Battle Born Charging

[BFL13]

This might answer some recent questions.

The table is not accurate wrt to the BB comments--don't go by it by the table itself. Wade through the questions and answers to get the true picture. Takes a while to go through the comments, but that's where the info is.

https://battlebornbatteries.com/charger-compatibility-table/

[Itinerant1]

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.

[BFL13]

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.

[Itinerant1]

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.

[BFL13]

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.

[Itinerant1]

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.

[Itinerant1]

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.

[Mobilesport]

@Itenerant1
The purple covers on top of your batteries?
Look like they snap on and off easily.
And all of the slots? Is that so the battery can breath?

[Itinerant1]

Sorry not for responding sooner.

My battery system came with components that was designed for operating as a unit, not add pieces and parts as you go.

The patented BMS systems manages charging, discharging and output controls, as well as provide statuses of Lithium Ion battery packs and all individual battery cells. They also provide critical safeguards to protect Lithium Ion batteries from failures and damages.

The central processing unit (CPU) of the BMS system interfaces with sense boards (daisy chain) to obtain voltage and temperature data from each individual cell, and it interfaces with shunt sensor to read pack current. The CPU is powered by a 12V DC source. It detects ground fault error, calculates the State-Of-Charge (SOC) of the battery pack, provides video output signal for display of pack voltage, pack current, SOC level, as well as alarm status. The CPU also provides alarm outputs for protection against over-voltage, under-voltage, over-current and over-temp conditions. EMS-CPU comes with three parts: the CPU itself, a shunt sensor and a computer cable connecting between the CPU and the sense board strings.

The system as a whole looks like this.


Senseboards connected to all cells (daisy chained).

[BFL13]

Lots of good questions!

No idea how Itinerant1's monitoring set-up works that shows so many amps still being accepted at 98% SOC. He does still have loads running. A Trimetric only shows amps to the battery, but his system is somehow connected to his BMS, and it is all very peculiar, so he can explain it. Beats me.

He does seem to have 500AH for his battery bank as noted earlier where his % SOC change matches the AHs. It is not clear if that takes any heat loss into account, but is "close enough" seems like.

OK, your monitor can't tell what is going on until first you get the BB battery full, connect the monitor, set up the monitor with the AH size of the bank, and do a cycle.

Now the monitor can measure the AH going down and back up and see how many it took. It should allow for heat loss on the way back up. ( No heat loss discharging)

So without the monitor hooked up, first charge the battery as full as it can get at 14.4v setting on the converter. No loads on the battery either! (You can use the monitor for its ammeter doing this, but ignore anything else it says)

When amps get down to about 4 amps, BB says the battery is full. So if it sits there and stays at 4 amps, then those 4 amps must be going to heat. Watch battery temperature!

With an AGM , now down to its 0.5amps (per 100AH of bank) it is full at that 14.4 too. But if you leave it there, you can see the battery temp still rising. At some point amps will start back up, rising from that low of 0.5 amps. Oops! STOP that. Reduce to 13.6, you are done. (past done--stop earlier before amps start climbing again.)

OK, so what about the BB which is not an AGM? I am guessing here:

Let amps get down to 4 amps. If they go lower, let them go lower. Your battery voltage can't get any higher than 14.4, which is the converter voltage.

By now at the low amps, voltage drop will be small so compare battery voltage with converter voltage. If they are the same 14.4, the battery is full. Once amps stall at some low level, declare that to be as full as that battery can be.

Now, set up the monitor so its AH counter is at zero, set the bank to 100AH (for now) and do a cycle down to say 50%. See what happens.

By setting the monitor to Li, that probably ? sets the heat loss factor (charging efficiency) for the AH count on the run back up during charging. All being well, your AH count should match the % SOC on the way back up, and when the monitor says you are at 100% amps should be what they got down to before when you got to full.

If the monitor's AH count does not match for 100AH of bank, then your 100AH setting was wrong. eg, at 32F it would be more like 85AH, where the 100AH is only for 77F. (assuming Li is like AGMs for that) so you have to allow for that.

If temperature does not account for any mis-match, then your battery might be "aged" so it has lower capacity than when new. You can sort that all out later if need be, once the first set of numbers come in.

I see that Li batts age by loss of lithium. That compares with sulphation of a lead-acid battery and also to shedding of plates.
So expect to adjust your bank AH setting on the monitor to a lower number each year over the years. Also fiddle with it as required at low ambient temperatures if you want any accuracy that day.

Since the charging efficiency the monitor uses can be off a bit, there will be an accumulating error in its AH count when recharging over several cycles. So you have to reset that every so often by getting the battery to true full (never mind what the monitor says) and then start over with the monitor's AH counter reset to zero at true full battery.

