New Battery on Amazon and Ebay - Global Power 12V100AH LIFEPO4 - $399! Has anybody actually bought one yet? Torn it down yet?

[SolarRat]

I just received my balancers in the mail (Jim has got to be the most responsive seller on eBay!). Very easy install and I'm charging up one of the batteries now...there are no lights on the balancer yet. If I understand the operation of the device correctly, the balancing (and the LEDs turning on) will only happen when the battery is being charged and the individual cell voltage reaches 3.45v, then it will stop balancing after 3.5v? I'm using a small power supply that I will adjust down as needed to keep it in the sweet spot for long enough to do some balancing. I assume the slower the charge the less charge cycles it will take? Can anyone confirm? I will use a fan to cool the board while it's doing it's thing if need be.

The issue many of us might have is that some of our cells were never able to reach 3.45v in the first place, so we'll see what happens when it happens.

 

[jwasilko]

The LEDs on mine stayed on after disconnecting the charger.

 

[wild01]

Missed that 3.45 turn on point. That's less than useful. Also just realized the balancer and bms have opposite pinouts. Don't accidentally switch them!!!! This would be very easy to do being that they have the same connectors

 

[SolarRat]

The LEDs on mine stayed on after disconnecting the charger.

All of them? And are you ok with that?

It would be nice if we knew how these balancers work. The lights come on near 3.45v and seem to stay on above that (charging or not). Lots of heat is produced while the light(s) is on, but I don't know if if this device is bleeding excess voltage to the low cells or just to ground. I assumed it should take from the high cell and give to the lower cells, but that does not seem to be happening on mine when measuring with an amp meter. The cell with the light on has a 225ma load, and so does b-, but no other cells do. I can only get one LED to light and maybe 1 other flashes after a while...before the bms disconnects everything.

My batteries could never charge above 13.7-8v because 1 cell would hit 3.65 before others even reach 3.35v. I've bled off the high cell (in one battery) until it's voltage is below the lowest cell but for some reason it always rises back to the highest pretty quickly. We'll see if these boards help...

On one battery I'm just charging and discharging and will let the balancer do it's thing. On another I'm giving the balancer help by bleeding off the high cells (while disconnected).

I feel like I am band-aiding a $300 gushing chest wound with a $2 Chinese mystery band aid. I'll update as I go, unless I throw everything into the canal first.

 

[SolarRat]

...One of the batteries previously always stopped charging at 13.6v to 13.8v, indicating a cell imbalance and bms cutoff due to an overvoltage condition for at least one cell pack. First charge with the balance board allowed the battery to reach 14.2v...

This doesn't seem possible with everything I'm seeing and measuring, so maybe you got lucky! Mine do seem to be getting better with repeated cycles, so I'll keep at it. I just hope all progress is not lost with an overnight sit.

 

[SolarRat]

Missed that 3.45 turn on point. That's less than useful.

Agree. I planned on only charging these to about 13.8v max but that probably won't trigger the balance. 14v it will be.

I guess it does make sense, so a low battery is not wasting energy balancing...but 3.45 is a fully charged cell. Maybe an adjustable "equalization" charge setting some LA controllers have could have a use after all...let it do a 14.2v charge once a month or so...

 

[wild01]

just looked up the components, those are 75ohm surface mount resistors, so yes just a passive heater, not an active balancer. basically a 1/4a load that turns on when the cell goes over 3.45 so best bet to balance with these is to put them on a benchtop power supply and set it to .25a until all 4 lights go on. cheapest solution possible, but better than nothing I suppose

 

[The Dish Doc]

I bought 4 of these for a 48 volt system (ebay). The tops can be unscrewed to get to the insides, picture attached. they are supposed to be multiple cylindrical cell battery. The display is a voltmeter that appears to be connected directly to the battery (before bms) and just estimates capacity based on voltage. According to the manual they are to be charged to 14.6v discharged to 10V it also says the BMS disconnect is 15.6V high and 8.8V low. Did not do any performance testing. They are installed in series on my Solar charged "power wall". Initially they all showed the same voltage within .1 volts so I didn't charge them separately. Problem I have is the BMS keeps disconnecting before they are charged above 13.8V. When one disconnect they all stop charging. I am guessing its a cell imbalance issue. How sad... I see if it gets any better as they cycle. I have a 48v Battery Equalizer on order that will allow the other batteries to charge when one cuts out.

