AGM batteries best prices available?

[davil]

https://www.impactbattery.com/lifeli...h-battery.html

[ranger58sb]

Originally Posted by davil

https://www.impactbattery.com/lifeli...h-battery.html

A quick Google search on "Lifeline GPL-31T" shows a couple sources at $328/329 each with free shipping.

And your local battery retailer may agree to match 'net prices, anyway.

Have you compared Group 31s to GC2s? Lifeline's GC2 equivalent is their GPL-4CT.

FWIW, I was able to fit 4x 4CTs (440-Ah total) into the space where I previously had 3x G31s (300-Ah).

-Chris

[davil]

Originally Posted by ranger42c

A quick Google search on "Lifeline GPL-31T" shows a couple sources at $328/329 each with free shipping.

And your local battery retailer may agree to match 'net prices, anyway.

Have you compared Group 31s to GC2s? Lifeline's GC2 equivalent is their GPL-4CT.

FWIW, I was able to fit 4x 4CTs (440-Ah total) into the space where I previously had 3x G31s (300-Ah).

-Chris

=================================================
you refer to this?
GPL-4CT - Lifeline Batteries

[john61ct]

Should not parallel more than 3x 12V batteries / strings to avoid imbalance issues.

Go to larger AH, lower voltage units,

personally just two parallel gives redundancy.

[transmitterdan]

Originally Posted by john61ct

Should not parallel more than 3x 12V batteries / strings to avoid imbalance issues.

Go to larger AH, lower voltage units,

personally just two parallel gives redundancy.

That makes no sense to me. A bigger AH battery is just more plates in parallel. Not that different than parallel batteries if they are cabled correctly. Mine are.

[masonc]

Originally Posted by transmitterdan

That makes no sense to me. A bigger AH battery is just more plates in parallel. Not that different than parallel batteries if they are cabled correctly. Mine are.

I can confirm, as a solar professional, using more than two strings is bad practice unless you are prepared to do a lot of extra preventative maintenance. Differences in impedance happen over time and affect the life expectancy of the cells. You can cure it by disconnecting all but one string and giving each string a good charge frequently.

[transmitterdan]

What constitutes a “string”?

[john61ct]

6x 2V cells in series are a single 12V string.

So is a pair of 6V, 3x 4V etc.

Having 2 strings is good for redundancy.

4 or more, differing resistance paths create unbalanced voltages among the batts over time.

Not serious damage or anything, but potentially seriously reducing longevity.

Same logic behind wiring parallel first, then serial.

[ranger58sb]

Originally Posted by davil

=================================================
you refer to this?
GPL-4CT - Lifeline Batteries

Yep, those.

I don't remember if you said how many G31s you had before, but the easiest comparison is capacity: 3x G31s = approx 300 Ah, 4x G31s = approx 400 Ah, 4x 4CTs (two pairs at 12V) is 440 Ah, etc.

But then there's space considerations. 4x 4CTs takes up slightly more space than 3x G31s and slightly less space than 4x G31s, etc. Also GC2s in general are taller.

IOW, you'd have to compare specs to what's possible (and desirable) on your boat. Not just space, but charging capability, and so forth.

And eventually cost enters into it.

At which point it's maybe useful to confirm for yourself whether the AGM advantages are worth the extra cost, and whether you can sufficiently recharge them all the time in order to get longest use. As I understand it from reading, Trojan T105s and Deka (East Penn) GC2s are well thought of, and much less expensive than AGMs, especially Lifeline AGMs.

IOW, I'm not recommending, just adding to the thread for your consideration.

-Chris

[masonc]

Originally Posted by transmitterdan

What constitutes a “string”?

A series connection of cells to achieve the nominal voltage.

[transmitterdan]

So explain how having 4 12 batteries in parallel with correct wiring and size cable is a bad thing? I'm not seeing how that has anything to do with strings.

[john61ct]

One battery at 12V is a string of 6x 2V cells internally.

If you bought 6x actual 2V batteries at the total AH capacity you want

As a single string will last longer than 4 strings

or 12x at half the AH each for 2 strings, 2s2p

the same, but then you also have redundancy.

[davil]

still shopping for price/quality
anybody had experience with these batteries
Renogy Deep Cycle AGM Battery 12 Volt 100Ah for RV, Solar, Marine, and Off-grid Applications

$ 199.00 too good to be true????

https://www.amazon.com/gp/product/B0...qh_dp_hza?th=1

[ranger58sb]

Originally Posted by davil

still shopping for price/quality
anybody had experience with these batteries
Renogy Deep Cycle AGM Battery 12 Volt 100Ah for RV, Solar, Marine, and Off-grid Applications

$ 199.00 too good to be true????

Haven't heard of that brand, but 12V and "deep cycle" in the same sentence is often suspect.

Ask the Renogy people how many cycles to 50% DoD they predict.

-Chris

[Maine Sail]

Originally Posted by davil

still shopping for price/quality
anybody had experience with these batteries
Renogy Deep Cycle AGM Battery 12 Volt 100Ah for RV, Solar, Marine, and Off-grid Applications

$ 199.00 too good to be true????

https://www.amazon.com/gp/product/B0...qh_dp_hza?th=1

Again, please do NOT buy your AGM batteries based on price. AGM durability and cycle life varies WIDELY. Longevity defines your total cost. You've now moved your search from cheap US made AGM's to cheap Chinese made AGM's, a move in the wrong direction I'm afraid..

I know Renogy's supplier and while certainly not the worst of the Chinese AGM's it is far from what I would consider a decent Chinese supplier for a deep cycle AGM product.. If you want a quality Chinese made AGM then you want to buy Fullriver Batteries. In fact I would take a Fullriver AGM over a Deka/East Penn AGM any day of the week but I would take a Deka/East Penn over 98% of the other Chinese AGM's.

You will get what you pay for buying AGM batteries by price alone. If you eat sushi based on price then by all means do the same with AGM batteries.....

The term AGM just means absorbed glass mat. Please don't assume all AGM batteries are the same quality. Nothing could be further from the truth..