Free 7 Day Trial RV GPS App RV Trip Planner Campground Reviews RV Maintenance Free 7 Day Trial ×


Reply
 
Thread Tools Display Modes
 
Old 10-12-2021, 03:46 PM   #1
Mini-Skoolie
 
Join Date: Mar 2021
Posts: 13
Making the right call on batteries

Okay, so for the past several months I was planning on getting 8 Duracell 6v FLA batteries in a 4s2p system for a 430AH 24v battery bank. I recently discovered that there are ampere, chins, or zooms LiFePo4 batteries that are only about 1.5x the cost for the added benefits that LiFePo4 has.

I was looking at the 12v 200AH batteries that have a 100a discharge.

When two of those batteries are put into series, i would get a 24v 200AH battery bank but it would still be limited to 100A discharge.

If I understand amperage and voltage correctly, this should mean that the maximum discharge of the batteries would be 100A*24v=2400W. Is that going to be a problem for my 2.4kW LV2424 inverter charger?

I really want to make the right decision here. I would prefer not to pay more for 4 12v 100AH batteries. 4 12v 100AH batteries in a 2s2p configuration would give me a 200a discharge which would also supply about 200*24=4800W but would cost me more money in the batteries and cables.

Or would spending less by going with the 8 6v FLA batteries be a better decision given the fact that I am very price conscious here and I may only be living in the RV for about 5 years. (FLA CAN last that long if maintained correctly). The FLA battery total would be ~$900. Total on the 2 Ampere LiFePo4 batteries would be $1500. 4 of the smaller Ampere LiFePo4 would be ~$1750 and the $1750 really feels like too much of an increase to justify the change to LiFePo4.

Ross&Hailey is offline   Reply With Quote
Old 10-12-2021, 03:59 PM   #2
Bus Geek
 
Join Date: Nov 2016
Posts: 2,515
The payoff for LFP is half the weight and volume

possibly longevity but cared for properly those Deka will last 7-8years anyway, just get them to Full as per trailing amps spec 0.05C,

and try to keep them from discharging much under 50% SoC, too often

Sam's Club and Batteries+ are good sources, maybe $2/Ah @24V

Your inverter will only pull a bit more than the attached AC powered devices, so under your control. Short peak bursts I think the EPM GCs will do fine.

Cheap LFP might not even give you much over 3000 cycles even with coddling

and that assumes no "events"
john61ct is offline   Reply With Quote
Old 10-12-2021, 04:05 PM   #3
Mini-Skoolie
 
Join Date: Mar 2021
Posts: 13
Thanks John. I've posted this to a few places and honestly expected people to recommend the LiFePo4 but surprisingly, just about everyone has recommended the FLA. I'll be happy to save the money then.
Ross&Hailey is offline   Reply With Quote
Old 10-12-2021, 04:52 PM   #4
Bus Geek
 
Join Date: Nov 2016
Posts: 2,515
There's no question LFP is "better" and many just love their bleeding edge gadget tinkering for its own sake.

But from a purely economic POV hard to justify an ROI that takes decades.

Now a racing yacht, where every kg counts, that's a different story!

Or where solar is not the main input and you want to recharge in an hour...
john61ct is offline   Reply With Quote
Old 10-12-2021, 06:42 PM   #5
Mini-Skoolie
 
Join Date: Mar 2021
Posts: 13
Quote:
Originally Posted by john61ct View Post
There's no question LFP is "better" and many just love their bleeding edge gadget tinkering for its own sake.

But from a purely economic POV hard to justify an ROI that takes decades.

Now a racing yacht, where every kg counts, that's a different story!

Or where solar is not the main input and you want to recharge in an hour...

