Frequently Asked Questions

All About Watch Batteries

We give you the chance to delve into the fascinating world of watch batteries. It might keep you interested long enough to make sure you order the correct battery! p>

Battery Chemistry:

Watch batteries come in 3 main types of chemistry, Silver Oxide, Alkaline or Lithium. The Lithium coin size cells are usually 3 Volt cells and the Silver Oxide and Alkaline button cells are usually 1.5 Volt. Your watch may take one or more of these different types of battery. The Lithium cells tend to be the larger button cell batteries and their references tend to be prefixed with either CR or BR. For example, a CR2032 is a Lithium 3v coin cell battery.

Silver Oxide and Alkaline batteries

Silver Oxide and Alkaline watch batteries have a 1.5v output so which battery do you choose?

You will find that Silver Oxide watch batteries tend to cost more than an Alkaline cell of the same size. So does this mean you can use the Alkaline watch battery of the correct size? Well, this depends on your application and also if the Alkaline version is available. In reality there is a much wider choice of Silver Oxide watch batteries. In fact, Rayovac make only two Alkaline button cell sizes but about thirty different Silver Oxide watch battery sizes. The advantage of the Silver Oxide cells over their Alkaline counterpart is in their ability to maintain a more stable voltage. This characteristic makes them better for clocks and watches and is absolutely essential for metering equipment (like light meters in cameras for example) where a stable voltage is required. An Alkaline cell though is good for high current devices where a stable voltage is not required, for example, in electronic toys and calculators. Many of those noisy books children like use LR44s (Alkaline), but can run equally as well using the Silver Oxide equivalent (Rayovac 357). Many electronic toys use LR44s or LR41s and there is no problem using a Silver Oxide watch battery of the equivalent size. Rayovac do not make a LR41 so we have no problem in suggesting to owners of the Thunderbird Soundtech toys (which use 3 x LR41) that they can use the Silver Oxide equivalent (Rayovac 392) instead.!

In summary, if your application calls for a stable voltage under load (watches, clocks, metering equipment etc.) a Silver Oxide watch battery is ideal. If your application does not require this and the Alkaline equivalent is available then you don’t need to use a Silver Oxide battery. The important point is, you can always use a Silver Oxide watch battery to replace an Alkaline watch battery but not always the other way round.

Battery Sizes:

Lithium coin cell battery sizes can be determined from their reference numbers. The first two digits refer to the diameter of the battery in millimetres and the second two digits give the height or thickness of the battery in tenths of millimetres. A CR2032, for example, is a Lithium cell that is 20mm in diameter and 3.2mm thick. A CR2430 is a Lithium cell that is 24mm in diameter and 3.0mm thick.

Other watch batteries also have a reference number which give a similar clue to their size. Take for example a Vinnic L1154. Now you could be excused for thinking this was 11mm in diameter and 5.4mm thick. Which is not far from the truth, but, in this case the first two digits refers to the diameter in the 11mm range and the second two again, as for the Lithium button cells, refers to the thickness in tenths of millimetres. A quick check in our reference table will show that all watch battery diameters in the 11mm range are 11.6 mm in diameter. Therefore, a L1154 is an Alkaline button cell 11.6mm in diameter and 5.4mm thick.

Other manufacturers use a similar reference numbering system for their watch batteries, and as a general rule wherever you see a three or four digit reference number for a watch battery it is likely to follow the rule described above. For example, a Sony SR626SW is a Silver oxide watch battery which has a diameter in the 6mm range and is 2.6mm thick. All watch batteries in the 6mm range have a diameter of 6.8mm. So a SR626SW is 6.8mm in diameter and 2.6mm thick giving a Rayovac equivalent battery, from the reference table, as a 377.

Rayovac, for instance, number their batteries without giving a clue as to the size of the watch battery, so to refer from these to other manufacturers' batteries you really need to use a cross reference table like ours.

Battery Prefixes:

What do the letters at the beginning of the reference number mean?

So what about these prefixes? This is just down to experience I suppose so here's a short list. Manufacturers who use SR to denote a Silver Oxide watch battery will tend to use LR to denote Alkaline. Those which use SG to denote Silver Oxide will tend to use AG to denote Alkaline.

Battery Prefixes:

BR/CR = Lithium
L = Alkaline
SR = Silver Oxide
LR = Alkaline
SG = Silver Oxide
AG = Alkaline

Battery Suffixes:

The letters at the end of the reference number are different, one is W the other SW. Which one do you choose?

In the Silver Oxide range of batteries a different suffix may be used on the same battery reference. For example, there is SR1130W and SR1130SW. The ¨SW¨ refers to use in low drain devices whereas the ¨W¨ refers to high drain devices. So what's the difference? Well you would tend to only use a ¨SW¨ battery in a watch without a backlight. A standard analogue quartz watch would be fine with a low drain watch battery, whereas a watch that used a backlight or alarm feature would really need a high drain ¨W¨ watch battery. However, a high drain watch battery can be substituted in all applications where a low drain is normally used. ¨SW¨ batteries will tend to have a slightly longer life when used in low drain devices than their ¨W¨ equivalent. If in doubt use the high drain "W" type since there is likely to be little or no difference in price.

