Rechargeable Batteries

Why use Rechargeable Batteries?

Eneloop low self discarge are the best rechargeable batteries.
Eneloop low self discarge are the best rechargeable batteries.

If your lights take standard AA or AAA batteries, I would highly recommend the use of a good set of rechargeables. The brightest battery operated lights usually have a battery life of only a few hours. For these the economic benefits of using rechargeable batteries don’t need explaining. Some lights however have an advertised battery life running into tens or even hundreds of hours. In this case, it’s tempting to think rechargeable batteries aren’t really necessary. However, it’s often the case that the brightness of these lights is not maintained throughout their battery life and actually, for a large proportion of the time, the light shows little more than a glimmer. By using rechargeable batteries and charging them on a regular basis, the light will always deliver its maximum brightness.

Best Rechargeable Batteries

There are a bewildering range of rechargeable batteries on the market from very good to complete rubbish. Fortunately, some of the very good ones are now very competitively priced.

There are two basic options:

i) Go for a high capacity standard rechargeable battery. For AA, the highest capacity is now at about 2900mAh. For AAA, they go up to around 1100mAh. Be aware that batteries don’t always deliver the capacity claimed. These Uniross AA 2700mAh Batteries and these Uniross AAA 1000mAh Batteries are very good.

ii) Look out for the new ‘low self discharge’ batteries. These have slightly lower capacity (2000mAh for AA and 850mAh for AAA) than those above but they have the massive advantage in that they stay charged up for much much longer when not used whereas standard rechargaebles tend to lose much of their charge within a few months. In this category the Sanyo Eneloop AA 4 Pack Batteries 2000mAh and the Sanyo Eneloop AAA 4 Pack Batteries are recommended.

Availability of the low self discharge batteries means that rechargeable batteries are now more appropriate for a much wider range of applications. Which is best for your bike lights really depends on how regularly you plan to use them. If you only occasionally use your bike at night the low self discharge batteries are probably a good choice as you wont then need to be quite so organised in having to remember to charge your batteries every time you go out.

Update – I’ve just noticed that there are now some higher capacity low self discharge batteries available. The XX AA Eneloop batteries have capacity of 2500mAh so seem to offer the best of both worlds. The choice seems to have become easier!

I highly recommend the use of an ‘intelligent’ charger. I explain why in my next post.

Technoline BL-700 Review

What’s an Intelligent Battery Charger?

Best Battery Charger - Technoline BL-700
Best Battery Charger – Technoline BL-700

One of the best battery chargers for AA and AAA batteries is the Technoline BL-700 which is an ‘intelligent’ battery charger. My old battery charger was not intelligent. Charging time was the only criterion I used in choosing that charger and the particular one I had (Uniross Sprint) was able to charge high capacity AA batteries in only an hour. The charger had a number of problems, the main one being that it would only charge batteries in pairs and it would only really work if those batteries were well balanced. Unfortunately many of my batteries were not balanced. The consequence would be that one battery would end up overcharged and / or the other would be undercharged. Even batteries that were purchased and always used in pairs would gradually drift to a state of imbalance and battery life was far shorter than expected. This was particularly bad for products which required the use of 3 batteries where the only option would be to try to keep batteries rotating in groups of 6. Intelligent battery chargers overcome this problem by independently monitoring and controlling the charging of individual batteries and offer a number of other features allowing the health of batteries to be assessed, and even allowing old batteries to be revived.

A few months ago I discovered the Technoline BL-700 battery charger which in some cases has made my batteries run for at least 50% longer.

Technoline BL-700 Features

The Technoline BL-700 has four modes and the mode for each battery may be set independently:

Charging Mode

The default mode as might be expected is ‘Charge’. The Technoline BL-700 is able to independently charge one to four AA or AAA batteries with charge current of 200mA, 500mA or 700mA. For the highest capacity AA cells this means a charge time of around three and a half hours. This is not the fastest charger on the block but you can be sure your batteries are being treated well and will likely deliver many more charge/discharge cycles than they would with a dumb charger. While the batteries are charging you can monitor battery voltage, charge current, time elapsed and charge accumulated (in mAh). The charger has built in thermal monitoring and will pause charging if it detects one or more cells is overheating.

Discharging Mode

Discharge mode first drains the batteries before then charging them fully. The reason for doing such a thing is to counter the so called ‘memory effect’ of rechargeable batteries where it’s said that batteries that are not regularly fully discharged and charged become eventually unable to deliver their full capacity.

Test Mode

Test mode fully charges the batteries, then fully discharges them, then charges them up again. During the discharge cycle the charger measures the capacity of the battery in mAh. This is a great feature and allows you to test out all your batteries to decide which to keep and which to discard. Before discarding, it’s worth trying a refresh first…

Refresh Mode

Refresh mode continually charges and discharges the battery until it detects no further improvement in battery capacity. Refresh mode can be useful for reviving old batteries that have not been used for a while and is sometimes useful for quickly bringing new batteries to their maximum capacity.

 Technoline BL-700 Ease of use

The only minor criticism I have regarding this charger is that controlling it is not entirely intuitive. I like products for which I can dive straight in and operate without opening the manual. This charger is almost there but there are cases where a button needs to be pressed and held down which is not obvious. Independent control of the batteries can be a little fiddly too. The manual is well written though and everything is easy once you get the hang of it.

Technoline BL-700 Conclusion

Technoline BL-700  Battery Charger
Technoline BL-700 Battery Charger

The Technoline BL-700 is an excellent battery charger. If you use rechargeable batteries and don’t already have a smart charger this is a good one to choose. Whether for bike lights or any other battery operated product, independent charging of batteries means that you will get the best possible capacity from your batteries.

Where to buy & Alternatives

The Technoline BL-700 can be purchased from here in the UK or here in the US where it’s known as the La Crosse BC-700. It looks identical to the BL-700 and I can only assume it’s the exact same product badged under a different name perhaps just bundled with an alternative mains plug.

If money is no object the MAHA C9000 offers a similar range of functions but offers even faster charge rates. It’s available here in the UK or here in the US.

N.B. The BC-700 version is also available from Amazon in the UK. I’m told that this is the German version and comes supplied with a European plug and wobbly travel plug adapter. It works but the connection can be a little loose which can cause the charger to keep resetting. If you are in the UK it’s well worth getting the official UK BL-700 version linked above.

Choosing some rechargeable batteries

There’s a very wide selection of NiMH AA and AAA batteries available nowadays including some with very low self discharge rates. Be sure to check out my recent post detailing what I think are some of the best rechargeable batteries.