Did you make that battery rack? It's nice.

 

[Bobert]

All of them? And are you ok with that?

It would be nice if we knew how these balancers work. The lights come on near 3.45v and seem to stay on above that (charging or not). Lots of heat is produced while the light(s) is on, but I don't know if if this device is bleeding excess voltage to the low cells or just to ground. I assumed it should take from the high cell and give to the lower cells, but that does not seem to be happening on mine when measuring with an amp meter. The cell with the light on has a 225ma load, and so does b-, but no other cells do. I can only get one LED to light and maybe 1 other flashes after a while...before the bms disconnects everything.

My batteries could never charge above 13.7-8v because 1 cell would hit 3.65 before others even reach 3.35v. I've bled off the high cell (in one battery) until it's voltage is below the lowest cell but for some reason it always rises back to the highest pretty quickly. We'll see if these boards help...

On one battery I'm just charging and discharging and will let the balancer do it's thing. On another I'm giving the balancer help by bleeding off the high cells (while disconnected).

I feel like I am band-aiding a $300 gushing chest wound with a $2 Chinese mystery band aid. I'll update as I go, unless I throw everything into the canal first.

I’ve been fortunate with my batteries. With 4 in series I have been able to get to 56 volts from the beginning with an active balancer on the bank. That’s 14v per battery. After 5 full cycles at 30amps I could reach 57v before hitting cutoff but at 5amps I would hit cutoff at 56ish. Now that I have the internal balancers the 30 amp charger hits 57.4 before quitting and 56.8 at 5 amps. I am close to the stated specs now on the charging side but the bms cuts out at 46 volts discharging. It is interesting to me and I have no other experience with lifepo4 batteries so I’m not sure if this is normal or not but a faster charg gets me to a higher voltage before cutoff than a slow charge but low voltage cutoff isn’t that way at all it cuts off at about 46 volts regardless of discharge rate. Now if I have a high (for me) discharge rate of let’s say 40amps the batteries will hit cutoff sooner and if I let them set for a bit I an get another 4 or 5 ah out of them but they still cutoff at 46 volts. I wonder if this is a normal scenario for lifepo4. As near as I can tell I am getting 90 to 98 ah out of the bank and I have yet to test it since I put the balancers in. I don’t have a very accurate way to do a discharge test just load up the inverter till I get a 20 amp load and then set a timer for 4.5 hours and watch the last of it’s discharge cycle and do some math. It’s easier on charging as I can set the charge rate at 30 amps and return in 2 hours and 50 minutes to finish up. That’s not as easy as it sounds because at just over 90 ah in the charge rate gradually drops from 30 amps to 25 and then rapidly to 8 amps and slowly Down to nearly nothing and then the voltage begins to vary between 56.8 and 57.2 which I assume is high voltage cutoff as the charger does the same varying voltage thing if the batteries are disconnected while charging.

 

[wild01]

Agree. I planned on only charging these to about 13.8v max but that probably won't trigger the balance. 14v it will be.

since these are passive balancers,they will still work. you're cutting off at 13.8 because at least one cell hit the 3.65/3.7v bms cell cutoff voltage. this will burn 1/4a off of that cell until it's below 3.45.

