Battle Born Charging

BFL13 wrote:

See the UB12100 110AH AGM for $210, at $1.9/AH and the
Espion360 120AH Li for $1,340 at $11.17/AH

So 11.17/1.9 = 5.88 times, not 4 times more per AH. But the point is usable AH.

Now let's put it in perspective some.

I'm going to use the info you posted for figuring #s but there are cheaper batteries to be had for this discussion.

I got my AGM info here for life cycle count, please correct me if wrong.
https://www.solar-electric.com/learning-center/deep-cycle-battery-faq.html/

"If"
AGM 110ah @ $210.00
500 cycles @ 80% DOD = 44,000ah, .004 cent per ah.
1000 cycles @ 50% DOD = 55,000ah, .003 cent per ah.

"If"
LFP 120ah @ $1,340
2,000 cycles @ 80% DOD = 192,000ah, .006 cent per ah.
3,000 cycles @ 70% DOD = 288,000ah, .004 cent per ah.

But now using 80% you need to replace the battery 4.36x ($915.60) or 50% compared to lfp 70% you'll need replacing 5.26x ($1,098.30). I'm sure during the time that AGM batteries are being replaced inflation might effect the price.

Now do you see the LFP is not 4x or 5x as much?

Some people buy 150K cars. Do they get to their destination faster?

But the real answer lies in the future. Fractions of pennies per kWh delivered during their life span.

In January of this year we went from 420 AHr of AGM to 300 AHr of LI.
Changed nothing else...Same solar (1050 watts) Same solar controller (80 Amp mppt).
Biggest difference are:
1. saved 170# of weight
2. voltage drop througout discaherge is much more level and higher.
3. Had to re-program the solar controller for LI
4. Now turn off the converter at home and let the solar do all the maintain.

I went with BattleBorn after seeing some youtube videos of their manufacturing processes and seeing one of their batteries disassembeled.

Based on my experience so far I am not sorry for the change :B

Housted

On drop-ins looking here:

http://www.bestconverter.com/AGM-and-Lithium-Deep-Cycle-Batteries_c_283.html

See the UB12100 110AH AGM for $210, at $1.9/AH and the
Espion360 120AH Li for $1,340 at $11.17/AH

So 11.17/1.9 = 5.88 times, not 4 times more per AH. But the point is usable AH.

True about usable AH that there is more with Li, but how much more? There is a debate on what the range is for Li to do say 20-80s or to do 20-100s or whatever. A 20-80 is 60%. You can do 40-100s with AGMs.

Number of cycles at a chosen SOC range might be a better way to compare them for intended use, haven't got into that.

Noted about weights and how often needed to go to lower SOC down South in winter, and resulting gen times as a factor.

More people with stakes in Li for RVs should provide their thoughts as an aid to others who are considering Li.......

First you need to figure the equivalent of power so LFP 500ah is 400ah usable. What would be AGM be 600, 700, 800ah?
Now what is the weight difference? My entire system weighs 500#, the 5 batteries weigh 143# or under 30# each. Weight as we all know is a factor, more so as a fulltimer.

During good solar days in spring, summer, fall they are fairly shallow unless there is a stretch of rain/ overcast days, but late fall to late spring they are not shallow with shorter daylight, the DOD can be 40-45% so this is where the LFP start to show their benifits, are your agms powering 80-150a loads for 10 minutes at a SOC of 30-80% before shutting down the system and having to drag the generator out? As I have stated in a year I might use a generator maybe a dozen times for a hold over charge of 2 hours (200ah/ 40%) can agms do this without shortening the life or at the very least you will have to plugin to a shoreline for equalization/ run the generator for a looooong period?

Can you start an evening at 60-80% SOC and not worry about the next day power "wants"?

This is where it becomes questionable as far as cost. My batteries cost $3,550 after the 30% tax credit 4 years ago. If building your own batteries now this can be done probably at 1/2 this price if not more. Dropins are not a good deal financially but the ease of "simplicity" comes at a cost.

