voltage reference thing

[carckton driver]

im trying to find one of these that comes with a calibration sticker. every time i see a youtube video with one it has a calibration sticker and all the reviews say they don't come with one. none of the pictures on either ebay or amazon show a calibration sticker or talk about one. so, does anyone have a link to one of these that they know comes with a calibration sticker? i have spent hours and hours trying to find one.
https://www.amazon.com/AD584KH-Prec...ols,85&sr=1-1-spons&psc=1&smid=A2K5DI8VX12AN1

 

[Engineer]

To be frank, a calibration sticker is meaningless without a test report showing the device is within spec. Cal is also supposed to be performed on a regular basis to ensure the device stays within spec. Your best bet is to buy one and send it out to a calibration house (eg. Trescal).

 

[sandblaster]

If one has a fluke high quality multi meter, one can check it one self. Not a cheap Harbor Freight but an industrial rated Fluke meter. They are tested and calibrated to be accurate. Is what the pros use and depend on.

 

[Jerold]

It's deep subject but typically output voltage, current ratings and variances are based on the conditions.Everything has a tolerance of input voltage and conditions and you need match the power source output under the conditions you expect.

They gave us the part number in the description, like we should be impressed. It used the Analog Devices AD584KH. This is a linear regulator not a switcher. The key here is that current in always equals current out.

This particular part is limited to 10 mA current output max. So unless you are literally comparing it to another voltage it probably won't work.

The better question is what do you want to do with it? If it's something precise, you can look for used equipment that comes from a reputable place - Check Ebay. It's not cheap but it's real. If you just need a 5V source for a Raspberry Pi, try a USB charger, the very worst it will do is not boot. BTW the Raspberry Pi uses something like 5A @ 2V so this wouldn't do it.

 

[slick2500]

Stupid question but what does this do?

 

[carckton driver]

If one has a fluke high quality multi meter, one can check it one self. Not a cheap Harbor Freight but an industrial rated Fluke meter. They are tested and calibrated to be accurate. Is what the pros use and depend on.

if i had a $500 calibrated fluke i wouldnt need this.

It's deep subject but typically output voltage, current ratings and variances are based on the conditions.Everything has a tolerance of input voltage and conditions and you need match the power source output under the conditions you expect.

They gave us the part number in the description, like we should be impressed. It used the Analog Devices AD584KH. This is a linear regulator not a switcher. The key here is that current in always equals current out.

This particular part is limited to 10 mA current output max. So unless you are literally comparing it to another voltage it probably won't work.

The better question is what do you want to do with it? If it's something precise, you can look for used equipment that comes from a reputable place - Check Ebay. It's not cheap but it's real. If you just need a 5V source for a Raspberry Pi, try a USB charger, the very worst it will do is not boot. BTW the Raspberry Pi uses something like 5A @ 2V so this wouldn't do it.

ultimately to calibrate my charger and cell checker or even just to check to see how off my multimeter is

 

[sandblaster]

Are in into racing? Not sure why this is a concern. One can check on what tolerance is allowed in measuring the voltage of battery cells and chargers. Unless you have a really cheap old chargers it has to meet a certain tolerance. Trying to understand why this is a concern.

 

[carckton driver]

Are in into racing? Not sure why this is a concern. One can check on what tolerance is allowed in measuring the voltage of battery cells and chargers. Unless you have a really cheap old chargers it has to meet a certain tolerance. Trying to understand why this is a concern.

because my charger and cell checker are off by as much .013 volts on just a 4s. furthermore, my charger is off by .008 between channels. its driving me nuts. i have verified this several times and its always about the same and consistent.
im into keeping my batteries as healthy as they can be and its my understanding the closer the cells are balanced and the closer they charger and discharge to each other the better.

 

[sandblaster]

Seems to me, everything is well within tolerance. Check what is the tolerance of cells is called normal. Serious doubt you will find a way to make the cells any closer than they are. When they talk of cell balance, it is not possible to get the cells all to be exact. And when are you measuring. Have observed a good size difference between cells after a run and after a full charge. There can be a larger difference after a run that seems to disappear after a full charge and balance. Memory says anything under a .0 difference is good. Your .013 or .008 is not worth the worry. Chasing after a windmill, to use an old nursery story. Suggest your energy and money would be better spent elsewhere. They are only batteries. A useable, replaceable part of the hobby.

Some of what you maybe reading could be very old information from the early days of lipo's. Once on the net it stays on the net never to be removed or updated. So much has changed, for the better. When lipo's were a new thing, the learning curve was great for all. Manufacturing and users. The improvement of lipo is HUGE from the early days when we were dealing with difference of a couple of volts per cell. Now the good batteries are made with matching cells and those days of a volt or two difference between cells is history. Your readings are excellent in my opinion.

