AGM Batteries - Group 24 vs. Group 27

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Christopher Laurencio

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I went to Cabelas today to buy new batts for my 24v upgrade, when I got there I noticed that the group 24 & group 27 batts are almost Indentical in Capacities and both are dual purpose deep cycle batteries. After much debate with all the marine techs in Cabelas and questioning the actual reserve capacity as a missprint, I was ensured that the batts are stated correctly. HMM, with size and weight being a consideration I opted for the smaller group 24's to power my 24v TM. Here are the specs.



Group Size Deep Cycle 24 27

Cranking Amps 1195 1200

Cold Cranking Amps 945 950

ReserveCapacity 178 180

Weight Lbs. 53 62.5

L"x W"x H" 10.87x6.75x9.87 12x6.75x9.87



Am I a bonehead? It seems to be a no brainer, but then again, am I forgetting something.

I would think that the group 24's would be fine for 24v applications and the reserve capacity is only a 4 minute difference when the batts are hooked up in series.
 
The group number is the size of the batt case, 24=10 inch, 27=12 inch, 31=14 inch. Most of the time the wet cell batteries the larger the case the more reserve time

BF
 
Bruce, the difference in reserve capacity is 178 minutes vs. 180. Is there something else that needs to be considered. The batts did not state amp hours, but the marine tech said it is measured at 23amps
 
Chris,we went to Cabelas today and bought a couple of reels.Did you get the Optima batt? I hate the day I have to replace my three trolling batts. I think you will enjoy the power and endurance of 24v.



CJ
 
I saw that, I think you made the right choice, weight vs reserve. You saved 18lbs vs 4 mins.

BF
 
A lot of it has to do with automobile manufactures and how much space they design into a vehicle for batteries.



If I had had to make the choice, I woulda done the same thing that you did, Bonehead! :)



me!
 
Red, I checked that out and it appears that there is a 20% difference in AmpHours, so why would the reserve capacity be almost identical on Cabelas Batts. It's not going to be buyer beware, the Cabelas sales rep's assured me that there was only a 2 minute reserve capacity diff. I guess I should know by now that some things are to good to be true? Are you saying that the reserve capacity is WRONG on the Group 24 or undersated on the group 27. I'm talking the AGM cabelas.



Would you think that I still get better Reserve Capacity from the two Gr24's than two Interstate Gr 27's?



356 vs. 320.



That is only if the reserve is true on the Cablela 24.



Red Please advise.
 
Whoa! Stop!



Amp Hours is the OLD way of rating batteries. (Like 30 years old.) It doesn't take into account the ambient temperature - which greatly effects the ability of the battery to produce power. Every manufacturer tested and rated their batteries at whatever temperature would make their's look best. (It's the American way!)



Somewhere back in about the early-70's, the manufacturers came up with a new, standardized rating: Cold Cranking Amps. With this new rating, all batteries were rated at the same ambient temperature. (I don't remember what that temperature is..... I think it may be 32*F.)



When comparing battery capacities, use Cold Cranking Amps NOT Amp Hours.



me!
 
If I remember correctly, the 27 was understated. Look at the amp hour rating, 75 vs 90. That is more measurable.



As far as the small AGM vs Interstate 27's, the bigger battery should have more reserve capacity. In general, good quality flooded batteries have the same or even more capacity than the VRLAs, gel or AGM. That is why everyone on this board suggests the flooded Surettes and Trojans. The AGM shines when it comes to rate of recharge, maintenance free, installation options and depth of discharge. Like we discussed over the phone, there is a huge difference between using the TM all day as the primary motor vs using the TM all day in between stops. The AGM can take a deeper discharge than the flooded.



I was going to buy the Cabela 27's but the freight was too high. PA wasn't opened yet. The price is good for the AGM 27. That is what I would get considering you already bought a charger set for flooded and AGM.
 
Me, im not going to get into another battery argumant with you here but i have a question. What on earth does Cold Cranking Amps have to do with a Deep Cycle application? Correct me if im wrong here but CCA is a rating of amperage over 30 sec at 0 deg. If he was selecting a starting battery i would think that is the spec to look at. But since he is looking for a deep cycle that will discahrge over time i would thing reserve capacity would be much more important to him. Am i missing sometign here? please explain.
 
Red, I'm just going to park my boat in Paterson and be done with it. I'll take up another hobby like cutting my grass or something. It appears I got the wrong Breaker, unless I stick with 8 guage, but would rather have the 6 guage breaker for the future. I looked at the BONDED 6 AWG and it is nicely packed in an outer shell and looks like it would be easy to pull thru boat, I'm wondering if the bonded would get hotter since it's all together in a blanket.
 
JimB, what do you think of the gropu24 with a 178 reserve capacity, is it BS? That's better than a interstate flooded 27 @ 160 RC.



Thanks



Please don't argue, this is my money were talking about :)
 
Jim -



"Cold Cranking Amps" is nothing more than a term used to define battery capacity - regardless of whether it is a long, slow discharge or fast.



Since most batteries - by far - are used in automotive applications, the manufacturers chose that terminology.



The term "Deep Cycle" refers to the ability of the battery to be completely drained and still be repeatedly recharged to full capacity.

(Not the rate at which it is discharged.)







Chris -



"Reserve Capacity" is not a standardized term. Don't worry about it! (Advice given as if it were my money! LOL!!)



me!
 
If what you are saying is true then from what i see the trojan group 24 startig battery that has 700cca and 125 reserve min would be a better choice for a trolling application then the scs 225's i own that have a 625cca rating and 225 min reserve? That just dosent make sense to me for some reason. This is why im confused by your answer. Here is the def of cca.



