Confused with batttery stats for Minn Kota Power Center

[300winmag]

So I have been to Costco and Walmart for batteries, I read several times the size 29 battery from Walmart will fit into the Power Center even though it's only designed for 27 and 24 and it does ;-) Battery will be used for a Minn Kota 55lb Endura Max.

The Costco brand Size 27 is rated for 120 Amp Hours and does not say reserve mins.
Walmart Maxx Everstart Size 29 is rated for 114 Amp hours and 210 reserve mins.
Walmart Maxx Everstart Size 27 is rated for 112 Amp hours and 180 reserve mins.
Walmart Everstart Size 27 is rated for 120 Amp hours and 180 reserve mins.
The Maxx series says it has 30% more power.... but it has less amp hours and the same reserve capacity as the non Maxx series soooo?? I would like to get the Size 29 form Walmart but is the extra weight( and it is noticeably heavier) worth it?I have always thought you went buy the Amp hours, the reserve capacity was a just in case your SOL number.
I love Costco's return policy as well... just take a look at Walmarts...

And the little round date stickers on all the batteries, are they month and year or day and month? I though they corresponded to day and month but if they did Walmart had ones that were coming up to a year old with no maintenance charge.

 

[fbpooler]

Re: Confused with batttery stats for Minn Kota Power Center

Just make sure whichever you purchase is a deep cycle type battery.

 

[300winmag]

Re: Confused with batttery stats for Minn Kota Power Center

Yup these are all deep cycle type batteries.

 

[Bifflefan]

Re: Confused with batttery stats for Minn Kota Power Center

After reading your post I think im confused. Way to many numbers and such.

Someplace on the box your motor came in, it will tell you the minimum recommended "amp hour" battery rating for your motor. My 24v 80lb Terrova is 105 ah. I have two group 31 batteries that are rated at 120 amp hours. I can run all day at all speeds with mine and still have power left over.
What that means is I can draw one amp for 120 hours from that battery or I can draw 120 amps for one hour.
The battery group ie: 31, 29, 24, or what ever makes no difference to the ah rating. It is only the actual size of the battery case.
Don't get hung up on 30% more power. That's just advertising mumbo jumbo.
On my buddy's boat, he has a 55 lb Edge. We get about 5 hours from an 80 ah battery trolling on a 19' fish/ski.

The short answer is, get the most ah and a battery that fits. You will be fine.

 

[300winmag]

Re: Confused with batttery stats for Minn Kota Power Center

a bigger size battery should have more capacity though, especially because of the noticeable weight difference... The reserve mins have to be in play here I'm thinking.

 

[fbpooler]

Re: Confused with batttery stats for Minn Kota Power Center

It depends on plate construction. Just use the ratings on the battery.

 

[300winmag]

Re: Confused with batttery stats for Minn Kota Power Center

But which ratings? More reserve mins or amp hours? If its more amp hours that means I'm going with a smaller battery but if it means more reserve mins im going for a bigger battery. I keep thinking the bigger battery the better when it comes to this If I can get an extra hour out of the size 29 with less amp hours and more reserve mins I will go with that but if im going to get the same usage out of a size 27 with more amp hours but less reserve mins then there is not point in the size 29.

 

[Bifflefan]

Re: Confused with batttery stats for Minn Kota Power Center

a bigger size battery should have more capacity though, especially because of the noticeable weight difference...

That statement is not correct in any way. Weight and size are not factors that determine capacity.

 

[Bifflefan]

Re: Confused with batttery stats for Minn Kota Power Center

But which ratings? More reserve mins or amp hours?

As I stated, use the "ah" rating for a trolling motor. Use a battery that is rated for what the manufacture states is needed.
If your buying a starting battery, use the "cranking amps". Size is what fits.
Don't get hung up on the other stuff, it not relevant.