 

[Diem Turner]

I occasionally like to use the passive balancing function on my ISDT battery checker and that will get the cells within 1-2mV of one another. I really don't think this does anything for the batteries as such as it does nothing for the IR of the cells, it just makes me feel better for a second or two.

 

[Jerold]

if i had a $500 calibrated fluke i wouldnt need this.

ultimately to calibrate my charger and cell checker or even just to check to see how off my multimeter is

Unless I'm missing something, you probably don't need to know exactly how many milivolts are on a LiPo? The typical LiPo Checker goes down to 10's of milivolts which is the same range as most handheld multimeters. The only thing more accurate would be a benchtop tester, then multi-meter, then LiPo Checker.

Any test equipment has a tolerance. Multimeters are something like 0.5%. The LiPo Checker is like +/- 1.5% (3x the meter), but does it matter if it's 14.6V or 14.7V?

The reality is Fluke is just a brand and they are not more accurate than other brands. EEV Blog tells the story.

If you want an actual Fluke and don't want to pay a ton of money look at the 1 series (101, 114, etc).

The 101 is like $43 on Amazon. Keep in mind this is the off shore version for factory workers. But then again you can buy a better meter from Klien for the same money.
https://www.amazon.com/Fluke-101-Multimeter-Resistance-Capacitance/dp/B00HE6MIJY/ref=sr_1_36?adgrpid=1341404750114538&hvadid=83838035938406&hvbmt=bp&hvdev=c&hvlocphy=86188&hvnetw=o&hvqmt=p&hvtargid=kwd-83838141887757:loc-190&hydadcr=29034_14559874&keywords=electric+multimeters&qid=1666901092&qu=eyJxc2MiOiIwLjAwIiwicXNhIjoiMC4wMCIsInFzcCI6IjAuMDAifQ==&sr=8-36

I've also seen a few Flukes for sale in the Forum Classifieds at a very reasonable price.

Some other options, including the meters mentioned in the video are below.
https://www.amazon.com/EEVblog-BM786-Multimeter/dp/B08N61LF4Z/ref=sr_1_11?crid=17OVKQVKB4ZIF&keywords=bryman+multimeter&qid=1666904231&qu=eyJxc2MiOiIyLjE4IiwicXNhIjoiMC4wMCIsInFzcCI6IjAuMDAifQ==&sprefix=bryman+multimet,aps,1032&sr=8-11&ufe=app_do:amzn1.fos.f5122f16-c3e8-4386-bf32-63e904010ad0
https://www.amazon.com/Multimeter-Auto-Ranging-Klein-Tools-MM600/dp/B018CLOSTC/ref=sr_1_12?crid=17OVKQVKB4ZIF&keywords=bryman+multimeter&qid=1666904291&qu=eyJxc2MiOiIyLjE4IiwicXNhIjoiMC4wMCIsInFzcCI6IjAuMDAifQ==&sprefix=bryman+multimet,aps,1032&sr=8-12&ufe=app_do:amzn1.fos.006c50ae-5d4c-4777-9bc0-4513d670b6bc&th=1
https://www.amazon.com/Multimeter-Auto-Ranging-Klein-Tools-MM420/dp/B0B57PFFYX?ref_=ast_sto_dp

I hope this helps.

 

[carckton driver]

so maybe all this accuracy isnt needed? knowing the voltage within .013 volts or having accuracy between two devices within .013 volts isnt needed?

Are in into racing? Not sure why this is a concern. One can check on what tolerance is allowed in measuring the voltage of battery cells and chargers. Unless you have a really cheap old chargers it has to meet a certain tolerance. Trying to understand why this is a concern.

thats funny. i have used the balance feature on my BG 8s but it took a reallllly long time, i think over 2 hours, after it came off the charger to balance out. it keeps lowering the voltage of the lower cells while trying to catch up the higher cell(s). to me its seems like its more of gimmick just because of how long it takes.

 

[Jerold]

because my charger and cell checker are off by as much .013 volts on just a 4s. furthermore, my charger is off by .008 between channels. its driving me nuts. i have verified this several times and its always about the same and consistent.
im into keeping my batteries as healthy as they can be and its my understanding the closer the cells are balanced and the closer they charger and discharge to each other the better.

That's all within the tolerance of the devices. I pulled up a Hitech cell checker for a reference and it's +/- 1.5%. For a DVM Fluke and most others are like +/- 0.5% + 1 digit.

