FAQ
What is Lithium Ion and why is it so good in batteries?
A combination of infusing Lithium – the lightest known metal (soft, silvery elements) with Ions – electrically charged atoms into "cells". Their composition gives the best power/weight/density ratio (within a reasonable cost) hence their relatively light weight is ideal for batteries to power a massive range of portable equipment, eg; personal computers, mobile phones, power tools, etc.
How should I store Lithium-ion batteries?
Lithium Ion Batteries are better stored in a cool place than if the battery was stored at room temperature. Lithium Ion batteries will discharge at about 1% per month (1% per day for NiCad) in the cold, whilst they lose about 5% per month at room temperature. This warmer storage will shorten the life of the battery too. So remember, the higher the temperature, the more “life” is used up hence cooling is essential. Storage in a hot garden shed will be worse for the battery than if left in a cool dark location.
The absolute ideal storage conditions would be c.40% charged at around 5°C. However, storing a discharged battery for a long period below freezing point is not recommended. Lithium-ion batteries can hold a charge for many months. It is best to store a lithium-ion battery with a partial of full charge.
Are the batteries serviceable, and what about disposal?
No, they are a totally non-serviceable item and disposal is much the same as for any other battery. It should NEVER be incinerated, or go to land-fill, but should be disposed of through accredited waste disposal sites. It can even be returned to an Approved Service Centre or Bosch Service Centre for disposal.
What are the advantages of Lithium-ion batteries?
Lithium-ion batteries have several advantages. They have a higher energy density, which means that they can store more energy than other types of rechargeable batteries. Lithium-ion batteries also have lower self discharge rate than other types of rechargeable batteries. Lithium-ion batteries have a higher energy density and, therefore, weigh up to 60% less than conventional batteries (NiCd/NiMH) while still providing comparable power. Short charge times in comparison to conventional batteries.
Charge time
Bosch has developed a special Hyper Charge technology for lithium-ion batteries, which protects the cell against overload, therefore increasing the lifetime by up to 400%. Due to a gentle rapid charging process, the batteries are charged to 75% after just half of the charge time.
Memory effect
Irregular charging with NiCd batteries can lead to a permanent loss in capacity of 30%. This effect does not occur in lithium-ion batteries. The Bosch lithium-ion battery can be charged at any time regardless of the charging state, without damaging the cells.
Self-discharge
Fully charged NiMH batteries already lose 50% of their power if they are not used for approx. 4 months. A fully charged lithium-ion battery is fully ready for use, even if it has not been used for months. The loss in capacity of 0.1% per day is extremely low.
How will grass conditions effect runtime?
Rotak Li has a limited capacity stored up in the battery. Once this energy level has been used then the battery electronics will turn off the battery and it will have to be recharged. Grass conditions will greatly effect how quickly this stored energy is used up. Cutting in damp, thicker lush grass will use up the battery capacity more quickly than cutting in lighter dry conditions. Walking faster will require the blade to work harder and therefore use more of the energy reserve.
How can I increase the runtime of Rotak Li-Ion from one charge?
To increase the cutting area it is suggested to cut the grass: more frequently, when grass is dry. Also to walk more slowly, raise the height of cut position, avoid overfilling the collection box and stopping if the chute becomes blocked. Frequent stop-starting of the motor will also more rapidly use up the battery capacity.
The area of cut (battery duration) is not large enough. What should I do?
There are a number of checks and actions that you can perform to remedy the problem:
– Cutting height set too low: increase height of cut
– Grass too long: Increase height of cut
– Grass wet or damp: Wait until grass is dry
– Grass is dense: Raise height of cut and walk slower, and cut more frequently
How will the battery cope with the strains of long and short, or tougher grass conditions?
The battery is controlled by “constant electronics” built into the circuitry and this automatically adjusts the power to maintain constant speed - just like cruise control. Together with electronic commutation, the battery and motor work together constantly converting power (and torque) into the designed blade speed. However, the area to be mown on one charge will be considerably shortened if the mower is having to work too hard in long grass. The Rotak Li-Ion has the same cutting power as the Rotak 43 with 1700w. So it is able to cope with difficult cutting conditions. However, to maximise the usage from the mower it is suggested the user will have to cut more frequently than with the mains Rotak.
How stable are these batteries, I’ve heard disturbing reports about over-heating and fires?
Bosch have designed and tested every aspect of this and now have over 75,000 professional power tools working exceedingly hard in tough conditions without problems. Whilst it is accepted that heat is generated within the batteries, these “red fins” are heat dispersers, and the charger unit itself has an in-built fan to further cool the batteries. There are also temperature sensors on board which shut charging down if faults are detected.