I really appreciate the wisdom John!
Ross&Hailey is offline   Reply With Quote
Old 10-12-2021, 07:26 PM   #6
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 15,573
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
I see everyone going FLA? Why that over AGM? I’ve been running AGM without issues .. are FLA better batteries?
cadillackid is online now   Reply With Quote
Old 10-12-2021, 07:45 PM   #7
Mini-Skoolie
 
Join Date: Mar 2021
Posts: 13
Quote:
Originally Posted by cadillackid View Post
I see everyone going FLA? Why that over AGM? Iíve been running AGM without issues .. are FLA better batteries?
Technically AGM are the same technology as FLA. The difference is that AGM are sealed and you can't perform maintenance on them due to being sealed. FLA batteries are not sealed which means they will off gas but you can maintain them which means they will last quite a bit longer than AGM if maintained correctly.

Another bonus is that FLA are WAY cheaper than AGM.

Hope that helps. If you already have AGM, i wouldn't worry about it too much.
Ross&Hailey is offline   Reply With Quote
Old 10-12-2021, 07:53 PM   #8
Bus Geek
 
Join Date: Nov 2016
Posts: 2,515
Quote:
Originally Posted by cadillackid View Post
I see everyone going FLA? Why that over AGM? Iíve been running AGM without issues .. are FLA better batteries?
FLA is cheaper up front per Ah, and since it lasts longer much cheaper per year as well.

Not nearly as fussy in its care requirements, more robust and tolerant of abuse.

Only downside (some think) is the need (ability) to replenish water / electrolyte. But access to measuring Specific Gravity is IMO a plus.

But just like with VRLA (GEL and AG) there are only a few quality makers of true deep cycling units, often more expensive and unavailable in consumer retail and automotive channels.

EPM/Deka/Duracell happen to be an exception, both cheap and great quality.
john61ct is offline   Reply With Quote
Old 10-12-2021, 07:54 PM   #9
Bus Crazy
 
Join Date: Oct 2020
Location: Near Flagstaff AZ
Posts: 1,091
Quote:
Originally Posted by cadillackid View Post
I see everyone going FLA? Why that over AGM? Iíve been running AGM without issues .. are FLA better batteries?
I think one of the reasons is that there seem to be more true deep cycle FLAs out there, like the ubiquitous L-16s, which have thicker plates than the AGMs I often see used...which are sometimes also labeled "marine deep cycle" batteries. A true deep cycle battery, and most golf cart batteries, have plates which are considerably thicker than the "marine deep cycle" type. I'd not use the "marine" AGMs in a true off-grid setup at a house or village.

Having said that, I've had great luck with the Duracell "marine deep cycle" 100ah AGM Group 31 batteries I've bought at Sam's Club. I recommend them often.
rossvtaylor is offline   Reply With Quote
Old 10-12-2021, 08:17 PM   #10
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 15,573
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
I already had AGM for starter and a couple for my house.. then my business partner and I scored a rack of 48 group 31(100 ah) AGMs that were a year old (we pulled them out 6 months ago).. so now I have 4 of them for house and a bunch to do ?? … they seem even better than the batteries plus blue tops I had previously.. they are technically UPS batteries (datasafe). Hopefully they can stand the cold and won’t freeze.

Is there ever a time you’d need to open an AGM? I thought the fact they are sealed means you don’t need to put water in them.
cadillackid is online now   Reply With Quote
Old 10-12-2021, 08:20 PM   #11
Bus Geek
 
Join Date: Nov 2016
Posts: 2,515
Yes best value batts on planet Earth, deep cycle golf cart batteries, 2x6V, around $200 per 200+AH @12V pair

labeled Duracell or Deka/East Penn, from BatteriesPlus as well

NAPA relabels them here: https://www.napaonline.com/en/p/NBP8144 Deka self-labeled also sold at Lowes.


comparable to Trojan T-105 but cheaper

_____
The Trojan L16RE-A last quite a bit longer than either if you don't make a habit of drawing below 40-50% too often

just not quite as cheap

Rolls/Surette, U.S. Battery, Crown, Superior are the other quality FLA makers of true deep cycling batts in the NA market.

Every other make are using that "marine" & deep cycling label fraudulently.