Battery Capacity and Shelf Life:

Battery capacity is given by the manufacturers in mAh (milli Amp hours) and this figure indicates how much current can be supplied by the battery and for how long. For example, a battery which had a capacity given as 50mAh will be able to supply 50 milliamps for an hour or 25 milliamps for two hours. We can provide this information if you like, but you don't need to know this if you are replacing a watch battery. It is really meant for the electronic buffs who need to know which battery to use in a newly designed circuit.

The shelf life of watch batteries is determined by storage temperature and their chemistry. Typically, at 21 degrees Celcius a Silver Oxide battery will lose less than 10% a year, an Alkaline button cell about the same and Lithium button cells less than 2% a year. This loss decreases as the storage temperature decreases.

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Help Choosing a Battery Charger

There are two main types of battery charger...

A timed battery charger and an intelligent battery charger. A timed battery charger will tend to charge rechargeable batteries for a fixed length of time, after which the battery charger may switch to trickle charge or simply switch off. These battery chargers are fine for batteries of a certain capacity. Say your battery charger takes 5 hours to fully charge 1700mAh AA batteries. Perhaps these batteries came with the battery charger. All will be fine and your batteries will reach their full charge. However, if you put higher capacity batteries in the same battery charger, it will charge for 5 hours at the same rate and your higher capacity batteries will only ever be partially charged (to about 1700mAh).

Ok, so how about I charge the higher capacity rechargeable batteries again before use, using the same battery charger?

You could do this of course as this will give the batteries a double dose. But how would you feel if, on a drinking binge, your capacity was say, 8 glasses of wine, and you were forced to take two lots of 5? You get the gist? The charger will spend another 5 hours charging the batteries, but of course you risk damaging the batteries by overcharging them. This will shorten their life. Quite an apt analogy perhaps? We get many customers who purchase the new high capacity Uniross 2500mAh NiMH AA batteries and find that the performance of these batteries is not much better than the 1700mAh batteries they were replacing. In most cases this is because the battery charger being used is a timed battery charger. The best solution is to use an intelligent battery charger.

What is an intelligent battery charger?

An intelligent battery charger is just that, cleverer than a timed battery charger. It is often microprocessor controlled and charges the rechargeable batteries until their full capacity is reached. Once they are fully charged, the battery charger stops charging and goes into trickle mode, preventing your batteries from being "cooked" thus prolonging their life.

Can I charge NiMH rechargeable batteries in my existing NiCd battery charger?

Sorry, no. Well you can, but the battery life will be severely affected by this treatment. Some battery chargers allow the charging of both NiCd batteries and NiMH batteries. Some battery chargers auto sense the battery type (like the Fameart UC05 Universal charger) and some require a switch to be used to select the battery type.

The Camlink Zeta and Z1 chargers are brilliant for charging batteries for digital cameras because they charge so fast..

Another option, slower, but an excellent, versatile charger is the Fameart UC05 Universal microprocessor controlled intelligent charger, which can charge both NiCd and NiMH batteries in all the popular sizes (C, D, AA, AAA and PP3).

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WEEE Regulations - Disposal of Electrical and Electronic Goods

The Waste Electrical and Electronic Equipment (WEEE) Directive is now UK law. The legislation aims to make producers pay for the collection, treatment and recovery of waste electrical equipment. The regulations also mean that suppliers of equipment like high street shops and Internet retailers must allow consumers to return their waste equipment free of charge.

The amount of WEEE we throw away is increasing by around 5% each year, making it the fastest growing waste stream in the UK.

Much of the UK's WEEE ends up in landfill, where the lead and other toxins it contains can cause soil and water contamination. This can have a harmful effect on natural habitat, wildlife and also human health.

Many electrical items that we throw away can be repaired or recycled. Recycling items helps to save our natural finite resources and also reduces the environmental and health risks associated with sending electrical goods to landfill. Distributors of new Electric and Electronic Equipment (EEE) have a part to play in reducing the amount of WEEE going into landfill sites.

Online-Batteries Ltd is obliged under these regulations to offer our customers free take-back of their WEEE on a like-for-like basis when they buy a new Electrical or Electronic product from us.

For example, if a customer bought a new battery charger from us we would accept their old battery charger and prevent it going into a landfill site by disposing of it safely. Customers must return their WEEE item to us within 28 days of purchasing their new item. Please contact us using our using our Contact Us form for a returns code before sending items back to us. Please note that the cost of returning items to our premises is borne by the customer.

Under the WEEE Regulations, all new electrical goods should now be marked with the crossed-out wheeled bin symbol.

Goods are marked with this symbol to show that they were produced after 13th August 2005, and should be disposed of separately from normal household waste so that they can be recycled.

Please note that Batteries are not included in the WEEE Directive their disposal is covered by the Battery Directive. They should be treated as HAZARDOUS WASTE and should be disposed of separately from household waste. Batteries can be taken to your local civic amenity for correct disposal. Waste batteries should not be sent in the post.

You can locate your local waste disposal site via your local council website or through websites such as www.recyclemore.co.uk. Click here to use the Recycle More waste disposal site locator.

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