Best Battery Per Penny

[bLEEp]

It’s been just over two years and my first set of old skool golf cart batteries is about done.
We are currently equipped with 4x 100 watt reboot eclipse panels, commander controller and renogy 1000 watt inverter.
I have about $1000 in the battery budget.
Of course renogy is reccomending 4x 100Ah pure Gel or two 200Ah pure gel.  
Anyone with some firsthand knowledge care to point me in a good direction?

 

[highdesertranger]

Gel, is that really what they are recommending? I had bad experience with Gel but that was many years ago. highdesertranger

 

[Almost There]

How many amp hours of battery are you looking at.

You mention you  have 400 W of solar but usual standards are at least  a 2 to 1 ratio of solar watts to battery amp hours. Even better (and necessary if you're in a northern clime) is a 3 to 1 ratio.

I've been running 4 - Trojan T105RE for the past 3 1/2 years and couldn't be happier with them. If you go with Trojan I recommend the REs over the standard T105s - a little harder to come by and a few dollars more but a great upgrade.

I added a battery watering system this year and would recommend that you include it in the budget from the start if you choose flooded led acid batteries if they are any place the least difficult to get to. It takes me 5 minutes to fill the batteries if I'm goofing off as compared to the hour it took before to pull, water and put back. I can also see at a glance if they even need watering.

 

[sushidog]

Handy Bob has been at it for quite a long while and he hates gel cells. I agree with highdesertranger and Bob.

Here's what he recommends: https://handybobsolar.wordpress.com/2019-lithium-batteries-truth/

The last batteries I bought a couple months ago was a pair of FLA GC-2s which should match with your solar array quite well. I'm planning on buying a couple 310-320 watt panels to go with them next month. In a couple years I'm planning on adding 6 more of these large panels to a 48v battery bank - made of 8 FLA GC-2s. They are the best bang for your buck if you can handle the weight. If you are thinking of stepping up to the l-16 group class, I really like the Rolls/Surrette S550. They are built like tanks and will easily outlast any in the GC-2 class by a number of years. (the manufacturer estimates their avg. lifespan at 12 years.) https://www.solar-electric.com/rolls-surrette-s-550-deep-cycle-battery.html

A pair of these will fit your budget, but I recommend adding another 4 panels (if you have the room) if you decide to go with these 428 ah beauties. Or if you don't have enough room for 8 inefficient low voltage panels, you could sell or scrap your old system and buy 3 of these 345 watt sun high-efficiency panels https://santansolar.com/products/sunpower-345w for only $375, giving you 1,035 watts for only 36 cents/watt in a small form factor. If you plan on mounting them flat, you could get by over-paneling a 60 amp Renogy rover for around $255 getting the most bang for your buck, as they say and be a perfect match for a pair of s550s.

The only question then is what to do with all this power? A small high efficiency air conditioner, maybe?

Chip

 

[Trebor English]

I believe in the concept of "learning Batteries" to save on tuition costs.  I have 2 1/2 years with my 75 amp hour $80 group size 24 trolling motor battery.  My concern is that I may have consistently charged it too much leading to corrosion.  I will find out when it dies.  If it suddenly goes open circuit I'll know for sure I did it and need to learn more.  It came with a 2 year warranty and I think I can claim successful completion of battery learning if it lasts to 4 years.  Short of that, I failed the course and need to learn more (most likely outcome).  

Flooded lead acid batteries allow the use of a hydrometer to measure the state of charge.  How much sulfur is in the sulfuric acid versus how much sulfur is in the lead sulfate in the plates is actually measuring state of charge.  If you have a $150 to $200 battery monitoring system it can estimate the state of charge if properly programmed and maintained.  Flooded lets you measure.  

Gel batteries have all the same problems that plague all lead acid batteries plus the bonus issue.  If you charge it too fast and bubbles form they stay forever.  The gel that immobilizes the acid also immobilizes the bubbles.  This additional failure mode that is unique to gel batteries is the main reason why they are not drop in replacements for flooded lead acid batteries.  

If your application requires that the batteries be mounted upside down then you need AGM or gel.  If your application requires zero maintenance then you need AGM or gel.  AGM or gel will last at least twice as long as a lead/antimony alloy trolling motor battery that doesn't get watered monthly.  Otherwise paying twice the price to get AGM or gel isn't the best price.

The thread title, "Best Battery Per Penny" is best answered, in the US, with the lowest price flooded lead acid battery.  If you killed your first set of golf cart batteries in two years it is my opinion that you might have more learning to do.  What is wrong with your first set?  Did they get a reduced capacity?  Did that happen by insufficient watering or under charging?  If one went open circuit from corrosion due to overcharging you probably would have said the battery died rather than "about done."

 

[B and C]

I agree with Trebor about learning sets. If you capacity has been walking downward, it is a sign of chronic undercharging.

 

[Gr8ful]

I posted this "battery universiry" once before. If you do itright fead acid deep cyclr 6v will last 12 years plus. https://batteryuniversity.com/