What are the best batteries for the money?

My brother wants to build a new solar system in Puerto Rico. I was wondering what type of batteries are the best. The last I heard 6 volt golf cart batteries are the best because they have thicker longer lasting plates. He's is thinking about 25 hundred watt system at 24 volts. Is there a good brand name out there for lead acid batteries?
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Below is an excerpt from a website which may be of assistance.
To identify the manufacturer, ask the dealer or check the battery's Material Safety Data Sheet (MSDS). The manufacturer's code number on the battery will also identify the manufacturer. For differentiating quality, features or warranty periods, battery manufacturers will sometimes have product lines within a trademark or brand, for example, Bronze, Silver, Gold, Platinum, Titanium, Premium, Heavy Duty, Commercial, Standard, Plus, Turbo, Calcium, Classic, Maintenance Free (MF), etc. They will also contract with other manufacturers to build and private label batteries to complete their product lines, for example, specialty batteries, that are not economically feasible to build themselves. Motorcycle batteries are listed in the Powersports starting classification and motive, traction, standby, stationary, solar, and Valve Regulated Lead-Acid (VRLA) AGM and Gel Cell. Sealed Lead-Acid (SLA) batteries are classified as deep cycle batterie
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
http://members.sti.net/offgridsolar/
E-mail [email protected]
Measuring/understand his loads is important (as is having no shade/power lines/trees that prevent full sun from hitting the array).
If he wants to run a refrigerator, that is really the dividing line between a small and cheap system (something like 1,000 WH per day), and a medium size system that supplies ~3,300 Watt*Hours per day or more.
A 2,500 Watt system does not really tell us how big the battery bank. What is needed is the Watt*Hours per day energy usage to design the battery bank. And will he have a backup genset (for bad weather, if he needs more power for tools to repair his home, etc.)?
Doing paper/back of the envelope designs is cheap. Building out a system that does not meet his needs (or the parts don't work well together)--Expensive.
-Bill
KID #51B 4s 140W to 24V 900Ah C&D AGM
CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM
Cotek ST1500W 24V Inverter,OmniCharge 3024,
2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
West Chilcotin, BC, Canada
Warranties are nice but we all pay for the yahoo's who murder their batteries then cash in on the warranty. Plus warranties are not always backed.
Pretty easy choice here. Golf cart batteries likely offer the biggest bang for the buck. Especially for the newbie.
http://www.smartgauge.co.uk/batt_con.html
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
> How do I prevent an unbalanced string?
Wiring such that all battery resistances are equal, and checking the parallel connection from each battery/string periodically with a clamp-on DC (not AC) meter while charging in bulk.
With 8 x 12v batteries, you presumably have 4 pairs (series strings) in parallel, for ~450ah. Using GC 6v (~225ah) batteries, you would have 2 parallel strings of 4, for about the same capacity. Fewer strings in parallel is easier to keep balanced.
Also, with 12v, you have 6 cells x 8 batteries = 48 cells total. With 6v GC, you'd have 3 cells x 8 batteries = 24, half as many to check and water.
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
KID #51B 4s 140W to 24V 900Ah C&D AGM
CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM
Cotek ST1500W 24V Inverter,OmniCharge 3024,
2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
West Chilcotin, BC, Canada
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
- Energy (Watt*Hours) = Volts * Amp*Hours = 12 volts * 110 AH = 1,320 Watt*Hours
- Energy (Watt*Hours) = Volts * Amp*Hours = 6 volts * 220 AH = 1,320 Watt*Hours
However, if you wanted to store 2x that amount of energy, you would use 2x 12 volt @ 110 AH batteries in parallel, or 2x 6 volt @ 220 AH in series.Why I like 2x 6 volt series configuration. You have 6 cells to check water levels on, and no balancing of current with parallel connections (and as you add more parallel connections, you really should use a fuse/breaker per parallel connection--More hardware and $$). Also it is very easy to see the health of each battery (6 volts across each battery). With 2x 12 volt batteries in parallel, both batteries have the same voltage and it is more difficult to do a quick sanity check on your bank.
Note that the 12 volt @ 110 AH and 6 volt @ 220 AH batteries are pretty much the same size and weight.
I like to suggest that ~2-3 parallel strings of batteries is the maximum I would aim for... Use larger AH batteries ( you can get 2 volt cells that are >>>1,000 AH). Fewer cells to check, fewer parallel strings, fewer electrical connections, easier to maintain:
https://www.solar-electric.com/marine-rv/batteries-and-accessories/deep-cycle-batteries.html?nav_battery_voltage=2+Volts
Temperature wise... Warm/hot batteries cut their life dramatically. The engineering equation is for every 10C (18F) increase in temperature, there is a factor of 1/2x less (aging) life (75F battery vs 93F, your 8 year bank would last ~4 years). So--If you can have batteries in a cooler/shaded room, or even in a cool basement--It can help a lot (proper ventilation and safety practices is important too).
-Bill
-Bill
- Assorted other systems, pieces and to many panels in the closet to not do more projects.
> Again thanks so much. What a great simple explaination for balancing. I have method 2. Method 3 looks easy and worthwhile to achieve. 2 more wires and two posts to attach to. Not sure where to find the post. Must be called a battery terminal post?
>
>
My "posts" (where the two equal length wires meet to parallel two strings of L16s) are just a bolt, washer, lock washer, and nut. It works fine for a couple of strings. With more than a couple, a flattened copper pipe with holes drilled could get the job done.
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
Whether or not we really need to use 4/0 is another topic. Even 2/0 is not far behind.