Today's Bionx P350 purchase

[yoyoman]

I decided that I'd take a chance on the local Bionx P350 36V NiMh craigslist - $300. The seller offered a 1 week trial, so I want to ask my questions now.

I've read about adding an external battery via the XLR charge port. I'll investigate that once I see how the battery performs. I just need it to go my basic 4.5mi ride to work. The whole distance back and forth without having to charge would be great so that I can skip carrying the charger.

Here's the battery pack and controller? It looks pretty normal to me .... is all the proprietary stuff under the shrink wrap or in the controller?

 

[yoyoman]

I put hybrid tires onto my Gary Fisher FS, mounted the Bionx in the rear, and I thought I was making good progress. Then, I realized that regular bike racks won't work on FS bikes. Dang it!

Thankfully the NiMh cells + controller will both fit in a handlebar bag that I have, and the included wiring will go the distance from the bars to the motor. Whew! Maybe this won't be so bar after all. The original battery bag with battery and controller was 12.6 pounds. With the batteries in front, that should give a better balance to the motor in the back.

I guess I'll test things tomorrow.

 

[neptronix]

hmm.. must be an older kit? i thought the modern bionx batteries came in a nice plastic case that you bolt to the water bottle holders or whatevers.

I believe the controller is inside the motor.

 

[yoyoman]

According to the manual, the 36V NiMh comes in the cloth bag while the 24VLiMn, 36V LiMn and 24V NiMh come in the plastic case.

 

[dogman dan]

Looks like you have a little electronics box there, so as long as you plug into that, any battery of the right voltage should work good. I always thought bionx should come with a lighter battery. I'd bite on that for that price.

 

[yoyoman]

hmm, maybe having the 36VNiMh soft case vs LiMn hard case will be an advantage here. I read before that regen current into LiPo can be dangerous. Does that go the same for my Bosch fat packs? Can something be added to make it safer?

 

[amberwolf]

AFAIK, the BionX motor controller is inside the hub motor.

The display/control unit is the "brain" that ties it all together, and tells each part what it is allowed to do based on the sensor inputs.

As far as I ever found, the NiMH version just runs right to the XLR plug, with one wire for thermistor, and the other two for pack postive and negative. So while you could just run another pack into it, it has to be the same characteristics as the NiMH or at least something sufficiently close that a diode arrangement on each pack would not be needed.

Regen into LiPo shouldn't be dangerous--NiMH can't take a heavy charge current for very long, so if it works for NiMH it should work for LiPo too, depending on the charge capability of your particular packs.

 

[yoyoman]

I just took it out for a spin in the dark. The throttle pushes it along as I would have expected, but the 4 assist settings were the fun part. The multiply effect was great, and I am eager to test level 4 on my big hills.

The sad part is that after just riding up and down the street, the battery gauge is on empty. When the seller plugged everything in yesterday, it was showing full. I put probes in the XLR holes and measured 38.5V. It is definitely a downer to see it so low so soon. I knew the pack was 4 years old, but I was hoping to go a mere 5 miles before getting to this empty point. I'm charging the battery now and will have to try again tomorrow when there's more light.

I guess that little black box is where all the wires are spliced.

 

[slayer]

nimh pack should be after a full charge around 43.5 volts but loose pretty soon it s capacity ...you should always run right after you charged them ...even a day after it will go down 38.5 volts ...and also know that after a couple charge discharge they will regain a little bit of capacity

 

[yoyoman]

Will the NiMh pack go all the way down to 36V? I'm in my trial period now with the seller. After that, if I decide to keep it all, I guess I can open the black box and wire in my Watts Up meter to get a more accurate reading of the battery. Ah, since I have the battery pack in the front, I might even be able to make it visible as I ride.

 

[slayer]

nimh will go down 34 volts after resting under load my 36 volts 15 ah 6 years olds will sag a lot under load and just at 18 amps will go downs 27 volts ...but i m sure they still give more than 10 ah ...i use them on my lawnmower so i did not test them to fulll capacity 15 ah ...i do mine and my neighbor for around 8 ah

 

[amberwolf]

Since that is a 30-cell pack (2 rows of 8 and 2 of 7), and it's probably also D-sized cells from what little I can see, that makes it nominally 36V (1.2V/cell), and about 42V at "full" charge of 1.4V/cell. 30V is "dead", at 1.0V/cell, probably 8-9Ah original capacity.

I don't know what voltage the BionX brain uses for LVC, though.

If it's 4 years old, and well-used, I'd derate that to maybe 3/4 just for calculation purposes (it's probalby better rthan that), based on my results from own very similar pack that used to be from a Giant Suede-E, IIRC. That charger looks pretty much just like mine, too.

So figure it's a 6-7Ah pack, and work from there.


If it has not been used in a while, it may indeed gain some capacity after it's been charged and discharged a few times.


BTW, it seems very odd that the pack thermistor is on the OUTSIDE of the pack--it's usually glued in between cells in the middle of the pack.


Oh, and regarding self-discharge, I just checked my pack that hasn't been used or charged in at least a couple of months, and it's at 38.2V resting, and 37.8V under a 28ohm load (an incandescent lightbulb).

 

[yoyoman]

The seller said the bike was not ridden for a year, but the battery was charged periodically. So, that's good news to hear that it may regain some charge. It's advertised as a 8Ah battery.

