Question about different battery brands - Page 1
Forum section: electronics / beginners

author: applehusky
author_rank: Newbie
timestamp: July 26, 2015, 07:15:32 pm
content: Hey all ^^I've got a question I cannot, for the life of me, figure out.I work at a watch and clock repair shop and am going to school for engineering. It turns out that sometimes, when I run a clock on a big name battery like Energizer or Duracell, it doesn't behave correctly, meaning it doesn't keep time, the pendulum doesn't swing but the clock works etc... However, a different brand, like Rayovac, or Kirkland will make the clock behave just fine. Keep in mind, all these batteries are new straight out of the package.Now this could just be due to other factors than just the brand of the battery. As I haven't done any scientific testing, I have no idea. I just wanted to know if there was anything different between those brands that could cause a clock to behave poorly or even not at all.Also, any suggestions on how to test such a hypothesis would be appreciated.Thanks ^^

author: Ian.M
author_rank: Super Contributor
timestamp: July 26, 2015, 07:31:59 pm
content: Possibly counterfeit big name batteries?You will need an external battery holder and some clip leads and a DMM so you can check load current and voltage at the clock's battery terminals.

author: SeanB
author_rank: Super Contributor
timestamp: July 26, 2015, 07:35:52 pm
content: Measure open circuit voltage of the cells, and the voltage of the cell under load. You might also be finding that different brands with different chemistries have both a slightly different open circuit voltage, and a different internal impedance under load.You probably will find the RayoVac and Kirkland cells are actually the same cell in a different wrapper, the Duracell is mostly all Duracell, and Energiser is mostly energiser. The differences will occur as the pendulum mech tries to draw a large current pulse from the cell to keep it swinging, so if the resistance of the cell os too low or too high the pulse does not have the correct amplitude ( high resistance with old cell) or occurs too soon with a fresh low impedance cel;l, and stops the pendulum.Ran into this with Gardena branded lawn watering units, which will run typically 6 months with a Duracell 9V battery, but any other brand lasts a week before showing as flat.Another one is the new clock in my office, running off a 12V SLA back up battery using a red LED and a 4k7 resistor and 1000uF to give a 1V3 supply. At 1V5 it runs fast, and as it is a silent sweep mechanism pulsing at 8Hz it eats AA cells at a rate of 1 per month. I got tired of changing them, so put in the older Tick tick type and took this one for me.

author: BillW50
author_rank: Contributor
timestamp: July 26, 2015, 07:48:31 pm
content: This may have nothing to do with this, but I heard batteries sold by Walmart are really rejects from the manufacture (i.e. Energizer and Duracell). The reason I heard is that Walmart will only pay X amount and if the vendor or manufacture wants more money, Walmart won't buy any. So the manufactures/vendors will just sell them their rejects instead. I have no idea if this is true or not and I may have read it in Consumer Reports or something.

author: miguelvp
author_rank: Super Contributor
timestamp: July 26, 2015, 08:10:38 pm
content: Quote from: BillW50 on July 26, 2015, 07:48:31 pmI highly doubt that a big manufacturer will compromise their reputation by selling rejects with their brand name on it.Then again, companies do stupid things sometimes.

author: SeanB
author_rank: Super Contributor
timestamp: July 26, 2015, 08:20:43 pm
content: By me Makro ( now owned by Walmart) just stopped selling Duracell, and sell Energiser, Ever Ready ( rebranded cells), Panasonic ( those probably are either fake or the bottom of the line brands) instead. Duracell I go across the road from them to the Home Centre and buy them from the opposition, and often pay less. There I can buy the OHL Mystery cells at a quarter the price, and this is the only place that sells a regular non alkaline D cell very cheap, which is a good source of carbon rods for experiments or welding. I did DIY a few carbon arc lamps with the rods and an old 12V car battery.

author: BillW50
author_rank: Contributor
timestamp: July 26, 2015, 08:21:43 pm
content: Yeah I don't know for sure either. But I also heard that big manufactures will unload their not up to standard rejects and they end up on places like eBay for unbelievable low prices. I should test the capacity of some of them to see if I can find any differences.

author: G7PSK
author_rank: Super Contributor
timestamp: July 26, 2015, 08:35:26 pm
content: Another factor with batteries that I have come across is length and diameter varies. A longer battery could put pressure on the case and thereby alter bearing resistance or gear meshing etc this is critical for clocks, when I was an apprentice horologist I was told that if car gear boxes were made to the same tolerance as watches and clocks they would not work, either the gears would not mesh or they would strip.

author: IanB
author_rank: Super Contributor
timestamp: July 26, 2015, 08:36:24 pm
content: It may not be directly relevant to the problem with the clocks, but the big name brands like Duracell or Energizer tend to be optimized for high power loads with heavy current drains. These batteries in general will be inefficient when used in a clock that runs a long time with a very low drain. By inefficient I mean you will be wasting your money on a capability you don't need.The best kind of battery for clocks is one that hasn't been designed for maximum buzzwords by the marketing department. Such batteries may often be found in dollar stores with brand names like Panasonic, Sony, Sunbeam, Fuji and so on. Occasionally you can even find batteries specifically labeled as "clock battery".