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Plasticnoob

How to test battery voltage in a 7.2 with a battery meter ?

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Hi I have the jg vz61 scropian and wanted to test the voltage to see when it's done charging because the charger with the gun isn't smart. As you know this battery is unlike any other airsoft battery..

 

I was trying to buy a battery meter checker but non of them state 7.2 it's 6, 9 12,15,22v

Edited by Plasticnoob

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I recommend buying a digital voltmeter or multimeter from this century, the thing you linked looks very primitve and inaccurate. A digital multimeter doesn't cost that much and is a very useful tool. You set it to a voltage that's slightly above the maximum voltage of the battery to get a measuring range that gives the most accurate read out. A multimeter usually has a 20V setting, this measures voltage from 0 to 20 volts and is the appropriate setting for the batteries we use in airsoft.

 

What renegadecow is talking about is to use the connector on the charger that came with the gun with an aftermarket smart charger to charge the battery appropriately. Your dad or a tech savvy friend can help you with this. I could easily have done this for you, but I live on a different continent so that's a no go.

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You say " You set it to a voltage that's slightly above the maximum voltage of the battery to get a measuring range that gives the most accurate read out. "

 

That would mean I need to set this to around 8 volt?

 

 

Would this work?

 

http://www.amazon.com/4-0-30v-Digital-Display-Voltage-Voltmeter/dp/B00B689UGA/ref=sr_1_2?ie=UTF8&qid=1429400042&sr=8-2&keywords=digital+voltmeter

 

411Y0nFyZyL.jpg

 

 

as I said before I am new to airsoft/and tech, trying to learn ;( I just want to be able to read what it states fully charged so I know when to stop charging, someday I hope to rewire the OEM plug into a smart charger

 

 

 

51erO9XhA-L.jpg .

 

 

^ this is the ends of the meter and this is my battery. I guess just put them on the metal slab there > on the right

 

17825-2.jpg?1386948839

Edited by Plasticnoob

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This is what you're asking for:

http://www.amazon.com/Dragonpad-Digital-Meter-Voltmeter-Multimeter/dp/B00UMU8MOE/ref=sr_1_1?ie=UTF8&qid=1429401250&sr=8-1&keywords=multitester

 

But again, charging by voltage is iffy. Some smart chargers do it, but uses an algorithm and not just direct readout. Using your trickle charger, look at its output and the capacity of your battery. Dividing the capacity by the output times 1.2 gives you how many hours it takes to fully charge your battery. This is the safest way to do it, but assumes from a near depleted battery. If your charger has a low enough output, you can leave it for much longer, say overnight without risk of damaging the battery because the overcharge just leeches out as heat.

 

Adapting the supplied battery port into a smart charger really is the best thing to do other than converting your gun to take lipo. You don't even need a soldering iron to do that, just twist the wires together and cover in electrical tape, but soldering is highly recommended. If you or anyone you know can't do that for you, buy this:

http://shop.ehobbyasia.com/bol-mpex-cr1-micro-ex-charger-for-aep-pistol-battery-us-plug.html#.VTLx05CwrtI

It's a smart charger dedicated for Micro EX batteries.

Edited by renegadecow
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Thanks but how do I use it for a battery? I do not understand 200k, 20k, 2 20 200 200u 15a etc...The other ones state volts on them, this must be in metrics?

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This is what you're asking for:

http://www.amazon.com/Dragonpad-Digital-Meter-Voltmeter-Multimeter/dp/B00UMU8MOE/ref=sr_1_1?ie=UTF8&qid=1429401250&sr=8-1&keywords=multitester

 

But again, charging by voltage is iffy. Some smart chargers do it, but uses an algorithm and not just direct readout. Using your trickle charger, look at its output and the capacity of your battery. Dividing the capacity by the output times 1.2 gives you how many hours it takes to fully charge your battery. This is the safest way to do it, but assumes from a near depleted battery. If your charger has a low enough output, you can leave it for much longer, say overnight without risk of damaging the battery because the overcharge just leeches out as heat.

Why do you get the impression I am charging by voltage? I am not. I just want to see what the max volt is in the battery once its been charged after a few hours so I know I am not over doing it and to see if I need to recharge my batteries before playing again.

It would be very helpful for me to know if my batteries are dead or not, I hate to "over charge" these because they are not smart charger used. This will tell me if I need to charge them for long or short period of time next time I play a game.

 

Charger_18CAEP_lg.jpg

 

this is my charger, it is by means not smart at all. The output is 240ma, I did the math and its like 2.4? hours to charge 500mah battery pack

500/240 something like this?

Edited by Plasticnoob

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Why do you get the impression I am charging by voltage? I am not. I just want to see what the max volt is in the battery once its been charged after a few hours so I know I am not over doing it and to see if I need to recharge my batteries before playing again.

Using voltage as a gauge if a battery is full = charging by voltage.

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The first product I linked is a multitester. It can gauge a range of different parameters depending on where you set the dial. For your purpose, set it to "DCV 20" which automatically reads the voltage of any battery under 20V you set the probes to.

I just notice there is no DCB 20" on this unit nor the others listed for sale on this page

/...is it V- 20? A- 20m ?

51kBmx6aILL.jpg

Edited by Plasticnoob

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Guest alberty

I don't know if it has been mentioned already, but aren't there commercially-availabe adapters for these AEP batteries that let you hook it up to a smart charger with Tamiya style plug?

 

Example (TM's model): http://imgur.com/yOXwk6A

 

I think CYMA makes a clone of this too.

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To clarify. Charging by in the context of battery charging has only to do with how we will determine if the battery is charged. So think of the above comments as more testing by measuring the voltage at the battery terminals with the battery unloaded or out of the gun.

So we have three ways of testing if typical batteries are charged.

1 testing the OCV (open circuit voltage. ) No charger no load connected ----- Least accurate
2) testing the battery voltage and current under simulated load Most accurate to understand your battery condition and capability.

3) testing the Delta Slope of the battery voltage under charge. The meters in a smart charger does this. What happens is as the battery comes to complete charge the voltage rises rises rises rises then it peaks and starts to fall while the charger is charging. The smart meter knows to stop now. This method is best to just charge your battery and stop before it damages it.
4) A smart meter can be set to put a specified amount of charge (Amp Hours or Ah or mAh) into the battery and stop. This is the safest.

The scorpion charger does not stop charging until you unplug it. #3 & #4 stop auto matically. #1 & #2 are tests done to the battery off the charger.

 

wage peace

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BTW your scorpion is a 5 cell NiMH battery. When a NiMH cell is charged it is about 1.6V so your fully charged scorpion would measure 5 x 1.6V =8V......So your should measure ~~~~8VDC on the meter when your 7.2V battery is charged and not shooting the gun.

 

 

wage peace

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You can't do this merely by watching the absolute voltage (V). At least not reliably. You have to look at the first differential or dV/dT.

 

There are simply too many variables when looking at the absolute voltage, such as: temperature, age of charge (if any), charge current, age of battery, cell balance, etc. And between roughly 60% to 95% charge, the voltage will often be flat or have little change. So, if you even try to use this method, you'll likely end up with a lot of partial charges.

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