(CCA) is the maximum amperes that can be continuously removed from a battery for 30 seconds at 0
 
I think they're saying as opposed to "storage" batteries such as you might find as a back-up for electrical power systems.
 
Amps hours is easier to apply to TM batteries because the bigger motors draw more than 25 amps. A battery is just a storage tank of amps. The higher the amp hour rating the more power. Simple as that.





 
Me i edited my post. I thinught i needed to explain my confusuion further.
 
Jim -



"Reserve capacity" is not a standardized term. If it's not standardized, then any manufacturer can set that rating by whatever parameters make their product look it's best.



Kinda like a stereo amplifier may be rated at 100 amps - but you need to find out is that amps per channel or total.



me!
 
In understand on the standards thing but since those two batteries i mentioned are from the same maker which would be the better choice in a trolling application? I would think the one with the much higher reserve rating and the only one that has an ah rating since that dont seems to use that rating for starting batts but thats just me. I would think when comparing batteries for a long drain setup like a trolling motor like Redrocket said amp hours would be a good thing to look at. There are standards on how much load they use and its easy to compare looking at the specs.



btw that reserve is rated on both batteries at 25a 80 deg f.
 
I'm going to try and return them today and get the 27's. They will fit in the batt compartment, it just adds 20 pounds to the total wieght and 2 inches two each batt long ways.
 
Jim -



From my personal standpoint.....



I chose my batteries first on the availability of warranty replacements. Years ago, I always bought Sears' Diehards; today it's Everstarts from WallyWorld. Both auto and boat, starting and trolling.



In my car, I always get the largest capacity for the group size that fits my car. Nothing less.



In the boat, since I'm not one who ever really pushes tm batteries to the limit, I kinda balance cost vs CCA vs what I have in my wallet at the moment! :)



I don't remember exactly what "reserve capacity" is supposed to represent to the consumer.



I base my judgement on the CCA of a battery - it's available power "before its voltage drops to unusable levels".



me!







(Do we have to be so friendly about this? Can't we start calling names or bashing or something like that to make it interesting? :) )
 
THANKS ALL. Can you guys meet me next time I go to Cabelas, or at least have a hotline available! LOL
 
Call me any time, Chris!



For bad advice:

Home is 618-288-5041; office is 800-325-9053.



Just keep it friendly - I have caller ID! LOL!!
 
Me

Im my cast i pick my batts for the boat based on durablilty over ther long haul. I have had so much grief from the everstatrs and dirhards and the like over the years. I dont care how easy the warranty is to use if you have to use it often. When i had the durlasts(sister battery to everstart) i had two sets fail in one season and both times were during two day tournaments when i was far from home and no warranty replacements were available in the area where i was. Talk about frustrating.



From what i can see the reserve capacity on my trojans is how many minuites the battery will last with a 25amp load at 80deg f. I have ones rated for 225 min and they last a good long time( actually ive never killed them) and im extremely hard on the tm batteries, I fish a lot of open water with wind and move around a lot. I like fishing docks too so im on it all day hard. I also looked at the amp hour rate too before i bought. the ones i have are 130ah, they were the best deal for the money i could find when i bought them, far greater capacuty theen the grou;p 30 duralasts i had for not a lot more money.



What i dont understand is how cca relates to a trolling motor. Your right cca has to do with the amount of amperage deleivered until voltage drops below a useable level but thats over a 30 second timespan not all day. How that would correlate to a trolling motor i dont know, starting yep the more cca the merrier if you live in a cold weather climate. But as for a trolling motor i dont understand where cca relates.
 
Here is an interesting link, I have found.



Another Interesting FACT, if I could EVER and I mean EVER make my mind up we wouldn't be having this whole discussion!

My wife is taking the batts back for me today :). She's the best, and she know's I'm a PIA.



I hope this indecision does not carry over into fishing, or I will be standing on my front deck trying to decide if I should use MOTOR OIL or Teq. Sunrise for a half hour.
http://www.windsun.com/Batteries/Battery_FAQ.htm
 
Halleluyah!

Something we can all agree on!

Chris is a PIA!!!!!



ROFL!!!!!!!!!
 
Oh! That's right! You're in accounting!

Make that "anal" as well!







I'm sorry (not really :) ), Chris..... I'm in sales..... And you know how people in sales feel about people in accounting! LOL!! :)







And Jim is in Information Systems.....

He thinks we're both out to destroy his equipment!
 
To Redrocket, Got the gr27's in the garage now, they had to get ones out the back of the store and they were in the cardboard boxes still. Guess what was printed in big letters on the box!



UB12900

and

90AH.



Nice research, thanks for the EXACT information!



Chris
 
Smart move. Your wife's motivation to drive back to Cabela's was the alternative which would have been the CCU.



It should be smooth sailing from here. PUN intended.



Good Luck!
 
Many batteries today are rated in CCA or RC. CCA is Cold Cranking Amps. CCA is approximately equal to the RC of a battery times five. [1000 CCA is about 190 RC]. RC is Reserve Capacity. You can convert RC to amp/hours by the following formula:



Amp/Hours = (Reserve Capacity / 2) plus 16

 
CJL, huh???? that dosent seem to add up. using your formula the scs 225's i have 1125 cca on the 675 its rated at. and if you go the other way it would only have 135 min reserve not the 225 its rated for.
 
Chris -



I don't remember hearing your final decision.....

Did you end up staying with SBC or did you take the new job?
 
Chris -



I don't remember hearing your final decision.....

Did you end up staying with SBC or did you take the new job?
 
Me,

I took the other job, I'm a "coulda/shoulda/woulda" person so still analyzing my decision. Like my wife says, I'm a PIA!



But then again, "Grass does not grow on a rolling rock".



My posts will most likely drop off considerably after this week, at least for while until I get settled in.



Chris
 
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