Ping 36v 20 ah, 5000 mile review.

[dogman dan]

Well, I'm usually full of crap when it comes to the electronic theory,,, But the hot motor does draw more amps, or turns more amps into heat than a cool motor, or something like that. You can feel it happen as you melt your motor. It's the same feeling as sagging sla's.

I'm running 36v on the commute home. I have heard air vents help, but by the time I tried it, the motor was toast, and the vents let the smoke out real good. I'm thinking of tying some cotton strips around the hub, inside the spoke flange, and keeping it soaked with water, but so far, I'm not seeing hub temps much over 160F measured inside, and cover temps at the same time are around 112. I think this brusheless aotema may be albe to take the heat at 36v. It should get hotter when its really blazing, but right now the hub seems to reach an equilibrium at around 165F. In colder weather, it reached the equilibrium at a lower temp.

 

[dnmun]

carry a little water gun, shoot a little spray on it when you stop, just enuff for it to evaporate, it would be hard and dangerous at speed, but a little water can go a long way in cooling if there is only enuff to evaporate, not running off, but resistance should go up as T*4, but the FETs carry current more easily as they get hot, which may be what you experience.

also you can run your nicads and lifepo4 in parallel too. the All-electronics.com place posted yesterday has the "battery combiners" parallel schottky diodes for cheap cheap. they had a new listing for the paired diodes in a 220T type package for $1.35. 25A60V.

get two and solder them through the tabs to the power cable going to the controller, and to the top of the two packs with the 2 pairs of legs coming out the bottom, to keep the series resistance to a minimum and get 50A surges without problems for $2.70.

 

[dogman dan]

When I stop at the base of the big hill, I get water at a fountain on the bike trail. If I splash some on the motor, the heat will drop about 5 degrees on the internal thermometer in about 30 seconds. The same drop without the water takes a five minuite wait. The water runs off too fast though, so I'm thinking about a tube sock tied around the hub or something like that to hold the water. Here, where we had 8 one hundredths of an inch of rain since January, air cooling won't work for doo doo till the summer rains come. 3% humidity yesterday, with no water molecules in the air, air cooling doesn't work. So far though, at 95F , I'm not seeing a heat level the motor can't tolerate yet. So most of the country has no worries, unless they climb more than 1000 vertical feet on a given ride.

 

[RTLSHIP]

last year there was some debate about whether WE brushed hubs get hotter than brushless. It's still not summer, but what's the answer. Of course we have to make some allowance for the fact that the magnets are fastened on better with the Aotema brushless.

 

[dnmun]

i think there is a thermal joint compound that sets up like epoxy. if it would hold onto the outside of your hub, you could make some small aluminum brackets that you could attach around the outside of the hub to dissipate more heat in the air. like little propellers, little heat sinks glued on with the thermal joint compound. maybe cut short, 1/2" long pieces of aluminum L stock, set up a jig where you had cut out a block of wood with the same radius as the hub, and then put the inside face of the bracket up and hammer it into a curve that would fit the outside of the hub. maybe use a piece of pipe on the inside to make the metal bend the same side to side, and hammer on the pipe on top of the sandwich. then epoxy them on.

 

[dogman dan]

On the same ride in the same temp, hub cover temps on the bd have allways been about 30 F higher than the bl motor. I remember once, measuring a temp on a 40 F morning, after 6 miles of downhill riding. 130F WTF! Same conditions on the brushless would be about 90F. Took me awhile to understand that downhill riding can still get hot if you ride fast.

 

[needWheels]

In theory the BD is 20% less efficient (or is it 30% ?) than the BL
so all that wasted power is converted to heat, hence the temp difference eh?

 

[dogman dan]

I found it pretty close to 20% less efficient on my bikes, but speed was just a tad higher on the bd. 24 mph on the bd, and 26 mph on the bl. I agree, the losses are made into heat, I suppose by the sparks on the commutator.

Just sold off the bd, and ordered a fusin 36v kit from worldwide electric bikes. The only brushed motor I'd still own at this point would be a heinzmann 36v gearmotor. It would suck power and get hot fast too, but it would make a dandy dirtbike for shorter rides. I'm hoping the fusin gearmotor, with it's power level switch might be a real efficient bike for longer paved road rides on weekends in the mountains of NM. It would be great if it can go up steep mountain passes a bit cooler than a direct drive. The truth will be found out soon.

