How to manually charge a LifePO4 with a variable voltage bench power supply?

[coalfield]

Is there a way I can use a VV PSU to charge a 12v LifePO4 battery, manually. Or should I steer away from this and only use a charge controller due to the different stages of charging?

I was thinking could I replace the solar input of the CC with a PSU to emulate a solar panel and benefit from the charge controller output?

I have this PSU:

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Looking to quickly charge the LifePO4 30Ah / 12V without using a small solar panel, my CC is 20A max.

 

[Texas-Mark]

Sure you can. I have a PS similar to the one on the right. First set the voltage and current (i.e. 14.6V 5A) and then press then press the output button. It will charge at 5A (constant current - CC) until it reaches the target voltage, then it will switch to constant voltage (CV). The current will then taper down to nearly zero when fully charged.

 

[coalfield]

Sure you can. I have a PS similar to the one on the right. First set the voltage and current (i.e. 14.6V 5A) and then press then press the output button. It will charge at 5A (constant current - CC) until it reaches the target voltage, then it will switch to constant voltage (CV). The current will then taper down to nearly zero when fully charged.

Thank you I have tried connecting to the charge controller input and it seems to work fine. I put it on 14.5V / 4Amps and charging looks to be fine. The overcurrent protection was kicking in so disabled it (I think the CC pulls as much current as it can).

Would you recommend as your message bypassing the CC, or would that still be ok?

 

[Texas-Mark]

Thank you I have tried connecting to the charge controller input and it seems to work fine.

I was talking about charging the battery directly from the PS, not powering the charge controller.

 

[coalfield]

I was talking about charging the battery directly from the PS, not powering the charge controller.

Yes but no reason an input to the charge controller would not be OK I presume, since its just replacing a solar input?

 

[Texas-Mark]

Yes but no reason an input to the charge controller would not be OK I presume, since its just replacing a solar input?

Sure, you could crank the voltage up, but it sort of defeats the purpose, when the PS alone will do a better job than than running it through the charge controller.

 

[Supervstech]

Sure, you could crank the voltage up, but it sort of defeats the purpose, when the PS alone will do a better job than than running it through the charge controller.

Actually, running through an MPPT charge controller can get more watts into the battery than directly connecting the power supply to the battery, because the supply is limited in output amperage, but should be able to up the voltage to 30 or more, and the cc can regulate that down to battery voltage.

 

[Texas-Mark]

Actually, running through an MPPT charge controller can get more watts into the battery than directly connecting the power supply to the battery, because the supply is limited in output amperage, but should be able to up the voltage to 30 or more, and the cc can regulate that down to battery voltage.

I was thinking more about getting a more precise charge. Add in charge controller losses and I think it would be a wash on the watts (given a 12V battery). Not even sure if the OPer has a MPPT controller. IMO it would be silly to run one of those power supplies through another controller. But that's just me.

 

[coalfield]

the controller I have is PWM, but running it through the CC was more peace of mind that it did not overcharge it (i think there is protection built in).

Not to worried about efficiency, its more to get it to 100% capacity so I can calibrate the shunt properly (and quickly) as the panel is only 60W max and taking a long time to charge up.

Managed to successfully charge it via the CC... the 14V and the current dropped to <100ma.

Thanks for all your advice its given some peace of mind I wasn't going to blow anything up!

 

[Texas-Mark]

but running it through the CC was more peace of mind that it did not overcharge it

IMO, I have more peace of mind using the PS directly. I know exactly what it is doing (i.e. the exact voltage/current I have it set to charge to.).

But glad it worked out however it was done.

 

[retrodog]

the controller I have is PWM, but running it through the CC was more peace of mind that it did not overcharge it (i think there is protection built in).

Not to worried about efficiency, its more to get it to 100% capacity so I can calibrate the shunt properly (and quickly) as the panel is only 60W max and taking a long time to charge up.

Managed to successfully charge it via the CC... the 14V and the current dropped to <100ma.

Thanks for all your advice its given some peace of mind I wasn't going to blow anything up!

I run mine through my charge controller. Mainly because the power supply is limited at 10A. If I run it through the CC, it can nearly double that.

 

[coalfield]

I run mine through my charge controller. Mainly because the power supply is limited at 10A. If I run it through the CC, it can nearly double that.

Yes I cant see it making any benefit going direct over through the CC tbh

 

[Isaac-1]

Let me ask, what is your goal in doing this, sure this can be done, and may in fact be a handy method of testing battery setups, but really should not be a end goal as variable bench power supplies are terribly inefficient, and tend to radiate a lot of heat for any given output.

 

[coalfield]

Let me ask, what is your goal in doing this, sure this can be done, and may in fact be a handy method of testing battery setups, but really should not be a end goal as variable bench power supplies are terribly inefficient, and tend to radiate a lot of heat for any given output.

Just an occasional way to get to 100% soc quickly. I.e before a trip or to calibrate a shunt

 

[Isaac-1]

There may be other / cheaper / faster ways to do that if you tell us the components of your setup, right now we are flying blind and making some assumptions, it sounds like this is an RV mounted system?

 

[coalfield]

There may be other / cheaper / faster ways to do that if you tell us the components of your setup, right now we are flying blind and making some assumptions, it sounds like this is an RV mounted system?

Its just a camping 30Ah battery but on a 60W portable panel. To be honest my main reason for charging via a charger was to get to 100% to calibrate a shunt, but will want to maximise the charge on occasions, but only once every few months if that.

 

[Isaac-1]

In that case, sure there are any number of 10-20 amp variable power supplies for under $60 on amazon that should do what you want, and charge your battery in about 3 hours, if you are in no big rush to charge, you can probably find a 3 amp model for under $35 that will charge it in about 10 hours. If you don't mind doing your own wiring you could probably even use something like https://www.amazon.com/Adjustable-DROK-110V-220V-Switching-Transformer/dp/B08GFSVHLS

 

[time2roll]

The key here is the power supply is a variable voltage. Set the voltage first, connect to the battery and let it rip. Stop when done.

 

[coalfield]

Thanks for the feedback I did purchase a VV PSU (Wanptek) in the OP. Still used it through the CC since it means I don't have to worry about setting the voltage (so much) and benefits from the protection of the CC. As @retrodog mentioned the CC also will increase the current output with respect to the input voltage allowing for a faster charge on Amp limited PSUs, however I didn't benefit from that my battery is so small.