 

[300winmag]

Re: Confused with batttery stats for Minn Kota Power Center

Hi bifflefan,
Thank you for your help but you say use the "ah" and half the other people on the internet say use the reserve capacity ratings for a trolling motor LoL, I am trying to get more then one persons answer on it as I don't want to just take a persons word for it and be stuck. Still as I read more and more it's half and half, that's why I asked here because pretty much everybody needs the same thing.
I was hoping to get a few more responses to sway me either way.

In general you are correct about " Weight and size are not factors that determine capacity" but from what I have seen in these types of batteries at Costco and Walmart the bigger the more capacity which is why the size 29 with less "ah" then a 27 and more reserve capacity threw me for a loop.

 

[aneal000]

Re: Confused with batttery stats for Minn Kota Power Center

That statement is not correct in any way. Weight and size are not factors that determine capacity.

^^^^ That statement calling out the previous statement about weight of a battery is not entirely correct. When you are comparing two lead acid batteries it is a really good rule of thumb. While plate design and construction is as important, the way you get more capacity is by adding more lead. You can smudge on your numbers and add marketing influence to the label, but in the end, a 50 pound "deep cycle" Group 27 will not perform as well as a 65 pound deep cycle Group 27 (numbers just used for reference). Also consider the following about Group #'s (24, 27, 29, etc..)


BCI GROUP NUMBER- The BCI Group Number defines a battery by describing the following characteristics:
A.) Its maximum dimensions (L x W x H)
B.) Voltage (6 volt or 12 volt)
C.) Post configuration
D.) The type of terminal used (top, side, flag, etc.)

It should be noted that the BCI (Battery Council International) Group Number does not designate a battery's capacity, it merely defines the above listed physical characteristics.


But to answer the OP, reserve capacity and AH capacity are the same thing - sort of - they both tell how much capacity a battery has the ability to deliver over time; textbook definitions below:

AMPERE-HOUR (Amp-hr or AH)- A unit of measurement for battery capacity obtained by multiplying the current flow in amperes by the time of the discharge in hours. Amp-hrs can also be used to help determine the proper charge rate for a battery. The amp-hr rating for an automotive battery is usually based on a 20hr discharge at 80? F, at a particular rate (determined by the amount of active material within the battery), until a minimum voltage of 1.75V/cell (10.5 volts for a 12 volt battery) is reached.
For example, if a 12 volt battery at 80? F delivers 4 amps for 20 hours before its voltage drops below 10.5 volts, its amp-hr capacity will be 4 amperes x 20 hours= 80 ampere-hours.

RESERVE CAPACITY RATING- The time in minutes that the battery will deliver 25 amps at 80? F until it falls below 1.75 volts per cell (10.5 volts for a 12 volt battery). This rating represents the time the battery will continue to operate essential accessories during night driving if the alternator or generator fails.

 

[aneal000]

Re: Confused with batttery stats for Minn Kota Power Center

It should also be noted that the slower energy is taken from a battery the more AH capacity it will have. You will often see a 20 hour rate (as posted above), 8 hour rate (higher current draw to discharge a battery in less time), 5 hour or less. Again, if you are comparing apples to apples make sure the AH discharge rates are the same on both batteries. A battery rated at an 8 hour rate (more realistic to how you plan on using it) will have a lower number than the same or similar battery with a 20 hour rate stated. In this case the reserve minutes are the only way to truly compare capacities on two batteries, as the same 25A load is applied to both.

 

[aneal000]

Re: Confused with batttery stats for Minn Kota Power Center

As I stated, use the "ah" rating for a trolling motor. Use a battery that is rated for what the manufacture states is needed.
If your buying a starting battery, use the "cranking amps". Size is what fits.
Don't get hung up on the other stuff, it not relevant.

Ok, you got me started... you are technically not incorrect, but you are muddying the water a bit here. AH ratings are extremely relevant and as long as you can compare two batteries rated at the same rate then this is a good option. Most reputable battery manufactures will post at different rates as seen in the attachment below. Also, as you stated, CCA or Cold Cranking Amps is a measure of how fast a battery can release it's energy. This is only relevant in starting type applications - not deep cycle applications. The OP is not looking at batteries with CCA ratings.