SLA battery question: real world expectations 48V

[Chalo]

Comfy recumbents (like BikeE, Sun, Trek and Cannondale 'bents and other big sellers by 'bent standards) are no better than normal bikes when it comes to aerodynamic qualities. You have to use a real silly feet-in-front-of-face bike to reap enough aero benefit to offset the less effective pedaling position.

Or you have to use a fairing, which works on an upright bike too, but is a bad idea for a range of reasons.

 

[LockH]

Getting OT here, but re a fairing "a bad idea for a range of reasons." Interesting. Care to elaborate?

 

[Chalo]

Getting OT here, but re a fairing "a bad idea for a range of reasons." Interesting. Care to elaborate?

To be brief, fairings are:
1) heavy, while also
2) fragile, while also
3) expensive in money and/or time,
4) unsafe in ambient winds,
5) difficult to park,
6) unreasonably hot when rider is exerting effort, and
7) tricky to enter and exit.

Cure all these problems and you end up with a car, with all the problems of a car.

 

[johninclaflin]

Two years ago I had a home built coroplast fairing on the Sun ez1sc, and the problem I had was visibility. Riding home one night I didn't have enough distance lighting to see the depth of a pile of sand the maintenance department had left at the highway edge. The fairing blocked the close in view, and I hit it at 18 mph and went over to the left. My left hand hung up between the fairing and the mount and I messed up some fingers as I went off the bike. When I got up off the pavement I was so mad that the batteries were no problem to lifting and throwing the bike. I have added a lot of lighting since then, and haven't added the fairing back yet. That said, I will ride with a clear fairing again some day. I had a RANS Velocity Squared recumbent with clear full front fairing and body sock, and it was as fast un-assisted as the ez1 ebike.

 

[renstyle]

Folks, I've been doing alot more reading on the SLA question... Thanks so much for your insight!

As many others have mentioned, the discharge C rate for "consumer/UPS" lead with even a light touch on the throttle is terrible, like 0.3C or 0.4C terrible. I was hoping that free lead would make the experiment worthwhile, then I saw this stuff (sorry if slightly OT):

(2) HK Multistar 6.6Ah $74 for the pair http://www.hobbyking.com/hobbyking/...0mAh_Multi_Rotor_Lipo_Pack_AR_Warehouse_.html

Turnigy Accucel-6 80W $29 http://www.hobbyking.com/hobbyking/...ancer_Charger_LiHV_Capable_AR_Warehouse_.html

(2) Lipo Battery Low Voltage Alarm 1S-8S http://www.ebay.com/itm/231871034687

Looks like roughly $121 all in, including shipping.

I've already got some XT-60 connectors, 12GA wire and shrink tubing to whip up a serial harness. Also have a 90W-16V power supply on hand to power the charger...

The controller I'm looking at is rated for 22A max from what I've been told, so could only deliver 1050W at most to the motor. I'm looking at the 10C constant discharge rate of these packs, which if my thinking is correct will only be able to discharge at a 3C max due to the limits of the controller (66A/22A = 3C).

I started thinking that 7.2Ah Pb would be sufficient for a short 5-6 mile trip, but the C rate was far lower than I had assumed.

Is a 6.6Ah, 12S Lipo pack ok to start with for a 5-6 mile trip? Charging at both ends? I apologize for trying to lowball everything, the extra $74 needed for another 2 packs isn't in the budget...

 

[Jon NCal]

For those lipos 1C = 6.6A

22A / 6.6 = 3.3C

Should be fine for your usage and short commute.