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Hi ,
I would like to ask one question about 5D44 calibers of Seiko watches. I have bought SRH007P1 model Seiko watch last week. It looks wonderful but it has only 1 month reserve in its K.E.S.U. which is very small when it is compared with 5J22 or 5M62 calibers. There can be any possibility that Seiko have used some kind of capacitor or extra something different. All Seiko kinetic watches have K.E.S.U. but there might be some a little bit differences in those new models. I am not sure. So, I would like to take your precious opinion about it. Thank you very much for your reply in advance. Warmest regards.

Dear Guerkan,

Thanks for sending in that interesting question and for your nice comments! Congratulations on owning the SRH007P watch, I'm sure you're proud of your new timepiece.

First things first. Seiko has never reverted to its old capacitor for energy storage due to the capacitor's problematic history. Secondly, no vintage Kinetic watch that used the old capacitor could hold enough power to keep the running for a month. There's no turning back to the capacitor. In fact, the 5D44 caliber uses the same Maxell TC920S rechargeable lithium ion cell that powers its entire range of Kinetics.
The key to the differences in power reserve amongst the calibers you mentioned is power consumption.

Your watch is equipped with a real time volt meter, which translates the amount of remaining power into hours, days, weeks and month. If you know something about volt meters, they present an additional load to the rechargeable battery. The 5M6x calibers have a power reserve button that swings the second hand to roughly indicate the remaining power, but that's an on-demand basis - not real time. The 7L22 Kinetic Chronograph uses a mechanically actuated resetting mechanism to snap back the hands in place. This costs nothing to the battery.

As for the 5J22 Auto Relay Kinetics, they have an automatic shut off function that stops the watch when no movement is detected in a span of 72 hours. That's why they're claimed to have a 4 year battery charge.

You can equate this to the fuel gauge in cars. Some are equipped with constant real time fuel gauges while others show you the remaining fuel in the tank only when you turn the key to the Accessories position. Cars with constant reading gauges will use a bit of battery power when they are not used for months.

Of course, the lead acid batteries in cars can hold a lot more power than a single tiny lithium ion cell used in your watch. The fact still remains that your real time gauge is drawing some current from your internal battery whether your watch is worn or not. That is why your 5D44 equipped Seiko is rated to one month, just like the hand made 9T82 Kinetic Chronograph from Seiko. The 9T82 isn't that energy efficient and all those fast spinning 1/10 and 1-second chronograph hands draw a lot of power from the rechargeable battery.

It might amuse you to know that all three of my Kinetics are dead due to neglect. I've not worn them regularly as I used to, therefore over time their batteries get depleted. I've gotten them fully charged by my watchmaker over a year ago and even then my watches showed difficulty in achieving the full charge. It'll cost me a lot to have all of them replaced simultaneously, so I'll continue to use them until they cannot power the watches at all.

Your rechargeable lithium ion cell is no different than the ones used in laptops, camcorders, cellphones, digital cameras, MP3 players and the like. They have a finite lifespan, don't like heat, age the moment they leave the factory and a total discharge will degrade their internal chemistry.

Hope this helps and feel free to ask if you have further questions!

cheers

Hello,

First of all, I would like to thank you for your detailed and long reply which satisfies my question completely. However, I just wondered the lifespan of my watch. I think it can not have 7 years (in normal conditions) like 5M62 calibers because of its 1 month reserve. Maybe 5D88 (the newest direct drive model) calibers use different rechargeable battery, since I have not seen any K.E.S.U. in its caliber pdf. At least, Seiko does not use this abbreviation (instead, it uses "exclusive rechargeable battery"). By the way, the batteries for 5M62 or 5J22 calibers are very easy to find on websites like eBay. Unfortunately, there is no any seller who offers rechargeable battery for 5D44. Maybe, they can exist with time. We will see in future. Next time, I will certainly prefer 6R20 caliber premier automatic.

Warmest Regards

Dear Guerkan,

When it comes to rechargeable lithium ion batteries, there are a few variables that affect its lifespan:

- the age of the battery
- whether it had been subjected to total discharge
- whether it was subjected to excessive heat
- variations in quality control during manufacture


Although Seiko manufactures its own disposable watch batteries, it does not make lithium ion rechargebles due to the complexity and cost of making them. As such, the company uses the Maxell brand TC920S rechargeable lithium ion cell or its equivalent. Maxell makes only one type - the TC920S. The market isn't large enough for Maxell to make other types of button type LiOn cells, unlike disposable silver oxide and alkaline button cells.

Seiko does not mention the type of rechargeable cell for the 5D44 or 5D88, but going by past history they've always stuck to the Maxell TC920S. The company doesn't want to refer the KESU as a "battery" as doing so will confuse customers (see my article here.)

There is no reason for you to buy a spare rechargeable cell now because by the time you replace the one in your watch, the spare cell would have aged and its power holding properties diminished. It may not even hold 50% charge by then.

For the same reason, people don't buy a 2nd laptop battery unless they are heavy users and work at places without AC power.

You have nothing to worry about until your watch develops problems reaching 1 month's charge, no matter how active you are wearing it. I have a friend who has a 5J22 Kinetic Auto Relay since the early 2000 and he wears it everyday - it's his only watch. I asked him if he had ever had his battery replaced and he said no.

So, don't be overly concerned with your Seiko 5D44. Replace the battery only when the time comes when you really have to. Otherwise, just enjoy your watch as usual.

cheers