On Going Deals on Batteries.

Seems something's a bit fishy with his batteries--or perhaps Li-Ion is just harder to balance than LFP.  The balancers on my LFP battery bank barely do anything anymore--but they did get pretty hot the first few times. 

I'll see how soon I can get those ordered.

You would think the balancers would work hard at first, then ease off to a steady lower work rate after the bank got 'trained'.  Unless there is a significant resistance issue with some cell(s).  Or perhaps it is the outflow of power of running a house's varying loads while solar power is coming in to replace what's going out.  Seems like that shouldn't matter....

Anyway, if the heat output doesn't decline after awhile, I'll have to figure out how to vent it to outside, or maybe mount the balancers outside.

I'll take 11 of them thank you much.  Will need heat sink of course, if I need to order them and you know where I can order those as well with artic silver compond. . .

I'll take the ones I can communicate with,  I'm sure you going to have some kind of app that I can use to watch my batteries beg to die from being abused?

Umm...maybe you could connect them to your Raspberry Pi and read the RS-232 serial string and have your Amazon Alexa read it out 😉.

No app, doesn't work that way, not that smart yet.  Just an RS-232 serial output string from the lowest balancer...

What?  You Mean I got to see if I can talk to it, I mean, I can talk to it nicely or, give it the finger, but, geesh, you makeing me work for it ain't you, thats it, yes, you making me want to beg. . .  *evil Grin*

I'll give you the puppy dog face if you make a app in python for me :P. . . .

On 3/19/2021 at 10:38 PM, kazetsukai said:

The BMS shouldn't be cutting while your MPPT is charging under any (normal, recoverable) circumstances, really. The MPPT should be set so conservatively as to never reach the over voltage protection threshold.

 

I think the issue of concern here is voltage rise across one (or more) series connected batteries where the batteries do not have coordinated BMSes (inter-battery comms) or an overarching BMS watching each battery.  Unless the string charging voltage is kept well below the point at which the cell voltage start to sharply rise you will find that the voltage across one battery will rise up to the point where the BMS goes into overvoltage disconnect and halts charging of the entire string.  This would be a much lower setting than if the charger were attached to a single or parallel set of batteries.

Even quality well matched batteries can have this issue, but the cheaper ones that work fine by themselves will definitely experience it.

3 hours ago, TheButcher said:

I think the issue of concern here is voltage rise across one (or more) series connected batteries where the batteries do not have coordinated BMSes (inter-battery comms) or an overarching BMS watching each battery.  Unless the string charging voltage is kept well below the point at which the cell voltage start to sharply rise you will find that the voltage across one battery will rise up to the point where the BMS goes into overvoltage disconnect and halts charging of the entire string.  This would be a much lower setting than if the charger were attached to a single or parallel set of batteries.

Even quality well matched batteries can have this issue, but the cheaper ones that work fine by themselves will definitely experience it.

Right, and in my case, if you got a different Amp hour rateing on built batts, and or different type of cells then the exact matching, then you can run into this issue.  I found out battle born and this anytime batt I have reaches 15v, doesn't cut off, which is good, but my built ones only get to around 13.40v.  

I'm hopeing once I get my GS invertes this will balance out, though, I will have a lower voltage set. thinking of 28.8v to 24v as my sweet spot.  Don't know until I get things up and run a stress test and charging test to see how things play out.

I looked around I have some head way, enough to make one 24v small, bat 16ah, and I'mt hinking of useing it as a booster for surges, on the lead side of the batts that will be running the slave, just so it helps from the sagging of agm batts.

2 hours ago, The Blind Wolf said:

I looked around I have some head way, enough to make one 24v small, bat 16ah, and I'mt hinking of useing it as a booster for surges, on the lead side of the batts that will be running the slave, just so it helps from the sagging of agm batts.

This I would not recommend; the Lithium batteries will be getting 100% DOD cycles before the lead-acid batteries even get touched.

Also, lead-acid require different charge voltages based on the ambient temperature--but Lithium can't handle that sort of treatment. 

Basically, you'll wear the Lithium batteries out, while the lead-acid die from age or sulfation (due to undercharge.)

On 3/19/2021 at 5:45 PM, Sid Genetry Solar said:

The one with the LCD (and RS-232 string comm) will probably be somewhere around $12/ea.

Those prices do not include heatsinks, wiring, etc.  You would need 16 units for your system.

I definitely want 16 of the lcd version for lifepo4 as soon as they are available.  I have some heatsinks already that should work, and will probably use more than one fan.  Also thinking of removing the heatsinks and fans from the soon to arrive byd modules as my existing byd's don't have heatsinks and don't even get warm.  Once I double the bank size current draw per module should be too low to produce any significant battery heat.  One or two of those heatsinks would probably do it for 16 balancer modules with one or two fans per heatsink. 

Can I order the balancers now?

1 hour ago, Sid Genetry Solar said:

This I would not recommend; the Lithium batteries will be getting 100% DOD cycles before the lead-acid batteries even get touched.

Also, lead-acid require different charge voltages based on the ambient temperature--but Lithium can't handle that sort of treatment. 

Basically, you'll wear the Lithium batteries out, while the lead-acid die from age or sulfation (due to undercharge.)

Well, how about Capacitors?  I think I heard you can take two 12v and put them like a 24v batt and have no issue.  If so recommend any?

I just know these AGM batts just can't handle instent surges well,c ause the power jack showed it when I ran a washer lol.

I'm going to use the AGM batts on the slave for the moment.  I will be building another battery bank once I get neough solar panels up to provide the needed power for the main bank.  Just going to use them for a bit.  I don't want to put stress on the main bank, since its not high enough to handle over 600A more then a mintue before all the bms shut down from over power.

Is your washing machine old style AC motor or a more modern design with VFD for the motors (mains to DC, chopped to run the motor at RPM needed etc).  The reason I ask is I have a supposedly 2000W HF inverter fed by 2 x 12V 120AH standard AGMs om seroes left over from earlier adventures in solar power, and it runs my Bosch front loader with VFD motor operation without problem with its slow ramp up in current draw.  The same thing will happily start a standard AC compressor fridge too.

.... or it could just be that your PJ inverter is a bit crap 😉

Its direct drive, on and off.  and useing a 8k 12v pj.  I've litterly seen it kick the fans on just from running the washer only.  I think its just a crappy inverter, cause I got the split board to replace in it to make it a true split phase, but I've been too chicken to attempt to replace the one in it with the new board, mainly cause the way Sean was going step by step and having to rig this and that, was like oh boy. . .Also, I might have messed it up when I took it apart and looked around inside, then put it back together, as if you try to put the charging cord to it, will trip the breaker, so not sure if I got something pushing against the coil, or I drop a screw in it which I don't think I did, cause  I at the time didn'tk now how to take it apart, until after I took it apart :P.  Found out all the screws and nuts on the bottem had to be taken out and the lide would come right off.  Oh well.

Again, not really...supercaps technically also need balanced.  There is no way around lead-acid battery sag...without bypassing the AGMs with some other method (i.e. Lithium batteries, supercaps, etc.)