Search found 445 matches

by curious
Mar 26 2012 7:20pm
Forum: Battery Technology
Topic: Hobby King LiFePo4
Replies: 53
Views: 9059

Re: Hobby King LiFePo4

So if I have 16ah of HK LiFePo4 will I be able to run 50 amps to the controller? That would be just over 3c discharge rate. They are claiming 30. It will probably work but I would suggest buying a123 pack from cellman if you want lifepo4 chemistry. Much better odds of getting few years of reliable ...
by curious
Mar 26 2012 5:56pm
Forum: Battery Technology
Topic: Hobby King LiFePo4
Replies: 53
Views: 9059

Re: Hobby King LiFePo4

They have comparable (lowish) energy density to a123 26650 but without electrical and mechanical robustness of a123 cylindricals. And the price difference is not that much either. Not sure they make much sense. OTOH if HK offered us pre-built packs of a123 20ah prismatics that would have been a tota...
by curious
Mar 18 2012 9:34am
Forum: Battery Technology
Topic: even simpler/cheaper LVC :)
Replies: 19
Views: 2975

Re: even simpler/cheaper LVC :)

IBScootn wrote:Really - that is exactly what I want. I only use HVC while charging and only use LVC while riding.
I assume you are going DIY route. What chip do you want to use to detect the HVC threshold ? Is it HVC only or HVC/balancer ? I can probably help you interface the chip output to the signaling chain.
by curious
Mar 16 2012 3:25pm
Forum: Battery Technology
Topic: even simpler/cheaper LVC :)
Replies: 19
Views: 2975

Re: even simpler/cheaper LVC :)

Any plans to alter it for HVC too? You mean transistor only or transistor/comparator version ? Transistor-only chain will not be accurate enough for HVC/balancer application (even if it can be designed). Comparator-transistor chain can be modified fairly easily for HVC/balancer apps. I think fechte...
by curious
Mar 15 2012 9:38pm
Forum: E-Bike General Discussion
Topic: Recumbent BikeE for Comfort and Efficiency
Replies: 255
Views: 36221

Re: ebikeE maiden Commute run

Alan B wrote:Nice, how does that front motor work out?
My wife rides slow and gentle, it is perfect for her needs. However when I try to ride it - the front spins when starting at full throttle (even on a dry pavement). Otherwise handling is not affected.
by curious
Mar 15 2012 8:09pm
Forum: E-Bike General Discussion
Topic: Recumbent BikeE for Comfort and Efficiency
Replies: 255
Views: 36221

Re: ebikeE maiden Commute run

Here is another EbikeE that I built for my wife. Shot in the process of charging with the balancer attached (you can see bunch of white LEDs on the top of the battery).
bikee.JPG
bikee.JPG (94.24 KiB) Viewed 2895 times
by curious
Mar 13 2012 11:15am
Forum: Battery Technology
Topic: even simpler/cheaper LVC :)
Replies: 19
Views: 2975

Re: even simpler/cheaper LVC :)

It looks like maybe the current in the series chain is a function of each cell's voltage. The cell with the lowest voltage controls the current in the chain. The chain current is sensed by the TC54 and can trigger at the desired set point. Does that sound about right? That is exactly how it works, ...
by curious
Mar 13 2012 9:36am
Forum: Battery Technology
Topic: even simpler/cheaper LVC :)
Replies: 19
Views: 2975

Re: even simpler/cheaper LVC :)

I have finally built and tested this LVC-lite circuit for a 16s A123 pack. The pictures from this thread were lost so here is another one: lvc_lite.GIF As I said before it is not as precise as multi-TC54xx chain but for a123 lifepo4 cells the LVC detection accuracy is quite adequate. The circuit is ...
by curious
Aug 15 2011 11:05pm
Forum: E-Bike Technical
Topic: Radial lacing on X5 and Strong 24"
Replies: 2
Views: 380

Re: Radial lacing on X5 and Strong 24"

Seeing radial lacing is by far the weekest way to lace a wheel Doc Does this common wisdom of bicycle wheel building really translate well to the large diameter hubs like x5 or HS/HT ? I am not so sure. Every broken spoke on my 26" x5 wheel (and there were many) failed at the nipple because of wron...
by curious
Aug 15 2011 10:22am
Forum: Battery Technology
Topic: even simpler/cheaper LVC :)
Replies: 19
Views: 2975

Re: even simpler/cheaper LVC :)

nebriancent wrote:oh and i forgot to ask ... what program are you using to sim/draw the circuit
LTSpice. It is a nice completely free SPICE simulator with graphical front end supported by Linear Technology.
by curious
Aug 12 2011 8:57pm
Forum: Battery Technology
Topic: even simpler/cheaper LVC :)
Replies: 19
Views: 2975

Re: even simpler/cheaper LVC :)

Warning, the following post is for perfectionsists and analog circuitry fans only :) Here is the temperature compensated version with the ideal/regular top segment (not practical as it requires extra power supply for current source I1). It is quite accurate and can be used for analog measurements of...
by curious
Aug 12 2011 6:40pm
Forum: Battery Technology
Topic: even simpler/cheaper LVC :)
Replies: 19
Views: 2975

Re: even simpler/cheaper LVC :)

adrian_sm wrote:So whats the average current draw of the circuit? Will it drain the pack if left connected?
About 4uA, good for few decades, perhaps more...
by curious
Aug 12 2011 4:39pm
Forum: Battery Technology
Topic: even simpler/cheaper LVC :)
Replies: 19
Views: 2975

Re: even simpler/cheaper LVC :)

