Spending too much $$ on batteries.

Reddog1 wrote:
I previously had a Lifeline AGM. When it went bad, I replaced it with a $200 Universal AGM Battery. That was with free shipping. I have had the Universal for a couple of years. I went to the Universal, only due to cost.

I ran numerous test on my Lifeline, discharging and charging. You can only fully discharge any battery so many times. I have not subjected my Universal battery to the same treatment.

The following are claims made by Lifeline:

LIFELINE RV BATTERY BENEFITS

User Safe

sealed construction

non-spillable

install in any position if properly supported.

submersible without damage

Maintenance free (no adding water or repairing corroded terminals)

Fastest recharge. (no current limitations with voltage regulated recharging)

Deep Cycle (thick positive plates to provide real deep cycle performance)

Outstanding cranking performance (aircraft cell construction lowers internal resistance)

Best charge retention (especially against flooded cell types)

Lowest discharge rates (Less that 3 percent per month unattended)


For me, not needing maintenance alone is worth the extra expense. With a good three stage charger the other points are a bonus. I think most of the claims are transferable to other AGM batteries. So far, they appear to be with the Universal Battery.

I do not think this is true; "... since you will be able to make use of lower cost flooded wet cells which are able to withstand deeper discharges than a AGM." I would have to see something that supports the statement.

Wayne

PBBATTERIES

And I quote..

“They (AGM) also have an excellent life expectancy as long as they are not over discharged (no more than 50-60%). AGM batteries can easily suffer premature failure if they are not charged correctly.”

TROJAN BATTERY TECH SUPPORT

And I quote...

“Deep-cycle lead-acid batteries generally fall into two distinct categories; flooded (FLA) and valve-regulated lead-acid (VRLA), with the VRLA type further subdivided into two types, Absorbed Glass Mat (AGM) and Gel. These differences have evolved because no single design is suitable for all applications.

Here are some of the advantages of using deep-cycle flooded batteries:
• Lower cost than deep-cycle VRLA batteries.
• Longer deep cycle life than deep-cycle VRLA batteries.
• Can be maintained simply by addition of distilled water.
• High discharge rate capability.
• Perform better in hot climates. (>90 degrees F)
• More available worldwide.
• Perform better then deep-cycle VRLA batteries when regularly in a partial state of charge.
• Long, proven history of use.

Some of the drawbacks of using deep-cycle flooded batteries are:
• Periodic maintenance by adding distilled water is required.
• Can only be used in an upright position.
• Produce gas (oxygen and hydrogen) when charged.
• May emit acid spray if overcharged abusively.
• Require ventilation.
• Higher self-discharge rate than deep-cycle VRLA batteries.
• Cannot be shipped by air.
• Cannot be used in the immediate vicinity of electrical equipment or anything highly flammable.

Here are some of the advantages of using deep-cycle AGM batteries:
• Less expensive than deep-cycle Gel batteries.
• Wider temperature range than deep-cycle Gel or FLA batteries.
• Slowest self-discharge rate of FLA, AGM and Gel batteries.
• Best shock/vibration resistance of FLA, AGM and Gel batteries.
• Best for high power applications of FLA, AGM and Gel batteries.
Here are some of the disadvantage of using deep-cycle AGM batteries:
• Don't perform as well as deep-cycle FLA or Gel batteries for systems that require regular deep discharge. (i.e. 80% DOD)
• Do not perform as well as deep-cycle Gel batteries in low power applications.”

(I will add, AGM are more expensive than FLA and AGMs have less capacity compared to FLA for a given size)

“If the duty cycle involves deep discharge cycling a Gel type may be preferred over an AGM type, however many renewable energy systems are sized to 20% to 50% depth of discharge so an AGM battery would suffice. Where the batteries are accessible for maintenance and maintenance costs are reasonable, flooded batteries will have several advantages over their VRLA counterparts.”

Basically in a nutshell, discharge AGMs BELOW 50% DOD and you WILL be replacing them (some AGMs are designed for STANDBY usage and will not tolerate being discharge more than 20% DOD). For BEST life (and capacity) AGMs should not be discharged below 20% DOD (that is considerable LESS capacity than FLA).

Deep Cycle flooded (like Golf cart batts) CAN be discharged to 80% DOD without damage although it may reduce capacity and life cycles a bit (for BEST life and capacity FLA should not be discharged below 50% DOD).

Discharge AGMs to 80% DOD and you will have a expensive, big, heavy doorstop.

If you want the most “bang for the buck” it is still hard to beat FLA batts such as Golf cart batts for price, capacity and abuse.

Not long ago I compared some GC batts at Sams club. They had standard flooded GC batts and AGM version GC batts side by side.

The AGM version cost $20 MORE and had 20% LESS capacity than the flooded.

For myself, I don't "need" a sealed battery, I don't "need" a spill proof battery. No, I simply need a reliable battery which packs the most Ahr capacity for the $$, flooded GC batts fill that need for me.

As noted some manufacturers of AGMs have changed marketing strategy which INFLATES the perceived capacity by using a 100Ahr rate instead of the standard of 20Ahr rate… (kind of deceptive isn't it?)