BK Precision 1692 3-15V, 40A DC Power Supply

[Sgt Raven]

Does anyone have any experience with a BK Precision 1692 3-15V, 40A DC Power Supply? You can set the voltage, but not the current. Would it work to charge 100AH LiFePO4 3.2v cells and 12.8v batteries? There is one locally for about half the retail price that they're claiming has been lightly used.

https://www.bkprecision.com/product...dc-40a-switching-digital-dc-power-supply.html

https://www.amazon.com/Precision-16...00068OUNY/ref=cm_cr_arp_d_product_top?ie=UTF8

One of the reviewers on Amazon said that putting a 200,000uF capacitor across the outputs helped smooth out any spikes. My understanding is a PS won't put out more amperage, than what is powering will draw. Does that apply to charging cells/batteries, too?

 

[FilterGuy]

Does anyone have any experience with a BK Precision 1692 3-15V, 40A DC Power Supply? You can set the voltage, but not the current. Would it work to charge 100AH LiFePO4 3.2v cells and 12.8v batteries? There is one locally for about half the retail price that they're claiming has been lightly used.

https://www.bkprecision.com/product...dc-40a-switching-digital-dc-power-supply.html

https://www.amazon.com/Precision-16...00068OUNY/ref=cm_cr_arp_d_product_top?ie=UTF8

One of the reviewers on Amazon said that putting a 200,000uF capacitor across the outputs helped smooth out any spikes. My understanding is a PS won't put out more amperage, than what is powering will draw. Does that apply to charging cells/batteries, too?

First, you might be able to get it cheaper here: https://www.zoro.com/bk-precision-s...=12619781&utm_campaign=4286516#specifications

That looks like an OK supply but it also looks like it only has voltage regulation so I would *not* use it for charging batteries. You need one where you can set max voltage and max Current.

When charging an empty battery, you start by limiting the current to the specified C charge rate for the battery as long as the voltage is below your max charge voltage. As the battery charges, the voltage will rise till it hits the max charge voltage. The charger will then hold the voltage and let the current start going down as the battery charges further. Eventually, the current will go to zero or near zero, at that point you must either remove the voltage (preferred) or drop the voltage to a safe float voltage.

 

[Sgt Raven]

First, you might be able to get it cheaper here: https://www.zoro.com/bk-precision-s...=12619781&utm_campaign=4286516#specifications

That looks like an OK supply but it also looks like it only has voltage regulation so I would *not* use it for charging batteries. You need one where you can set max voltage and max Current.

When charging an empty battery, you start by limiting the current to the specified C charge rate for the battery as long as the voltage is below your max charge voltage. As the battery charges, the voltage will rise till it hits the max charge voltage. The charger will then hold the voltage and let the current start going down as the battery charges further. Eventually, the current will go to zero or near zero, at that point you must either remove the voltage (preferred) or drop the voltage to a safe float voltage.

There is one here for $150. Without variable amperage, the 40A output is still below 0.5C for a 100AH 3.2v cell @50A. That is why I'm asking. I could also use it to power 13.8V equipment, which would be a plus. But not if I couldn't use it to charge cells, too.

 

[FilterGuy]

I guess it will work as long as the supply behaves well at max current. Also, I like to charge at a lower C rate, but I suppose if you did it once or twice at .4C it would be OK.

If you decide to use it, set the voltage *before* you hook up the battery. Also, don't let it just sit for a long time on the power supply. When the current drops off to 100ma or so, take it off the supply.

 

[Barold]

Someone else had posted a link to Circuit Specialists -

The two power supplies I am considering are these:
15V 40A
15V 60A
I am inclined to go for the 40A (though the amount of time I'll be waiting may be worth the extra $90) but do you think the resolution (0.1V is too broad to be usable for top balancing and charging our big LFP cells?

Edit/UPDATE:

I purchased the 40A charger from Circuit Specialists and it is due to be delivered shortly. Unfortunately UPS charges import duties on top of the $35 I paid to CS for shipping - this will encourage me to go to the Aliexpress route - as it added 48% to the cost of the power supply.

 

[Sgt Raven]

Someone else had posted a link to Circuit Specialists -

The two power supplies I am considering are these:
15V 40A
15V 60A
I am inclined to go for the 40A (though the amount of time I'll be waiting may be worth the extra $90) but do you think the resolution (0.1V is too broad to be usable for top balancing and charging our big LFP cells?

The seller never got back to me, the ad expired, and it's listed again. didn't respond this time, either....

Instead I found a lightly used Mastech HY-3005D-3... Linear Amp, not Switching Amp.
3 channels two at 0-30 5A and the 3rd is fixed 5V 3A.
Constant volts or constant current.
Channels 1 & 2 can be run in Series or Parallel, too for 10A 0-60V

I can use 14.4V to test my DC-DC charger and 45V to test the MPPT SCC