Battery Charger DC Input?

[Esperologist]

I'm hoping I can get some help here, I've been researching all over the web and it seems like there is no direct answering of what I'm wondering. Either technical jargon is used (I'm not an electrician) or it is so briefly looked at that it doesn't answer my question.

Simple Question : What happens when voltage or amperage supplied to a charger is changed?

Context : I'm sitting at work, looking at car adapters from about 5 different manufacturers but only 2 sizes. On our site, we have 3 listed and next to no information about them on there. Some of the automotive adapaters are specified to a particular model of flashlight or charger. Lack of data drives me insane, so I've been looking at numbers all over the place and trying to see if I can just reduce these to two piles based on the size of the connector or if there is more to it.

So, to make this easier for me, this will help:

Let's say we hav a charger that wants 10V DC at 1A.
1) What happens if I give it 10V DC at 1.5A?
2) What happens if I give it 10V DC at 0.5A?
3) What happens if I give it 12V DC at 1A?
4) What happens if I give it 8V DC at 1A?

From what I have found online, I get the impression that changing voltage is a bad idea but changing amperage is acceptable.
The closest I found to talking about good or bad was discussing it in Watts, but those are derived through math based on volts and amps... looks like W=V*A so 10V*2A=20W but also 20V*1A=20W... so if a device just asks for Watts, that assumes either Volts of Amps are constant.

I have chargers asking for varying DC Volts at varying Amps. Most want 12V, but I have one that will take 10V-16V and another 12V-24V and the flashlights have two wanting only 10V and another wants 8.4V.
When it comes to amps, they range from 400mA to 2A in the chargers and the flashlights are wanting a low of 1A and high of 3.5A.
I tried contacting Tenergy for some information about their car adapters. They gave decent answers, but it can be summed up as 'all our car adapters are the same except for the connector'. Although it is usefull to know, and the other information I got is useful, that doesn't mean I can use their car adapter with another company's charger or flashlight. All it tells me is that their car adapters output 12V DC at an undisclosed amperage. I can't even guess the amperage using their chargers since their listed amperage requirements range from 400mA to 1.5A... at least, in the models we carry from them.

Sorry for the long post, kind of demonstrates me obsession with expanded data volumes.

 

[Bimmerboy]

In essence, the charger will only draw what it wants, so if the supply can provide more current than the charger wants, it will have no effect. In fact, some headroom is a good thing as the charger won't tax the supply to it's limit.

Therefore:

Let's say we hav a charger that wants 10V DC at 1A.

1) What happens if I give it 10V DC at 1.5A?
A: Nothing, as the supply is not actually forcing 1.5A through the device. It will only give what the device asks for, and can do so up to 1.5A.

2) What happens if I give it 10V DC at 0.5A?
A: The supply will not meet the device's demand, and the device won't function properly.

3) What happens if I give it 12V DC at 1A?
A: Depending on component tolerances, the device may fry if given too much voltage.

4) What happens if I give it 8V DC at 1A?
A: The device may not function properly, or at all due to lack of "potential", meaning there is not enough voltage for some components to operate.

Let me know if you want more clarification, and/or have more questions!

 

[mattheww50]

Without knowing the specifics of the devices involved, at best the answers are an educated guess. In general a power supply that can provide more than the required amperage will always work. The only circumstance where it may not work is if the amperage required by the device is very small relative to the capacity of the supply. Some supplies have problems with voltage regulation at very small loads, such as drawing 1 amp from a 100 amp power supply.

Some devices are designed to operate over a fairly wide range of voltages. For example if your device is intended to be operated from a 12V DC outlet in your car, is is probably designed to function properly on any input voltage from 11-16volts, because that's whats available at the outlet, the actual voltage will vary according to operating conditions of the vehicle. I should point out that some car adapters contain voltage regulator circuits. So for example I have sat nav (GPS) in my car that runs off the cigarette lighter outlet. It contains a voltage regulator circuit to provide 5 volts from any input voltage between 11 and 16 volts. Consequently not all 12v adapters will work with all devices because while the input is 11-16 volts, the output can be something considerably different.

Whether the device will operate properly on .5amp is unknown. Some battery chargers simply reduce the charging current when that happens, other will not function at all. The latter is more likely than the former however.

 

[ChrisGarrett]

I once mistakenly hooked up my 14.5v/4.5A Rat Shack IC3 wall wart to my Maha C-9000. On discharge, things worked perfectly, but when I went to charge back up, the Maha would begin the charging cycle and then go blank and reset itself in an endless loop.

It took me a few minutes to figure out what was wrong and after that, I took a silver Sharpie and marked all of my wall warts with the charger name on them.

Chris

 

[Esperologist]

Thank you.
Okay, so here is what I gather from this:

So long as the device can handle the voltage given, there is no issue there.
It could be that all the chargers can handle 10-16V since that seems to be the range that comes out of the vehicle port. However, if the device can't handle it, lows will likely result in nothing occurring and highs might fry the device.

When it coms to amperage, as long as it is reasonably close, it I fine. Being under might slow it down or even stop it and being over is fine unless it is to much over.

The easiest way to let you know what devices are in play would be to link to the store I work at.
The second is just to say that most of our battery chargers are from Tenergy with some alternate sources and some flashlights from Fenix and EagleTac. Our car adapter cords are either from Tenergy or came with products.

So, I am probably safe to list all the devices that want 12V as using the same car adapter since the amperage from a car adapter shouldn't be able to get extreme enough to be a problem?

 

[ChrisGarrett]

Don't forget that you have different barrel/pin sizes on these adapters and devices, so don't assume that one will work with the other.

Also, LaCrosse and AccuPower are an odd lot, as they do 3.0v at 2.8A.

Chris

 

[Esperologist]

Yup, I've built a list of which of our devices fit (size) which car adapters... I don't have specific measurements or anything, so I'm mostly just going with the 'try it and see if it fits' to measure them. I've got a couple that we either don't have in stock or are in sealed packages so I can't verify them.
I also have a list of what each device has listed on their body, AC adapter or car adapter for their ratings. I think need to go through them all again to see because at least one has no input listed on the body but has an AC adapter with 12V at 3.5A but a car adapter with 12V at 1.5A to power it. So, don't know what the device wants, but I know what it is getting... but also don't need to since it comes with both adapters.

Is that their charging rate or their power input requirement?