8:50 i have seen this many times, when these AGM (Acid Gel Mat) type batteries for UPS etc become discharged and not charged for long time, there internal resistance goes very high. To "wake" them up, so that they start charging, is sometimes +30V needed before they start responding and start drawing milliamps of current. Sometimes a few taps with a AC powersupply is needed. But from experience i have learned, if they start charging after these few tricks, the charging proces is not like a new battery, they still charge very slow and start dropping there voltage really quick when the charger / powersupply is disconnected. And if the battery is older then 4to5 years, they are gone. For criticial UPS devices and Home alarms, these batteries get replaced every 2 years. Also with this type batteries, a rule of thumb is when they start accepting a charge, is not to exceed 10% of there capacity in charge current. For example, for a 7Ah battery , the maximum charge current is 0,7A, this will extend the lifetime. Many devices that use a AGM battery have a very crude charging circuit, they supply 13a14V at few amps of charge current when the battery is flat. A AGM battery needs a special charge curve, starting with a high voltage like +30V at very low milliamps, and when the battery starts charging, the voltage supplied to the battery drops in stages to arround 13.8V, and the current goes up in stages, but not exceed 1a2Amps. Then when the battery becomes fully charged, the supplied voltage stays constant, and the chargecurrent drops to a few mA's '(Trickling charge mode), but this special charge curve does not exist in most devices that contain a AGM battery. And last, the reason that most chargers don't start charging if a 12V battery is below 6V, is that these chargers have a buildin very simple but effective short circuit protection. If you connect a multimeter accross the + and - , you almost measure near 0 volts, this is because in the end stage of these chargers, they use a series transistor. This series transistor is connected with the base through a resistor and zenerdiode to the positive output terminal of the charger, where the emiter of the transistor is connected to the negative output terminal. This transistor only pass current, when it's receives a current that is supplied from the battery.

@KissAnalog

9 ай бұрын

Thanks for this great feedback!

When batteries discharge, sulfur from the electrolyte joins with the lead plates to form lead sulfate. When the battery is properly charged, it forces most of the sulfur back into the electrolyte. However, when a battery is drained too low or is left uncharged for an extended period, thick layers of lead sulfate will form on the plates and impede current through the [depleted] electrolyte. A battery desulfator sends pulses of high voltage through the battery terminals in an effort to break through the layer of lead sulfate and allow the battery to charge again. When a battery shorts out and draws high current, it could be because a cell separator has broken down or been damaged. Chunks of the lead plates will sometimes break off in older batteries. It would be interesting to see the effect of simple things like re-routing the wires vs adding filter capacitors. It would show that not every improvement needs to be complicated.

@KissAnalog

9 ай бұрын

Thanks for your great feedback!

I recommend you to use a Diode or an Ideal Diode to protect your PSU if you turn it off with a connected battery supplying voltage and current to the PSU, many people burned their PSU because of that.

@KissAnalog

9 ай бұрын

That is a great idea - especially when you don't know how the output is controlled.

@jstro-hobbytech

9 ай бұрын

Just a normal reverse protection diode?

@JohnUsp

9 ай бұрын

@@jstro-hobbytech yes, preferably with low drop voltage or you can use an "ideal diode" which is 2 MOSFETs (Google that)

It looks like a good quality product.

@KissAnalog

9 ай бұрын

Thanks - I'll have to do a follow up to see what our final verdict is;)

@ 22:10 The first thing I noticed is, they used some kind of "snap in" IEC power and fuse connector, but they also chose to put hot melt glue on it to hold it in place? Another strange thing, is, the fan is configured off center from the heat sink, I wonder why they just didn't think to swap the IEC power connector and fan's positions on the back panel, and then the fan would have a full air flow path directly onto the heat sink.

@KissAnalog

9 ай бұрын

Yes you are right - but the epoxy on the IEC is actually pretty stiff. The fan I think is positioned so that it blows around the heatsink to cool other parts of the PS.

It would be interesting to see the effects of rerouting the AC wires and of adding capacitors across the two sets of output terminals. Tips and tricks from a real power supply engineer? Yes!

@KissAnalog

9 ай бұрын

Thank you! I think it will be intersting to see if I can make a difference:)

@jstro-hobbytech

9 ай бұрын

I always want to do it wirh mine. Just to see.

Yeah show the adjustment it's all interesting, see what if any improvement it will make separating the wires

@KissAnalog

9 ай бұрын

Thank you - I'll do that;)

Great review. I was surprised you didn't put a multimeter inline to measure the current to see how it compares to what the supply read out was stating. Was the battery able to hold a load now or is it dead?

@KissAnalog

9 ай бұрын

Thanks - I should have checked the current but when I use a resistor for load and the voltage is monitored - it becomes ohms law at that point. But when I short the leads - that would be a great way to verify the meter. Yep - that battery was not happy - I think it has a shorted cell.

Modding/hacking these cheap PSUs would make a great video

@KissAnalog

9 ай бұрын

OK thank you!

