What kind of battery should i buy to use as a storage?
Something i can pick up locally at Walmart or AutoZone.
Willie, Gordy The Renogy Wanderer datasheet states the CC is Compatible with Sealed, Gel, and Flooded batteries. I'm pretty sure this is what he is inquiring about.
Both Willie and Gordy are correct. When you first put the system together, if you find that you undersized the battery bank you can add more batteries. However no procrastination. You need to add the additional batteries ASAP. The longer you wait the more wear on the older batteries the greater the greater the hit on the new batteries. If you expand the battery bank with new batteries say two years later, the hit on the new batteries would be huge and financially the cost would be huge also.
Lets clean up the above statement from the datasheet.
Flooded Lead Acid batteries have a liquid electrolyte and are not sealed.
AGM (absorbed glass mat) have a liquid electrolyte and are sealed.
Gel Lead Acid batteries have a gelled electrolyte and are sealed.
The statement on the datasheet should of been written as: Compatible with Flooded Lead Acid (FLA), Sealed Gel LeadAcid, Sealed absorbed glass mat (AGM) Lead Acid. All three of these are lead acid chemistry. Another way of making this statement would be to say Compatible with Lead Acid batteries only. Compatible with all types of Lead Acid batteries.
You can find Lead Acid batteries at Walmart, Autozone, Costco etc. Lead Acid is the most common battery chemistry in this size of battery.
If you look at page three of the manual it said “Use only sealed lead-acid, flooded, or gel batteries which must be deep cycle”. They messed up that statement up also. Use only Deep Cycle Lead Acid batteries would of covered it.
There are three classes of Lead Acid batteries, Starter battery, Marine and Deep cycle. The charge controller will work with Starter and Marine batteries but in the long run it will cost you more financially and your be attending the system more frequently.
Starter batteries have thin plates. The thin plates allow more current, power and storage capacity for a given physical size. However because the plates are thin they are more prone to warping and pitting when discharged. For this reason they will not last long for your application. Stay away from starter batteries for this application. If you go with Starter batteries you will be paying more in the long run because you will be replacing the batteries more frequently. Don’t let the prices and numbers on starter batteries seduce you. If you do, your regret it when your wallet shrinks more then it needs to.
Deep Cycle batteries have thick plates. The thick plates allow less current, power and storage capacity for a given physical size. However because the plates are thick the batteries do not wear out as quickly. Deep Cycle batteries cost more upfront for a given capacity. But because they last so much longer they cost less then starter batteries over the long run.
Marine batteries are a compromise between Starter and Deep Cycle. The plates are thicker then starter batteries but thinner then Deep Cycle. These are designed for boats. The have enough current and power to start a small engine but durable enough to run a trolling motor also. You don’t need dual function so marine batteries are not the best choice for your application.
The Deep Cycle class is the way to go.
FLA vs AGM
The two are the same except the AGM has an absorbed glass mat between the plates and is sealed. The AGM cost more up front but is more durable and economical in the long run.
Gel Lead Acid the least sensitive to depth of discharge but is more sensitive to over charge. If the charge controller does not get the charging correct Gel ends up with shorter life span due to charging damage. Gel Lead Acid has not been working out as well as AGM. Many are replacing Gel with AGM. I would not suggest Gel with a low cost Charge Controller.
My suggestion for your application, Deep Cycle AGM.
When shopping for batteries, Make sure the datasheet said AGM specifically. Deep Cycle specifically. If it said Marine Deep Cycle, avoid it. There are lot of marking ploys design to make you think your getting more then your getting.
References: Renogy Wanderer - 30A PWM Charge Controller Manual