Questions about USB/Charger.

[freewheeling]

I currently have a Model C erg with a PM2+ monitor and was considering my upgrade options. I gather that the Model D and E have a dynamo that can be used to either power, or charge batteries in, the monitor (depending on whether it's a PM3 or PM4). I also understand that I can upgrade the monitor on my Model C but that it won't be powered by the erg and won't charge the batteries. So here are my questions:

1. Can my Model C be modified to install a dynamo? (Either C2 or third party.)
2. Can the C2 dynamo in the D & E be modified to charge other devices such as a phone, iPod, etc. that normally connects to the USB port?

[Citroen]

Stop worrying - it's only the PM4 that has the rechargeable batteries. The power generation feature on a model D/PM3 is only there to stop the D-cells going flat so quickly (9months rather than 6months in daily gym usage). If you get a PM4 simply remove the rechargeable battery pack and fit a pair of D-cells.

[freewheeling]

Stop worrying - it's only the PM4 that has the rechargeable batteries. The power generation feature on a model D/PM3 is only there to stop the D-cells going flat so quickly (9months rather than 6months in daily gym usage). If you get a PM4 simply remove the rechargeable battery pack and fit a pair of D-cells.

I think you misunderstood me. I like the idea of using my erg to charge batteries, and would like to use it to charge other USB devices. We have frequent power outages, especially in winter, and it would be useful to use the charging function of the C2... or a third party dynamo fitted to the Model C.

[bloomp]

If you notice the numbers that Dougie put out there, using the rower on a frequent basis gives you approximately a 50% longer battery life on the D-cells. That's hardly enough power to charge a phone, iPod or whatever other electronic device you had in mind. Not that you couldn't try to fit a dynamo to the erg, but it would not do anything significant.

The USB ports in use on the PM3/4 are also not powered. That's why you must plug it into a computer to pull any data from it (and why the monitor only saves to a log card). It would not be able to interface with a flash drive or any other USB equipment requiring power. Why? Well again, there is hardly enough power produced by the erg in the first place so it is pointless to be able to attach something to the USB port that would drain any power left in the D-cells.

[Bob S.]

I like the idea of using my erg to charge batteries, and would like to use it to charge other USB devices. We have frequent power outages, especially in winter, and it would be useful to use the charging function of the C2... or a third party dynamo fitted to the Model C.

The intermittent nature of the rowing stroke (alternating drive and recovery) makes it impractical to use an indoor rower for driving a dynamo. A more likely candidate would be a stationary bicycle, since the pedaling motion is continuous and steady.

Also, the C2 is designed to convert the energy you expend into blowing air. If you try to have some of that energy diverted into running a dynamo to charge power cells, the only way that you could get much of the energy to the dynamo would be to cut off the air flow as much as possible - like sealing up the cage or removing the blades of the flywheel/fan.

With a set of bicycle pedals connected to a dynamo, just about all the energy expended can go to the dynamo.

Bob S.

[freewheeling]

Thanks. There are hub dynamos for bicycles, but they're mostly designed to run on the front wheel since the rear wheel is usually the drive mechanism, so they're mostly impractical for stationary "trainers" because the front wheel isn't even on the bike or it's stationary. I figured since the Model E was already set up to charge the monitor batteries the same thing might be available as an aftermarket item for the model C. I don't think continuous rpms are necessary for such systems because they can store using capacitance as a buffer and transfer a continuous charge. Oddly, there are only a couple of devices that use the hub dynamo output to charge via a USB port. You'd think such a thing would be obvious, but apparently the market is so small in the US that they don't have them. Most of the systems that exist are sold in the third world. The main thing dynamos are used for on bicycles is a headlight system. Most aren't even DC, but AC.

Oh well, worth a shot.

[freewheeling]

BTW, I don't know of any dynamos connected to the pedals. It's possible in theory, but there's not much space there. Wheel hubs and "bottle" dynamos that use friction against the rim are more usual, but again very few that have the right kind of output. It's an odd situation.

[Bob S.]

BTW, I don't know of any dynamos connected to the pedals. It's possible in theory, but there's not much space there. Wheel hubs and "bottle" dynamos that use friction against the rim are more usual, but again very few that have the right kind of output. It's an odd situation.

What I had in mind was replacement of the rear wheel with a cog driven dynamo. I remember reading many years ago about this being done. In one particular case, some guy put such a device together and connected it to a battery that ran the TV. The idea was to make his kids work in order to watch their TV programs. I have never seen anything about such a rig available on the market - just home made products. I suppose that the flywheel of an erg could be replaced in the same way. In that way, most of the energy expended would go into the dynamo instead of just blowing air.

In either case, it involves a major revision of the machine.

Bob S.