 

[wild01]

I’ve been fortunate with my batteries. With 4 in series I have been able to get to 56 volts from the beginning with an active balancer on the bank. That’s 14v per battery. After 5 full cycles at 30amps I could reach 57v before hitting cutoff but at 5amps I would hit cutoff at 56ish. Now that I have the internal balancers the 30 amp charger hits 57.4 before quitting and 56.8 at 5 amps. I am close to the stated specs now on the charging side but the bms cuts out at 46 volts discharging. It is interesting to me and I have no other experience with lifepo4 batteries so I’m not sure if this is normal or not but a faster charg gets me to a higher voltage before cutoff than a slow charge but low voltage cutoff isn’t that way at all it cuts off at about 46 volts regardless of discharge rate. Now if I have a high (for me) discharge rate of let’s say 40amps the batteries will hit cutoff sooner and if I let them set for a bit I an get another 4 or 5 ah out of them but they still cutoff at 46 volts. I wonder if this is a normal scenario for lifepo4. As near as I can tell I am getting 90 to 98 ah out of the bank and I have yet to test it since I put the balancers in. I don’t have a very accurate way to do a discharge test just load up the inverter till I get a 20 amp load and then set a timer for 4.5 hours and watch the last of it’s discharge cycle and do some math. It’s easier on charging as I can set the charge rate at 30 amps and return in 2 hours and 50 minutes to finish up. That’s not as easy as it sounds because at just over 90 ah in the charge rate gradually drops from 30 amps to 25 and then rapidly to 8 amps and slowly Down to nearly nothing and then the voltage begins to vary between 56.8 and 57.2 which I assume is high voltage cutoff as the charger does the same varying voltage thing if the batteries are disconnected while charging.

yes this is because internal resistance is going up faster @ a higher amp charge. basically you are not actually hitting 57.4 AT THE BATTERY. use the onboard volt meters on the battery and you will see this. you are probably managing to charge the actual battery to a higher voltage with a lower a charge, but on the charger side a higher imput amperage will result in a higher voltage reading. if you add up the 4 readings on the onboard digital display on the battery, you will get a more accurate( and probably lower) reading

 

[SolarRat]

just looked up the components, those are 75ohm surface mount resistors, so yes just a passive heater, not an active balancer. basically a 1/4a load that turns on when the cell goes over 3.45 so best bet to balance with these is to put them on a benchtop power supply and set it to .25a until all 4 lights go on. cheapest solution possible, but better than nothing I suppose

I wonder what happens when a fully balanced battery reaches 3.45 per cell. I guess there must be a certain voltage differential between cells for it drain a cell...well, I'd hope! I wonder what that differential is? 100mV? Yikes.

Yes, I'm using a bench supply and feeding .25-.5a. It doesn't seem to matter, as these cells are practically already in the knees at 3.45v, so the voltage of the highest cell quickly (minutes) rises to the 3.65 cutoff anyway.. You'd think feeding .23a into what I measured as a .225a drain would slow it down, but nope.

I haven't seen more than two lights yet. It seems cells 1 and 4 might be paired somehow...same with 3-4.

 

[Bobert]

yes this is because internal resistance is going up faster @ a higher amp charge. basically you are not actually hitting 57.4 AT THE BATTERY. use the onboard volt meters on the battery and you will see this. you are probably managing to charge the actual battery to a higher voltage with a lower a charge, but on the charger side a higher imput amperage will result in a higher voltage reading. if you add up the 4 readings on the onboard digital display on the battery, you will get a more accurate( and probably lower) reading

I can’t actually see the volt meters on the batteries because of where they are installed but I can check each of the voltages with a voltmeter easy enough. I’ll try that when I get the time to do another cycle test. The batteries hold at 57.2 for a decent amount of time so I should be able to get a reading.

 

[SolarRat]

since these are passive balancers,they will still work. you're cutting off at 13.8 because at least one cell hit the 3.65/3.7v bms cell cutoff voltage. this will burn 1/4a off of that cell until it's below 3.45.

