Can I use a bench power supply to charge this battery lifepo4 battery?

tsunami3775

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I know the manual doesn’t mention it but I was wondering if I could use my bench power supply to charge this battery? If I can’t, why not? Just wanted to understand and maybe learn something
 

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Horsefly

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Sure. Adjust the PS voltage before connecting it to the battery. Connect it up, and when the voltage on the terminals of the battery reaches the PS set voltage and the current drops down to almost zero, disconnect and stop charging. (1) Don't adjust the power supply while it is connected to the battery, (2) Don't leave it charging at that voltage for hours after it reaches the full voltage.

Be patient.
 

tsunami3775

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Sure. Adjust the PS voltage before connecting it to the battery. Connect it up, and when the voltage on the terminals of the battery reaches the PS set voltage and the current drops down to almost zero, disconnect and stop charging. (1) Don't adjust the power supply while it is connected to the battery, (2) Don't leave it charging at that voltage for hours after it reaches the full voltage.

Be patient.
Awesome thanks
 

AE4KR

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...use my bench power supply to charge this battery?
A little more info on your bench supply would be helpful. If it's the type which can set max voltage and max current independently:

(1) With no load on the supply, set the supply voltage to the battery's preferred charge voltage, 14.4V in this case.

(2) ASSUMING your supply has adjustable current limiting, short the leads on the power supply, and set the current limiting to the battery's preferred charge current, 20 amps in this case. (The supply may not provide that much. If it's a typical bench supply that will do 0-30 volts at 3 amps, set the current to 3 amps so it will run at full capacity.) While you're setting current, it's normal to see voltage drop to almost zero.

(3) Disconnect leads from the power supply before connecting them to the battery. Connect the + and - leads first to the battery, then to the bench supply.

(4) You should see current jump to the limit you set. Voltage will drop below 14.4 and slowly climb as the hours tick by. As it reaches full charge, voltage will reach 14.4 volts, at which point current will start to slowly decline.

(5) For this 100 amp-hour battery, disconnect the supply to stop charging when current drops below 5 amps if your supply can provide that much, or as soon as it drops even slightly below the current limit setpoint if using a smaller supply.)

Note that a small, 3-amp bench supply will take more than 33 hours to bring this battery to full charge if it's completely discharged. Some bench supplies have dual outputs of 3 amps each which can be paralleled to provide 6 amps. That can cut the time almost in half. If your supply will do the full 20 amp recommended charge rate for this battery, full charge will happen in about 5 hours, or less if the battery was not fully discharged.

As Horsefly said, it's important to battery life to stop the charge once its complete, and not leave it cooking.
 
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Smokin

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Never Short the Leads coming from a Power Supply.
 

Horsefly

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Never Short the Leads coming from a Power Supply.
Not true, at least for most of the bench supplies that allow setting constant current and constant voltage. The only way to set the current is to short the leads and adjust:
  1. Turn on supply with leads not connected to anything.
  2. Measuring only with a good multimeter and ignoring the display, adjust the voltage to the target level.
  3. Turn off the power supply.
  4. Short the leads together.
  5. Turn on the supply.
  6. Adjust the current to the desired constant current level. Because this is a less critical measure, you can use the power supply display to arrive at the desired current.
  7. Disconnect the leads from each other, and connect them to the target battery / cells.
 
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