Smart Solar 100/30 & Litime 12v 100AH Lifepo4 Voltage spikes at Absorption

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geefpv asked Jun 7, '24

Smart Solar 100/30 & Litime 12v 100AH Lifepo4 Voltage spikes at Absorption

Hi, im reasonably new to solar, but have

Renogy 200W Panel (2nd coming)

Victron Smart Solar 100/30 (fw 1.6.3)

Litime 12v 100AH Lifepo4 Battery

Renogy 2000W inverter (wasnt even powered on or any load at the time)

(the charge controller is connected to the battery by Renogy 10AWG Copper wire) all connections are secure/checked

I did a fair bit of reading and watching youtube vids and had a basic grasp, so initially i set the smart solar to rotary postiton 7 (victron default of 14.2v absorb 13.5v float)

Now my first charge was all going fine, Bulk got it up to 14.2V and triggered to Absorb, but then after a few seconds of being stable at 14.2, it started spiking to 16-17v, then back down to about 13.8, then back up to 16/17v and repeated like a seesaw I left for 5 mins but it didnt show any signs of stopping, so i disabled the charger, the battery voltage measured on a meter was at around 13.8v but slowly dropped off over the next 20minutes.

re-enabled the charger and it went to bulk brifly, then absorb and the same issue with the spiking

I reached out to litime and confirmed settings, they said the settings i was using were OK, but that they actually reccommended higher voltages!

14.4v absorb & 13.8v float

so i changed the settings to life po4 preset, and adjusted the voltages, but exactly the same!

by this time the sun was going down, i switched on the inverter and made use of the power overnight, all good!

Next day Same happened at Absorb, so i disabled charger

Next day I set down at 14v absorb, 13.5 float.... same issue!

now ive reached out to both victron support (who got me in touch with the seller of the item) and also still in talks with litime, but so far zero real answers

I dont have a second battery or charge controller to test or swap out to figure out which device is the issue? at first i though the battery.... but then why is charging bulk stable up to 14v, 14.2v, 14.4v yet the second it switches to absorb on any voltage, the spikes start?

(even tested as low as 13.8v on absorb and spikes)

(is it possible my victron has some issue with its absorb mode?) im guessing some spike trips the BMS on the battery and just keeps repeating

out of ideas and not sure which to return, the controller, the battery or BOTH

p.s last night i noticed the smartsolar android app updated and the firmware to 1.6.4, so currently today its charging up (slowly as cloudy) on the new firmware, but not holding out any hope.

thanks!

MPPT SmartSolar overvoltage fault

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geefpv commented · Jun 07 at 01:09 PM

hmmm firmware 1.6.4 may of actually done something?!

sun came out here after 10am and been bulking and 10minutes ago hit absorb, was watching and waiting for the inevitable spikes...........

i'd set a conservative 14.1v absorb and it has been there for 10mins zero spikes! rock solid so far

Will leave this absorb for a couple of hours and maybe this will help balance the cells or something and ill try again bumping it up to 14.2 over the weekend.

so maybe a false alert will update next week!

thanks

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geefpv commented · Jun 07 at 01:57 PM

well it lasted about 30minutes rock solid satable in absorb at 14.1v but now back to its spiking......... totally at a loss on what it is (but this is by far the longest it lasted with fw 1.6.4) prior to this spikes would be seconds after hitting absorb...

any thoughts? controller or battery knackered?

thanks

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screenshot-20240607-145350.png (188.7 KiB)

Sten answered · Jun 07 at 02:57 PM

Looks like unbalanced cell in the battery. Try reduce your absorption voltage to 14V and set the absorption time longer. Over time you should see an improvement. It can take long time to balance cells in a dropin battery because they mostly have a to low balance current.

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geefpv commented · Jun 07 at 03:03 PM

Thanks, I had yesterday tried down to 13.8v but immediate spikes... there is a definite change in something with the new firmware as the first absorb today at 14.1 has been mostly stable for 2 hours now (that 1 spike that quickly recovered) and stable again since.

(i think the default absorb time is 2hours so hoping it comes out soon.... or it could be 2 hours since that spike?) either way ill drain it a bit, set it to 14v and im away for teh weekend so it can just hopefully sort itself out until i get back sunday evening.

appreciate all the help!

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geefpv commented · Jun 07 at 03:09 PM

bingo, firt time it managed a whole absorb cycle and hit float (albeit for that 1 spike) wayyyyyyyyyyyyyyyy better than past couple of days, as you suggest hopefully it just needs longer absorb to balance the cells fingers crossed, again many thanks!!

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geefpv commented · Jun 10 at 09:11 AM

well over the weekend left absorb at 14.1, and both times, it was stable but 1 large spike after 30-40minutes) but back to normal....

Absorb times were set to 2 hours (so according to the battery over 14v for 2hours shoul dbe its balance cycle)

i tried going as low as 13.8 absorb and still seeing the same, hits absorb..... stable for a while, then a spike, then back to normal....

So im still none the wiser here if its the battery or the charge controller at fault

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geefpv commented · Jun 15 at 05:46 PM

Well after a week of lower voltage and long absorbs its now working perfectly back on the stock rotary 7 profile 14.2v/13.5

Zero spikes at all!

So does point to the unbalanced battery!

Many thanks for the help in sorting this!

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Answer 1 · 2024-06-07T14:19:03Z

outsourcedguru answered · Jun 07 at 02:19 PM

I don't have an answer for you but I'll note that I wouldn't use 10 AWG either in the charging circuit to the batteries nor from the batteries to the inverter. I've calculated that the maximum current would be 16A to the batteries in this case.

