Tips to obtain maximum charge capacity and life from your NiMH rechargeable batteries

Tips to obtain maximum charge capacity and life from

Nickel Metal Hydride (NiMH) rechargeable batteries

Connevans part number 2267NMH

Store and charge batteries at 20°C or less. The loss of charge over one week is minimal. You may expect up to 1% loss of charge per day at room temperature due to self discharge, increasing significantly if the battery is stored at higher temperatures. There is no loss of charge if the battery is left on trickle charge by leaving it in a quad intelligent charger (pt.no.22684) or VC209 full cycle charger (pt.no.2268VC). Connevans recommend that you use two sets of batteries with one set in use and one set spare (on charge or charged).

Make sure that the batteries are cool before charging. The charging process is most efficient below 20°C, so allow a battery that has been in the sun a chance to cool before charging.

Do not charge batteries in warm areas such as in direct sunlight, in enclosed cupboards where air cannot circulate, near radiators or other warm equipment. Charging at elevated temperatures reduces the amount of charge that the battery can hold. Allowing air to circulate around the charger and batteries will help to keep the temperature low. Remember that when the battery is sitting in the charger, it will be 5-10°C warmer than the ambient temperature.

If you have VC209 (pt.no.2268VC) automatic full cycle chargers, make sure that the switch is in the 110mA position.

If you do not use intelligent or automatic chargers, make sure that you use a time clock to control charge time. Repeated overcharging will seriously reduce battery life. The correct charge time for 2267NMH batteries is 14-16 hours. A suitable timer can be found on page 47 of the 1999-2000 Connevans catalogue.

Do not recharge batteries more often than you really need to. Full cycling is better for battery longevity than top-up charging. Repeated top-up charging will seriously reduce battery life.

CRM-200 and CRM-220 equipment require different battery management. A fully charged new 2267NMH battery will last for up to 8 hours in CRM-200 equipment and for around 40 hours in CRM-220 equipment. This probably means that batteries from CRM-200 equipment will need to be charged every 1 to 2 days and batteries from CRM-220 equipment every 1 to 2 weeks.

Do NOT leave a battery in a radio aid to run totally flat overnight. A radio aid will totally drain a battery if left on which can result in reverse cell polarisation upon re-charge. Radio aids must be treated differently to equipment such as video cameras which turn themselves off automatically when the battery runs low.

Battery testers will not accurately indicate the amount of charge left in a rechargeable battery - sorry. The battery tester cannot tell the difference between a partially discharged new battery and a fully charged useable but slightly tired old battery.

When should you recharge a battery? Ideally you should wait until your equipment indicates that the battery is low before re-charging - in many situations this is not realistic as it would mean definitely interrupting a lesson. If you regularly re-charge a 2267NMH battery which is fully charged you will seriously reduce the life of the battery. If you regularly re-charge a 2267NMH battery which is partially charged you will slightly reduce the life of the battery. Our advice is that as long as you believe that more than three quarters of the charge in the battery has been used then it is OK to recharge it. If not keep using the battery! (You can guess the amount of charge by hours of use - 30 hours for a CRM-220 and 5 hours for a CRM-200. The use of an intelligent charger will also help prolong the life of the battery.

Keeping matters in proportion. A 2267NMH rechargeable battery only costs Ł 4.10 at the 10+ price break. If well looked after a battery can last 2 or 3 years in use, so accepting a slight reduction in battery life to make it easy for users is really not a problem.

FOR THE TECHNICALLY MINDED

It is sometimes possible to recover a battery which will not accept charge in a VC209 (pt.no.2268VC) full cycle charger.

There are a few special cases where a larger charge than normal is recommended either to achieve or restore the full performance of a battery. In these cases it is permitted to charge at the normal rate of 0.1CA (i.e. 11mA) for 2267NMH batteries for 24 hours. These are:

First recharge after prolonged storage i.e. 6 months or more

Deep-discharged batteries which have unintentionally been discharged into reserve i.e. significantly lower than a terminal voltage of 6.3 Volts. [This can happen if equipment is left on for a long time after the battery low indicator has been activated.]

In the above two cases, this restorative charge cannot be applied with a VC209 (pt.no.2268VC) automatic full cycle charger and you will need to use an ordinary charger (2268P) with time clock (697D).

The Intelligent 9V quad charger (pt.no.22684) also has some 're-activating' modes which work quite well - please refer to detailed operating instructions included originally with the product.

/D on Studio/QPC/Information sheets/battery tips v1.2 5/5/00