20A Current limit for 16V switchmode power supply

Anyone know if you can get a 20A PSU ≥16V with a current limit?
Or an external inline jobbie for a SMPS?
Or fairly simple circuit I can stick onto one of these?



I'm trying to turn a 45A solar controller (expecting a current source) into a mains battery charger. I've already let the magic smoke outtov the predecessor 15A @ 24V after a year of infrequent but hard service.

Low budget solution would be best, I'd consider a lesser amperage if it helps. I'd buy a battery charger if they were as good as solar controllers.

whizbang

Not really sure what you are looking for here, You already have a solar controller, and you want to run it off mains to charge batteries??

If so, you need a power supply to match the input of the solar controller. Go for something with an output pretty close to the max input voltage of the solar controller.
How much current do you really need ?

Meanwell is a fairly well regarded brand, well known on Ebay.

I want to changeover from PV input to mains when opportunity allows on the solar inputs of the controller.
A > 45A power source will murder my 235Ah bank hence I want to limit the input, not to mention a 750Watt 16V PSU is mega bucks, which would be better spent on a programmable mains charger and furthermore the input is out of spec for the solar controller.
Solar controller is overspec-ed for functionality.

Budget is under €75 for a smps with current limit maybe more if it's quiet, I was getting loads of magnetostriction from the last setup with a smps driving a PWM controller. I added a few filters and improved things but it was still irritating.
I may just spring for a less than ideal fixed algorithm mains charger I can't really justify the expense of a good one given the use I'd give it.
But there's nothing on the market I'd deem suitable for less than €150, nothing programmable for less than €250 (at least that I've found).

Requirements are;

• ≥15A output,
• load compensating,
• temperature compensating,
• 4 stage; absorption @ 14.5v - 14.7v, float @ 13.5v and equalise @ 15.5v)
• Preferably programmable (editable, not selectable).

I already have a solar controller that does all this, cost a lot less and has a much higher output capability.


I found this last night.



Do you think I could parallel two of the 10A outputs to make a 20A limit?

whizbang

whizbang wrote: »

How much current do you really need ?

20A give or take @16V

25A max, 15A min.

whizbang

I see where you are going, Battery chargers are so important to get right, and so difficult... I dont know if i would trust fleabay to look after my batteries..

The link you posted looks like a pile of crap, nothing useful at all.

I can't see anything wrong with using the PSU you posted, except as you know, they don't like having a high speed switching load. Maybe a car audio capacitor can do 16v?

The current is a bit of a distraction, if the PSU can do rated current 100% of the time, then go for it; the batteries will charge initially at a max of 26A, and then current will drop as per controller requirements.

Sir Liamalot

Well having already let the magic smoke outtov a few supplies I'm convinced otherwise. The controller takes what it can currentwise.
The last SMPS blew a thermistor and a line filter cap. after minimal use and running at 115% rated. Most of these smps are capable of 110% rating under duress.

I have an LC choke on the output of the PSU with a 22 000uF cap.

The original question stands;

Sir Liamalot wrote: »

Anyone know if you can get a 20A PSU ≥16V with a current limit?
Or an external inline jobbie for a SMPS?
Or fairly simple circuit I can stick onto one of these?

Any thoughts on this?

whizbang

I have a poor opinion of anything that comes in that kind of a pre-made case, no specific reason, just gut..

I tried to repair a bunch of 24v battery chargers that came in cases exactly like that one. Not one of them had the same fault. I gave up in the end, as the control system was just too poorly designed.

You're right. I had a look inside it and it's all Capxon capacitor junk.

Hi-Res gubbins.

In the end I ordered this. It's pretty good but still not a patch on my solar controller, I don't like some of the set-points but I may mod. it later. I'll test it first and see if it's necessary.



As regards the cheapo Chinese PSU I ordered the 32V 05A as a sacrificial PSU too.
Apparently it performs well but I'll be swapping all the caps.

That'll give me the extra 5A I wanted and if it's as noisey as it's predecessor I'm just going to cut it and use it as a lab supply for tinkering. My current lab power is my last 250Ah battery set and a 150W potentiometer.

I've already spent the price of the Chinese jobbie replacing HRC fuses. :pac:
If it all goes to plan the Victron can do the knuckle-work and the PSU will take over the float set-point and running loads maybe. Two chargers are better than one..entropy, and redundancy systems.

You can run a solar controller and a mains charger at the same time, the solar controller reads the mains charger as a charged battery and backs off (it kinda works on a depleted battery the solar controller will idle when the mains charger hits absorption @ about >80-90% battery SOC).

Thanks for the pointers.

My concerns of the 16V20A are the leads are too small...easy remedy though and passive cooling with 40W waste heat at full load? :eek:
That'd need a fan mod. too I'll bet. Cheap though.