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Gdetrailer

PA

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Joined: 01/05/2007

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Posted: 04/11/20 03:52pm Link  |  Quote  |  Print  |  Notify Moderator

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.

StirCrazy

Kamloops, BC, Canada

Senior Member

Joined: 07/16/2003

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Posted: 04/11/20 06:26pm Link  |  Quote  |  Print  |  Notify Moderator

Gdetrailer wrote:

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 myself have never understood why some one would buy an AGM for a normal RV setup. up here they are more like 50% more expensive and as long as you have a vented battery compartment why spend the extra?

Steve


2014 F350 6.7 Platinum
2016 Cougar 330RBK

babock

Los Angeles, CA

Senior Member

Joined: 12/18/2007

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Posted: 04/11/20 06:40pm Link  |  Quote  |  Print  |  Notify Moderator

StirCrazy wrote:

Gdetrailer wrote:

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 myself have never understood why some one would buy an AGM for a normal RV setup. up here they are more like 50% more expensive and as long as you have a vented battery compartment why spend the extra?

Steve
Other than

1) Less self discharge
2) Never add water
3) Lower internal impedance which makes them better at driving higher current loads like inverters with lower voltage drop.
4) Because of the lower internal impedance, they also charge faster than an FLA battery

I use them in both my boats mainly because of the self discharge characteristics.

freetime58

Winnipeg

New Member

Joined: 10/05/2019

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Posted: 04/11/20 07:21pm Link  |  Quote  |  Print  |  Notify Moderator

Gdetrailer wrote:

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.




Been using AGM's for 15+ years in my boat, so not really an internet Lemming FFS, all 4 are Northstar, will never go back to lead acid because of all the benefits AGM's provide. Money has never been a concern for me and I do like bragging rights........so I guess I'll continue. I'm probably making the jump to LiFePO4 (Lithium Iron Phosphate) batteries, those replacement batteries should be about $5000....now those are some serious batteries.

* This post was last edited 04/12/20 08:54am by an administrator/moderator *   View edit history

StirCrazy

Kamloops, BC, Canada

Senior Member

Joined: 07/16/2003

View Profile



Posted: 04/11/20 07:31pm Link  |  Quote  |  Print  |  Notify Moderator

babock wrote:

StirCrazy wrote:

Gdetrailer wrote:

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 myself have never understood why some one would buy an AGM for a normal RV setup. up here they are more like 50% more expensive and as long as you have a vented battery compartment why spend the extra?

Steve
Other than

1) Less self discharge
2) Never add water
3) Lower internal impedance which makes them better at driving higher current loads like inverters with lower voltage drop.
4) Because of the lower internal impedance, they also charge faster than an FLA battery

I use them in both my boats mainly because of the self discharge characteristics.


I add water twice a year, and its only a couple oz in each. a good charger minimizes water loss but ya I do have to add a bit.

self discharge is never an issue as the solar keeps it topped up when it isnt plugged in and normally it is always plugged in at home.

have no issues running my inverter and with the solar and/or being plugged in charging is never and issue, so in my case spending almost 400 bucks for a 180ah 6v agm vs 140 for a 210ah 6v lead acid just doesn't make since, but in a boat, that's a different story.

Steve

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