What to look for in a deep cycle battery

[Bambinoruth714]

I am to buy buy 8 batteries for my soalr system. I have a schneider 4048, outback flexmax 80 and 12 320 solar panels. What type of battery would you recomend?
And please what is 100 AH, 200 AH, what id the difference?

 

[Browneye]

Are you looking at lead-acid or lifepo4?
The difference in amp hour ratings is their capacity for energy storage. A 200 has twice as much as a 100.
You can estimate what they will power based on the amp-load rating of your device(s).

What is your application? Mobile? Fixed? I'm assuming the latter, with 8 batteries. How did you decide on 8? What do you intend to power with your batteries?

Lead-acid batteries, whether flooded, sealed, or absorbed glass mat (AGM) provide a recommended 50% capacity to avoid serious degradation.
Lifepo4 doesn't really have that limitation. They are also happy in a semi-charged state, whereas lead batteries do best when kept fully charged, or completely recharged immediately after discharging.
Lifepo tends to run about two to four times the cost, but tend to last more than twice as long.

 

[Wellbuilt]

I have a out back system 36/48. With the fm80 , I use 16 6v sams club 215 amp hour batteries 8 6v 215 amp hour
batterys will make 1 48v battery @ 215 amp hours I have 2 48 v strings at 215 AH so 430 amp hours .
My battery where 1500 $ and are on year 3 and still read good ?
I would use these and get some experience , if you murder them it’s no big deal .
you don’t want to burn up 10 k worth of battery’s the first week .
I use 10% of my battery over nite so if I had only 8 6v battery I would use 20% over nite .

 

[upnorthandpersonal]

And please what is 100 AH, 200 AH, what id the difference?

Before you buy anything, you really want to familiarize yourself with all terms related to batteries. An Amp-Hour is a measure of capacity. It's not a very good one though, since a 100Ah battery at 12V stores less energy than a 100Ah battery at 48V. Therefor, I prefer to use Wh (Watt-Hours) - just multiply the Amp-Hour rate of a battery with its nominal voltage. Now you can compare apples to apples, and that 100Ah 12V battery stores 1.2kWh, while that 100Ah 48V battery stores 4.8kWh: 4 times the amount of energy stored.

In addition, if you use lead-acid and want to have any decent life out of them, you should not discharge these below 50%. This means that a 1.2kWh battery in reality is more of a 600Wh battery. With lithium chemistry such as LiFePO4, you don't have this limitation and you have a lot more cycles in general.

 

[joanna_lannie]

persistent topic. If you have money and plan to use it for a long time, buy LiFePO4 batteries. LiFePO4 battery safety is good and has excellent performance. If you have a small budget and a short life cycle, lead-acid batteries are your best choice (GEL batteries or AGM batteries are recommended).

 

[Browneye]

AGM’s are for racing and off-road applications, or unattended use. They don’t perform any better than FLA’s, but don’t require watering and can be oriented any which way.

 

[12VoltInstalls]

GEL batteries or AGM batteries are recommended).

Why? They cost more, die faster.
AGM for backup or a track car; flooded to use as solar storage. Or LiFePo

Therefor, I prefer to use Wh (Watt-Hours) - just multiply the Amp-Hour rate of a battery with its nominal voltage.

the amp-hour rating is based on a certain discharge rate at nominal voltage. That parameter of judgement gets lost a bit in watt-hours.

 

[sunshine_eggo]

persistent topic. If you have money, cycle it frequently and plan to use it for a long time, buy LiFePO4 batteries. LiFePO4 battery safety is good and has excellent performance. If you have a small budget and a short life cycle, lead-acid batteries are your best choice (GEL batteries or AGM batteries are recommended).

Revised.

Why do you keep linking to a cell supplier, especially one that is biased and willing to mislead?

Depth of Discharge

I'm having trouble getting anything from manufacturer. How do I know what my battery's depth of Discharge is? A calculation based on battery chemistry vs other specs etc? Or what "better practice" should I use to know what settings to put into my SCC/Inverter?

diysolarforum.com

LFP is a garbage choice for standby systems that sit there fully charged most of the time waiting to provide backup power. FLA is your best choice if you're willing to check fluid levels a few times a year. AGM is your best choice if you don't want to mess with checking batteries. LFP is just something that's going to degrade sitting there doing nothing.

 

[joanna_lannie]

Revised.

Why do you keep linking to a cell supplier, especially one that is biased and willing to mislead?