Nice rant here from MaineSail, thoughts and prayers Rod

https://marinehowto.com/what-is-a-deep-cycle-battery
john61ct is offline   Reply With Quote
Old 10-12-2021, 08:22 PM   #12
Bus Geek
 
Join Date: Nov 2016
Posts: 2,515
Do not open any SLA or VRLA sealed lead.

UPS type is **very** different from deep cycling

but hey if cheap enough and working OK use them until they die why not, for non mission critical use case.
john61ct is offline   Reply With Quote
Old 10-13-2021, 01:15 PM   #13
Skoolie
 
shaymcquaid's Avatar
 
Join Date: Jul 2018
Location: Just south of Dallas.
Posts: 165
Year: 1999
Coachwork: Thomas
Chassis: 40' MVP-ER
Engine: Cat 3126
If you are really razor thin on your budget acid batteries will work, ofc.

But if you were to wade in to simple diy lipo4 battery bank you can blow flooded batteries out of the water.

Remember...its bad to go below 50% with flooded batteries.
(I had them on my cabin cruiser boat.)

I've built a diy lipo4 bank and I'm not looking to the past any longer.

Good luck with what ever you decide.

oh P.S.,
The ah rating doesn't reflect the discharge capability.
Discharge capability is measured in ''C" on the data sheet.
shaymcquaid is offline   Reply With Quote
Old Yesterday, 11:44 PM   #14
Skoolie
 
Join Date: Jun 2021
Location: Baja often, Oregon frequently
Posts: 176
Year: 1996
Coachwork: Our hot little hands...
Chassis: Ford CF8000 ExpeditionVehicle
Engine: Cummins 505ci mechanical
Quote:
Originally Posted by Ross&Hailey View Post
...AGM are sealed and you can't perform maintenance on them...
.
We built our Concorde LifeLine AGM bank new in early-2003 ('2002' is molded into the cases)
.
Wearing goggles, every year or so, I pry the lid (under the decal), and un-screw the six cell-caps to verify the fluid level.
.
Nearly two decades, four of our original eight are still puttering along.
I think the key to longevity is using a couple-three percent during peak photovoltaic hours, then immediately re-filling.
LargeMargeInBaja is offline   Reply With Quote
Old Today, 02:28 AM   #15
Bus Nut
 
Join Date: Dec 2018
Location: Mt Vernon, WA
Posts: 506
Year: 1996
Coachwork: Bluebird, Collins
Chassis: G30 Bluebird Microbird, E350 Shuttle Bus
Engine: 1995 Chevrolet 350, 1992 Ford 460
I manage some Lifeline AGM batteries. Two questions: Did you ever need to add water when you inspected the cells? And please explain what “couple-3 percent” means? Does that me 33%? Thanks.
Doktari is offline   Reply With Quote
Old Today, 03:07 AM   #16
Skoolie
 
Join Date: Jun 2021
Location: Baja often, Oregon frequently
Posts: 176
Year: 1996
Coachwork: Our hot little hands...
Chassis: Ford CF8000 ExpeditionVehicle
Engine: Cummins 505ci mechanical
Quote:
Originally Posted by Doktari View Post
...Lifeline AGM...Did you...add water...what ďcouple-3 percentĒ means? Does that me 33%?...
.
Good points!
.
a -- the bank rarely needs water, at most maybe a couple-three times a decade.
Based on our experience, if any cell needs water more than a couple-three times a decade, that might indicate an issue with THAT INDIVIDUAL CELL.
.
b -- using our invertors during peak photovoltaic times -- noonish-3pm -- we are merely pulling through the bank.
I use the amount 'a couple-three percent' as an approximate use.
A specialized tracker could show if our use is one-percent or if we use 6.73-percent of our full bank.
So far, we avoided needing a specialized tracker.
Some things are less important to us.
.
Irregardless, our photovoltaic provides the juice.
The bank is merely in the way -- a buffer -- between our roof-mounted genset and our appliances.
.
As you might imagine, using electric appliances outside of peak photovoltaic would empty our bank quicker, working the bank harder, and potentially toasting our bank.
We are prolonging replacement until the final battery of the original eight goes toes-up.
.
Mind you, we have six (6) 305-Watt panels for a total of 1,830-Watts, so we usually fill as fast as we use.
LargeMargeInBaja is offline   Reply With Quote
Old Today, 05:56 AM   #17
Bus Geek
 
Join Date: Nov 2016
Posts: 2,515
means 2% to 3%
john61ct is offline   Reply With Quote
Old Today, 08:19 AM   #18
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 15,573
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
Quote:
Originally Posted by john61ct View Post
Do not open any SLA or VRLA sealed lead.

