Battery ?

I haven’t read the whole thing; I just figured out you’re looking for a DMM? Here’s my take on why I’m happy with a cheaper DMM (maybe someone else already wrote something similar…).

1) I want to measure parasitic drain, and let’s say I measure 20 uA resulting in a self discharge time of 20 years. A 10% error is extremely high, resulting in 22uA and ~18 year discharge time, but nevertheless this is sufficiently accurate for me. I’m interested whether self discharge time is 20 years, 10 years, 1 year, or one month. That’s the kind of ball park range data I’m interested in, so there is no need for an accurate DMM.

2) I want to check status of my four 18650 cells after using them in a 4S flashlight. Let’s say my DMM says that voltage of one cell is 3.657 Volts. I’m not interested whether the actual voltage is this value, or perhaps it’s 3.75 or 3.51 Volts; the error would again be fairly large. Even if my DMM is not accurate, repeatability is high; this means that the voltage of my other three cells should be about 3.657 V as well. If this is not the case, then something is wrong with my cell, and I should monitor it during charging and next discharge.

Basically you pay a lot more for enhanced accuracy, and accuracy over many years of use (Fluke), but I’m not interested in absolute accurate values of voltage, current, lux (it’s on my DMM). I’m interested in differences in values of voltage, current and lux, and cheaper DMMs are good enough for this purpose.

Thanks for the reply! What are some of your opinion on the Uni-t UT61E the good and the bad and any issue?

I guess It all comes down to how much to how much you want to spend for accuracy and your needs.

With the cheap DMM, can you measure house current 110v and 220v?

See here: Review of UNI-T UT61E

Usual yes, but it is more dangerous.

In your review, What do you mean by current ranges are bad at low voltage use and they have to high burden voltage? Are batteries considered low voltage with NiMh being at 1.2v and Li-Ion at 3.7v?

Yes, batteries are low voltage. Depending on range you can loose up to 1.1 volt over the meter.

Is it because of the leads are junk or is it just the meter? Can a calibration fix the lost of voltage?

I will not call the meter junk, but it is not always good at measuring current. Calibration cannot fix it, using a higher range and loosing some digits is often a solution.

@ HKJ I was calling the test leads junk and not the meter (I worded it wrong). Is having the extra digits in a meter worth it or is that just in the UT61E model? Do you have any more reviews on DMM on your website?

If you need extra digit or not depends on you and what you do. You usual also get considerable better precision with one digit extra. I like the resolution and have meters up to 7½ digits.
One example on resolution:

A cheap meter says a LiIon has 4.18V specification for meter says 0.5%+2, this means voltage is betwen 4.14 and 4.22 volt.
A better meter says a LiIon has 4.183V specification for meter says 0.5%+2, this means voltage is betwen 4.16 and 4.21 volt.
A better meter says a LiIon has 4.183V specification for meter says 0.1%+2, this means voltage is betwen 4.18 and 4.19 volt.

I have been meaning to do more DMM reviews, but never had time to do it.

Hi everyone,
I want to share with you my experience with reconditioning batteries method which I find on Candle Power Forums.

Few days ago I was interesting of reconditioning rechargeable batteries after watching the video on “”ezbatteries site”:http://ezbatteriesreconditioning.com Of course I was very skeptical because It looked too good for me. I could not believe that it could be possible, so I decided to check it. I was looking for movies before “how to recondition batteries” on youtube and other websites but I didn’t find any specific information in this topic. Especially when it comes to recondition rechargeable batteries (aa, 18650 etc.) or laptop batteries. I tried before only with car batteries and method turned out to be successful (epsom salt method - is easy to find on youtube). I had to take a risk and spend 47$ for this “extra” guide and… It really works :slight_smile:
Actually I have about 10 reconditioned batteries and I’m in the process of testing performance of this batteries. So far it looks pretty good. I use deep cycle batteries (lead-acid) in my workshop from 2008 and I also wants to test this method for these batteries in the coming days. Soon will share the information about reconditioning this type of batteries. Does anyone have any experience with battery reconditioning? I will gladly share the informations.

A few very expensive meters do it another way and mostly eliminates burden voltage (This does not make them perfect ammeters).

The best way to get a low burden voltage is a DMM with fairly high resolution and then use a higher range than required, like you say. Knowing the DMM and when to do that select next range is very useful.

Many DMM’s have 3 current shuts:
uA shunt, mA shunt and 10A shunt, matching the settings on the switch. This means the low uA and low mA range has low burden voltage, but the high uA and high mA (often x000uA and x00mA ranges) has high burden voltage. To get low burden voltage select next higher range for these two ranges when using more than 10% of the range.
I.e. when measuring 0.5mA (500uA), do not do it on the uA range, but select the mA range.
Same with 50mA and up, use the 10A range (Most meters are missing a xA (like 2A) range).
A meter like UT61E with a 22000 reading will give a acceptable resolution in most cases.

In total there are 4 options for measuring current:

  1. A normal ammeter (DMM in current range)
  2. A external shunt with a DMM, this way the best shunt value can be used.
  3. A feedback ammeter, but it is way to expensive for most people.
  4. A clamp meter, they are usual not good at low current and precision is not as good as the above solution.

1) is the worst in burden voltage and 4) is the best (In some situation 3) can be slightly better).
Except 3) all can be found at hobby friendly prices.

It is not that long time ago (Sometime last year) there was some talk and also a group buy of a cheap UNI-T clamp meter (UT210E) that could measure DC on the clamp. With carefully zeroing it could work down to a few mA. Big Clive is using the same clamp meter in his recent videos.

Correct you are HKJ. :+1: Here is a link to the thread about the UNI-T Clamp Meter (UT210E)

Thanks for the replies!

Amen to that…. :+1:
HKJ has forgotten more than I know or will most likely ever know.
Same goes for gauss.

Thanks for sharing & trying to help us mere mortals out. And I say that in all seriousness……. :+1:
.
:slight_smile:

Can Eneloops be stored in the kitchen with heat from the oven or does it has to be stored in a cooler place?

AFAIAC it makes little difference as long as it is not in the hot oven or on top of the hot stove. :smiley:

I have had them stored in truck glove box or under seat for years, thru cold
of winter (0 F) , hot of summer (120 + F inside truck), and anything in between. I can tell no real world or use difference. They all still hold rated capacity & work just fine.

I am sure there is a “text book” answer that would be different and give semi strict parameters of use & storage…. but for me, the real world route is & has been working just fine.

My .02 …. ymmv. :slight_smile: