Depth of Discharge, AGM

[John61CT]

I remain confused.   I can talk SOC or DOD.   The Wikipedia reference is generic and a starting point for discussion with manufacturers of specific battery products.

Were you able to understand my clarification of the wiki article quote?

There are only a handful of known-good makers if deep cycling products, FLA on the one hand, GEL or AGM on the other.

Only they can be trusted, the other 98% of the market is full of shysters.

 

[John61CT]

LFP has the same type of relationship between average DoD and cycle lifetime, just the curve is less steep in the middle ranges.

The 2000 cycles vendors tout is very conservative. If you follow the "avoid the shoulders" usage guidelines, triple that or maybe ten times that is possible - if nothing goes wrong.

But the cost per usable AH is 5-10 more in upfront investment, therefore very risky for those starting out.

Best for LFP discussion to take place elsewhere or this thread gets derailed.

Post questions to an existing LFP thread, or start your own.

 

[BobW55]

Thanks for posting that chart.
I was surprised to find that there is not a "Goldie Locks" zone.
Always figured that there would be a 25-35% discharge region that was best for long battery life.

 

[John61CT]

No, it really is up to each user to decide.

You need to balance bank lifespan against,

higher up-front investment and carrying more weight

Those only cycling occasionally can go deeper since calendar aging becomes the greater factor

 

[craggers]

the problem with the "Deep Cycle" label is a lot of them are not true deep cycle batteries.
ss
remember it is always cheaper/easier to conserve power then it is to make it.

highdesertranger

hii h d ranger,  i was wondering this question when i get around to buying a battery ;  if you seen egnimatics nomadics video Curtis shares his Nissan Van build he runs his refrigerator untill it hits 10.5 volts  then it shuts off,  just saying

 

[John61CT]

Lots of idjits on YT.

10.5V for lead should never be touched except for specialized commissioning and testing routines on a bench with precise power supply and measurement tools

and then immediately recharged.

Maybe 10 times in a bank's life.

An LVD set that low is protecting the load device, not the battery.

 

[tripper]

If he was using the stock ciggie lighter cord there probably 1 to 1.5 volts in drop so the battery could be at 11.5 - 12 volts when the fridge is cutting off.

Trojan makes true deep cycle batteries and they have at least one distributer in each major city, their prices are good, I think around $160 for a 105 AH flooded lead acid deep cycle battery.

 

[Exexpeditor]

I think 70 percent is over kill. 50 percent is ideal. I always tried to boost mine back up in between 30 and 50 percent.

 

[Zil]

This is link to Trojan's site on Solar AGM batteries. If you scroll down you will find a graph of life cycles compared to depth of discharge. It is Trojan, but will give you an idea of your question for other brands. https://www.trojanbattery.com/solar-agm-2/

 

[John61CT]

Those charts are **only** useful to compare longevity between lines within one manufacturer's offerings.

Each company has their own different lab standards.

Many are untrustworthy.

And lab tests do not reflect real life results.

 

[craggers]

Lots of idjits on YT.

10.5V for lead should never be touched except for specialized commissioning and testing routines on a bench with precise power supply and measurement tools

and then immediately recharged.

Maybe 10 times in a bank's life.

An LVD set that low is protecting the load device,  not the battery.

ohh  that was my Bad,  the 10.5 Volt battery voltage to the refrigerator cut off point never gets hit with 2 Walmart Group 31 lead acid deep cycle batteries,   
i'm looking at a Trojan AGM 100 amp hour deep cycle battery for my Current needs.