Depth of Discharge

I'm having trouble getting anything from manufacturer. How do I know what my battery's depth of Discharge is? A calculation based on battery chemistry vs other specs etc? Or what "better practice" should I use to know what settings to put into my SCC/Inverter?

diysolarforum.com

LFP is a garbage choice for standby systems that sit there fully charged most of the time waiting to provide backup power. FLA is your best choice if you're willing to check fluid levels a few times a year. AGM is your best choice if you don't want to mess with checking batteries. LFP is just something that's going to degrade sitting there doing nothing.

There are always those who support lead-acid batteries and those who support LFP batteries in this forum. Are you going to do your best to kill one of them? I think this question is like apples and pears, you can't force anyone to like only one. In addition, I think my statement is relatively neutral. If you have money, buy LFP, which can maintain performance for a long time, of course, if you use it frequently. It is relatively more beneficial to buy lead-acid batteries if they are not frequently used. OP didn't mention the usage requirements, what's wrong with the two battery suggestions I mentioned? Don't be too mean, and thank you for letting me know more about FLA.

 

[Abson]

lifepo4 (LFP) is ideal for use in solar systems, and from a practical point of view, LFP can continuously discharge to a depth of discharge of 100% DOD better than any lead-acid battery.

LFP is a garbage choice for standby systems that sit there fully charged most of the time waiting to provide backup power.

I don't know what makes you hate LFP so much, but you can't deny that LFP is a great invention.
This is a peaceful forum, and we want to have a peaceful discussion, rather than outright denying that LFP is garbage!

 

[sunshine_eggo]

There are always those who support lead-acid batteries and those who support LFP batteries in this forum. Are you going to do your best to kill one of them? I think this question is like apples and pears, you can't force anyone to like only one. In addition, I think my statement is relatively neutral. If you have money, buy LFP, which can maintain performance for a long time, of course, if you use it frequently. It is relatively more beneficial to buy lead-acid batteries if they are not frequently used. OP didn't mention the usage requirements, what's wrong with the two battery suggestions I mentioned? Don't be too mean, and thank you for letting me know more about FLA.

You're forgetting about the other "those". There are those that support using the best battery for the situation. That's the group I'm in.

When you link to that website, you're linking marketing data masked as technical data.

Are you in any way affiliated with batteryfinds.com?

lifepo4 (LFP) is ideal for use in solar systems, and from a practical point of view, LFP can continuously discharge to a depth of discharge of 100% DOD better than any lead-acid battery.

No LFP battery recommends this. ALL LFP batteries and cells are rated for 80% DoD.

I don't know what makes you hate LFP so much, but you can't deny that LFP is a great invention.
This is a peaceful forum, and we want to have a peaceful discussion, rather than outright denying that LFP is garbage!

This is pretty laughable. Saying that I hate LFP confirms you've never read anything else I've written on this forum, AND it clearly indicates you don't understand the post to which you're replying.

 

[12VoltInstalls]

discussion, rather than outright denying that LFP is garbage!

He was saying a poor choice in this application. Lead acid is inexpensive and for a purely backup service battery the life expectancy and expense is a better spend.
LiFePo is often a better spend probably for most systems but some circumstances still will be best served with lead acid.

 

[Rednecktek]

LiFePo is often a better spend probably for most systems but some circumstances still will be best served with lead acid.

As a fan of lead acid, I can't argue with statements like that at all.

Are you running your batteries in really hot or below freezing conditions? Buy lead.
Are you on a really tight budget? Buy lead.
Are you only using your batteries a couple times a year? Buy lead.

Do you use your batteries every day? Get Lith.
Do you have limited physical space? Buy lith.
Do you want this system to run for decades without having to mess with it much? Buy Lith.

Back to the OP and original topic, it comes down to the age old "It Depends".

As for the capacities, the really simple way to think of a solar setup is water and buckets:

The Ah or KwH rating of the battery is how big a bucket you've got. A 200Ah bucket holds twice as much water as a 100Ah bucket.
The wattage from your solar panels is how fast you can refill the bucket.
The load or draw on the system is how big the hole in the bottom of the bucket is.
The capacity of the system in runtime is how long the bucket will hold water if it's got a hole and you can't refill it. The smaller the hole or bigger the bucket, the longer you can have your sprinklers running.
An inverter is a pump that takes the water from the bucket and converts it to a high pressure spray.
The rating of the inverter is how much water it could hose you down with at a time. A 1Kw inverter can feed a garden hose, a 5Kw is more like a fire hose.

Does that help at all?