joeyhatch11

How do I measure MAH on my Lipos? I have a craftsman multimeter but I dont see a setting that will tell me that. Just one setting that says "MA" But when I connect my leads all it does is beep. Any ideas? Thanks, Joe

Airbus 9e

I think most LiPo chargers will tell you how many milliamps the pack took....

joeyhatch11

Yeah but mine is in the mail. I ordered it on Friday. Right now I'm using my Esky charger from my Lama V3. Just curious to see if my meter would have a the function like that. Thanks though

DaveG55

A multi meter will not directly measure mAh. It will only measure current flow (amps or milliamps) when it is connected in series in a working circuit.

Jeremy Z

1) Stop using that charger. It is only a matter of time before it puffs your pack. (voice of experience) Although you plug the balance tap into the charger, it does NOT balance charge. I just sold my Lama V3 to a buddy at work. I'm sure I'll miss it. FYI: Hobby Lobby has 2S 20C LiPos that are better than the E-Sky ones for $16 ea.

2) mA = unit of current flow. mAh is how many mA flowed in one hour's time. You cannot measure mAh with a DMM. The current flow changes constantly. As an example, if you had a 3300 mAh pack, completely discharged it (for the sake of example) then charged it at 3.3 A, it would take one hour. If you had the pack completely full, and discharged it at 33 A, it would last 6 minutes.

For now, don't worry about it. You'll have your proper charger in no time. Hold off on charging that battery any more until you get a proper balancer or balancing charger.

joeyhatch11

Hey Jeremy, I've been using that Esky charger for both my Esky lipos and the smaller ones I was using in my Losi Mini-T. Also using it for my 11.1v 600mah I have in my transmitter. I've been using the charger for a better part of 2 years and haven't had any issues with my lipo. I dont over discharge them and the cells charge/balance well. I understand what you mean about them not balancing them 100% but when I meter the cells, they are only .1-.2 off. Sometimes they'll say, 4.1v and the other cell will read 3.98. Maybe you had a bad cell in one of your packs and that's why it puffed up. But thanks for the advice. My new charger will be here soon enough. then I wont have to worry about a thing. Thanks, Joe

BigTb17

When you set the meter to the mA setting did you connect the leads directly to the positive and negative of the battery? Just wanted to give you the heads up that that can be bad for the battery and the meter. When you have the meter in the mA or Amp setting the meter is providing a path for electricity to flow through the meter and the meter will then measure how much current is flowing. If you connect the leads directly to the battery at that point it is almost like a direct short. The reason the meter was beeping was most likely because the amperage was over the range the meter can measure in mA mode. When you connect the leads like this it is hard on the battery, and you can even blow a fuse in your meter (if it is fused) or possibly damage it if the battery can supply enough amperage.

Just thought I'd mention that. When a multi-meter is in mA or A mode it should only be connected in series with a seperate load in order to measure the draw of that load.

joeyhatch11

the meter is fused but nothing happened to either the lipo or the meter. I didnt hold it on there long. It just beeped and didn't show any readings so i disconnected. Thanks for the heads up though. I'll be sure not to do that again. Hahahaha

Jeremy Z

Interesting. I wonder if they changed the charger?

When I metered mine, they were way out of balance.

However, I probably over-discharged mine, as the basic ESC that came with that chopper didn't have a low voltage cutoff. I flew it until I couldn't hover any more.

No problems with the Polyquest battery or Hyperion balancer, or with the other E-Sky battery with a tap for the Hyperion balancer.

I remember reading an article that that charger doesn't balance though, so the fact that yours are relatively balanced is lucky.

joeyhatch11

Well let me tell you this. I just finished charging my 4000mah 2S lipo on that Esky charger and the cells balanced great. Both are reading at 4.15V. Im really curious to see what the capacity is on these lipos once fully charged. Can't wait to get my new lipo charger.

Access

To measure mAH, hook the meter in series with a load placed across the battery. Be sure to select a proper resistive load with the right range as to not overpower it or the meter. Using the meter to measure current outside its rated range will kill it. Many meters have both a 0-300-or-so mA range and a 0-5A or 0-10A range.

Get some graph paper and fully charge the battery. Every minute or so, graph the current vs. time until the battery is fully discharged. Then find the area under the curve and you have the mAH of the battery. Not that hard really. Some of the more advanced charges can do this for you.

BTW most multimeters you need to move the plugs around to measure current. That is probably why it was beeping constantly at you. DO NOT hook it directly across the battery in current-measuring mode.

He is right that those so-called 'balancing chargers' don't do the job. They don't charge very evenly to begin with, and they basically just stop when one cell has reached the max and not balance past that. I've verified this and when I posted to these boards about it, enough people had similar problems.

Jeremy Z

Access, your method of finding mAh charged will work, but I don't think very many folks would be willing to go through that, hehehe.

It might not be too bad if the person was sitting right there anyway, and had Excel running.