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ITTSB Blog Specific > ITTSB - Small projects by Kiriakos & User reviews
Battery Impedance Meter SM8124 mini review
Kiriakos GR:
Today I will add and another example from the world of lead acid batteries, and more specifically for the type which this is used in the application of UPS battery-backup systems.
My APC SUA 1000XL this using two 12V 17Ah, when replaced them I did select New Panasonic SLA Battery LC-XD1217PG.
This according to datasheet should have less than 12 mOhm internal resistance, and a life cycle of 10 years.
Yesterday that is 6.5 years in use, my SUA 1000XL did not pass the battery self test, according to SM8124 tester, this measured 30 mOhm at the first battery and 50 mOhm at the second.
While individual battery voltage stays at 12.4 Volt, them are unable to supply a constant 10A DC that is required by the self-test function.
Every serious SLA Battery vendor this will offer a datasheet for its and every product that he makes.
All that you need to do is search and find it, or simply email this vendor so you to receive a copy. ;)
Kiriakos GR:
Today I will add and another example from the world of Ni-MH 1.2V
This pair of batteries was originally purchased somewhere in 2003 and them at 2012 they lost their 50% of capacity and two of the four cells them become unusable.
But these specific two they did survived and was serving in less demanding applications as for example my mosquito zapper. :)
Them today are totally unable to accept charging and their internal resistor this is 38 mOhm.
Even so I am thankful to Sanyo because back then they was making quality parts when today their NIMH cells no matter their model /specifications, them does not last over four years.
Kiriakos GR:
I just steal a tip which I found at the user guide of a Japanese battery analyzer.. ;)
Generally, industrial battery is recommended to be replaced when the internal resistance comes up to double of the unused battery.
Kiriakos GR:
Here is another example from the world of motorcycle batteries, the dry ones which activation this is required.
This is a YTZ9L-BS made in Taiwan, and possibly the best quality VS price choice among other YUASA batteries build all over the world.
I took my internal resistance measurement of this battery near to the end of it activation, this is now charging at 14.40V and charging current this have drop to 120mA and dropping.
This measured 12 mOhm and I suspect that it will not go lower than that.
Kiriakos GR:
SM8124 today this is now EOL , measuring accuracy at milliohm range of +/- 3% +1 Digit among with +/- 1% +1 Digit for voltage, these are now less attractive as marketing point.
SANPO SM8124 this is no more listed at it manufacturer product page and I have the impression that SANPO does not interested to compete in this market any more.
Somewhere in 2017 a new economy battery Impedance Meter YR1030 this circulates in the market.
Digital controls and screen looks appealing, internal lithium battery this is a bad idea, but precision of 0.7% at milliohm range this is a good sign if this is true. :P
Either way beware of Asian pricing wars, YR1030 lowest price which I found this is at 12$ US
Personally I think that any one owns SM8124 he does not have to think YR1030 as better just because of the better accuracy specification.
When a battery gets bad and this now has double or triple internal resistance, this is now a brick which it must be replaced ( no matter which meter you own). ;)
YR1030 electrical specifications
Range - Minimum Resolution - Accuracy ( Accuracy format: ± percentage accuracy + least significant digits.)
20mΩ 0.01mΩ 0.7%+7 (when ZR function is enabled)
200mΩ 0.1mΩ 0.5%+5
2Ω 1mΩ 0.5%+5
20Ω 10mΩ 0.5%+5
200Ω 0.1Ω 0.6%+5
Specifications are valid within 5% - 95% of the measuring range.
Bellow 5% of measuring range the error may be greater than the above accuracy.
Voltage measurement accuracy:
2V 0.001V 0.8%+5
20V 0.01V 0.8%+5
28V 0.1V 0.8%+5
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