for any selection switch, simpler is always better when it comes to electrical on a boat.

 

[Silvertip]

Re: Battery Questions

You will not get any more power or duration out of two identical batteries in parallel than you will running the same two batteries individually. In fact you will likely get slightly less run time. Two identically sized batteries will rarely have exactly the same capacity and the motor cannot chose which battery the current comes from. As a result the weaker of the two batteries will cause the pair to equalize. Don't get me wrong - there is nothing inherently wrong with a parallel setup. But there is no distinct advantage except perhaps for convenience.

 

[Splat]

Re: Battery Questions

Agreed, contrary to popular belief running 2 batteries in paralelle will increase run time, but will NOT double it.

Running on a battery switch is a better option. If for nothing else to give you a point when your half way through your power allotment for that trip.

Bill

 

[halas]

Re: Battery Questions

You will not get any more power or duration out of two identical batteries in parallel than you will running the same two batteries individually. In fact you will likely get slightly less run time. Two identically sized batteries will rarely have exactly the same capacity and the motor cannot chose which battery the current comes from.

That is a really not an unusual concept. It is still better without the switch in my opinion.

 

[Texasmark]

Re: Battery Questions

Agree with most of the aforementioned.

1. I'd mount the batteries as close to the motor as is convenient as there will be SOME power lost in getting the power to the motor and the shorter and larger the conductors the less the loss.

2. Agree on run one down then just swap. Agree on no two are the same and the weak one bleeds off some of the charge on the good one as the voltages equalize....to the weaker voltage. Second thing about just outright swapping, is the fact that the one you set aside will recover some of it's charge just sitting so in a tight, you could later on in the day, put the first one back on and get some more go out of it; not like a new one, but not like a dead one either.

3. A good 24, even though it is just a 2" shorter 27, is better than an aging 27.,

4. Agree to do nothing till you find out where you are with your current setup.

My 2c,

Mark

 

[Silvertip]

Re: Battery Questions

Halas -- why is this so hard to understand. An example of this is if you have one fuel tank that holds 20 gallons does not mean you can go twice the distance on the amount of fuel you have in two 10 gallon tanks. Very same concept. Or you can look at it this way. Deep cycle batteries have a reserve minutes rating which indicates how long the battery can supply a 23 amp load. 23 amps is a battery capacity standard not a number I just chose out of the blue. The actual number is 25 amps but most batteries show the 23A number. So -- a group 24 battery this poster has shows a 140 minute reserve. So if his motor actually drew 23 amps constantly the battery would last 140 minutes. Now if he had two of them in parallel he could run 280 minutes. So what's the difference between 280 from a parallel setup or running 140 minutes on one battery and then switching to the other for another 140 minutes. Where I went to school, 140 + 140 = 280.

 

[halas]

Re: Battery Questions

That is correct but I prefer no selecting switch in my small boat without outboard with alternator.
Would be nice to know what kind of boat andyfender has and for what purpose.

 

[trendsetter240]

Re: Battery Questions

Though I do agree with the statements above I will add that you should not drain the batteries down to their reserve rating. i.e. if you are using two batteries individually, one after the other, do not run the first battery down until it's dead. Doing this will drastically shorten the lifespan of the battery.

Batteries last longest when kept above an 50% charge and ideally 70% or higher. Using two individual batteries you should switch to the second after you have used about 25% of the first.

This is where parallel setups are more convenient. You have a much larger capacity battery and therefore will use less of the batteries charge in some cases. (if it takes 100% of one battery for you to troll all day then you are better off using 50% of both batteries than 100% of one.)

The difference can be quite dramatic being that a battery may only last 50 cycles if you drain it completely it may last 500 if you only drain it to 75% on each trip.

HTH.. good luck!

 

[Silvertip]

Re: Battery Questions

Geez -- you do not drain the batteries completely by drawing the test spec load for the stated reserve minutes. Deep cycle batteries have a discharge curve very different than a standard auto battery in that the curve is very flat until they reach the point where the voltage drops sharply. That is when the spec load can no longer be held and has nothing to do with a "completely dead battery". And get over this double the capacity nonsense. Yes - two batteries in parallel have double the capacity of one single. They do not have double the capacity of two singles operated individually. The disagreement here is over a permanent connection. If a switch is not used or desired, you have two options: 1) connect them permanently in parallel or 2) Operate them separately. As was stated in a couple different ways, no two supposedly identical batteries have identical capacities nor will the lifetime of both batteries be identical. To squeeze the longest run time out of each battery, run them individually.

 

[trendsetter240]

Re: Battery Questions

Geez -- you do not drain the batteries completely by drawing the test spec load for the stated reserve minutes. Deep cycle batteries have a discharge curve very different than a standard auto battery in that the curve is very flat until they reach the point where the voltage drops sharply. That is when the spec load can no longer be held and has nothing to do with a "completely dead battery". And get over this double the capacity nonsense. Yes - two batteries in parallel have double the capacity of one single. They do not have double the capacity of two singles operated individually. The disagreement here is over a permanent connection. If a switch is not used or desired, you have two options: 1) connect them permanently in parallel or 2) Operate them separately. As was stated in a couple different ways, no two supposedly identical batteries have identical capacities nor will the lifetime of both batteries be identical. To squeeze the longest run time out of each battery, run them individually.

My point, and I suppose I could've worded it better, was that whatever setup you go with try to keep the DOD (Depth of Discharge) between 25% and 50%. This will give you the best bang for your buck and the longest life out of your batteries.

And yes, the reserve capacity is the number of minutes a fully charged battery at 80F will discharge 25 amps until the battery drops below 10.5v. 10.5v is 1.75v per cell in a 12v battery and that is considered fully discharged.

 

[boat1010]

Re: Battery Questions

Wow!!

 

[Robbabob]

Re: Battery Questions

Is it too late to say, "here we go......?" or is it, "now you've done it?"

Terrific input by all...... just find the information that matters and have fun with the new setup!

 

[Andyfender]

Re: Battery Questions

That is correct but I prefer no selecting switch in my small boat without outboard with alternator.
Would be nice to know what kind of boat andyfender has and for what purpose.

Its a 14' Grumman 4.4 Utility Boat, weighing around 225 lbs. Pull start.

AF

 

[halas]

Re: Battery Questions

My battery is :
Energizer Deep Cycle
Model E24DC-N
Cranking Amps 675
RC Minutes 140
Cold Cranking Amps 550
Age of Battery 5 Months Old

I know this is a Group 24 battery, it is good enough to power a 12 v 55lb thrust Trolling motor? Should I replace it with a Grp 27 Battery?

Thanks

AF

AF,
Did you buy that battery at Sam's Club?
I think that is a pretty good power source.