These SLA UB12100 batteries come in different capacity sizes. While a 10Ah model might sell for $20 a 100Ah Deep Cycle one will cost around $200. Here is a review from an customer of an online vendor;
By
Amazon Customer on April 27, 2016
I have purchased four of these in the past six months. Three of the four were DOA. One arrived with 9.7 volts and if you know anything about lead acid batteries, 9.7 volts means that irreversible damage of some sort has occurred. Another had 10.5 volts and another had 11.0 volts. Same story for all three of them, garbage from the moment I took them out of the box.
I went through a ton of effort charging and discharging them because the first seller told me that the manufacturer said that deep cycle batteries sometimes have to get a few cycles on them before they reach their peak performance. BS! Any battery that arrives with less than 12 volts charge has either sustained internal mechanical damage or has not been maintained with a proper charge while in storage. Either way, I went through the hoops for the manufacturer to satisfy their sadistic needs. While I was at it, I discharged the batteries with a measured one amp load so I could calculate the depth of discharge in relation to the rated capacity. As it turns out, the batteries were showing a total capacity of around 40 amp hours, about one third of what I paid for!
Another customer swears by them;
By Robert on February 19, 2015
Verified Purchase
Just what I ordered. Fast shipping especially @ 70+ lbs. Last one lasted 8 years in my Eurovan "cabin" running frig & accessories.
They might be good batteries in the 100Ah size, Deep Cycle units but apparently some of the online vendors might not keep a fresh inventory. I do not think a battery in the cheap $20 10Ah size which is not a deep cycle will provide adequate service. Why don't you go with a regular 100Ah deep discharge battery from Walmarts under $80 with a 6 month warranty.