Replacing my agm cell tower batteries

Hi,
I have been fighting with my cell tower batteries for too many years. I would like to go lithium, but there are so many choices.

I have a 48 volt outback solar setup. Flexmax 80 connected to 9 250w solar panels. The inverter is a FXR2348E.

I’ve been running into battery issues with aging agm cell tower batteries.

My loads are:

All LED high hats
Efficient refrigerator
½ horse water pump used sparingly
1 60” tv with Roku
Washer/dryer
Dishwasher

My ethernet connection on my mate3 took a dive for the second time. So I don't have any stats from opticsre.
I have a generator that can take the larger sustained loads if the cost of batteries is too high. Cabin is used on the weekends.

Thanks

Bump.

Before anyone can recommend anything, you need to know your requirements.

Your inverter also has a continuous draw of around 15-20W (guesstimate based on size). That really adds up in 24 hours.

The dryer is a mega load at 2-3kW typical.

Your FM80 should still keep something like 120 days worth of logs accessible through the unit's menu. This will record daily kWh harvest as well as battery voltage limits and should be a good reflection of your use.

If you've ran your generator, an estimate of power use can be gleaned from the amount of fuel you used based on genny specs.

Between the two, you could build a good picture of your needs over something like a 30 day period.

Cell tower batteries may not be a good choice as they're often designed for backup only - they live life floated and are capable of a handful of high current deep cycles to provide backup power. They tend to have poor cycle life even at only 50% depth of discharge. Their poor performance in this application likely contributes to your troubles. They are something of a blend between starter and deep cycle batteries.

Thanks I will get some detailed information. I have to get my replacement mate3. The network card fried again..

Here is some usage from the past 3 days.
For the heavy loads I can use my generator. Dryer and water pump.
Thanks.

What do you think about this pack?


He said I was able to add more packs to increase output.

Should I get a BMS or will my outback charge controller handle the charging properly?
Thanks

Absolutely don't buy that pack. You need to be an expert to handle it (toxic, flammable, explosion risk), and the seller's "not LiFePO4 junk" comment is complete shite.

The 48V claim conflicts with the description.

2kWh is probably kinda light.

What is your existing AGM capacity?

My current batteries are 4 deca unigy 170ah.
They are totally shot and I bought them used. Never worked properly.
Thanks

4 * 12V * 170Ah = 8.2kWh

If those were working properly, they would likely meet your needs for a few days without solar if I'm interpreting your usage chart correctly.

Big Battery has some LifePO4 (LFP) batteries with BMS for a pretty reasonable price. It would be a much more turnkey solution.

This is the only LiFeP04 battery they had in stock.

I don't a warrenty listed for it. I guess I will contact them.
Any other suggestions on batteries?
Thanks

" BigBattery offers a 30-day warranty from delivery date on all of our products. "

I am likewise watching for an affordable second-life 48V battery pack.

The A123 lists a nominal Voltage 42.9V and max charging of 46.8V.

Not sure how well it would play with my 48V golf cart, solar panels and inverter.

Sorry. I missed the A123 is 13S. Disregard it.

48V golf cart? What are you talking about?

snoobler said:

Sorry. I missed the A123 is 13S. Disregard it.

48V golf cart? What are you talking about?

Click to expand...

Show & tell
https://diysolarforum.com/threads/g...st-with-four-hqst-12v-100w-solar-panels.6984/

Mixing FLA/AGM with Lithium is a bad idea in the vast majority of cases. If you needed to join them for an emergency/temporary situation, that's one thing, but planning for it as a matter of course it just a bad idea.

snoobler said:

Mixing FLA/AGM with Lithium is a bad idea in the vast majority of cases. If you needed to join them for an emergency/temporary situation, that's one thing, but planning for it as a matter of course it just a bad idea.

Click to expand...

Will replace the old FLA set with an affordable second-life lithium set. If I keep the existing FLA around they will be repurposed on a separate system.

While looking through this forum I found this pack.


Would it be a good fit my my case?
Do I need a BMS with my outback equipment?

Thanks for the help.

Not sure. I don't know those batteries. Search the site for BYD to see others' experience.

snoobler said:

Absolutely don't buy that pack. You need to be an expert to handle it (toxic, flammable, explosion risk), and the seller's "not LiFePO4 junk" comment is complete shite.

The 48V claim conflicts with the description.

2kWh is probably kinda light.

Click to expand...

I am a new member as of today, joining to share my experience with the Chevy Volt batteries pictured above. I bought two of them to replace the dead Trojan batteries that were in my 2008 Club Car Precedent golf cart when I bought it a couple months ago, so I have to admit I knew NOTHING about golf carts and NOTHING about Lithium ion batteries when I bought them to power the cart. Long story short, I installed them, tested the cart once (and it drove perfectly), then left it in the driveway for a couple of months while I waited for a properly programmed Schauer charger to arrive.

When I lifted the seat up a couple days ago, I encountered the scenario you see in the photos. One battery was significantly accordioned, the other was horribly so -- I had to gently crowbar it out of the battery compartment, wearing as much protective equipment as I could find. So I have to second Mr. Snoobler's opinion that these are hardly a plug'n'play option for lithium-powered golf cart neophytes like myself. I have them sitting as far away from danger as possible until I can safely dispose of them, and consider myself fortunate that they didn't explode.

And now I'm curious to know if anyone else has had similar experience with these or other Li Ion batteries in other off-label applications. I've searched a popular golf cart forum and found one other instance but with different batteries. I'll be happy to provide what details I can if anyone is interested.

Sadder and marginally wiser...

If you were considering $600 for 2 kW lithium batteries,
you could spend $1200 for 5 kWh AGM, SunXtender. Cycle life is supposed to be about 5000 cycles 15% DoD or 500 cycles 80% DoD.
How many kWh do you expect to draw at night? Ideal would be to operate heavy loads during the day while batteries remain full.
I use mine (now a 20 kWh bank) for grid backup so they normally just float. Have so much PV I can run anything in the daytime, with batteries only providing starting surge, everything else from PV.
I think lithium becomes cost effective if it will cycle deeply for 10 years. If cycling is shallow enough that AGM has 10 year life, then it could be cheaper.