need a quicker startup procedure...

[wesnewell]

Assuming a 16s pack. 3.1*16=49.6V, while 2.8*16=44.8V. Seems simple enough to me. When I drop below 100V, my meter then reads out in tenths. So a simple glance at the meter would give you pack voltage to the tenth of a volt. Might not be so good as a capacity meter as it is with lico, but it'll certainly lets you stop usage before you over discharge. When you get right down to it all your alarms do is monitor voltage and give you an audible alarm when cell voltage drops below whatever you set it for. I realize it monitors every cell, but a decent pack won't get that far out of balance until you hit the cliff and that should be somewhere below 3V. Manufactures recommend not going below 2.5V, with 2.1V where damage occurs.

 

[rocwandrer]

Assuming a 16s pack. 3.1*16=49.6V, while 2.8*16=44.8V. Seems simple enough to me. When I drop below 100V, my meter then reads out in tenths. So a simple glance at the meter would give you pack voltage to the tenth of a volt. Might not be so good as a capacity meter as it is with lico, but it'll certainly lets you stop usage before you over discharge. When you get right down to it all your alarms do is monitor voltage and give you an audible alarm when cell voltage drops below whatever you set it for. I realize it monitors every cell, but a decent pack won't get that far out of balance until you hit the cliff and that should be somewhere below 3V. Manufactures recommend not going below 2.5V, with 2.1V where damage occurs.

I don't really know what I'm talking about with certainty, but I'll use my example, which is 12s, 4ah or so.

How often do you look at the fuel gauge in a car? What if you had to lift off the throttle to do it accurately? If I've got 38.16 v after dropping the throttle, I know nothing because that is basically the resting voltage of my pack for 90% of the discharge curve. When I hit the cliff, it is going to drop from 38.16 to around 37 over the course of about 2-4 minute at full throttle. It would be safe-ish to run it to this point. Then it takes about an additional 1 minute for my pack to go from "empty" to "damaged".

I don't think you will ever see 2.8v as a static voltage like you argue. The time at full throttle to pass from 3.0v to 2.0v is about 4 minutes for my pack with my controller at WOT, by my estimation. What a pain it would be to constantly be having to lift off the throttle and check the volt meter every minute. So one wouldn't do that, right? One would guesstimate the discharge level, and start checking if it got to be enough time to be worried about it.

One of my little $3 cell checkers started going off about 2 minutes away from work this morning. I could have cooked the batteries in about double that amount of time, and before the alarm, I was thinking I'd used just 60% of the battery or so.

Your scheme would work fine with Lipo chemistry, even given the size battery I've selected. I don't think it would be a good idea, at least for me, using a tiny LiFePo4 pack. If I do power assist on a family bike, it will have a much larger battery, and a volts/watts display on the handlebar. I may well use resting voltage and total amps used since last charge as gauges in that scenario. I still don't think I'd be comfortable using just pack voltage on LiFePo4.

Edit: Also, I don't have the luxury of a decent pack. I have unbranded chinese junk that I still haven't figured out exactly yet. I know it has less than the rated capacity, but I haven't figured out how much less.

 

[dogman dan]

Here's my 2 cents.

Definitely mount the controller on the bike, so you don't have to unplug anything but the battery itself. That will help some.

Get a wattmeter. Voltage alone is not as good a way to monitor lifepo4. Once you are familiar with what your total real world avaliable ah is, you can then monitor by both voltage and by ah used.

Ride farther, that way you get more out of each setup procedure. Take the fun cut home, instead of the short way.

 

[rocwandrer]

Here's my 2 cents.

Definitely mount the controller on the bike, so you don't have to unplug anything but the battery itself. That will help some.

Done-ish. The battery still sits under the controller, so it is a pain to pack/unpack, but it is definitely better. When I get time, I'm going to make a custom front low rider pannier bag rack for the fork. I mocked it up tonight, and it is going to be ultra stealthy. Some of you guys will like this a lot The panniers will cover the hub and wiring, and contain everything but the throttle, which will be wired to trace the front brake cable housing. Battery in the big pannier pouch, controller and wiring in the small one. Pannier on the other side for my lunch and a thermos, or whatever.

Get a wattmeter. Voltage alone is not as good a way to monitor lifepo4. Once you are familiar with what your total real world avaliable ah is, you can then monitor by both voltage and by ah used.

Done. Though I've been using the ah for a full charge as my power consumption meter to get a handle on the battery performance. Looks like my "4.4 ah" batteries are more like 3.8 ah. I had been counting on using 3.6 ah from the 4.4 ah pack, and my estimates were good, that's what I need. Maybe a 2s booster pack, for a 16% increase in wh to get me to 80% DoD on a commute roundtrip?

So far, the watt meter has told me:

15w-35w with the wheel in the air, full throttle, halls hooked up. 40w, wheel in the air, halls disconnected. Temperature was about 0F, so there was probably substantial grease drag in those numbers.

