OnTheRoadAgain
Solar Enthusiast
- Joined
- Feb 22, 2021
- Messages
- 643
Quite a few times I read about people overcharging their LiFePO4 battery packs and I just didn't understand.
Now that I have one, it makes perfect sense. But ONLY now that I'm trying to charge my own. Yep, I'm not the brightest of bulbs.
So, I want to charge my battery to 13.4v. So I set my CC/CV Power supply to 13.4v. The battery is at 13.2v
The charge rate is 2.8amps (goverened by laws of electronics) and will take 21.03 hours according to the BMS at this moment. The temptation is to reach over and crank up the voltage so that it charges at the full 10amps the power supply can offer......but that's the trap. People walk away, fall asleep or forget they have turned the voltage way up and when they have that OS moment later and remember, it's too late. The battery is all swollen and at 15volts
I'll bet you a shiny nickel more people do this than confess to it. They just don't forget to monitor it.
Now, you might ask.......why is the battery charging so slow? If it's at 13.2v and I'm trying to charge it to 13.4v?
The answer is because that difference in voltage is not great enough to "push" the voltage along faster.
You need more voltage to do that.
Current is like water.....voltage is like water pressure. If the water on both sides of the faucet is at the same pressure, no water will move when you open the valve.
Likewise, if voltage is the exact same on both sides of a circuit, no current will flow. The greater the difference, the faster the flow.
This is of course assuming (uh-oh..here comes Q-Dog) that there is no BMS or there is a BMS but it fails to protect the battery.
Personally, I never like to trust the BMS to be the only sentry on duty protecting my xpensive battery
So for those new to this....that's the reason people increase the voltage to dangerous (for the battery) levels on a power supply, to cut down on the charge time.
If I crank the voltage way up, the charging amps jump way up and the charge time drops to 5.7 hours.
As obvious as that seems now, it didn't really make sense until now.
Oh, and as the battery charges, it will draw less current so the voltage will change and it will charge even slower.
So a dilemma....how to charge your LiFePO4 faster....yet still safely?
I guess you can buy a dedicated charger, but be careful some of them rely on your BMS to stop the charging.
I tried to find one that can be programmed and set at 13.4v, but came up short. The only solution was over $300 (too much)
Now that I have one, it makes perfect sense. But ONLY now that I'm trying to charge my own. Yep, I'm not the brightest of bulbs.
So, I want to charge my battery to 13.4v. So I set my CC/CV Power supply to 13.4v. The battery is at 13.2v
The charge rate is 2.8amps (goverened by laws of electronics) and will take 21.03 hours according to the BMS at this moment. The temptation is to reach over and crank up the voltage so that it charges at the full 10amps the power supply can offer......but that's the trap. People walk away, fall asleep or forget they have turned the voltage way up and when they have that OS moment later and remember, it's too late. The battery is all swollen and at 15volts
I'll bet you a shiny nickel more people do this than confess to it. They just don't forget to monitor it.
Now, you might ask.......why is the battery charging so slow? If it's at 13.2v and I'm trying to charge it to 13.4v?
The answer is because that difference in voltage is not great enough to "push" the voltage along faster.
You need more voltage to do that.
Current is like water.....voltage is like water pressure. If the water on both sides of the faucet is at the same pressure, no water will move when you open the valve.
Likewise, if voltage is the exact same on both sides of a circuit, no current will flow. The greater the difference, the faster the flow.
This is of course assuming (uh-oh..here comes Q-Dog) that there is no BMS or there is a BMS but it fails to protect the battery.
Personally, I never like to trust the BMS to be the only sentry on duty protecting my xpensive battery
So for those new to this....that's the reason people increase the voltage to dangerous (for the battery) levels on a power supply, to cut down on the charge time.
If I crank the voltage way up, the charging amps jump way up and the charge time drops to 5.7 hours.
As obvious as that seems now, it didn't really make sense until now.
Oh, and as the battery charges, it will draw less current so the voltage will change and it will charge even slower.
So a dilemma....how to charge your LiFePO4 faster....yet still safely?
I guess you can buy a dedicated charger, but be careful some of them rely on your BMS to stop the charging.
I tried to find one that can be programmed and set at 13.4v, but came up short. The only solution was over $300 (too much)
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