Lifepo4's getting hot on charge

[Kartman]

Hi

I just charged my brand new pack at 1C for the first time today and monitored the temp through the cycle. Got up to 45 deg celsius on the outer cells.

Just wondering is this is normal and acceptable?

 

[dogman dan]

Seems a bit warm to me for the actual cells. 35-40 was more my experience with ping lifepo4.

But they did not charge at 1c. That's pretty fast charging.

 

[dnmun]

are you sure it is the pouches that got hot or was it the BMS during balancing?

 

[Kartman]

Yea definitely the cells, I felt them all by hand had used an IR thermometer. I wouldnt call them too hot, just pretty warm.

Actually it's a little more than 1C, it's a 10ah pack and the charger puts out 16ah....

 

[dnmun]

cut the charging current back to .5C where it should be and then see how hot they get.

 

[dogman dan]

IMO, just like the specified discharge rates, the max charge rate they spec is not going to make the battery all happy.

So charge slower, unless you have reasons to charge faster that justify it.

 

[rscamp]

With something like this, we should be thinking in terms of temperature rise over ambient. 45 Deg C absolute temperature means one thing in a 20 Deg C ambient and quite another in a 35 Deg C ambient. What matters to us is the 25 or 10 Deg C rise.

 

[dnmun]

the risk is loss of capacity from charging at a rate higher than the cell can handle. temperature effect is secondary to loss of the lithium to the cycle. eventually it will not store the same amount of charge as it originally did. that happens rapidly as the charging rate is pushed above the level specified for the product.

 

[Kartman]

Ambient temp was 25 c, so temp gain was approx 20 c.

The distributor tells me theyre happy to be charged to 3C. Which I guess they are, it's just a matter of will it reduce their life by a significant or insignificant amount.

I can half the rate by cutting the input from 240vac to 120vac, might do that then keep the 240v option for fast charging. Or double the number of sells

 

[dnmun]

should be obvious that they lied and changing the AC source voltage for the charger does nothing.

 

[Kartman]

Surely different Lifepo4 cells can take different rates of charge?

It's an Elcon charger, 115vac results in 6A, 230vac gives 10A at 72v according to manufacturer.

 

[dogman dan]

I'd charge on 110 then, unless in a hurry. Cool pack is a happy pack in my world, charging or discharging. It may handle hot fine, but it will handle cool better.

Heat the thing up though, if you want to win a race.

 

[wb9k]

I'd charge on 110 then, unless in a hurry. Cool pack is a happy pack in my world, charging or discharging. It may handle hot fine, but it will handle cool better.

Heat the thing up though, if you want to win a race.

Agreed. Heat is the enemy of battery life. All batteries should be charged as slowly as they can be while still delivering the required energy needed in the time given. Fast charging just for the sake of fast charging is a bad practice. Don't do it unless you MUST do so to get the service you need from your battery.