 

[dogman dan]

Still a decent price for the bionx system, even if you do have to run it on some other battery. No big deal if you lose regen because you use a diode to run for instance, a ping. Ping V2.5 bms can handle regen up to 5 amps. Likely about all you'd get anyway. Bionx and a 15 Ah ping would be pretty killer for those that like to pedal.

 

[yoyoman]

So, does my bionx not have a proprietary battery like I have read about in the forum? Is it be/c I have a model that precedes the can-bus change.

I don't run a BMS with my Bosch fatpacks. With this bionx, is it something I should add?

FYI: my battery only charged to 40.6V ...

 

[yoyoman]

FYI: my battery only charged to 40.6V ...

Yay, I put it through another charge cycle and got 43.6V

 

[amberwolf]

No need for a BMS with NiMH; if you want a cell-level LVC you could set one up for 1.0V per cell, adding "balance taps" to each cell, but there isn't one pre-made that I'm aware of to do that.

That NiMH pack is definitley not proprietary (you and I could swap packs and except for the cut-open green shrink on mine, resealed with duct tape, we wouldn't likely know it had happened. :lol

But the electronics in the BionX, including the stuff in that black box in teh battery bag, *is* proprietary, and if it doesn't work or doesn't say that eerything else is working, you probably can't use the system (without hacking things). I dunno when they went canbus.

 

[yoyoman]

I brought up the proprietary part be/c many people have written about how expensive replacement batteries are from Bionx. That doesn't seem to be a problem here ...

 

[amberwolf]

Not for the NiMH, if you can find good cells you could even make your own. Although finding good NiMH cells or packs seems to be a lot harder than one might expect--there's just a lot of badly-overrated junk out there.

If the other packs they make have a BMS in them that talks to the rest oft eh BionX system, then while you could always replace the cells, you'd still have to use their BMS.

If the BMS doesnt' do any communications, but only a signal you could emulate, you'd be able to replace the whole pack with whatever you wanted.

 

[yoyoman]

I rode the bike up and down the street again, which is a pretty flat ride, and I was surprised that my battery pack was already a little warm. Sure, I did ride it in assist level 4 for a while, but that still seems early to be warm.

The voltage level I see 30min after charging matches what NYCE Wheels' website says I should expect, so I think I'll be good to go after a recalibration.

Now, I just need a good seatpost rack that can handle the 12.6pounds well. My handlebar bag isn't meant to carry this much weight.

Heh, I fubar'd my bleeding of my brakes, and it's possibly more than just air in the lines now. It seems to be leaking from the hose. So, I'm going to go old school and just put a v-brake on their for now. A v-brake is better than no brake!

 

[amberwolf]

NiMH is pretty high resistance, internally, and gets worse as it ages, so I'm not really surprised if it got warm. Plus, as it charges, part of the charge cycle will heat it up pretty good, during the last balancing stage. Might be even worse with the thermistor on the outside of the pack instead of inside, unless they took that into account when picking values.

 

[deardancer3]

I have a bionx system almost exactly like yours, have had it a long time and do some work for bionx. it is on a 20inch wheeled giant revive semi recumbent so some of the stats will be different from yours.

email me off line and i'll see what i can do to give you some clues to increase success, like

the pack likes to keep heat in--- put a spacer under the cells and partially unzip the pack zippers to give some ventilation to make cooler. also put a white pillow case over the pack to reduce solar heat gain. put a digital thermometer in the pack. charge the pack with the pack zippers open and using a smalll fan if possible.

There are two thermal sensors for the pack, the big one on the outside is a thermal switch that disconnects pack power if the cells get too hot.

A NON STANDARD thermal resistor is buried inside the cells and is the one used for charging. NON STANDARD thermal resistor means that most nimh chargers wont work with your pack. Also you need an additional 3-5 hours after the charger light goes green to get from 90% to 99% pack charge... this charger teminates charging early (it uses all the normal NIMH charging formulas) then trickle/taper charges for a while at about 150-250 ma even though the charger light is green.

The charger some times terminates way too early if it senses the voltage dip that sometimes indicates full charge.

Charger will not charge if pack is below 40F or above 110F, pretty common for many NIMH systems.

your system does not like low wheel speed, the motor gets pretty inefficient whe going slow and that puts a big drain on the NIMH cells causing them to get warm. do your best to approach hill climbs with decent speed and keep speed up, (PEDAL!) especially on 26" wheels. yes on this system you can put a helper pack on the charger port, but it is not simple.

where are you located?
d

 

[yoyoman]

Right now I've been charging the battery out outside of the bag since I'm still setting things up. I will try out your hints the next time I ride. I'm just happy that I found out that I could recalibrate the battery gauge!

Whoa, are you in San Diego too? I live in University City.

 

[deardancer3]

Whoa, are you in San Diego too? I live in University City.

soemtimes i winter in oceanside, ca, but prpbly not this year. might be in socal somewhere when the sno flies here in the rockies.

d

 

[yoyoman]

I rode to work today, my first real ride. Multimeter read 41.6V after a night on the charger the Bionx meter read 38.1V after my 4.5mi trip. I wish I had a way to gauge the amps I used.

The bike doesn't take off very fast, but in assist mode 4, it can get to a top speed pretty fast. I like how assist mode 4 makes pedaling in high gear feel like it's in low gear.