[Mobilesport]

BfLs calculations said that I put 130 ah into a 100 ah battery, I'm curious to what his calculations would be if he calculated your chart.
BFL?

So can you use amps tapering to figure out the soc?

When I was looking at your
chart I noticed that at the
98% soc point your amps had only tapered to 57 amps , I would think that they would be closer to 5 amps or
something considering you were close to
100% soc , idk.

One way I can tell my soc is by
listening to the generator, at first when
the amps are really pumpin you can tell the generator is really working and as the amps taper the generator gets quieter and
quieter and when the generator gets to the lowest noise level the battery is full.

I got rid of the cheap Kisae capacity monitor and replaced it with a Balmer sg200.
I found the Balmer sg200 in the link that BFL posted.

The Balmer is supposed to do everything automatically after I set the
battery chemistry type to (Lifepo4) and then program (tell it I have a 100ah battery)
It's pretty easy to set the Balmer monitor up , the cheap one I never knew if it was set up correctly

I'm trying to figure out how far my amps should of tapered at the point the Balmer reads 100% soc , I'm trying to figure out if the Balmer is giving me the correct soc % reading.

I was thinking when the Balmer reached 100% soc that the amps would be real low like 3 amps.

When my Balmer reached 100%soc my amps were about 40 amps if I recall.

This is Itinerant1 chart I was referring to that maybe BFL will calculate.
It's also the one that shows the amps had tapered to 57 amps at the 98% soc point.

[Itinerant1]

I raised the incoming AC to 15a from the EU2200i ran with no issues. Just did a 2 hours of run time knowing that what little solar being produced would finish a full charge. Green/ Blue background for different days, orange for using the generator during a day.



Last one, I promise. 😉

[BFL13]

Another big factor in what size gen can do what is that the charger's load on the gen relates to the charger's output, which in turn depends on the battery's voltage at the time, rising with SOC.

Peak load on the gen is just before amps taper as you reach set Vabs (minus voltage drop at the battery)

With the Li here showing 14.2 battery at 98 amps that is 1391w output. If the Magnum is the typical 85% efficient, input would be 1637w, and with PF correction to 99 that would be 1654 in VA supply.

My non-PF corrected 75 amper pulls 1700 VA from the gen, so with the Li's lower voltage and PF correction, you get another 23 amps charging for the same gen VA supply.

Compare that with a non-PF corrected 60 amper set to 14.8 on lead-acid batts when at end of Bulk battery might be 14.5v with voltage drop. Output is 14.5 x 60 = 870w. 85% efficient, so input is 1024w. BUT the charger has a PF of 0.7, so VA needed from gen is 1462. So that 1600VA from the "2000" is where it's at for a 60 amper.

I am not happy to use the battery voltage after voltage drop instead of the converter's voltage, which is higher, when calculating output watts, but that is the way it seems to work according to past discussions and results on this topic. Using converter voltage makes the gen VA requirement higher. IMO the converter is the load the gen sees, but what do I know? 😞

[Itinerant1]

Magnum 3000w IC is 125a, I lower the AC input to 13a so it's charging at 100a +/-. I like this setting for ease of timed hold over charging.

Tomorrow I'll have throw a possible hold over charge if I do I'll adjust the AC incoming to 15a and see how it looks. Extra 25a shortens the charge time. It's supposed to rain like the dickens tomorrow but even today with rain and heavy overcast the batteries got to 81% from 68% and watched tv/ dvds good portion of the day.;)



I would do this with my other generator (eu2000i) and charge with the same results, I have set the incoming to 15a but you could hear the generator working hard.

[BFL13]

Mobilesport wrote:
@ Itinerant1
Isn't your battery charger around 120 amps?
If so I'm surprised that your Honda 2200 is powerful enough to power your charger.
I think the maximum battery charger i can use with my Honda 2000i is about a 75 amp battery charger .
Anyways excellent chart.

He said his Magnum was dialed down to 13a(120v) so it would run off the 2200, and it was doing about 98 amps. Since the Magnum is PF -corrected, the 98 amps was not too much for the 2200 (1800w running)

(He was getting another 10-15 amps from solar.)

I doubt the 2000 (1600w running) can run a 75 amper. My B&S P2200 (1700w running) can just manage--with overload light flashing the whole time until amps taper to 68, when lamp finally turns steady green--- my non-PF corrected 75 amper set to 14.8v. Expect a 60 amper is the most for the 2000.

Sadly, there are few chargers under 100 amps that are PF corrected, since you can run up to a 75 with a 15a circuit. (PD 80 needs a 20a circuit)

[Mobilesport]

@ Itinerant1
Isn't your battery charger around 120 amps?
If so I'm surprised that your Honda 2200 is powerful enough to power your charger.
I think the maximum battery charger i can use with my Honda 2000i is about a 75 amp battery charger .
Anyways excellent chart.