Go to the app, visit the SmartSolar and see the Trends tab. Set the first value at battery voltage and the second to battery current. Expand the scope of the search to the last week. Slide the image left/right until you've centered on the highest current value. Click the "..." icon, carefully slide left/right and determine the highest current value you've seen in the recent past. My own "high-water mark" for battery current is well above 20A.

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geefpv commented · Jun 07 at 02:41 PM

Hi thanks!

the specific charger to battery cable is

Renogy® 8ft 10 AWG Wire Copper Tray Cable for Connecting Charge Controller and Battery : Amazon.co.uk: DIY & Tools

I am currently only using 1 200w renogy panel, but have a second coming.

you think more than 10guage from charger to battery needed?

(as for Battery to Inverter im using the dual cables supplied with the renogy 2000w) but really only drawing small loads for now anyway, its more for future prooofing

doing a check on the current as you said... (its only been connected for 4 days) and the highest amps battery current is about 13-14a (image attached)

there is no load on this only the 200w panel charging

Also this is showing the status right now, so fw.1.6.4 has definitely made an improvement!

shows the charge up to absorb, then after 35mins or so it did start to spike, but quickly recovered and its currently back stable at 14.1v

on the previous firmware in the last few days it never managed to stay in absorb without instant spikes and it never recovered to stable.... the charger was disabled manually after 10-20mins of spiking.

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Answer 2 · 2024-06-10T11:39:52Z

Sten answered · Jun 10 at 11:39 AM

It is normal for a battery where cells is out of balance to cut the charge even with only 13,8V.

The BMS in those dropin battery mostly only have a balancing current of a 100-200mA.

So even when you charge with a low amp at 13,8V the voltage on a cell can go over the limit and the BMS stop the current into the battery.

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geefpv commented · Jun 10 at 12:04 PM

ok thanks ill keep trying for a week or so and see if it improves, from what i can see in the battery manual the "balancing" occurs after 14v, so im just going to try leaving settings for the next week to 14.02v absorb for 4 hours... 13.5v float and see if it gradually gets better.

Thanks again for the help and advice!

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Answer 3 · 2024-06-11T21:23:53Z

flyview answered · Jun 11 at 09:23 PM

I am seeing the same thing with a couple of 140Ah TimeUSB batteries, which apparently use a LiTime BMS. As others have said, it's likely the battery has a cell that gets too high in voltage even at an overall voltage of 14V. Once the BMS shuts off the battery, the controller will spike in voltage because the battery is no longer accepting it. Then it will turn back on briefly and back off, causing the spikes. What's really annoying in my setup is I have 2 batteries in parallel and if one or both shut off, one of the two may not come back on until disconnected from the other battery! I was emailing with their support and they weren't of much help, but after a few exchanges they basically said to try a lower absorption voltage.

What's been working for me is to set an absorption voltage of 13.8V. I'm hoping over time the cells will balance and I can slowly up the absorption voltage to something like 14.2V without the BMS shutting it off.

Another thing to note is that the voltage your controller sees may not be accurate if your controller is far from your battery and you don't have a Victron smartshunt sending it the true voltage. If this is the case, your controller may see a higher than actual voltage when there is a lot of power coming in. This should however, help your case, since the actual absorption voltage will be lower at the battery than what it thinks it is.

My thread on diysolarforum about this:

https://diysolarforum.com/threads/timeusb-140ah-lifepo4-tested-capacity-and-concerns.83300/

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geefpv commented · Jun 12 at 08:14 AM

Hi, thanks for the reply! Yeh as others have said here it could just need lower voltages set....(and seems to be getting better each day here now)

This was my first setup so i just expected to use the default preset 14.2v/13.5v float and be done however after seeing the spikes (at first they never recovered just spikes until i turned the charger off)

so as others have said what ive done over the last few days was to leave at 13.8v absorb until no more spikes at absorb and have slowly been upping this each day (currently at 14.05v today and will see how it goes) ive been leaving the absorb at 4hours to give more time for cells to balance (if that was whats causing it)

I've also added a smart shunt 500 today (but regarding voltage readings, i confirmed the voltage spikes with a multimeter across the battery, so i don't think its only the controller reporting the spikes)

so hopefully over the next couple of weeks the battery will sort itself out, it was just a bit worrying at first as it was my first setup, but does make sense as people say that these batteries just need a bit of breaking in at lower absrobs wile they get balanced

appreciate the help!

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klim8skeptic ♦ geefpv commented · Jun 12 at 12:21 PM

@geefpv so as others have said what ive done over the last few days was to leave at 13.8v absorb until no more spikes at absorb and have slowly been upping this each day (currently at 14.05v today and will see how it goes) ive been leaving the absorb at 4hours to give more time for cells to balance (if that was whats causing it)

You could set your mppt (or other batt charger) to float at absorp voltage. That will give more time for balancing to occur. (If you trust your batt not to burst into flames)

Many batts have weak cell balancers. Today I looked at a 100Ah batt with 35mA balancer current. If that batt had a 10% (10Ah) difference between the high cell / low cell, that would take 285 hours to balance out.

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ralphd geefpv commented · Jun 29 at 07:16 PM

@geefpv were you able to increase the voltage to 14.2V, get the cells balanced and eliminate the spikes? I’m having the same issue and wanted to see if you were successful before I try the same thing.

Thank you!

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