crystalyte 4011 vs evtech puma
I want to upgrade my bike with a budget of around $800, and so far have narrowed it down to a couple of options. If anyone has any thoughts on best choice or my "facts" I would appreciate it - thanks in advance.
current setup: 46v 13ah nimh on evg bike 24v brush motor - so motor is in 26" rear wheel with 7 speed, 135mm dropouts.
Usage Pattern: most of my rides are 10 to 17 miles, in hilly area of AZ (Sedona and surroundings). Sometimes I need the bike to go 32 miles with hills and long stretches of slight incline usually with headwind, I typically like to pedal quite a lot, as much as necessary to get home and be easy on the batteries. I can just about get away with the 32mile run on the current setup but it overtaxes both bike (and rider), and I want a long lasting system (and knees). So for the upgrade, my requirements as per the wattsup would be around 1000 watt peak, up to 600 watt continuous, 32 mile range or higher. I need the assist no higher than 20mph cruising, I go faster but usually just on the downhills or with tailwind, 15-18mph cruising is ok.
so here is where I am at for the $800, (with pros and cons):
1. 4011 hub, add 24v15ah ping lifepo on rear pannier (8pounds weight) to make 70v total 13ah max, e-crazyman 72v controller. quiet, good hill-climbing, average weight, some drag, extended range (35plus miles?) with moderate assist levels 20mph max, more weight on back with extra battery
2. evtech puma hub, with added 4.8v nimh cells inside bike for total 50v13ah, e-crazyman 48v controller. some hub noise, hi-torque, light, expensive hub, gears can wear/slip?, no drag, no need for extra battery over rear wheel
What do you reckon, 1 or 2? Or is there a better choice entirely for the moolah?
I love the EV tech hub. It is powerful. light weight, and very efficient, and has no drag whatsoever . I read at the Endless sphere forums that their was some compatibility issues with the e-crazyman controllers and the geared hubs, so be careful to look into that.
I run my EV tech hub with a 48 V 20 Amp crystalite controller and a 48V 15 AH Ping Battery on a 20 inch wheel suspension bike folder. This combination is amazing. I can go 20 miles with lots of hills at an average speed of 20 MPH, and still have nearly 52 volts left in my battery. I don't even know what the full range is yet.
forget about the 4011. High voltage is wasted on it and its not very efficient. If your going to go with a crystalyte then a 408 at 48 volts wouuld be better. The Bmc is great but why not just use your existing motor and get another ping 48 15ah battery and use it to boost your existing range with the nimh?
many thanks andys and nick for your replies.
Nick your reply has given me food for thought and I am thinking a possible solution for me would be get a ping or other nimh battery to boost the range as you suggest, I assume you mean hooking up the packs in parallel and not just using one then the other. parallel would sure ease the amp load etc.
However I am not experienced with running packs in parallel. If I have 48v nimh 13ah already setup in the bike and I put a ping 48v on the rear, lets say a 48v10ah to save weight as they are only 10 pounds. So I have on paper max 48v 20ah of usuable energy right, as the packs basically share the load and so as not to damage the lower capacity ping cells (or just have them cut out)? But what about the different chemistries of nimh and lifepo and hence the different voltage charateristics, does that make such an idea a non-starter? Or do the voltages just kind of merge and as long as they are kind of the same, no damage is done? I am not clear on what actually happens in a parallel hookup in that sense and how strict it needs to be. I will dig around for more info but if anyone can explain here that of course would be neat
It is slightly tricky using two packs in parallel if the voltage is different. One pack will discharge into the other to some extent when they are resting and possibly when under discharge. How much current flows between packs depends on three things; the voltage difference between the packs when resting, the charge resistance (how much the voltage increases) on the lower voltage pack when charging and, the discharge resistance (how much the voltage drops under discharge) of the higher voltage packs when discharging.
Of course, as you mention, with 2 different chemistries the picture is further complicated by the differing voltage profiles by each pack as the capacity drops.
There shouldn't be a problem unless one pack overcharges another or there's a short circuit on one pack causing the destruction of the other pack. There might also be difficulties with the ping bms, but you'd have to ask them about that.
The simple solution is to use each pack indpendently, another solution is to use a schotty diode between the packs to insure that they don't discharge into one another but still share the load between them. you can get these them at http://ebikes.ca/store/ amongst other places. The downside is a slight voltage drop across the diode (about 1 volt)
I used to use two nimh packs in parallel without diodes and it worked out really well for me. The current that flowed between the two packs was minimal when both were charged and non existant under discharge. If one pack was charged and the other discharged then the two would naturally balance each other out but at a fairly slow rate so no problem there.
But it is complicated, so I think most people go for a diode or using each pack independently.
yeah I see now that you could just have the 2nd pack independant make it totally simple. And then you could just stick it on the rear whenever you needed it rather than having it there permanently, which would make sense for my usage patterns, I mean if you only need extended range 20% of the time, why carry around the extra for the other 80%. I am leaning toward doing this why not keep it simple as poss. is there a customary way to wire the system for an easy switch to a secondary pack (i guess I am looking for a few names of electrical things such as "schotty diode" to point me in the right direction) or do people just manually unplug one and replug in the other. reason I ask is the nimh I have to plug into a 4 to 1 series and the ping I would just have the one plug to run into the controller etc.
Say with the diode installed. My nimh 48v pack starts out at 58v peak fresh off the charger, and the ping 48v pack starts out as 54v fresh off its charger, hook the two together with the diode and the watts-up reading shows the midway voltage minus a volt around 56v?
Tbh, I'm probably not the best person to ask about wiring as my bike wiring is always that much untidyier than many of the other EV's on this site. That said The schotty diode on ebikes.ca seems to do everything for you, just hook up 4 anderson powerpole connectors (also sold on that site) to the diode and then plug 1 or 2 packs as you need them.