This is what I found in a quick search for agm battery, just a rough cost factor but LFP are not 4x the cost.
Lifeline 6v 400ah (119#) are $690 x2 =$1380 (12v 400ah), 12v 800ah (476#) is $2760 +/- .

Weekend warriors probably not worth it unless weight is a factor and money is not.

The way I'm living/ boondocking there is no dought in my opinion LFP are better than agm. Last strech of boondocking without hook ups before having to get some work done on the 5th wheel was 1,072 days, we're on day 122 of this strech of boondocking.

Standing back and looking at your day, how would it be any different if you had 500AH of AGMs instead of the Li batts? (over the year since every day is different for solar etc)

Not saying this is how it is, but wondering what your own analysis is on how your Li time would compare with the same time only with AGMs instead.

Whatever the benefits of Li are, do you see much of that really? Eg, you are going to full with shallow cycles which AGMs would like too, and your charging amps are not so high, being what AGMs could take too.

Say you had 500AH of AGMs and after four years doing your routines (AGMs not getting a true full charge often enough say), they now need replacing, but the Lis are still going strong.

The Lis cost say four times what the AGMs cost, so if the Li batts last sixteen years you just break even on money? If the Lis get too low at eight years, you paid twice as much as for AGMs? Eight years seems what those boat guys got?

Perhaps Lis would better suit somebody with less solar to take advantage of operating at lower SOCs or whatever? Perhaps there is a threshold for how much solar Lis would be no better than AGMs but just cost way more?

Just thinking there must be some way to figure out whether it is worth it to go Li depending on your RV set-up and lifestyle.

Using solar to charge/ carry loads I wouldn't want to shut the power off going to the batteries.

Using it as a day to day power source, its a different story. Set the solar controllers float voltage so it covers the loads, but are putting in essentially zero amps.

This way you are not throwing away your excess solar. I've been reading for years posters saying you need to charge to full and then turn off your charge sources.

Turning off your solar would be crazy as you would be throwing away good power and unnecessarily cycling the batteries.

This works for me as a fulltimer boondocking all the time cycling the batteries everyday. For most folks that use their trailers for a few months or plugin more than boondock/ dry camp using a one size fits all charging source maybe floating will stress the cells in the battery so under those circumstances floating is bad.

Interesting set of figures. Sure helps being farther South for solar.

A few days ago at 49.1N I was getting about 30 amps from my 830w at high noon. In May I will see more like 46 amps.

Not able to get accurate AH count in your table vs SOC change. With the numbers changing so much can't average, don't know how long amps stayed as read. It is better to report the accumulated AH with each SOC reading to get a match.

I am having trouble deciding if that would be valid even so. The SOC at the start of the AH count has not been independently determined. Your numbers are internally consistent, but they would be. Hmmmm.

Anyway four years doing that counts as success for sure. Big thing is you don't mind going to full every day, while some are suggesting not to do that for longer Li battery life.

How would you control that if you wanted to? You would have to shut off the solar going to the battery while still letting solar run the loads in the afternoon. Can't do that with some solar controllers like Morningstar.

Here are readings from charging only with solar, at 09:30 the fridge was turned over to electric (cycling through out the day). It just happened that at the recording times the fridge was consuming power every time. Unless it's an overcast/ rainy day this is basically the way the system is used everyday the rest of the year till fall sometime. I didn't add any readings from the microwave use during the day it would just add another 144a inverting on top of the other loads during that period of time.

I did turn the fridge off 12:47 after that reading just show the extra amps charging even at that high SOC (I would normally just leave the fridge on electric till the end of the day), then turned it back on at 13:00 just when the absorbed end and the float started. I would leave the fridge on cycling to roughly 95% SOC before switching back to propane, doing this extends the refill time on a 30# tank from 17-19 days to 23-25 days.


If you add the "charging" amps from the GBS display to the "Inverting" amps (loads being powered) that will show the total being produced.

Example at 09:31 18.9a (charging), -30a (loads)= 48.9a from solar (659 watts).

After switching to float the inverting loads are being covered by solar.




Here are solar production from past days.

Yes they do snap into place on each individual cell. They're there to protect the cells so nothing can be shorted across them, a nice feature for this particular brand.