NiMh Batteries
Battery pack NiMh batteries started to gain widespread acceptability and use in LEV's worldwide during the late 1990's, due to their size, weight, environmental credentials and durability. NiMh batteries typically cost two and a half times more than an equivalent lead acid battery. However, NiMh batteries more than doubled the life of a lead acid battery and therefore the lifetime costs were similar to SLA overall.
Urban Mover was the first LEV company in the world to use the very latest 4th generation NiMh batteries manufactured for us by the battery giant GP, used in our earliest ebike range - the UM24, UM36, UM44, UM44L and UM55. This incarnation of NiMh battery weighed less than half the weight of its equivalent lead acid counterpart and had a much higher charge density per kilogram. The 4th generation batteries also retained up to 85% of a fully charged battery if left for 3 months unused - compare this to previous NiMh technology that lost approximately 20% - 30% per month if left unused. The 4th generation NiMh batteries were also more tolerant to part charging.
However, due to higher raw material costs (especially Nickel), the increased cost of NiMh batteries now and the advent of mass produced Lithium-ion batteries from quality companies such as Panasonic, we now use Li-ion power packs as standard on all our bikes. Li-ion is typically half the weight per Ah (compared to NiMh), flatter current and voltage discharge (meaning more effective range per Ah) and similar cost.
Urban Mover™ - Battery Comparison Chart
| Lead Acid | Silicon | Ni-Cad | NiMh | Li-ion | Li-Pol | Li-Pho | |
| Safety | Good | Excellent | Good | Good | Good | Excellent | Superb |
| Nominal voltage | 2 | 2 | 1.2 | 1.2 | 3.4 | 3.6 | 3.2 |
| Wh/Kg Energy density (gravimetric) | 35 | 50 | 41 | 80 | 120 | 160 -180 | 110 |
| Volumetric energy density | 80 | 130 | 120 | 200 | 280 | >320 | >240 |
| Cycle life | 200 | 400 | 250 | 400-500 | 400-500 | >1000 | >2000 |
| Memory effect | No | No | Yes | No | No | No | No |
| Operational temperature (C) | -15° to +50° | -50° to +70° | -20° to +50° | -20° to +60° | -20° to +60° | -20° to +60° | -25° to +60° |
| Flexible form factor | No | No | Yes | No | No | Yes | Yes |
| Self discharge (% per month) | <0 | <0 | <10 | <20 | <5 | <5 | <5 |
| Environmental impact | High | Low | High | Medium | Mid-Low | Low | Low |
| Initial purchase cost | Low | Medium | Medium | Medium | Mid-High | High | High |
| Lifetime cost (based on range and cycle life) | High | Medium | Medium | Medium | Low | Very Low | Very Low |