Robert Lai
Well-known
There was a thread not long ago (which I can't seem to find now), in which someone asked if the 1.35V battery adapter made in Thailand by Pratedthai was any good.
Someone else claimed that the Thai adapter was a fraud because he measured the voltage with a battery inserted in the adapter, and the voltage was 1.5V.
To verify whether the accusation is justified, I tested the following:
CRIS MR9 adapter
Pratedthai adapter (abbreviated PThai)
Wein Cell
Alkaline 625 cell
in the following meters:
Leica MR-4, Canon 7s, Canon FX
All of the cameras and meters have been recently overhauled, and read accurately.
I used a GB GDT-11 multimeter in the 2V measuring range to obtain the voltages put out by the various combinations.
Here are open circuit (essentially no load) voltages using new Everready 386 1.5V silver oxide batteries in the adapters. The Wein cell is a couple of months old in use.
CRIS - 1.52V
PThai - 1.52V
Wein - 1.345V
Alkaline - 1.94V
So, here you see that the CRIS adapter and the Pratedthai adapter behave the same way. With no load (or microampere currents), they don't reduce the voltage at all. However, a light meter will put a drain on the battery in the milliampere range. With that much current flow, they WILL reduce the voltage to the stated 1.35V.
Here are the results:
Wein Cell = CRIS = Pratedthai in all meters.
The battery check functions all indicated good batteries.
The meter needles read identically regardless of the cell or adapter used.
The odd one out was the Alkaline cell.
Although the no-load reading was very high at 1.94V, when placed in the meters, the cell failed in all of the meters.
Battery check indicated exhausted battery.
The meter needle barely moved, and indicate the wrong exposure (off by many stops).
My conclusion:
Wein Cell = CRIS adapter = Pratedthai adapter.
The Pratedthai adapters are not a fraud. They work, and work great. I no longer need to purchase Wein cells with their corrosion risk as a result.
Someone else claimed that the Thai adapter was a fraud because he measured the voltage with a battery inserted in the adapter, and the voltage was 1.5V.
To verify whether the accusation is justified, I tested the following:
CRIS MR9 adapter
Pratedthai adapter (abbreviated PThai)
Wein Cell
Alkaline 625 cell
in the following meters:
Leica MR-4, Canon 7s, Canon FX
All of the cameras and meters have been recently overhauled, and read accurately.
I used a GB GDT-11 multimeter in the 2V measuring range to obtain the voltages put out by the various combinations.
Here are open circuit (essentially no load) voltages using new Everready 386 1.5V silver oxide batteries in the adapters. The Wein cell is a couple of months old in use.
CRIS - 1.52V
PThai - 1.52V
Wein - 1.345V
Alkaline - 1.94V
So, here you see that the CRIS adapter and the Pratedthai adapter behave the same way. With no load (or microampere currents), they don't reduce the voltage at all. However, a light meter will put a drain on the battery in the milliampere range. With that much current flow, they WILL reduce the voltage to the stated 1.35V.
Here are the results:
Wein Cell = CRIS = Pratedthai in all meters.
The battery check functions all indicated good batteries.
The meter needles read identically regardless of the cell or adapter used.
The odd one out was the Alkaline cell.
Although the no-load reading was very high at 1.94V, when placed in the meters, the cell failed in all of the meters.
Battery check indicated exhausted battery.
The meter needle barely moved, and indicate the wrong exposure (off by many stops).
My conclusion:
Wein Cell = CRIS adapter = Pratedthai adapter.
The Pratedthai adapters are not a fraud. They work, and work great. I no longer need to purchase Wein cells with their corrosion risk as a result.
Last edited:
Solinar
Analog Preferred
I use the Kanto variant of the MR-9 battery adapter in my Olympus 35RC.
My advice to everyone is to check the operation of the MR-9 adapter with a hand-held meter set in its reflective mode against your camera's meter readings in a variety of light.
