Is it OK to keep charging when the LiFePo4 battery is 100% charged?

[Gypsy Freedom]

do you have a car? you could hook it up to that even in the car. or just pull the battery out of the car for an afternoon?

just a thought

the numbes you stated were the presets for one of the led acid ones. you have it set to lifepo4 12v (blue indicator) so those numbers are out. under the lifepo4 setting it only shows 14.4 volts

the BMS has no way to determine full or 100% it would just be referencing voltage so the BMS should never engage with volts only at 14.4. and i suspect the charger (you might confirm with the company) will only hold 14.4 for a short time and then stop charging.

you might also use the remote or the bluetooth to set specific setting for each stage. but i think i would check with the company first to confirm how long the charger will hold the boost voltage at 14.4

 

[Gypsy Freedom]

when you say the volts spike to 15.x something for a split second. what is the voltage right before that. does it creep up on that high volt then drop or does it sit at 14.6 for a while then make a quick spike and drop back. what does it drop back to and how long does it stay there before spiking again?

 

[poot_traveller]

do you have a car? you could hook it up to that even in the car. or just pull the battery out of the car for an afternoon?

just a thought

the numbes you stated were the presets for one of the led acid ones. you have it set to lifepo4 12v (blue indicator) so those numbers are out. under the lifepo4 setting it only shows 14.4 volts

the BMS has no way to determine full or 100% it would just be referencing voltage so the BMS should never engage with volts only at 14.4. and i suspect the charger (you might confirm with the company) will only hold 14.4 for a short time and then stop charging.

you might also use the remote or the bluetooth to set specific setting for each stage. but i think i would check with the company first to confirm how long the charger will hold the boost voltage at 14.4

I'm confident the issue is with the controller spiking when the battery disconnects. I don't mind the issue being the controller spiking, because controllers are cheap, Li batteries are not.

I'll contact the company and see how long it holds boost at 14.4 and see what they say, and I'll ask them for the recommended LiFePo4 settings.

 

[poot_traveller]

when you say the volts spike to 15.x something for a split second. what is the voltage right before that. does it creep up on that high volt then drop or does it sit at 14.6 for a while then make a quick spike and drop back. what does it drop back to and how long does it stay there before spiking again?

It is at 14.4v (from memory) then goes to 14.6v for a couple of seconds, then 14.(something), then 15.(something), then 15.8v. This all happens in about 20 seconds.

Then it quickly drops back to 13.8v in about 5 seconds.

It will repeat this process again and again roughly every 10 minutes.

Another possible reason I can think of is the controller or battery over heats and shuts down at roughly 38C. Or at least I think one of them shuts down because it stops charging my laptop. Or may be that's the inverter shutting down, all I know is something shuts down when it hits 38C.

 

[Gypsy Freedom]

you might consider asking the charge controller people why their controller is putting out more than the 14.4 volts in that setting. they may acknowledge the controller is having a problem and send you a new one.

cant really tell anything more from here unless you can test the controller on another battery that has no bms and confirm whether the controller is allowing the high voltage or if it is holding steady. but i suspect there is a problem with the controller

 

[poot_traveller]

They're not sure why it's getting up that high. I'll get another opportunity to monitor it in a couple of days when I have Sunday off and I'll see what it does then. I'll also take another look at the settings when I get back to the camper in a couple of hours.

 

[Gypsy Freedom]

a reputable company that cant explain why their product is operating out of spec (over volt) should offer to send you a replacement

i am guessing they did not design this unit, but rebaged something they bought over seas, AKA china. and as such have no idea how to trouble shoot beyond what is in the manual they sent out. which in my book was kinda thin

keep us posted, if you get it hooked up to a lead acid battery with no BMS in the way and it still does the same thing. that would be pretty conclusive...

good luck

 

[jonyjoe303]

If the lifepo4 is fast charge at high enough amps, as soon as the bms sees 14.6 volts (even if its just a surface voltage) it will shutoff, also if one of the cells goes out of balance (higher voltage then the others) as soon as that cell reaches 3.65 volts the bms will shutoff even if the overall voltage is less then 14.6 volts. 

Here is a picture of what I'm talking about as far as balance on a lifepo4, this battery had balancing problems with one cell reading 3.60 volts while the other 3 read 3.40 volts, this always cause the bms to stop the charge early even when I was charging at low amps. In your battery you would never know if you had good balance unless you could read all the cells voltage. If your charging at low amps ( 4 amps or less) and the bms cutsoff before 14.6 volts, then you might have a balance issue. The battery is still good but you will not be able to fully charge to 100 percent. With lifepo4 being able to see all 4 cells voltage is extremely important, maybe there is connector on your battery where you can monitor the cells voltage. On this battery I fixed the balancing problem and now they all read 3.40 volts and will stay in balance till full charge.

The controller only monitors overall voltage, even if it says it has a lifepo4 setting, it won't account for an out of balance battery. My controller I use is 6 years old and doesn't have a lithium setting, but it still does the job. Any controller will work on any lithium battery as long as the battery is in perfect balance. To me it sounds like your controller is working fine, because my controllers behave similar when they encounter a lithium battery that has a bms that stopped the charge. If your controller bulk setting is set to 14.4 volts and your battery bms is shutting off that points to battery being out of balance. 

 

[poot_traveller]

a reputable company that cant explain why their product is operating out of spec (over volt) should offer to send you a replacement

i am guessing they did not design this unit, but rebaged something they bought over seas, AKA china. and as such have no idea how to trouble shoot beyond what is in the manual they sent out. which in my book was kinda thin

keep us posted, if you get it hooked up to a lead acid battery with no BMS in the way and it still does the same thing. that would be pretty conclusive...

good luck

It could be the controller, or it could be something much more simple like me misunderstanding what the remote display is reading. I'll keep you guys posted. Thanks for the help

 

[poot_traveller]

If the lifepo4 is fast charge at high enough amps, as soon as the bms sees 14.6 volts (even if its just a surface voltage) it will shutoff, also if one of the cells goes out of balance (higher voltage then the others) as soon as that cell reaches 3.65 volts the bms will shutoff even if the overall voltage is less then 14.6 volts. 

