Help me find TRUE 4.1xV, 3.0 to 5.0A AC/DC adapters

[SamTexas]

I'm looking for ACtoDC adapters with a TRUE output voltage between 4.10V and 4.20V. And an output current of at least 3.0A. If you have one that actually meets both the V and A requirements, please post the exact brand, model and a picture of that adapter. I would really appreciate the info. Please make sure the voltage is measured in NO-LOAD (open circuit) condition.

Important note: Never mind what the specs says, or what is printed on the adapters themselves. Most of the time, the output voltage is a lot higher than claimed. I have wasted sufficient time and $$$ on those.

 

[BatteryMooch]

Wouldn't you want the adapter's voltage to be spec'd when under a typical load for your application? That's typically when the voltage matters as long as the no-load voltage doesn't fry anything for the few microseconds to milliseconds it's at the no-load voltage after it's been connected to the load.

A no-load voltage of 4.1V-4.2V could be anywhere from 4.1V down to 3.0V when under a 3.0A load (depending on the adapter, i.e., regulated, unregulated, etc.).

 

[neptronix]

One thing you didn't mention sam, is that they have to be current limited.
Without current limiting, the batteries you are hooking them up to will attempt to draw amps in the 10a-1000a+ range and blow the ac/dc adapter within seconds.

Cell phone and other gadget adapters do this, because they're designed to be battery chargers.
You will have a very hard time finding something like this because most gadget batteries charge at about 1/2C.

So you'd be looking for an adapter meant for something that only runs on 3.6-3.8 nominal volts, but has a 6AH-9AH or larger battery.
I can't think of any such device, but that's where you'd get an adapter like this.

 

[SamTexas]

Thanks CamLight for the reply.

Wouldn't you want the adapter's voltage to be spec'd when under a typical load for your application?

Actually no. So far, I have found that the no-load voltage will actually be the battery voltage if connected long enough. For example, I have used a Nikon EH-62C (open voltage 4.50V, 1.5A) to charge a 5.2Ah pack (in a fire proof place). Overnight, it actually charges the battery to 4.50V! (No, there was no explosion, no fire)

A no-load voltage of 4.1V-4.2V could be anywhere from 4.1V down to 3.0V when under a 3.0A load...

That's exactly what I want. As the battery is charged up, the voltage will rise to the open voltage and never beyond.

Without current limiting, the batteries you are hooking them up to will attempt to draw amps in the 10a-1000a+ range and blow the ac/dc adapter within seconds.

The max current will be lesser of the desired load current or the maximum current provided by the charger. The batteries want more, but cannot force more from the charger.

 

[neptronix]

Only if the charger has current limiting.
In the first post you mentioned that you wanted ac-dc adapters.
Figured i'd mention that there is a big distinction between the two.

Without current limiting, the battery will try to suck all of the amp hours it needs instantly.
( imagine the battery trying to suck 5 amp hours in 1 second from something that can't control the amount of current it outputs. )

adapters / wall warts don't have any current limiting at all.

BTW many single cell chargers are designed to cut off at a certain voltage, so while they may output something like 4.2-5v no load, they will all stop at the 4.1v-4.2v mark.

No battery that i know of charges to over 4.2v, so no worries.

 

[SamTexas]

I'm still looking for those 4.1xV, 3.0 to 5.0A adapters. If you own or owned one, please let me know the brand/model number. Thanks. Sorry for the above distraction. Hopefully it will be the last.

BTW many single cell chargers are designed to cut off at a certain voltage, so while they may output something like 4.2-5v no load, they will all stop at the 4.1v-4.2v mark.

Show me one, just one and I will believe you. PM me once you have located and tested it. I will buy it, test it and if it worked the way you described, I promise I will create a new thread to acknowledge your help.

 

[number1cruncher]

Sorry I don't have an example, yet. I'm looking...

However, I have found a 3.3V 3A smps inside a network switch, so low voltage moderate amp supplies are around. We may have to look inside stuff to find them though.

 

[BatteryMooch]

Thanks CamLight for the reply.

Wouldn't you want the adapter's voltage to be spec'd when under a typical load for your application?

Actually no. So far, I have found that the no-load voltage will actually be the battery voltage if connected long enough. For example, I have used a Nikon EH-62C (open voltage 4.50V, 1.5A) to charge a 5.2Ah pack (in a fire proof place). Overnight, it actually charges the battery to 4.50V! (No, there was no explosion, no fire)

A no-load voltage of 4.1V-4.2V could be anywhere from 4.1V down to 3.0V when under a 3.0A load...

That's exactly what I want. As the battery is charged up, the voltage will rise to the open voltage and never beyond.

Ahhh...of course. I forgot about that.