Best Regards,
My advice to everyone is to check the operation of the MR-9 adapter with a hand-held meter set in its reflective mode against your camera's meter readings in a variety of light.
Best Regards,
KismetSky
Established
Thanks for testing all of these Robert! This mirrors my experience with the Pratedthai adapters - they give the same (light meter) reading as my Wein cells and use much cheaper silver oxide batteries (10 pack for $12).
Tijmendal
Young photog
Where can one order the Pthai adapter?
Incidentally I received three of the old mercury 1.35v batteries yesterday, but I don't know how long those will last for.
Incidentally I received three of the old mercury 1.35v batteries yesterday, but I don't know how long those will last for.
kanzlr
Hexaneur
I use the Pradethai for years and it works flawlessly.
Solinar
Analog Preferred
@Robert La, et ali - it seems that you need a 10K ohm resistor wired in parallel between the two test leads of the voltmeter in order to check whether for the required drop in voltage from a MR-9 adapter is present. With the 10K ohm resistor - the battery is under a load similar to an analog light meter.
See the following link, second paragraph in the section called "Limitations":
http://www.smallbattery.company.org.uk/sbc_mr9_adapter.htm
Best Regards,
See the following link, second paragraph in the section called "Limitations":
http://www.smallbattery.company.org.uk/sbc_mr9_adapter.htm
Best Regards,
Robert Lai
Well-known
Hi Andrew,
Thanks for finding that information. At least we know that around 100 microamp draw is required for correct function, with a limit of 200 microamps.
Thanks for finding that information. At least we know that around 100 microamp draw is required for correct function, with a limit of 200 microamps.
Eugen Mezei
Well-known
If draw is required, does it makes a difference between cameras where the battery powers only the meter and cameras where it also powers the shutter? I guess the shutter magnet draws a lot more amp.
sc_rufctr
Leica nuts
Up for good info... I just bought a Leikaflex and was looking at battery options.
pepeguitarra
Well-known
Thank you. I agree with your testing, I have them all too.
Tim Murphy
Well-known
Dear Board,
I'd like to ask this same question. I've seen many references to the Pradethai adapter but I cannot find them for sale anywhere?
Regards,
Tim Murphy
Ronald M
Veteran
Cris works in some cameras, not in others. I had 5 at one time.
Clip on Leica meters were OK . Nikormat seems ok. Leicaflex SL worked at high light level, not at low.
I think the problem comes down to current draw. If the meter requires a lot, the adapter can not pass it. I don`t remember details, but high,low variation was an issue. Meters cells require more current at one end of range compared to another.
Wein are good and last if you remove from the camera and cover the holes stopping the chemical reaction. Next session you need to reopen the air holes and wait a bit of time.
Alkakines are like a dead watch, correct twice a day. Unless
the meter has a bridge circuit to eat up the surplus volt.
Clip on Leica meters were OK . Nikormat seems ok. Leicaflex SL worked at high light level, not at low.
I think the problem comes down to current draw. If the meter requires a lot, the adapter can not pass it. I don`t remember details, but high,low variation was an issue. Meters cells require more current at one end of range compared to another.
Wein are good and last if you remove from the camera and cover the holes stopping the chemical reaction. Next session you need to reopen the air holes and wait a bit of time.
Alkakines are like a dead watch, correct twice a day. Unless
the meter has a bridge circuit to eat up the surplus volt.
YouAreHere
Established
Dear Board,
I'd like to ask this same question. I've seen many references to the Pradethai adapter but I cannot find them for sale anywhere?
Regards,
Tim Murphy
Typo I think. The eBay seller is Pratedthai. See for example,
http://www.ebay.com/itm/130646083632
Other options on eBay can be found by searching, without the quotes:
"(mr-9,px625)"
Tim Murphy
Well-known
Dear YouAreHere,
Thank you very much. You've been a big help. I've been searching for these for a while and never knew that I had the seller's name wrong because the only way I ever saw it written was apparently wrong?
Regards,
Tim Murphy