Difference between Ezee kit and bikes ?

[jkirkeboe]

Does anybody know if there is any differences between the Ezee kit and what's on their bikers (like the Forza or Torq) ?

I know the motor is rated differently, 350W on bikes and 400W in the kit, but I assume it can still be the same motor but with different rating ?

What about the controller, the kit one will do ~25mph with 48 volts input I have heard, will the bike one do the same or is it in any way restricted to 20mph or 36 volts ?

 

[APailthorp]

If you are talking about the kits from Renaissance Bicycle Co., I think those kits are specified with a High Voltage Cutoff of 60V. I believe that is a custom modification, not sold by others, but I'm not sure.

My Forza has a specified (and verified) HVC of 44V. So yes, the Forza is effectively limited to a "36" volt system (I actually see up to 41.7V off the charger, and under load it typically will start around 37.5V, meaning adding even 6V more some how will likely trip the HVC). With the included battery, the Cycle Analyst I installed regularly shows draw over 600W sustained. On the flat over 400W is not unusual.

The trade off for a 44V HVC is that the Forza is a an extremely well integrated bike. A 36V 10Ah LiFePo nested behind the seat post with a controller squirreled away there too makes for a nice compact package. I'd love to have a 48V bike that could scream up hills (the Forza likes a little help), but I haven't seen anything short of a Kona Ute that would carry the batteries needed in as nice a way as the Forza carries what it has.

-->Aaron
p.s. if anyone knows of a "semi-longtail" frame like the Forza, where there is significant space between the seat post and the forward edge of the tire, in a mountain bike style front suspension friendly design, I'd like to hear of it.

 

[spinningmagnets]

APailthorpe, Google "electric mountain bike" and use the image search (top left). My plan for the next build (a year from now?) is to acquire a hard-tail mountain bike (front suspension, front disc brake) and to attach the rear suspension from a second bike (used MTB's cheap at thrift store) to make a "DIY longtail" (there was a thread a while back)

The high BB from MTB is good for jumping urban curbs. I converted my MTB to semi-recumbent seating which is more comfortable. I now wish it was slightly longer to be more stable with weight distribution being rear-heavy right now. I like rear suspension a lot, but how to make longer? Buy hardtail and add rear susp. Cheap and easy. That, plus add smooth tires and I'd be set.

 

[jkirkeboe]

If you are talking about the kits from Renaissance Bicycle Co., I think those kits are specified with a High Voltage Cutoff of 60V. I believe that is a custom modification, not sold by others, but I'm not sure.

My Forza has a specified (and verified) HVC of 44V. So yes, the Forza is effectively limited to a "36" volt system (I actually see up to 41.7V off the charger, and under load it typically will start around 37.5V, meaning adding even 6V more some how will likely trip the HVC). With the included battery, the Cycle Analyst I installed regularly shows draw over 600W sustained. On the flat over 400W is not unusual.

The trade off for a 44V HVC is that the Forza is a an extremely well integrated bike. A 36V 10Ah LiFePo nested behind the seat post with a controller squirreled away there too makes for a nice compact package. I'd love to have a 48V bike that could scream up hills (the Forza likes a little help), but I haven't seen anything short of a Kona Ute that would carry the batteries needed in as nice a way as the Forza carries what it has.

I do have a Forza on order, just wondering about future possible upgrades. The Ezee battery case can be had for $25 so a 48V/10Ah battery can be built in two parts, one in the battey case and one strapped to the rack.

If anybody knows more about the controller, I'm very interested. Does Renaissance sell separate controllers and if they do, will it fit where the stock controller is ? Can the original controller be upgraded/modified to 60V somehow ?

 

[APailthorp]

>Does Renaissance sell separate controllers
I don't think so, it would be nice if they did. I think our best hope is that when eZee.us gets going more, they will want to sell a U.S. spec 48V bike... and will see the opportunity in offering an upgrade kit.

I have thought about replacing the controller with a non-eZee controller. I think that could be accomplished, there is a reasonable amount of space where the stock eZee controller mounts. Such experiments for me will wait until the warranty is up on the electronics, or I can have a second bike to avoid downtime.

>Can the original controller be upgraded/modified to 60V somehow ?
My email with Justin got the following reply on that very topic:

I've done it, it was a serious chore for several reasons, and not
something I would recommend attempting. There is a hefty layer of
conformal coating on these controller circuits that makes tracing and
reworking the surface mount electronics most unpleasant.

Please post if you make any progress in souping up a Forza.

 

[jkirkeboe]

My Forza has a specified (and verified) HVC of 44V. So yes, the Forza is effectively limited to a "36" volt system (I actually see up to 41.7V off the charger, and under load it typically will start around 37.5V, meaning adding even 6V more some how will likely trip the HVC). With the included battery, the Cycle Analyst I installed regularly shows draw over 600W sustained. On the flat over 400W is not unusual.

I've had my Forza a couple of weeks now and just got the Cycle Analyst installed. It does about 21-22mph on the flats with a moderate pedaling effort.

I got the new 3.3kg Li-Poly battery. It is nowhere near 41.7V. It's at 40.4V when the charger goes green, 40.2V after disconnecting charger and 40.1V after blipping the throttle.

This gives me a little headroom with a 44V HVC, so I'm thinking of adding a small booster pack in a saddlebag. I'll just cut the positive wire going to the keyswitch and run two wires up into the saddlebag, terminating in Anderson connectors. Then I can just join them together for running without booster pack or connect the booster pack in series.

So, what to choose for a booster pack ? After some research I have landed on a single 10Ah Headway LiFePO4 cell. 3.2v nominal and 3.65V hot off the charger (charged separately of course, no BMS should be needed with one cell) equals about 43.85V total, which is less than 44V

Hopefully this would give me 1-2mph higher top speed and/or a little more range ? LVC is no problem, I assume the Ezee pack has a BMS and the I'll keep an eye on the CA too.

What happens if the Ezee controller trips the HVC ? Just a restart needed ? No fuses blowing or anything like that ? I assume you know since you verified it

Does anyone know of a reason this setup wouldn't work ?

 

[jkirkeboe]

Update!

I remembered that I had some NiMh D-cells lying around (Titanium 12Ah). So I quickly made a 3.6V pack of 3 of them and wired up the Forza. CA then showed 43.7V.

BUT. No throttle action! HVC was obviously cutting out

Turns out that CA is NOT a reliable volt meter, it showed 1.4 volts low! My battery, as you suggested, had a resting voltage of 41.7V, not 40.3V.

Ok, quick surgery and the pack was suddenly 2.4V instead.

Much better! Works as a charm. No-load speed increased 2.3kph (1.5mph) and loaded speed nearly the same. I didn't have much time for testing, I'll check the numbers more closely tomorrow.

I drew 20A from the battery continously for 2-3 minutes, the NiMh booster pack did not get warm to the touch at all. Looks like it can deliver the needed current (about 2C peak).

All in all, a nice performance upgrade for an hour of work and $0

(ok, I'll have to buy a 2s NiMh charger...)