15 amps at very low speed without pedaling. How is it that the shunt doesn't prevent this high amp rate at low rpm?

11.5 amps at moderate speed full throttle, with pack voltage sagging to 38.2v. I guess I didn't shave much off the shunt at all...

8 amps at cruising speed, wide open with nominal pedaling (I was aiming for equal or less than I will do when my knee hurts). Maybe I did shave some off the shunt :?

Ride farther, that way you get more out of each setup procedure. Take the fun cut home, instead of the short way.

I'm using this thing every trip while it is the new toy, and I'm still figuring it out. The plan was to take the long way whenever possible and make up the extra wh with my legs so to speak, but have the assist for the short way, when my knees are bothering me, or when I would be tempted to use a car to get their quicker. I know you were kidding, but seriously, too much futzing around, and it isn't worth it. I'm probably not a good candidate for an ebike in that I live so close to work that on the surface, there is little point in the assist.

 

[John in CR]

Considering that my prep time for any of my ebikes consists of throwing my leg over the bike, inserting key, turning it on, and looking at the CA to check voltage to be sure I'm not taking off with a low battery, then yes you need to make some big changes. Convenience will be liberating when you achieve it.

 

[rocwandrer]

Considering that my prep time for any of my ebikes consists of throwing my leg over the bike, inserting key, turning it on, and looking at the CA to check voltage to be sure I'm not taking off with a low battery, then yes you need to make some big changes. Convenience will be liberating when you achieve it.

I'm hoping to get nearly there. I wont quite get to that point, as the battery will need to be removed from the bike when not in use. It is currently cold enough so that the water vapor in my breath is condensing and then freezing in my beard. I've got to store the bike in this environment (because I lack other options), and the battery inside (so it will work when I leave in the morning.)

I need to find time to put the pannier rack on the bike, and then I can have:

1.) slide battery into pannier
2.) plug in electrical connector and hit switch(es)
3.) go

 

[John in CR]

If I was forced that route I'd make a form fitting hard case backpack battery with a precharge resistor circuit on my connector. The wire tethering the rider to the bike and its most convenient routing is something I haven't solved yet, but I'm sure it's solvable. A little folder I could bring inside is another option I'd consider.

John

 

[dogman dan]

Ah, re the long way, with that small a battery you would have a limited distance per setup. I was assuming you had a bit more.

That small would backpack pretty easy, or pop into and out of a small toolbox pretty easy.

 

[rocwandrer]

If I was forced that route I'd make a form fitting hard case backpack battery with a precharge resistor circuit on my connector. The wire tethering the rider to the bike and its most convenient routing is something I haven't solved yet, but I'm sure it's solvable. A little folder I could bring inside is another option I'd consider.

John

I think a pannier bag is as good as a backpack without the issue of the wiring...?

This about 600 sq ft for 3 people and a dog, I'm not even bringing a folder inside... It is also part of the deal we made when we bought the place. The garage/shop is bigger than the living space we use, so no bikes in the house.

 

[ian.mich]

1.) open hard-sided battery case
2.) plug in cell level monitor
3.) connect plug inside case to make ported wires outside the case live
4.) close case
5.) install battey case in mount on bike and cinch retension strap
6.) plug in phase bullets and throttle
7.) check throttle, futz with throttle cable that is finicky
8.) zip up soft pouch battery is in

9.) depart

oh my god that is the worst prep ever, no offence. but why???

 

[rocwandrer]

1.) open hard-sided battery case
2.) plug in cell level monitor
3.) connect plug inside case to make ported wires outside the case live
4.) close case
5.) install battey case in mount on bike and cinch retension strap
6.) plug in phase bullets and throttle
7.) check throttle, futz with throttle cable that is finicky
8.) zip up soft pouch battery is in

9.) depart

oh my god that is the worst prep ever, no offence. but why???

Boils down to a combination of impatience to start trying this system out, and lack of time (so far) to make a better system.

 

[mythprod]

I'm a newb still and only have experience with LiFePO4 so far. My controller's bolted on to where the vertical water bottle would go with some padding in between it and the frame to minimize vibrations. The battery is just on the rear rack, I can undo the bungees and bring the battery inside if I wanted to. I have a couple of cheapie meters to check voltage on the battery - one meter in my backpack and the other on the counter. This winter I just bring the whole bike inside, it's in the kitchen but relatively out of the way, so I don't even remove the battery. So as far as the bike goes, I charge it at night when I get home, then ride it to work and charge at work and bring back home. I now have a charger at work, at home and keep one in the pack (along with fuses) for good measure.