UPS type is **very** different from deep cycling

but hey if cheap enough and working OK use them until they die why not, for non mission critical use case.

so far they are way out-performing the blue-tops I had in the bus.. my usage of them is not likely to run them down very far.. I programmed my victron charger with the datasheet for the batteries.. while my bus alternator will charge them partially when I have been parked, the victron is ultimately how they will get topped off each night when plugged into the shore power.



since they were free and my blue-tops while doing the job were 5 and a half years old i decided to put some in.. we will see how they do this winter..



what is different about UPS AGM batteries than regular AGM marine style?



-Christopher
cadillackid is online now   Reply With Quote
Old Today, 09:11 AM   #19
Almost There
 
Join Date: Feb 2019
Location: Portland, OR
Posts: 80
Year: 1994
Coachwork: N/A
Chassis: Chevy
Engine: N/A
Rated Cap: 14,000lbs
Quote:
Originally Posted by rossvtaylor View Post
I think one of the reasons is that there seem to be more true deep cycle FLAs out there, like the ubiquitous L-16s, which have thicker plates than the AGMs I often see used...which are sometimes also labeled "marine deep cycle" batteries. A true deep cycle battery, and most golf cart batteries, have plates which are considerably thicker than the "marine deep cycle" type. I'd not use the "marine" AGMs in a true off-grid setup at a house or village.

Having said that, I've had great luck with the Duracell "marine deep cycle" 100ah AGM Group 31 batteries I've bought at Sam's Club. I recommend them often.

May I chime in with an honest query?
I'm also at the point of dropping a lot of cash on my batteries and have looked at a LOT of different options so this discussion interests me.



There's no Sam's club within 100 miles of me and they won't show me the price even (rude!) but if I look up those AGMs I'm seeing them for between $250 and $350 for 100AH. Since you can only discharge AGMs safely to 50% I'd need two of them for 100AHs of usable charge, so a total of between $500 and $700.


You can now get very good LiFeO4s for around $350 for 100Ah and you'd only need one for 100 usable Ahs. The difference in weight is pretty significant too: 23lbs vs 174lbs.


So I can only think I must be missing something else - is it just a reluctance to use newer tech? Or are people not realizing just how cheap reliable Lithium is now?



(My source for choosing a lithium battery is Will Prowse, who clearly knows his electrical stuff and recently disassembled several of the cheaper new batteries to see what they were made of )
ladybird_bus is offline   Reply With Quote
Old Today, 09:32 AM   #20
Bus Geek
 
Join Date: Nov 2016
Posts: 2,515
Blue tops are no more suitable for true deep cycling usage than

the usual fraudulently labeled AGM sold in consumer retail.

Batteries designed for standby / UPS power are also not deep cycling batteries.

Only the FLA Duracell (EPM / Deka) are good for deep cycling.

LiFePO4 of good quality are not cheap, at least 7x the cost per usable Ah. Yes if nothing happens for 20 years good value but that's a ling ROI.

Will P is a YouTuber, with all that implies. No real expert, but he has learned a lot in recent years, and despite some basic errors, his videos do help people learn the basics.

If you want true deep cycling longevity in AGM, Lifeline, Northstar and Odyssey are the three good ones in the NA market.

Call them and ask for a distributor near you, do not pay for shipping.
john61ct is offline   Reply With Quote
Reply

Tags
batteries, batterybank, fla, lifepo4, solar

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 04:40 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2021, vBulletin Solutions, Inc.