Batteries - simple question

freetime58 wrote:

Gdetrailer wrote:
AGMs by their nature have nearly 10%-20% LESS capacity for the same size.

What????? Not true at all. A quick check of group 31 specs from Northstar AGM, Exide, Interstate and Trojan for Flooded Lead Acid proves you completely wrong! LOL Northstar AGM had better specs than all but one example, that one example was tough as they used a different discharge rate in their testing than all the others.....which is something to watch for when comparing specs....some manufacturers use a lower discharge rate to get better numbers.

Now if you're talking Opitma........ Spiral cell AGM battery, they are terrible with some of the lowest capacities in the industry. Stay away from Optima!!!!

I am not talking about comparing "group31" batteries, nor am I comparing Optima Spiral cells. Many AGMs are not spirals.

AGMs by their CONSTRUCTION TAKE MORE SPACE per Ahr than flooded and that IS a fact.

Here is an example of easy to get Duracel brand which is sold at Sams Club.

AGM

Specifications

1 amp hour rate: 103
100 amp hour rate: 220
20 amp hour rate: 190
3 amp hour rate: 145
5 amp hour rate: 163
6 amp hour rate: 167.8
8 amp hour rate: 173.7
Battery Electrolyte Composition: Glass Mat
Battery End Type: Top Post
Battery Purpose: Starting Lighting Instrumentation
BCI Group Size: GC2
CCA at 0 degrees F: 680
Freight Class: 65
MCA at 32 degrees F: 900
Minutes at 15 amps: 718
Minutes at 25 amps: 409
Minutes at 5 amps: 2304
Minutes at 50 amps: 171
Minutes at 75 amps: 94
Minutes at 8 amps: 1409
Reserve Capacity: 380
Terminal Type: SAE
Volts: 6

Duracell GC2 FLOODED

FLA GC2

Specifications

20 amp hour rate:215
5 amp hour rate: 157
6 amp hour rate: 156
Battery Electrolyte Composition:Acid
Battery End Type: Top Post
Battery Purpose: Deep Cycle
BCI Group Size: GC2
Contents: ONE EACH
Freight Class:65
Minutes at 25 amps: 395
Minutes at 75 amps: 105
Terminal Type: DIN
Volts:6

Now, unless you have been taught some "new math" 190 Ahr of AGM IS LESS than 215Ahr of GC2 FLA!

AGM is only 88.3% the capacity of THE SAME SIZE GC2 FLA.

To add insult to injury, the last time I priced those GC2 AGMs they were going for $109 each vs GC2 FLA at $89. That puts the GC2 FLAs at 81.7% LESS COST than the same size GC2 AGM.

So, in reality, you WILL pay MORE for AGM and GET LESS capacity for the SAME BATTERY SIZE and will not get any longer service life.

I think even if you compare YOUR "preferred" "premium" brands you WILL find a similar difference in CAPACITY AND COST.

With Premnium brands, you get a longer warranty, but you PAID MORE for that battery which means you PAID UPFRONT for that extra warranty. You will not find any real extra life..

Compare them, don't be an Internet "Lemming" and play follow the "leader".

If you want the bragging rights for paying more and getting less, by all means spend your money and buy the AGMs.