Marathon M12V90F

[Man of God]

My nephew works for a cell phone Co. on their tower installations and has access to The Marathon M12V90F Battery. I was wondering if that would work well for a battery backed solar system?

[Sunking]

No not at all. Stationary batteries are for Emergency Back Up power. They are designed to deliver extremely high rates of current for a given capacity. To do that means they only have get 100 to 200 cycles. For RE systems you want a battery with 3000+ cycles.

How do I know this? I have worked with or for Telecom for 30+ years designing battery plants for them.

[Man of God]

Thank you Sunking. Figures they would be the wrong batteries since I could get them at a discount. Oh well..!

[Alex909]

Sunkin. Where do you look for the battery cycle rating? What batteries brands are good for solar or off grid? Thank you

[sensij]

Sunkin. Where do you look for the battery cycle rating? What batteries brands are good for solar or off grid? Thank you

The data sheet is a good place to start. Here is the sheet for the OP's battery in question. Even if you know nothing else about batteries, if you can't find a cycle rating on the data sheet, that is a bad sign.

Trojan, Rolls Series 4000 are worth looking at if you are wanting FLA.

[Sunking]

Sunkin. Where do you look for the battery cycle rating? What batteries brands are good for solar or off grid? Thank you

Spec sheets. A deep cycle battery will have some form of cycle life rating. Otherwise it is not to be used for cycle applications.

Telecom Stationary batteries. are a SLI battery brother meaning a telecom stationary battery is more like an auto SLI (cranking) battery than a deep cycle battery with a twist being they can be deeply discharged real dang fast, and be recharged real fast in an hour or two. With batteries, you are going to get what you pay for.

Telecom batteries are an oddball of the battery world, new they are one of the most most expensive batteries you can buy, used they are worthless. Telecom or really any type of operation that uses station batteries has a ton of Red Tape tracking batteries from cradle to grave. Once installed the company is responsible for tracking those batteries. They pay big bucks to have the batteries removed and disposed of. They are a liability.

So 10 or so years ago I and the telecom industry got smart. We turned an assist and pile of Red Tape into an asset. We sell them to SUCKERS, and pocket the cash for Christmas. They come available at the end of a calendar year. The company takes the tax write-off, and the engineers pocket the cash. Everybody wins except the SUCKER, err I mean buyer. Once you sign the receipt, you are now responsible to the Employment Prevention Agency.

The beauty is at firrst you will be one happy happy camper because those batteries will perform like no other battery. You can hit them with huge discharge of up to 4C with little voltage sag. Then as a month or two go by, you start to notice performance has slipped. In 5 to 6 months they will no longer hold or give a charge. You now have a toxic 2000 pound boat anchor to dispose of. The only good news is you can recover some of your losses by selling them as scrap. But be aware a recycle center will not pay what they normally pay for dead batteries. Most of the stationary batteries are in steel jars, not plastic. That means the recycle center cannot feed them in a grinder to separate the case from the lead inside. They have to do that by hand with labor. In fact you may have to pay for tahem to accept them. That is when you realized what was really going on when you thought you had the deal of a lifetime. You got screwed and not a dang thing you can do about it.

Now be aware there are battery manufactures that make good batteries. As mentioned Trojan and Rolls make good batteries. However just because you might buy a Trojan or Rolls, does not mean you are getting the best. Both have entry level (2-year battery), mid level (3 to 4 year battery), and high end 7 to 10 year battery. Now here is the irony, most let price be the deciding factor and you end up buying an Entry Level battery. You just bought the most expensive battery you can buy. Smart money would have bought the high end battery at twice the cost per watt hour of storage. Example the high end battery may cost $1000, and the low end cost $500. About 2 or 3 years down the road, you get to replace the $500 battery for $550 when replacement time comes. After 9 year 3 replacements and you end up spending some $1600. That is when you figure out the $1000 battery is less expensive and kick yourself.

OK my list for Solar batteries:

• Trojan Premium and Industrial line (5 and 8 year battery). Signature line is the low end 2 year battery.
• Rolls are tricky but the 4000, 4500, 5000, and "S" (Renewable Energy) lines have 5 to 8 year battery
• HUP Solar batteries are top end of all batteries made by Enersys come with the best warranty out there. 12 months is full parts, labor, and shipping cost. 13 to 84 full credit parts only, and 85 to 120 months prorated.
• Another work horse and a 15 year battery is Crown Fork Lift batteries.