Which means at 14.65V you have this possibility

Tester​	Battery Voltage (actual)​	Tolerance​	Vmin (read)​	Vmax (read)​	Δv (possible reading)​
DVM​	14.65​	0.005​	14.58675​	14.73325​	0.1465​
Checker​	14.65​	0.015​	14.43025​	14.86975​	0.4395​

The DVM and battery charger both have an additional power supply that creates an internal voltage reference. The LiPo Checker does not. So the DVM and Battery charger will always be more accurate, because the voltage reference for the checker is derived from the voltage you provide. i.e. voltage being checked is the same source as the reference voltage. Sort of like giving yourself a sobriety check - Yup looks good to me.

Even though you may see a difference up to 400mv for a 4S battery with a LiPo checker, if it's real (not likely) it averages to 100mV per cell. Storage charge at 3.65V or 3.75V per cell, isn't going to make that much of a difference. You're more likely to damage it in crash.

I would trust your charger and don't sweat it. Go have fun, the batteries will be fine.

 

[carckton driver]

That's all within the tolerance of the devices. I pulled up a Hitech cell checker for a reference and it's +/- 1.5%. For a DVM Fluke and most others are like +/- 0.5% + 1 digit.

Which means at 14.65V you have this possibility

Tester​	Battery Voltage (actual)​	Tolerance​	Vmin (read)​	Vmax (read)​	Δv (possible reading)​
DVM​	14.65​	0.005​	14.58675​	14.73325​	0.1465​
Checker​	14.65​	0.015​	14.43025​	14.86975​	0.4395​

The DVM and battery charger both have an additional power supply that creates an internal voltage reference. The LiPo Checker does not. So the DVM and Battery charger will always be more accurate, because the voltage reference for the checker is derived from the voltage you provide. i.e. voltage being checked is the same source as the reference voltage. Sort of like giving yourself a sobriety check - Yup looks good to me.

Even though you may see a difference up to 400mv for a 4S battery with a LiPo checker, if it's real (not likely) it averages to 100mV per cell. Storage charge at 3.65V or 3.75V per cell, isn't going to make that much of a difference. You're more likely to damage it in crash.

I would trust your charger and don't sweat it. Go have fun, the batteries will be fine.

you lost me with that chart. for the DVM, if the tolerance is .005, no idea where that number came from, then why are the max and min off by WAYYY more than the tolerance? wouldnt the also, whats a DVM? a multimeter? also not sure what hitech cell checker your talking about or where you got that from (Assuming you meant hitec).
" difference up to 400mv for a 4S battery with a LiPo checker, if it's real (not likely) it averages to 100mV per cell." you lost me there again. im not talking about total voltage of a battery, almost certain i never mentioned that.

 

[Velodromed]

Is this all because that 2017 post you responded to over a Lipo incident made you concerned?

 

[carckton driver]

Is this all because that 2017 post you responded to you over a Lipo incident made you concerned?

no. i had to go and look at my posts. i have no idea how i ended up in a thread from that long ago. i swear i was on the first page of wherever i was. pretty sure it showed at the bottom of a thread or post i made where it shows "similar threads"

 

[Velodromed]

no. i had to go and look at my posts. i have no idea how i ended up in a thread from that long ago. i swear i was on the first page of wherever i was. pretty sure it showed at the bottom of a thread or post i made where it shows "similar threads"

It’s fine man, many of us have done the same and got hacked on a bit for it. All good

 

[Jerold]

you lost me with that chart. for the DVM, if the tolerance is .005, no idea where that number came from, then why are the max and min off by WAYYY more than the tolerance? wouldnt the also, whats a DVM? a multimeter? also not sure what hitech cell checker your talking about or where you got that from (Assuming you meant hitec).
" difference up to 400mv for a 4S battery with a LiPo checker, if it's real (not likely) it averages to 100mV per cell." you lost me there again. im not talking about total voltage of a battery, almost certain i never mentioned that.

Sorry. I talk too much some days.

The tolerances are in the user manual for each tester and it is a percentage of the voltage. If it's 0.5% and you have a 14.65V battery the meter might read between some where between 14.6V and 14.7V. I use this as an example only it may not be your specific situation.

The min and max are relative to what you are measuring. Relatively, +/-100mV is close when you have a 14.65V battery. However, +/-100mV is way off is you have a 1V source.

If you want to just check your DVM that device on Amazon will be good enough, but you still have tolerances on the power supply and the DVM.

The difference between engineer and science is the number of decimals. From an engineering perspective, the difference you are seeing won't matter.