How did I miss this video haha I've been looking at the 120v 3 amp ones for a while but I have 2 kaiweets and a 3 output siglent along with meanwell supplies around my workshop with quick connects I've made. Along with atx ones as well. Also an isolated variac and a 1000kva isolation transformer that I have yet to find a use for. I'm not a fan of low quality digital rotary encoders. It seems I have to tweak timings whenever I use one in a project. I've started buying 6 wire ones and use heavy steel knobs. That brand is the one I've been thinking about buying. They have great prices.

@KissAnalog

9 ай бұрын

This is nice to find a 20 Amp 30V supply and right now it is on sale and has a coupon to take it to about $145: amzn.to/3Z5JVfw

Great review on this power supply! I just recently purchased the 60V20A version of this Nice-Power supply, mainly for lithium battery charging. Since it can do 1200 watts, I figured it would be able to charge LiFePO4 12 volt batteries at higher than 20 amps. I was wrong... Any way to change some settings with all the variable pots on board to get higher low voltage amps? (Even if at expense of getting less than 20 amps at 60 volts.) Or should I just suck it up and buy the 15V60A version instead?

@KissAnalog

16 күн бұрын

Great question! Yes, I think you would be happy with the 15V 60A version. I don't think you need to charge more than 15V and 60A would give you lots of current to charge with. Then one I have would be great for 24V batteries;)

Dead battery will take low current and as the voltage comes then the current will rise and the voltage will dip. At one point when it reaches full charge the current will drop to almost no current. This is because of the internal resistance created by the electrolytic solution and plates. Electrolytic solution is sulfuric acid and distilled water, of course you know this.. :)

Eddie, maybe you could measure the common-mode emissions by running a CE102 test?

@KissAnalog

9 ай бұрын

Thanks - I will see what EMI measurements I can do.

I usually set the voltage to the maximum I want before I connect the battery. Then connect the battery with the current down the whole way. Connect the battery and increase the current to where I want it. I set a lead acid to 15.2 volts at 1c current rating. Lead acid needs to get above 15v to properly desulfate it.

@KissAnalog

9 ай бұрын

Thanks for your feedback! I think when you have experience and it works - then why change what works;) The only thing I'd worry about is touching the terminals with the voltage set at max and then touching the terminals. There could be gases around that can actually cause a flash burn - which can be dangerous. But if you have an on/off switch so that the terminals are connected - then that would be better. I think it also depends on the battery size on what charge current that is recommended.

@kgsalvage6306

9 ай бұрын

@@KissAnalog If you have the current turned down the whole way there would be no current flowing when you initially connect the battery. An output switch would be a good thing though. Could possibly add one to it using a relay.

@KissAnalog

9 ай бұрын

I think a switch would be a great addition, The switch could be used to turn on and off to shock (desulfate) the battery possibly.

The PE Chrimping is not very nice too. And i would use a thicker cable for it. And is the Powersupply really a SELV one? So that you coul do a PELV one with grounding it? Can’t you turn the frount cover 180 °? So the switch move to the left down corner?

@KissAnalog

9 ай бұрын

Thanks for this great feedback. But, remember that the chassis ground is just used to bring other test equipment to the same potential. It isn't really used as a PE as it doesn't have a way to trip a breaker so it doesn't need to handle fault current. I have a new video coming out talking about he placement design of this PS.

@zoom_h2625

9 ай бұрын

@@KissAnalogIt could be a German safety thinking… But if there is a connection between the primary site an chassis, the the PE should be able to transport the energy to trip the MCB fast. In Germany it is 0,4 seconds, for this time the MCB needs about 80A PFC *better“ 120A. And a lesser resistance of the PE will lower the touch voltage.

That is classical half-bridge with controler on secondary side. On imput that is two common mode inductors one for "main" and one for axillary power supply (probably flyback contrler). That optocupler is not for main power supply it is for axillary power supply. The main controller is on the secondary side and can sense voltage directly (axillary smps provide power supply for main smps controller). That is basically the same design used for many years in old ATX power supply's (AT power supplies have the same secondary side controller but no axillary power supply, it used self oscillations of main transformer to provide initial power to secondary side controller, before it take control)

@KissAnalog

9 ай бұрын

Thanks for the great feedback! Yes I agree that we have an aux supply and it is most likely a flyback. I'll have to do a video and walk thru this and explain why I think this layout could have been better.

@mrlazda

9 ай бұрын

@KissAnalog I do not understand why people complicate. The easiest way to do this type of power supply is to copy the layout of ATX power supply. This type of power supply is (at least for me) the easiest you can design ( the most complicated part is flyback on it), it is easy to compensate (it work ok with voltage mode). I do not get why they pick layout like this. It is not more compact than ATX power supply and imput filtering for axillary supply look like afterthought (and why is it needed in first place, they already have it for main power supply, so they can share it)

@KissAnalog

9 ай бұрын

Yes I agree - the layout is actually kind of bad;) I'll do a video and go over this.

HI Eddie, thank you for a very nice review. 😁🙏

@KissAnalog

9 ай бұрын

Thank you! I appreciate you!

@KissAnalog

9 ай бұрын

thanks so much!

good 32 or 48V power supplies are kind of difficult to find especially for audio, when the TPA3255 can accept up to 48V and claims 600W , one should have the power adapter that can support the rated RMS power of the amplifier to make a good use of the full capabilities

@KissAnalog

9 ай бұрын

I agree with you! Thanks for the great feedback!

my experience is that if a battery reaches 0 or close to that, it is damaged inside and will never become a good battery again and I tried everything with only peak voltage out a pwm try to freeze -18 it 24 hours , then charging dropping it shaking ona big viberator thing try to change electrolytes inside , but eventually never had a good result 80% or something, but no always lower then 40% sometimes 10 %

@KissAnalog

7 ай бұрын

Thanks for that info! Yes batteries do not like being over discharged

Hi, do you recommend a benchtop programmable power supply at 100V to 120V? I am looking at Hantek HDP180V8S, Kuaiqu SPPS-D1203-232, and the Wanptek KPS1005D. Has to have PC software and for the main purpose of charging Lithium-Ion batteries in electric scooters

@KissAnalog

7 ай бұрын

Thanks for asking! I do really like my Wamptek as it has preset programmable buttons in the front that are easy to use: amzn.to/3Sa1FF1

@nicholasheidl8481

7 ай бұрын

@@KissAnalog I just purchased the new Wanptek APS1203H after some serious thoughts about all of them. It does has most what I want and until I get it, I don't know if I can preset CV and CC together. However, for $179 AUD I know it will cover the important needs.

@KissAnalog

6 ай бұрын

I think you will really like this PS. Please let us know.

23:17 that will be a common mode choke for the low voltage rail of the circuitry. At 20:48 you see a current transformer on the right side, next to the 2 big black filter caps, but why a current transformer on DC ? I first thought that this was the 20A current regulation, but the primary winding is to thin for 20A, and at that place, it's DC. At 20:53 you see 3 current shunts near the back, between those 4 smaller caps, i think those are used for the DC current regulation.

@KissAnalog

9 ай бұрын

Yes, I think you are on the right track. The 3 current shunts are most likely for the DC current sense output. The current transformer might be used for current sense on the switching FET. The layout is very jumbled, so I think it makes it difficult to trace without looking at both sides of the boards and removing the heatsink.

@BjornV78

9 ай бұрын

@@KissAnalog , maybe a look with a differential probe across that current transformer? Normally a current transformer is for AC only. Not yet seen a current transformer used as a pulse transformer. But because it's next to the big filter caps, it seems that it is DC, but that doesn't make sense, or is it to measure the AC ripple? In normal use, a current transformer like such a donut needs a amplifier (Op-Amp) to bump up the few millivolts of output to a level high enough to use it. But if it is for measuring the ripple, the DC signal would saturate the core. So it is not clear what that current transformer is doing there.

@KissAnalog

9 ай бұрын

I'll have to explain how this is used in a SMPS.

Thanks!

@KissAnalog

9 ай бұрын

WOW thank you for your generosity!

This is probably unrelated to the video that you're currently doing right now but I need someone to help me decide between a 60 volt 5 amp benchtop power supply or a 30 volt 10 amp benchtop power supply. Which one should I buy? I'm using it for testing and reactivating Ryobi 18 volt and 60 volt batteries at will not accept a charge. I've looked on KZread and all over the Internet and no one tells you the advantage or disadvantage of a 30 volt vs 60 volt benchtop power supply. Please help. Making a video this would be great.

@KissAnalog

9 ай бұрын

Great question! I'd go with the 60 V power supply so that you have the range and you really don't need the high current. But here is a Nice-Power bench power supply that has both - 10 Amps and 60 V range: amzn.to/45Jf3U8

@westsidebum1

9 ай бұрын

​@KissAnalog, thanks for getting back to me. That was so helpful! I saw online that there was another guy who had the same question that I did, and he couldn't find any answers. You are awesome!!!! You should do a short video on this subject, though, because it seems to be something that a lot of people would need to know. There is no information anywhere out there about this. I think he would get a lot of hits on a short video about this topic.. again you're awesome!!!!!

@KissAnalog

9 ай бұрын

Thanks for your feedback! I think you must be right. I'll do that;)

6V Battery: Recharge at 7.2V-7.5V (cycle use) or 6.75V-6.9V (float/standby use) and 0.05C (350mA for a 7Ah battery) 12V Battery: Recharge at 14.4V-15V (cycle use) or 13.5V-13.8V (float/standby use) and 0.05C (700mA for a 14Ah battery)

@KissAnalog

9 ай бұрын

Thanks for the great info!

😀👍🏻♥️👍🏻👍🏻👍🏻👍🏻👍🏻👍🏻👍🏻👍🏻

@KissAnalog

9 ай бұрын

Thanks so much!

The Voltage and Current adjustment is the worst I ever see, even the worst and cheap power supply is better than this one.

@KissAnalog

9 ай бұрын

The current is pretty course - which I think affects the voltage at the low level, but the voltage actually has a nice pot.

came here to hear a review but couldn't handle more than 5mins and even then was fast forwarding thru the waffle and 'YEH"s. you really need to work on your delivery mate it is really hard to listen to. Had to look elsewhere for a review.

@KissAnalog

2 ай бұрын

Sorry about that. Good luck!