E-Motorized Police Bicycle

Little Rock, Ark. to use new electric bicycles to patrol streets
By Rainer Sabin
The Associated Press

LITTLE ROCK — Retired Gen. Wesley Clark once hawked WaveCrest electric bicycles for police departments as a Washington lobbyist. Now, his hometown of Little Rock is the first major department to bite.

The city recently purchased 10 electric bicycles, at $3,000 each, made by Virginia-based WaveCrest.

For the last two years, WaveCrest and the city of Little Rock have discussed using the equipment for police operations.

Read More...Little Rock, Ark. to use new electric bicycles to patrol streets
 
One problem with using electric bicycles for police is that the working shifts are usually at least 8 hours long. The cops don't need to be moving all the time, but they do need to move quite a bit throughout the shift. A battery pack which is low on power means that the extra weight of the electric bike components causes the bike to perform poorly under pedal power alone, without electric assist. And the officer always needs to keep a reserve amount of power or the ability to pedal at speed for an emergency.

So electric vehicles don't do very well in this type of use, they just don't have the range to keep moving for that many hours in a day.

Maybe a hot swap of batteries every 3 or 4 hours would be a way to get around this.

I think that a good quality pedal powered bike is better than an electric bike for this purpose, due to range issues.
 
Just like two way radios they have spare batteries and a charging station for them. If you only use a 10 amp hour battery then the total weight of the system can be less than 25 lbs. If you can get the officer to actually do some pedaling then each battery would hold up at least 4hours. The downside is the expense of batteries.
 
48V 10aH will give you about 20 minutes at full throttle, at least on my electric bike. Thats not enough power for even half a shift.
 
48v 10ah at 480wh is very small battery in E-bike terms, either way the Police dont have to use the assist the entire shift, when they do they will be pedalling anyway so power consumption will be alot less than running WOT. As to extra weight, its negligable IMHO the size of the setup wouldn't weight alot, it not like trying to pedal a bicyle with a HT motor bolted to it...

KiM
 
The problem is that there is resistance when pedaling with the motor off. At least on the hubmotor that I have used, it takes more pedal power than a bike with no hubmotor.

And on pedal bikes, cutting down the weight to a bare minimum is important for good performance.

I'm not saying that it is impossible to put together a e-bike for police use, but that it has to have a hefty battery system to make it work, and the batteries have to be the lightest available. If you don't have a large battery capacity, you are better off with a quality pedal bike.

E-bikes are great for commuting and trips to a destination and back within their range. But when you ask an e-bike to serve a use that is essentially mobile for long periods of time, that is the most difficult thing for an e-bike to do.
 
skyl4rk said:
The problem is that there is resistance when pedaling with the motor off. At least on the hubmotor that I have used, it takes more pedal power than a bike with no hubmotor.
Click to expand...

Geared hub motors have no cogging whatsoever, they freewheel when no power is applied, you likely have a direct drive hub motor which do have alot of cogging. Geared hub motored bikes you can ride as per a 'normal' bicycle with no resistance from the motor. I would assume these are what is used on these Police bikes as they perform better on low voltage setups than direct drive hub motors and are better hill climbers on low voltage systems. ~36v20ah lithium polymer setup would weigh under 10lb if only used for hill climb assist throughout the day you would have plenty of capacity.


KiM
 
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The Brandeis U guy said he can pedal without the motor (sounds like it freewheels with minimal resistance) and only charges every other day. The piece looks like it was originally produced as a news piece for the college, not as an ad, so I don't think there's a lot of manufacturer's hype. But I could be mistaken about that. I find in my own experience that my 350W brushed through-the-derailleur mtb with 24V 20ah LiFePO4 can go 28 miles with moderate assist. That's 2 hours at my leisurely 14 mph normal pace. I think if I were patrolling a specific area and not trying get somewhere, I could probably get at least 4 hours out of the same pack. As the expression goes YMMV - jd
 
I listened to him quote how long it would take to get to different places on campus. I am thinking that he has a station where he can pick up a charged battery if needed also. I was looking at an electric assist for myself but am not happy with the limitations and the expense.
 
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