 

[RTLSHIP]

I got back my Aotema controller from Terry. Looks like I am confused because there may have been little or nothing wrong with either of my controller. The controller and wiring use to rest in my front basket and this is bad for the wiring.
I put controller & in safe spot on the rear rack. Problem solved.
Mr Dogman, if my take off voltage is around 56-58 v, how far down can I safely go? Maybe 50v? on a 48/15 lifepo4.
A ten mile trip takes me from approx 56 to 52. Charge time is 2 1/4 hrs. on a 5 or 6 amp charger.
There is obviously more range in this pack. Still breaking it in.

 

[needWheels]

I think the BMS cut the packs off at 46 volts.
Because the cheap BMS do not check the cell balance so well, it's probably not safe to let it go to that point.

 

[dogman dan]

I've run my "cheap" bms down to cutoff many many times. Usually, to get a bit further, I reset it, ride some more real slow, and drain it even more. Took me awhile to trust it though. For a long time I was real freaked out every time I drained the pack that far. It is a good Idea though, to explore how far it can go carefully, rather than just start riding till it quits immediately. The trouble with a bms, cheap or expensive, is that it doesn't know the status of individual cells, just the status of a paralell string of cells. At some point, you have to just trust your cells and trust your bms and ride the thing, or you will worry yourself sick every ride. It is important though, to know what the pack normaly can do, so you can tell if it starts to do less.

 

[needWheels]

Yeah but your cells are ping's which are better quality. I wouldn't call them cheap but midgrade.
You also have a reasonable warranty on your cells. On the really cheap packs I would never push them past cutoff (2.80-2.85 volts per cell?)

That's why I overbought the capacity I needed in the hopes they will last slightly longer if I never deep drain them. If I could have afforded a ping I probably would have gambled on a 36v 16ah to keep down weight and rely on 2C.

With a "20ah" pack (really 16-18ah by my calculations, at least I can cruise at (under?) 1C.

dogman do you know the real amps used by a BD36 at WOT on level ground on your 48v ping? I can't remember if you have a docwatson. I know you have that $5 harbor freight meter which I am debating getting myself even though it's analog.

 

[dogman dan]

Well, this is the pingbattery review thread. The point I was trying to make was that all the bms on duct tape batteries are pretty similar and if they are functional, they seem to work pretty good. The scary part is finding out if it functions . By the time you find out it doesn't, you have a dead pack. Once you have carefully found out that the lvc works ok, then you can start riding with less worry.

Yes you are right, I may be able to get away with stuff on my ping that might kill cells on a round cell pack. But mine is just a v1 pack, with pretty weak 1c cells in it.

Others with real ampmeters have reported level ground amp levels of about 20 amps 36v on a full throttle bd36. The brushless motor pulls about 15-17 which seems to confirm the 20% better efficiency. My calculated average was about 20 amps too. They can pull a good spike on an uphill start though. 50 amps for a half second wouldn't suprise me on the bd36. I never ran the bd36 at 48v all that much since my ping is a 36v. I ran it some on slas at 48v till I got my ping, and recently ran it some on 48v nicads. I never put the cheap ampmeter on the bd motor though, and now I've sold it.

 

[RTLSHIP]

dogman, you have 3000 miles ++ on your Ping pack. Is 15,000 miles possible presumably with limited capacity/range?

 

[dogman dan]

At first, I figured my 36v 20 ah pack, could possibly go 20,000 miles. 20 miles per cycle, 1000 cycles. Over the summer, I decided that might be a bit optomistic, since the last 500 cycles would presumably have less capacity than the first 500. By fall, reading about all the problems with many types of lifepo4 packs, I began to think that 10,000 miles would be a more realistic expectation, at least in terms of it being still able to do my pretty hard ride home. So I was thinking, maybe it will go 20,000 miles, but as soon as it can't get me 15 miles, I'll need a new battery or a booster pack to be able to make it home.

But, I was thinking that at about 1500 miles last fall. Now, with 3400 miles as of today, and still no hint of lost capacity..... I begin to wonder if I'll be getting a lot more out of this thing that I was thinking. 20,000 miles? 30,000 miles? who knows. But I'm getting pretty sure that a good set of cells can go an amazing distance. One stinker in there though, and its a different story. For once I'm lucky and have one that may last me 5 years, even at 4000 miles a year.

So I'm starting to think that yes, 15,000 miles out of a good lifepo4 pack is not a fantasy, but the expectation will still take most of us a few more years to prove. For a 48v pack, with perhaps 25 miles in it at 80% discharge, the number gets even higher, say 25,000 miles life expectancy. Ride slower, on a more efficient motor, and it goes through the roof. Say you have a 200-300 watt motor, and ride 15 mph all the time. Now you are looking at 30-40,000 miles. Wow, that will mean your battery outlasts quite a few saddles! I have to wonder, if not abused, how long does the motor last? A few bearing changes maybe, and a couple controllers, and your cost per mile could get too small to measure. Cool.

