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Battery: 13.37 volts on multimeter; 10.4 volts on Controller remote meter?

jesfl

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May 17, 2020
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Will someone please explain to me how the heck a lithium battery can test 13.37 volts with a multimeter . . . and then 2 minutes later when connected to my system and my EPEVER Tracer 4215BN cause a low battery alarm and read 10.4 volts?

(1) For four straight days, I charged my 12-volt 150Ah LiFePO4 battery using the 10 amp battery charger that came with it. (I cannot get it to charge using with my Tracer controller.)

(2) It was charged to 13.36 volts two days ago. This morning, after two more days of charging, it added 0.01 to the charge, to 13.37 volts. All testing with my multimeter. Obviously, the battery is not going to charge to a higher voltage.

(3) So as a test, I connected the battery to my system with my Tracer controller. IMMEDIATELY there was an alarm from my inverter (low battery). The MT50 remote meter for the Tracer controller showed 9.1 volts, then after 4-5 seconds it read 9.7 volts, and a few seconds later it increased to 10.4 volts and stabilized there. To silence the alarm, I turned on the solar panels and the Tracer immediately signaled a full battery and charged at a full battery low 1-2 amp rate.

(4) After 7 hours of charging in bright sun, I turned off the solar panels and the MT50 meter again read 10.4 volts!

(5) I then, again, disconnected the battery completely from the system and tested it with my multimeter. It read 13.36 volts.

How is this possible?

What is happening?
 
How is this possible?
Sounds a little odd but let me ask a couple questions to see if something offers some clues.

First, 13.37v would be about 75% (very rough) charge. Did it settle to a lower voltage after charging?
Was this measured while a charge was being applied to the batteries? ... if so, that will be artificially high as
the charge voltage is part of what you are reading.

Any history on your batteries/cells? Brand, age, anything interesting we should know?

>>(4) After 7 hours of charging in bright sun
What panels? How wired and what charger?

Happen to have a pic of your setup?

My initial guess would be that your battery is not being charged enough. It should readily charge to 14v or so to be sure its been fully charged.

Maybe your answers will point out something someone can grab onto...
 
10A charger should take 14ish hours to charge a 150Ah 12V battery to full.
13.7V is 3.42V per cell
Charger should be outputting 14.4V to get a full charge.
If the charger is only putting out 13.7V it won't charge the battery fully.
 
Thank you to both of you.

Answers to the MisterSandals questions:

"First, 13.37v would be about 75% (very rough) charge. Did it settle to a lower voltage after charging?
Was this measured while a charge was being applied to the batteries? ... if so, that will be artificially high as
the charge voltage is part of what you are reading."

-- After charging, the batteries settle 0.01 to 0.03 volts. Checked several days in a row.
-- Measured with 2 different multimeters with batteries totally disconnected from everything.

"Any history on your batteries/cells? Brand, age, anything interesting we should know?"

Long story in previous beginners post. Briefly, I have 3 -150 LiFePO4 batteries, first used in late August of last year. Off-brand Chinese, my bad decision to buy those. My DIY system (per Will Prowse beginners' model) worked perfectly for 4+ months, Then batteries died and will not charge. In previous post, others suspected controller and/or BMS in the batteries? But, all 3 BMS units and/or batteries going bad simultaneously just makes absolutely no common sense to me. Everything is properly fused/breakered. No fails there.

">>(4) After 7 hours of charging in bright sun What panels? How wired and what charger?"

8 - 100 watt panels, 2 strings of 4 wired series-parallel. Regularly seeing mid-70 volts and 10-11 amps in AZ sun on remote meter for controller. EPEVER 4215BN 40 amp solar charge controller. With help from Forum, I have tried three different sets of lithium settings in the controller setup. No difference.

The chargers (3) are apparently 10 amp unit that came with each battery. I don't know how to test to see if they really generate 10 amps?

Note: I failed to mention that, at first, I left the Tracer controller at factory settings, because I thought that was the right thing to do for a beginner. Will Prowse's words in his setup video were something like: "I love this controller . . . (and something like) . . . don't change setting in the user setup because it's too complicated for beginners . . .". In a previous discussion, others believed that setting could have been the problem? But, again, worked fantastically for 4+ months, Now reset to User/lithium settings.

"Happen to have a pic of your setup?"

Two months old pix (attached). Some changes are ongoing in process of elimination attempt. None have solved the problem. Battery cables upsized from 1/0 AWG to 2/0 AWG. All wires shortened. Wires from batteries shortened to 2.5 inches. PV panels to controller 10 AWG, 13 feet. Now controller to battery increased from 10 AWG to 6 AWG. Previously tried taking out busbar connections and directly bolting everything to batteries. No change.

"My initial guess would be that your battery is not being charged enough. It should readily charge to 14v or so to be sure its been fully charged.

Maybe your answers will point out something someone can grab onto..."


Thank you. I'm open to ANYTHING

Response to Supervstech


10A charger should take 14ish hours to charge a 150Ah 12V battery to full.
13.7V is 3.42V per cell
Charger should be outputting 14.4V to get a full charge.

If the charger is only putting out 13.7V it won't charge the battery fully.

So solutions? Beginner here. How do I test the charger to check output? Boondocking in AZ desert. No 120V power except genset. Buy another lithium 120V charger & run genset? If so, what (inexpensive) lithium charger via amazon.com or Walmart does someone suggest?

Any other "process of elimination" testing or system modification suggestions?

Thanks again to all.
 

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Folks,

FYI, this is the charger that came with the battery and that I have been using in the attempt to charge the batteries. See attached. No other details/specs.BtrPower Lithium Charger S.jpg
 
My DIY system (per Will Prowse beginners' model) worked perfectly for 4+ months, Then batteries died and will not charge. In previous post, others suspected controller and/or BMS in the batteries? But, all 3 BMS units and/or batteries going bad simultaneously just makes absolutely no common sense to me. Everything is properly fused/breakered. No fails there.
This is vaguely familiar. But the history was an important part missing from this thread.

I am guessing that your battery warranty period or any expectations of help from China are over. I think if you can isolate a single battery and determine its bad, opening it might reveal something. I've had nickel strips completely rusted (yea i know, they shouldn't rust) on battery packs. Possibly something you can identify as a failure point and possibly something you can fix.

Sorry, that's all i got.
 
Thanks once again.

Battery still in warranty (1 year) but seller is gone and will not respond to emails. New eBay sellers will not help, but say they have contacted old seller, but I doubt that's true and understand that they don't care. And so it goes . . . The only help the new seller offered is "charge the battery until full and the BMS will reset." Don't even know if it is a BMS problem (but that is more and more likely). I am skeptical of that solution of course. And, I'm trying everything to "charge the batteries . . . bit it ain't happening.

Anyone else have ideas . . . ? ? ?
 
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