The Trojan j150 is an excellent battery. My next battery will be the Trojan T-1275, which is very similar. But slightly smaller for the same weight. Same amount of lead, less electrolyte, which is a compromise
It is built with thicker plates with more space under them for sheddings to accumulate before shorting out the cell, and can hold more electrolyte. Their SCS line in the group 24/27, and 31 lines have only half the expected cycle life as these taller scrubber/ golf cart batteries, and are often the same price. Trojan's 24/27/31 size group batteries are among the very best deep cycle 12v batteries, many miles ahead of any other easily obtained marine/dual purpose battery, but the fact is the case size of 24/27/and 31 were originally designed for starting batteries. Shoving deep cycle or dual purpose plates inside of them is a Compromise.
http://www.pbase.com/mainecruising/deep_cycle_battery
It is my opinion however that these RE batteries are no different internally than their regular lineup without the RE in their title.
Even Concorde, who make the Lifeline AGM battery that I've found to be so impressive, offer a SunExtender line marketed for solar/wind installations, but when one downloads the Sunextender user manual, there is absolutely no difference from the regular Lifeline AGM PDF users manual. The same charge recommendations exist on both.
The marketers saw that there is a significant market for a battery aimed at the solar or wind power people, and ordered up a bunch of New stickers with 'renewable' and green letters to slap on their already existing lineup. That is my opinion.
Trojan recommends a 10 to 13% rate, 10 to 13 amps per 100AH of capacity. They do not have an asterix saying that their RE batteries are an exception and are quite happy with lower currents, that they reformulated the plate paste material and electrolyte/Lead ratio for the Low and slow solar regimen. Only a Sticker with some green on it, and a glossy marketing page proclaiming their greatness in this application, and perhaps a higher price to help convince the consumer..
Flooded batteries are happier with lesser charging currents than AGM, of that there is no doubt, and the deeper the discharge of the battery, the more important it becomes to achieve higher charge rates, and this is not only because there is only so much time available before the next discharge cycle begins and because more energy is required to refill the battery, but because the higher charging currents are required for the chemical reaction to occur throughout the depth/thickness of the plates and achieve a true full charge and not a pseudo full charge which is practically indistinguishable to all but those who monitor Amp draw and amp hours consumed and the voltage held during discharge.
It is basically impossible to perfectly treat a battery. Even if floated at a perfect temperature compensated voltage and never cycled at all, the battery is only expected to last 10 to 12 years. Batteries have a 100% failure rate! The only factor is the time until they fail, and that variable is directly related to how they are treated.
And while some manufactures consider a battery's cycle life to be over when it only has 80% of its original capacity, others do not state at what remaining capacity they consider their battery to still be viable. My Old group31 battery can hold 12.7 volts for a day after a recharge, it can still power an ARB fridge for 3 days easily, but in my estimation has well less than half of its original capacity of 130AH.
Those of us relying on battery power, and want to get good to excellent cycle life, maximum cycles per $$, from the battery, need to meet the batteries basic needs of prompt and full recharging after every discharge cycle. The best place to start is the battery manufacturer recommendations, but these are not written in stone. I've noticed manufacturers change their 'ideal' recommendation in the last decade. It is up to the user to ultimately fine tune their charging regimen to that which allows the battery to hold the highest voltage during each subsequent discharge.
With Flooded batteries, the Hydrometer is the ultimate tool for determining how well the battery responds to any particular recharge regimen from a certain level of discharge. Watching the voltmeter when discharging, and knowing the discharging loads via an Ammeter is extremely helpful as well. An Amp hour counter/battery monitor, while not 100% accurate, is also an invaluable tool, when programmed correctly and occasionally rezeroed.
http://www.pbase.com/mainecruising/programming_a_battery_monitor
With an AGM battery the Hydrometer is Useless. Then the other tools become that much more important in determining when the battery is indeed fully charged, but also when the rate at which 'full charge' was reached is actually acceptable.
There is no magical device which one can just attach to a battery which can determine state of charge and health. Impedence testers are not reliable on Deep cycle batteries:
http://www.pbase.com/mainecruising/impedance_testers
The recharging needs vary among battery types, and they change as the battery ages, and the Northstar AGM group27's demands are greedier than most other AGM batteries. If its demands/requirements are met then it will give excellent service. If they are not met, it will give marginal service for a premium price, and leave a bad taste in the consumer's mouth. The Older Blue top line of Northstar battery the OP can get at less than half price, and adequately recharged every cycle, might not yield a good cycler per dollar ratio. It might be very poor. I'd guess this Aged but uncycled battery has even higher demands than a newer Northstar that has not been on the shelf for 2.5 years. If the OP cannot properly recharge this battery initially via a high amp recharge from a depleted state, the probability for success in the cycle per dollar category becomes quite questionable
I find my Northstar battery to be quite impressive, but I can meet its high amperage recharge requirements.
18 months ago, when I bought it, I first got the bluetop because the battery distributor cut 75 dollars off of the price. I'd bought another flooded battery at the same time which was supposed to be a relabelled Crown Deep cycle group31, but when I weighed it it was 10 Lbs light and corresponded to their marine battery, which I did not want. When I returned the marine battery, quite furious and practically frothing at the mouth with the bait and switch, I returned the bluetop too and pulled an All grey new northstar from the shelf that had the highest resting voltage, and paid the extra for the newer battery.
While ultimately it comes down to cycles per dollar, I view batteries as experiments on which to learn and be comparable to the lifespans of other batteries, and I want to start the experiment with an uncompromised product, not one which appeared to be a good deal pushed by the seller to clear out their old stock.
Meeting high amp high $$ AGM recharging demands when cycled below 70% state of charge is practically impossible via solar alone. The Same applies for most AGMs but not to the same degree. Since AGM's are twice as expensive, one needs to think twice before thinking that they are the simple obvious solution to offgassing, and that any charging source is adequate, hoping any charging source is adequate, and believing the 'just fine' brigade, that it is.
Lesser $$ AGMs like Deka intimidator or Universal battery list a maximum recharge rate of 30 amps per 100AH of capacity. It is my opinion that these batteries are better suited to low and slow solar only, but that these still benefit from charging amps upto the 30% listed maximum.
Please do not consider spiral wound/six pack style batteries for deep cycle applications. The design reduces available capacity by 25% compared to a rectangular AGM of the same size footprint. The main benefit from the six pack design is resistance to vibration and physically stronger casing. So good for rock crawlers rally cars or wave jumping jet skis, but of no benefit to a Van dweller.
Understand the manipulation of the marketers. They are professional liars, just like politicians. They claim to have your interests in mind, but really all they care about is maximizing the weight of their wallet. Even the reputable brands have to do this, just to compete.