So the bike isn't the issue for me. My main prep issue(s) (which I thought this thread might've been about) is just prepping the other stuff needed. I have a few tools I carry with me that never leave my backpack, so those aren't really an issue. With me it's mostly the clothing. On 30F and colder days I usually like to layer up - sweats and pants, 2 pairs socks, a tech shirt , hoodie, ski insulated coat for the core, thin knit gloves and thick ski gloves for the hands, neoprene face mask, balaclava and snowboarding helmet (which covers the ears) and goggles for the head. There's a very specific order to put the crap on or something has to be taken off to finish, usually phone-related. I keep my phone on the handlebar neck to tell how fast I'm going (currently using ulysses speedometer) and also listen to music while getting to work. Often a popup comes up and I have to stop and reset it, which means I have to remove both sets of gloves to work the touchscreen of my phone. Sometimes in the morning I forget to put in my earbuds before putting all of that head gear on, so I scold myself while removing it all and putting in earbuds, putting it all back on, etc. Sometimes I forget my garage door remote so I have to come back in the house and grab it (I don't have one for the bike yet so I have to steal from my jeep, those are cheap just haven't purchased one yet). When I come back out to close the garage, I find pandora has turned off because I unplugged the earbuds (to separate myself from the bike to go grab the garage door opener), so I'm taking my gloves off yet again to work the phone. I'm getting better / more efficient at this but it's been pretty maddening trying to remember everything and in what order they all go on. I've almost got it down where I don't need a list but am thinking of making one anyway. I can't wait for summer, it's so much easier just hopping on the bike and leaving.

 

[rocwandrer]

Sounds like you need a laminated, ordered checklist, touch screen glove liners, and 5 minutes more to spare so you aren't so rushed.

Also, 3 pairs of socks is a very bad call. There are different right approaches to warm feet, but 3 pairs of socks isn't one of them. From my experience with winter camping, commuting by bike year round for 10 years, snowmobiling, and so on. The best socks if you have issues with cold feet are ragg wool. Real ragg wool, not that crap with with cotton and elastic in it. The elastic bands at the top of socks contribute to cold feet, doubling up socks contributes to tight spots. Ragg wool is extremely warm, even when damp, and is just stretchy enough to just about work without elastic.

Also, a wind blocker overshoe can do a lot more than insulation, depending on your preferred footwear.

 

[mythprod]

2 pairs of socks ...

And I agree, some sort of wool socks would be better than cotton. I'm sporting the basket pedals that came with my bike and some sort of booties / shoe covers might alleviate the wool / multiple sock business altogether. If I really want to go redneck I could cut out and slip on the bottoms of a couple of 2-liters over the baskets to get rid of the cold caused by wind ... :lol: My preference is as little to change out as possible when I get to work. The more I have to take off when I get there, the more I have to put back on before coming home. I would think this is more or less the universal goal, minimize prep time, closing the gap between time it takes to prep and get to work by car and to do the same on the bike. If it's not universal that's my goal at least.

Touchscreen glove liners are a good idea, going to look more closely at that. Could roll my own too I guess Convert your gloves to touchscreen friendly.

 

[rocwandrer]

2 pairs of socks ...

And I agree, some sort of wool socks would be better than cotton. I'm sporting the basket pedals that came with my bike and some sort of booties / shoe covers might alleviate the wool / multiple sock business altogether. If I really want to go redneck I could cut out and slip on the bottoms of a couple of 2-liters over the baskets to get rid of the cold caused by wind ... :lol: My preference is as little to change out as possible when I get to work. The more I have to take off when I get there, the more I have to put back on before coming home. I would think this is more or less the universal goal, minimize prep time, closing the gap between time it takes to prep and get to work by car and to do the same on the bike. If it's not universal that's my goal at least.

Touchscreen glove liners are a good idea, going to look more closely at that. Could roll my own too I guess Convert your gloves to touchscreen friendly.

Terribly sorry. No idea where I got 3 from. Same conclusion from me though...

I work on a college campus that sells more parking passes than it has parking spaces. In the spring and fall, I can get to work quicker on my road bike than I can in my car. The time it takes me to drive to work, find a far away parking space (quicker than finding a close one by more than the walk time increase), and walk to the building I work in is more than the time it takes me to ride to the building I work in.

It is currently taking me longer to setup the bike and my winter clothing than it takes to ride in cool (not cold) weather. It is also not really working out to mix electric assist and recreational off road riding on the same bike. The extra weight at the front makes a big difference in the rough terrain handling, and I'm constantly worried I'll break the motor hub.

I did remount the battery and controller in a kayak bag re-purposed as a handlebar bar, with the controller staying with the bike and just the battery coming inside the house. I also got some balance tap extensions and ported them outside the box, so I don't need to open the box anymore. I think this would have been an improvement, if it weren't for the weatherpack connector failing to snap shut this morning...

 

[rocwandrer]

I don't think this price beats the big box stores by much, but: http://www.groupon.com/deals/gg-agloves-sport-touchscreen-gloves