 

[needWheels]

You are right and I apologize for drifting away from the "ping" theme.
I didn't know v1 was only rated for 1C continuous, it was pricey back then for that.
It will definitely be interesting to see how long it lasts.

I just noticed you actually updated the thread which was originally a 1500 mile review!
So you are doing 3000 miles per year?! Nice!

 

[miro13car]

dogman,
you should remember what climate do you use yours LiFePo.
I bet your pack is mostly not subjected to freezing temp, unlike in Canada, here in praires/Alberta, Manitoba/ even in April you start your ride in below zero .
What is never mentioned that this chemistry loves hot climate- your climate.
There is no doubt it prolongs life of LiFePo.
my LB/BMI cells are almost like termometer - in mid of summer my 10Ah battery would deliver 11Ah easly, in fall close to freezing temp will not deliver even 9Ah.
It agree with Sandia Labs tests done on LB cell.
MC

 

[RTLSHIP]

15 to 20 k is a real possibility with a healthy pack. I've read about 70,000 miles for some car batteries. 30 year claims, too.
With these kinds of possiblities, money can be saved with less damage to our environment.

 

[dogman dan]

Absolutley right about the climate. When I realized what the working temp of this chemistry was in farenheight, I stopped worrying about charging it in a garage that is 120F. my nicads though, I'm never charging in a hot garage.

Last winter, in my mild climate, I would be riding home in 40-50 F, and riding to work in 20F. On the cold mornings, I would use a lot more capacity getting there, and since I work a real short day, I would not be able to get a full charge by the time I left. I found I needed a full charge to get all the way home, 14.5 miles, using the bd36 motor. So my range had dropped about 25% in weather under 50 F. Another reason I object when people calculate exactly the size they need. Better add about 20% for cold weather buddy. So to have a 20% reserve in winter, thats a full 40% bigger that you calculated! I quickly learned that in the winter, I needed to put some insulation in my battery box, so the heat from discharge could warm it up some. That seemed to help with the range issue. Starting out with the battery at room temp would help but that's not always practical or possible. I would have some cut outs from the bms too, till it warmed up after a quarter mile when it got really cold. ( to me anyway)

3400 miles on the ping v1 36v 20 ah as of yesterday. It seems to behave as though it was brand new, but I haven't actually rode the standard range test since about 1000 miles ago. The range test is done at 80F or above, and little wind. So it's pretty much impossible to find the no wind conditions in springtime in NM. yeah I know, get a cycleanalyst.

 

[RTLSHIP]

what's the logic or "dogma" behind charging up a life pack only 90%?

 

[dogman dan]

It has to do with avoiding too much overcharging. Personally, I prefer knowing it's balanced. With other chemistries, like the prius, it may make more sense. I seem to remember somebody saying lifepo4 is more tolerant of overcharging, like compared to older lipoly, that liked to catch fire. I really don't know how full charging vs 90% charging would affect cycle life. My own opinion is staying balanced is real important, and that is why I try to avoid 100% discharges. I ride so much, my battery has been on a charger 22 of 24 hours five days a week for a year.

 

[RTLSHIP]

ok. I understand now. deep discharges can/will reduce lifepo4 lifespan. Fully charged pack is good so the BMS can balance, etc. Any harm in leaving a pack half charged for a day or 2? I have never done that with my pack.

 

[dogman dan]

Shouldn't be any harm in leaving lifepo4 undercharged for a few days. I have heard it is supposed to like being left partially charged for long term storage. Problem is, some have had a mysterious trickle discharge they didn't know about happen that ruined cells after a whole winter. but a day or two , uncharged, with the controller disconnected shoud be ok. Mine just sits on the charger 24-7 and only gets taken off if I drive a truck to work. So it gets about 14 hours and gets unplugged in the morning.

 

[RTLSHIP]

Mr Dogman, you've said a geared hub motor is on the way. Will you use ping 36v? What kind of speed?

 

[dogman dan]

It arrived last night, and will have to use the ping, since it is a strictly 36v kit. See the World wide bikes fusin review thread for details. I am going to have to do a lot of math to keep track of the mileage on the ping with two bikes going on it at one time. Good excuse to get another ping in 48v for the aotema bike, but the pay off charge cards program must continue.