36v 20AH Lifepo4 Duct Tape Charging Issue

[The Mighty Volt]

Hi there, I have my Cammy_CC Lifepo4 connected to the charger via the BMS and connected in turn to a Watts-Up Meter

The battery is rated 36v and has been used once from full, for a few miles.

The Watts Up says that the battery is currently charged to over 45v, but the BMS/Charger show no sign of cutting out yet.

Is this normal? What can I expect if I leave the charger on?

Thanks.

PS voltage is still rising, bit by bit....around 45.18 V right now.

 

[Velocipede]

45V is 3,75V per cell (or parallel group of cells).

What is the voltage supplied by the charger with no battery attached (measured with a voltmeter)? It should give an indication.

You are right that it's a bit high, but thundersky recommends charging their LiFePO4 to 4,2 volts (not an usual recommandation).
You do not risk a catastrophic failure waiting a bit more to see where it will end.
If it does end much higher than this, you could try to turn the voltage down on the charger.

 

[Ypedal]

How many amps/watts are flowing ?

 

[The Mighty Volt]

The charger is a rated 36v 5A unit, which puts out slightly more than that, around 38.8 volts or so

Hello again All....the BMS finally stopped taking charge at 45.22 volts.

The charger light turned green. When I disconnected the charger and reconnected it, the light turned from green to orange, before immediately reverting to green. So it seems to have been working.

Battery has been slowly lowering its stated output since it stopped charging, its around 43 volts right now.

 

[dogman dan]

Sounds pretty normal to me. A brand new pack will need to sit on the charger a lot, so leave it plugged in for long periods. The first few cycles will take more time to balance. As I type I'm waiting on my new 48v ping to do the same thing. It's sitting at 60.4v about the same as the charger output. But the last dang bms light won't light up yet after a few hours on the charger since it went green the first time. The first charge, even after balancing for more than an hour had 12 of 16 lights lit. I took it out for a 1 mile ride, and the next charge lit 15 lights. It really does take a few charges to get a brand new lifepo4 to balance. Maybe not for better cells, but these have not been cycled at the factory. Well off to take another 1 mile ride, hoping to fully balance tonight before I go to bed.

 

[The Mighty Volt]

Sounds pretty normal to me. A brand new pack will need to sit on the charger a lot, so leave it plugged in for long periods. The first few cycles will take more time to balance. As I type I'm waiting on my new 48v ping to do the same thing. It's sitting at 60.4v about the same as the charger output. But the last dang bms light won't light up yet after a few hours on the charger since it went green the first time. The first charge, even after balancing for more than an hour had 12 of 16 lights lit. I took it out for a 1 mile ride, and the next charge lit 15 lights. It really does take a few charges to get a brand new lifepo4 to balance. Maybe not for better cells, but these have not been cycled at the factory. Well off to take another 1 mile ride, hoping to fully balance tonight before I go to bed.

Hi Dogman, and thanks as ever for your constant replies!

My Aotema is due in the post soon, how many miles should I rack up testing the Aotema before I put the lifepo4 back on charge?

I think the battery has only 2 or 3 miles worth of travel under its belt so far, and has been charged fully twice, 1st when it was delivered {took only a few minutes} and second after I used it for the aforementioned 2 or 3 miles.

Thanks again.

 

[dogman dan]

Just take it for some shorter rides, like under 10 miles for a few cycles. By somewere between 5 and 10 cycles the battery will be broken in and taking a full charge. You can see what I am doing in my breaking in the ping thread. Overkill, yeah, but at least let the thing charge overnight and get fully topped up before you do any 20 mile rides. To speed up the process, I did a few very short rides to keep the battery from taking so long to get full.

After a ride till the battery cuts out, sometimes my first ping would get unbalanced, but I found a 1 mile ride followed by a second charge would usually balance it, so I'm using the same idea on the new battery.

 

[kilowatt]

I have this same pack and asked Cammy about the balancing voltage. When the charge reaches 45 volts, this is where the battery floats until it is balanced. After removing the charger the battery will quickly go to 42 volts which Cammy says is normal. Hope this helps.

Kilowatt

 

[The Mighty Volt]

I have this same pack and asked Cammy about the balancing voltage. When the charge reaches 45 volts, this is where the battery floats until it is balanced. After removing the charger the battery will quickly go to 42 volts which Cammy says is normal. Hope this helps.

Kilowatt

Thanks for that. That actually sounds familiar. Right now I think I have around 9AH out of a 20AH pack, as it has only be charged twice or so and run for well under 10 miles.

I used it today with my new Aetoma hub, and got respectable speeds.

I will keep you all posted. Voltage right now is around 39 so I will keep ragging it down until it is ready for charging again.