Here is a picture of what I'm talking about as far as balance on a lifepo4, this battery had balancing problems with one cell reading 3.60 volts while the other 3 read 3.40 volts, this always cause the bms to stop the charge early even when I was charging at low amps. In your battery you would never know if you had good balance unless you could read all the cells voltage. If your charging at low amps ( 4 amps or less) and the bms cutsoff before 14.6 volts, then you might have a balance issue. The battery is still good but you will not be able to fully charge to 100 percent. With lifepo4 being able to see all 4 cells voltage is extremely important, maybe there is connector on your battery where you can monitor the cells voltage. On this battery I fixed the balancing problem and now they all read 3.40 volts and will stay in balance till full charge.

The controller only monitors overall voltage, even if it says it has a lifepo4 setting, it won't account for an out of balance battery. My controller I use is 6 years old and doesn't have a lithium setting, but it still does the job. Any controller will work on any lithium battery as long as the battery is in perfect balance. To me it sounds like your controller is working fine, because my controllers behave similar when they encounter a lithium battery that has a bms that stopped the charge. If your controller bulk setting is set to 14.4 volts and your battery bms is shutting off that points to battery being out of balance. 

You bring up some good points. I'm going to carry out a test in a couple of days to try and get to the bottom of this. Thanks for the information, much appreciated.

 

[Gypsy Freedom]

while some of the things mentioned are possible. they are just wild guesses at this point. you want to start isolating where the trouble is. so you are not chasing ghosts.

simplest way to do that is test charger on another battery. if problem follows charger then figure out how to deal with the charger
if it does not follow the charger then explore the battery. but with it all sealed up, if the problem is an out of balance not much you can do about it short of trying to warranty it. unless you cut it open.

 

[poot_traveller]

while some of the things mentioned are possible. they are just wild guesses at this point. you want to start isolating where the trouble is. so you are not chasing ghosts.

simplest way to do that is test charger on another battery. if problem follows charger then figure out how to deal with the charger
if it does not follow the charger then explore the battery. but with it all sealed up, if the problem is an out of balance not much you can do about it short of trying to warranty it. unless you cut it open.

I'm going to isolate the problem starting with me because I might be the problem.

I'll monitor the remote display and re-read the manual to make sure I'm understanding the readings correctly.

 

[highdesertranger]

"I'm going to isolate the problem starting with me because I might be the problem"

great line and great attitude.

highdesertranger

 

[poot_traveller]

it is disconcerting that they contradict them selves. they claim there is a balancer included but right on the side of the battery it says dont charge with out using a balancer? how do you add your own balancer if you dont have access to the individual cells?

It does say on the side of the battery under general guidelines and warnings No.2 : "cell balancer included all models"
https://www.trademe.co.nz/motors/ca...tm?rsqid=5ead1b95d4034d49a2e58ad5e3d4cae7-001

 

[jonyjoe303]

yes balancers are inside with the bms, the ones I seen on some of those batteries look like the picture below, each cell has one, total 4 in a 12 volt lifepo4. The only problem with these balancers is they usually don't start balancing until a cell reaches 3.60 volts, thats near the max of 3.65. So if you are fast charging the battery and it goes out of balance, the balancer won't be able to bleed amps fast enough to stop the cell from reaching the cutoff voltage. 

With solar, it always charges at max amps until the bms stops the charge. A regular AC lifepo4 charger as the battery gets close to 14.6 it starts to reduce the amps, allowing the balancers to keep the battery in balance. 

 

[poot_traveller]

It's hard to say what balancer is inside my battery as no one can see inside. Hopefully it's not like the balancer in your picture.

 

[66788]

With lifepo4 you can never tell if its really 100 percent unless you can monitor each cell voltage or the bms has tripped to stop charging. If you have the bulk setting on your controller to 14.6 volts, theres a good chance its not getting to 100 percent, maybe 90/95 percent especially with a 160 watt panel. Only way for the battery to get to 14.6 volts is if there is no voltage drop between controller and battery. Check the voltage on the battery terminals will give you a better idea what the highest voltage the battery is reaching. If it never reaches 14.6 volts during the time its connected to solar, then its not getting fully charge everytime. 

Just set your float setting to 13.8 volts or lower and you can keep it connected all day long. At such low voltage you might be charging at 1 amp or less which is insignificant. I have the float on my controller set to 14.3 volts and the battery is recieving "o" amps, the controller is just replacing the amps being used.

If you don't have a coulombmeter, get one. My coulombmeter is connected directly to the battery terminals, it will never show 100 percent the first time you install unless the battery terminals actually have reached that voltage. Once the battery gets to 14.6 volts (the coulombmeter is calibrated at the high end) you can now be sure that amps used is accurate as it counts the amps in/out.

Picture of my coulombmeter and also the chargery bmst8 I use. Both show 100 percent on my 220ah lifepo4 battery. Right now the battery is connected to solar controller which is producing about 4 amps, the coulombmeter shows battery is only getting less then 1/2 amp of charge power ( the other 3.5 amps is powering laptop/fans/lights). The chargery bms8t doesnt track anything less then 1 amp (it shows 0 amps charge rate) all the cells read 3.44 volts (max 3.65 for lifepo4). Even though the battery only shows a voltage of 13.8 volts, thats acceptable since it has previously reached 14.6 volts and the controller has switched to float and just replacing whats being used.

Orale!  A "Culo meter"!