New Ni-CD drill battery Vinteky / tiggopower : Capacity tests - Mini Review

[Kiriakos GR]

Intro
Since 1996 I am owner of one Bosch cordless drill (last generation of Made in EU ones), over the years I did rebuild it battery about four times.
Fifth time this arrived, and I did a smart move to save cost, I did purchase one Makita battery pack instead so to use inner cells so to rebuild my own Bosch pack.

Within 2017 Ni-CD production this is now by 99% China made goods.
European Union this banned Ni-CD technology since 2016.

Major issue with Made in China Ni-CD this is honesty speaking of electrical specifications, fake capacity and half damaged cells this is what you get most of times.
This is a story of one exception which I discovered and only downside this is internal battery resistance this be double than what Panasonic (Best choice if it was available – production stopped) batteries has to offer.
 
Few words regarding battery marketing within China,  eight cells battery (9,6V) with Makita battery case this leave from Chinese small factory at a price of 7$ USD, this is imported to EU and sold by Vinteky branding.
Vinteky branding this is registered in UK and owner this is the small factory in China.
Tiggopower TG290D this only text available over Ni-CD cells, and this information alone is not helpful so you to identify capacity of actual Ni-CD battery cell.
Tiggopower website this is on-line but no one answers emails.

This specific Vinteky LMK012 battery pack followed the route from China (7$ USD) to Germany (EUR 15.99) Ebay, plus EUR 10.00 shipping to Greece.

Speaking of battery capacity verification, I did use several tools, my new constant current DC load , among with wireless data logging of voltage and current and temperature, and I did several repeated charge and discharge cycles always by taking in to account basic Ni-CD electrical properties.
In conclusion I did precision laboratory work, so to prove mostly to my self that I was not cheated.
My mission ended successfully after six cycles, and especially when my equipment's they did measure battery capacity this be exact as is written at the product label.

Bellow they are my own testing cycle’s details, and pictures of charging and discharging curves.
Major discovery for me speaking of new experiences, this is seeing with my eyes full-charge detection by temperature & voltage signature.
Voltage signature this is top of charge curve, this event lasting about three minutes, this is the point that battery cell stops absorbing charging energy because this is now full, after this point all incoming energy this is solely converted in to heat.

This presentation – Mini Review has nothing to do as advertising material, I do consider my self as lucky about getting Ni-CD cells that they are not suffering from severe issues, and therefore they worth the description as acceptable in performance as NEW (No-Name) products.
Best reviewer for such products this is a regular carpenter, these fellows they do use cordless drills all day long.
They could answer in the question of battery straight after several discharge cycles.
What I am able to say and sign it even on paper, this is that specific battery cells that I got, they did passed successfully my own electrical inspection.
Double milliohm internal resistance this translates that this battery pack was assembled and be in storage roughly 20 months ago.
There is bar-code over the carton box of this battery, but these numbers does not indicate production date.

Specific battery for MAKITA tools this it does using two sensors about detecting overheat condition.
Battery Minus contact point this is common point for both sensors.
First sensor this is thermostat’s with few milliohm resistance, when battery run hot this thermostat’s (reset able resistor) gets open.
Second sensor this is NTC (thermistor) , this is a resistor that resistance changing due temperature, when battery run hot this NTC resistance decreases to few kilo Ohms, when battery this is at 20 Celsius then resistance this is approximately 10 ~11 Kilo Ohms.

Both sensors they are there so to cooperate with fast MAKITA chargers.
With old chargers with out automatic charge control, it is highly important to use a timer, and it is your responsibility to disrupt charging at specified by the manufacturer directions.
For example my very simple Bosch charger this is a three hours charger for 1500Ah pack, it is critical that battery this to be removed after this period.
Poor performing battery (used for several years 4~5 or more) does not benefit from longer charging period.




Named specifications’:
NI-CD 2.0 Ah - 19.20 Wh
Cell label print: tiggopower.com TG290D
Pack label : Vinteky LMK012

First charge / discharge test
Internal resistance 110 milliohm Full charge & 120 milliohm 50% charge.
Charge 400mA
Discharge 2.0A 
Discharge Cut-off 6V
1680 Ah (about)

Second charge / discharge test
Charge 400mA
Discharge 1.5A 
Discharge Cut-off 8V
1788 Ah
17.34 Wh

Third charge / discharge test
Charge 1.4A   (required time 90 minutes)
Discharge 1.5A 
Discharge Cut-off 8V
1926 Ah
18.82 Wh


Fourth charge / discharge test
Charge 1.4A   (required time 91minutes)
Discharge 1.5A  (Battery unused for 1 Hour before test) 
Discharge Cut-off 8V
1960 Ah
19.11 Wh

Fifth charge / discharge test
Charge 1.4A   (required time 132 minutes)
Discharge 1.5A (Battery unused for 8 Hours before test) 
Discharge Cut-off 8V
1892 Ah
18.36 Wh

Sixth charge / discharge test
Charge 400mA (required time 5H + 5 minutes)
Discharge 1.5A (Battery unused for 1 Hours before test) 
Discharge Cut-off 8V
1997 Ah
19.38 Wh (named specification 19.20 Wh) Success Story !!