...voltage across one of those 3906 transistors is going to be awfully high? No, it is split more or less evenly, not exceeding single cell voltage, certainly not full pack voltage. ...an explanation of the stages of circuit operation would be helpful to those non-engineers among us The top segment...
by curious
Aug 12 2011 2:35pm
Forum: Battery Technology
Topic: even simpler/cheaper LVC :)
Replies: 19
Views: 2975

even simpler/cheaper LVC :)

I've been toying around with current-mode chaining of LVC circuits in the simulator recently and realized that you can build a super-cheap LVC using just one TC54 chip and current mode transistor chain as a sensor/aggregator. It will not have the same threshold accuracy and temperature stability as ...
by curious
Aug 10 2011 12:51pm
Forum: Battery Technology
Topic: New CellLog-based BMS "Lite"...
Replies: 27
Views: 3840

Re: New CellLog-based BMS "Lite"...

There is a 200ma shunt regulator version - AP431 made by Diodes Inc (albeit for a somewhat higher price). BTW am I correct that 431 cathode can not go below the reference input ? We use a divider on the input side, so we can dial in exactly when we need the shunts to come on. Anything below this po...
by curious
Aug 10 2011 5:10am
Forum: Battery Technology
Topic: New CellLog-based BMS "Lite"...
Replies: 27
Views: 3840

Re: New CellLog-based BMS "Lite"...

There is a 200ma shunt regulator version - AP431 made by Diodes Inc (albeit for a somewhat higher price).
BTW am I correct that 431 cathode can not go below the reference input ?
by curious
Jun 15 2011 10:30am
Forum: Battery Technology
Topic: turnigy wattmeter - is Ah reading cycling ?
Replies: 10
Views: 1343

Re: turnigy wattmeter - is Ah reading cycling ?

I also got one of these HK-010 and in the watt meter mode it does indicate Ah continuously, so it is indeed possible to use it as cheap fuel gauge. But there are few convenience issues also: (i) you must press a button to enter watt-meter mode every time you start the trip, (ii) if you exit watt-met...
by curious
Jun 13 2011 11:48am
Forum: Battery Technology
Topic: Is Regen Braking bad for Lipos?
Replies: 22
Views: 3196

Re: Is Regen Braking bad for Lipos?

Harold in CR wrote:I live about 1500' elevation, and, it's nearly ALL downhill, in a 2.5 mile stretch.
Harold in CR wrote:At the moment, my initial controller will have NO features.
In your case rheostatic braking makes perfect sense. There was a large thread on it a while ago.
by curious
Jun 10 2011 8:59pm
Forum: Battery Technology
Topic: Is Regen Braking bad for Lipos?
Replies: 22
Views: 3196

Re: Is Regen Braking bad for Lipos?

Regen is bad for any battery if the battery can't take what the regen is dishing out. Actually it is not that bad. Controller/motor combos that we use are fairly lossy, typical efficiency is around 70% and it works both ways: for a 1W mech. power at the wheel we need like 1.4W of battery power duri...
by curious
Jun 10 2011 7:35pm
Forum: Battery Technology
Topic: Is Regen Braking bad for Lipos?
Replies: 22
Views: 3196

Re: Is Regen Braking bad for Lipos?

The coasting issue is fixed by holding the throttle open just a tad, so you are only putting 0.xx amps out. Then regen isn't activated, and you coast when you want to. This is controller specific. Kelly does not require throttle management for coasting (although it can be programmed this way), on m...
by curious
Jun 10 2011 6:44pm
Forum: Battery Technology
Topic: Is Regen Braking bad for Lipos?
Replies: 22
Views: 3196

Re: Is Regen Braking bad for Lipos?

In a programmable controller regen cutoff voltage should be set at or slightly below full pack voltage. Unless you live at the top of large hill this is not really an issue. so many folks on the Tidal force forum had issues with it I've used proportional regen for two seasons with zero problems. It ...
by curious
Jun 09 2011 1:58pm
Forum: Battery Technology
Topic: A123 20AH cells source?
Replies: 520
Views: 64429

Re: A123 20AH cells source?

They're still bugging me for paperwork from 30 cells that I bought over two months ago. OMG! Now we have our own customs that want to give us hard time. Perhaps it is time to move to some reasonably civilized SE Asia place. I kind of like the food there (except insects, dogs and cats :? ). I know t...
by curious
Jun 09 2011 12:53pm
Forum: Battery Technology
Topic: A123 20AH cells source?
Replies: 520
Views: 64429

Re: A123 20AH cells source?

Anyone willing to contribute some personal time and arrange a small group buy from Mavizen ? :-). I need at least 25, perhaps 40-50 pcs.
by curious
Jun 01 2011 5:16pm
Forum: E-Bike Technical
Topic: New Crystalyte Motor series (HT35 / HS35 and HT24 / HS24)
Replies: 1395
Views: 201844

Re: New Crystalyte Motor series (HT35 / HS35 and HT24 / HS24

Well my HS3540 does not make any resonating sound, in fact i have to struggle to hear any operating noise on my motor. Maybe its the meger 20amps at 36v that i am currently running it on but either way, its practically silent, my freewheel makes more noise to be honest. moment its a custom batch or...
by curious
May 31 2011 12:13am
Forum: E-Bike Technical
Topic: New Crystalyte Motor series (HT35 / HS35 and HT24 / HS24)
Replies: 1395
Views: 201844

Re: New Crystalyte Motor series (HT35 / HS35 and HT24 / HS24

How does HT/HS series compare to 9c and x5 in terms of rolling resistance ? Closer to 9c or x5 ?