Right, but that is what scares me. If ALL cells above 3.45 get shunted to ground then any charge above 13.8 is creating a tiny powerful heater inside the battery. If someone charges to 14.6v, that poor little balancer will cook away for weeks. There must be some parameters that must be met first...like a voltage differential

 

[wild01]

I can’t actually see the volt meters on the batteries because of where they are installed but I can check each of the voltages with a voltmeter easy enough. I’ll try that when I get the time to do another cycle test. The batteries hold at 57.2 for a decent amount of time so I should be able to get a reading.

you might see a difference at the battery posts, but probably not much of one, the onboard meter is hooked in AFTER the bms, so it is reading the voltage at the cells, I just checked one I'm testing on my bench and even at very low charge rate, my multimeter and charger say 14.1-2 and the onboard says 13.9

 

[SolarRat]

...and then the voltage begins to vary between 56.8 and 57.2 which I assume is high voltage cutoff as the charger does the same varying voltage thing if the batteries are disconnected while charging.

This is the main problem, and very damaging to the entire system. The battery is disconnecting from the charge source and the load. Neither like when that happens. Yet many here seem to think it is normal.

 

[wild01]

I wonder what happens when a fully balanced battery reaches 3.45 per cell. I guess there must be a certain voltage differential between cells for it drain a cell...well, I'd hope! I wonder what that differential is? 100mV? Yikes.

Yes, I'm using a bench supply and feeding .25-.5a. It doesn't seem to matter, as these cells are practically already in the knees at 3.45v, so the voltage of the highest cell quickly (minutes) rises to the 3.65 cutoff anyway.. You'd think feeding .23a into what I measured as a .225a drain would slow it down, but nope.

I haven't seen more than two lights yet. It seems cells 1 and 4 might be paired somehow...same with 3-4.

I'm balancing one with a real active balancer right now, you've got me curious, so once it fully balances I'll plug the passive board back in and see if it still bleeds them all down to 3.45.

 

[SolarRat]

you might see a difference at the battery posts, but probably not much of one, the onboard meter is hooked in AFTER the bms, so it is reading the voltage at the cells, I just checked one I'm testing on my bench and even at very low charge rate, my multimeter and charger say 14.1-2 and the onboard says 13.9

The onboard meter is very inaccurate. The battery posts are after the BMS also. If you disconnect the balance leads from the BMS, the battery output goes dead. Now, with this balancer board installed, instead of 1 connector there are 4. If any one fails the battery goes dead (my boat is stranded).

 

[wild01]

This is the main problem, and very damaging to the entire system. The battery is disconnecting from the charge source and the load. Neither like when that happens. Yet many here seem to think it is normal.

@5a it's probably not a big deal, @ 30a more so, and @the full 100a the bms probably wont survive very many times. it's just like throwing a breaker or disconnect, the higher the flow it have to stop the bigger the chance of letting out the magic smoke.

The onboard meter is very inaccurate. The battery posts are after the BMS also. If you disconnect the balance leads from the BMS, the battery output goes dead. Now, with this balancer board installed, instead of 1 connector there are 4. If any one fails the battery goes dead (my boat is stranded).

symantics here I mean 'upsteam' of the bms as in it's not reading the teminal voltage it's wired strait to the cell pack

 

[SolarRat]

@5a it's probably not a big deal, @ 30a more so, and @the full 100a the bms probably wont survive very many times. it's just like throwing a breaker or disconnect, the higher the flow it have to stop the bigger the chance of letting out the magic smoke.

Exactly! But many people seem to not be aware that this is not normal, and the lifespan of their CC and load will probably suffer.

symantics here I mean 'upsteam' of the bms as in it's not reading the teminal voltage it's wired strait to the cell pack

The onboard meter is wired straight to the pack? If so, it should read higher than my Flukes on the terminals, but it reads lower on both. Regardless, those meters shouldn't be trusted. I bought a 10 pack of them on amazon years ago for various projects, and they were all over the place. And any meter that only reads one digit past the decimal is pretty useless on a lithium battery anyway.