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  1. E

    best pre-charge solution

    I like using a light bulb of some higher voltage than the battery. There is still a tiny spark, but the charge up is faster and more complete, because a bulbs resistance is lower when it's cold and higher when its hot. On my 50v system, I ended up with a 20 watt, 110vac halogen bulb. Watch it...
  2. E

    Received Pouch Cells From A123rc

    I will try to flatten the cells that way. I see examples of soldering and bolting to the tabs. Using a hot iron will rosin core solder stick to the annealed aluminum? Thanks
  3. E

    Received Pouch Cells From A123rc

    Bigmoose, the tab sizes are as you described. The neg tab is .007" thick, copper with maybe nickle plating. The pos tab is all nickle color, don't know what material it is. Will solder stick? These cells do sound like a hit or miss gamble. If they hold up through bench testing, I'll install...
  4. E

    Received Pouch Cells From A123rc

    There has been a lot of concerns about ordering pouch cells from A123rc, and what your might receive. I just received my cells this morning, 6 business days after order placed, with the free postage selection. I don't have a picture. The cells are all full tabbed, tabs are slightly bent, but...
  5. E

    Icon Legend - What the heck do all these mean?

    How are pictures inserted? I see the "Img" symbol, but how to use it? Thanks
  6. E

    Please help me decide LiPo/A123 (electric outboard)

    Hello all, Your e-boat project sounds very interesting and I have always wanted to one too. But what little e-time I have, I have spent on ebikes and emotorcycles. Your friends are right on with the motor rating vs duty cycle vs cooling and about 6 other variables to keep happy, or the end...
  7. E

    What batteries are you using?

    16, 36v dewalt packs made into 16s 10p. ~50v at 23ah pack. Makes honda cr85 dirt bike go like stink. So far reliable, perdictable, no heat, solid power. Should be good for another 5-6 years use. Ebay, ~ 105. per pack.
  8. E

    waste of time. don't bother.

    24v is a good starting voltage. Using relays or switches you could parallel 2 12v batteries for a low speed and switch to series for 24v high speed. The arc going to high won't be too bad, but the low speed will be interesting. With relays, there is a danger of the contacts welding themselves...
  9. E

    waste of time. don't bother.

    Thats where I buy my sprockets too. I also use a #35 chain to a jack shaft and then a #42 chain drive on the final. What surprises me is the jack shaft is a 3/4" keyed aluminum shaft and is still holding. I thought the key way would start getting sloppy and I would have to change shaft...
  10. E

    waste of time. don't bother.

    How many volts and what type of batteries are you using? A free spinning etek draws about 4 amps. if you are using say a 36 volt battery pack, then 4 x 36 = 144 watts. You will already be at your motor controller's limit without an external load. Does your controller have an amp and voltage...
  11. E

    waste of time. don't bother.

    I checked the McMaster Carr book and I think bicycle chain pitch and roller diameters are the same as on an ansi #41 sprockets. However #41 sprocket is too wide to fit a bicycle chain. It has to be machined thinner, till it fits a bicycle chain. I have not come across bicycle type sprockets...
  12. E

    waste of time. don't bother.

    If your refering to the eariler eteks, shafts come in 3/4" and 7/8". 19mm (.748") is close to the 3/4" size. McMaster Carr, online mail order, has many roller chain sprockets to choose from in 3/4". A sprocket with a 20mm (.787") bore would be too loose to attach. Try to seek out friends or...
  13. E

    Cell-Log, Battery Monitor

    Thanks all for your responses. I know this won't cover the balancing portion of a bms. I was hoping to use the lvc alarm to stop riding and the high voltage alarm for bulk charging out in the field. Is it possiable to wire a relay or circuit to stop the charge when any cell reaches 3.6v first...
  14. E

    Cell-Log, Battery Monitor

    I didn't hink to include that. http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=9282 Thanks, Wesley
  15. E

    Cell-Log, Battery Monitor

    Hello all, I've been looking at the Cell-Log Cell Voltage Monitor, by Hobby King. Seems to do everything I need from a bms. It has programable over and under voltage alarms and a voltage display for each cell. The monitor is good for 2-8s batteries. The only concern is it draws 8 ma per cell...
  16. E

    EMF destroyed voltmeters!

    The cap and resistor in series sounds like the solution, will try it this week. Do you know of a non micro processor circuit that will automatically pick and display the lowest voltage cell in a battery string? Thanks, Wes
  17. E

    EMF destroyed voltmeters!

    Thanks Swbluto, Those are all good ideas. I'll start with a cap, but where is the best place to put it? Close to the battery or at the meter? What would be a starting value? Not knowing the polarity of the inductive pulse, ceramic over electrolitic cap? The meter reads through a double pole...
  18. E

    EMF destroyed voltmeters!

    Hi all. I'm having a problem where the spark from switching the battery power on to my speed controller (alltrax), destroys the voltmeter that monitors the battery pack. The digital volt meter's back light comes on but the screen is blank. I believe the spark causes a big energy field that...
  19. E

    Big voltage drop!

    Greg, My battery packs each have 2 copper strips for bolt through posts. So unbolting to perform balancing is a lot of work. The other option is solder on short leads with deans connectors for daisy chaining, simuliar to what you did. Dnmun, You right about voltage sag. At the end of the...
  20. E

    Big voltage drop!

    Greg, Your right about all the cable handling. Sounds like you are very diligent about your battery maintance. I could make a list, but seems there is no way around all the manual cable handling. This is of course without the use automatic electronics. a) Bulk charge, 2 med cables, careful...
  21. E

    A123 newb...will this work?

    The packs will discharge evenly enough as long as they all get the same charge and the paralleling leads/cables to them are all the same length. The current drain limitation is either the internal wiring or most likely the fuse. Because the packs are in parallel, if one fuse blows, the rest will...
  22. E

    A123 newb...will this work?

    Sorry, the Kollmorgen I've heard about makes large brushless motors for rc aircraft. 400watts rating is likely a continous nominal power. Its closer to 3 x that on a hard take off, 43 amps. My concern would be the bms fuse in the dewalt pack will pass some 15-20 amps, not sure, but its not up...
  23. E

    A123 newb...will this work?

    Not a stupid idea at all. Conceptually it should work for some distance. Besure 28v is ok for your motor and controller, they will be working fairly hard. Monitor the current. 2 or more batteries will give you more useful range and the pack will have a longer life. The pack output wiring may not...
  24. E

    Big voltage drop!

    Greg, Thanks for the charge plot and explanation on your system. I have 4 of those 3.3v, 20a powersupplies and eventually 16 of them so no balancing needed. But I didn't fore see the size of cables needed. Your bulk charging requires only 2 wires and a way to monitor each battery. Also easy to...
  25. E

    Big voltage drop!

    The powersupply is set for 3.6v. The voltage sag, or voltage drop is from the light weight leads, checked with a meter. I could use some ideas on how to deal with this when the powersupply to the battery pack (in the bike) is about 2 1/2 ft away. I know shorter is better, but in use, this is the...
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