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  1. S

    how many amps should i plan for a Diy battery and which nickel strips?

    Nickel is almost free so use as much as you can. Go for the thickest your welder can handle and as wide as you can fit. Instead of amps, I like to think about discharge rates measured in C. I'm building a 20Ah 48V pack for a 1,800 watt motor but I intend to cruise at around 500 watt output...
  2. S

    E-bike or E-motorcycle?

    I can pretty safely say those stats are BS. What I hear is that most motorcycle accidents are alcohol related and most of the motorcycle accidents reported as not alcohol related are just cops and emergency responders trying not to give a gravely injured rider legal problems too. What I know...
  3. S

    The BEST connectors, period

    Compared to an XT90, yes but if you can't fit a connector the size of a Speakon, connector quality probably isn't your biggest issue.
  4. S

    The BEST connectors, period

    I'm glad to hear that is working for you. I know Speakon connectors are designed to handle some current, but I have never really tested them at high current. Now I'll have to think about them for other things.
  5. S

    Creative Cooling Ideas?

    I think I have found a source of paraffin wax to use for phase change cooling. I'm going to try it out. I can't say who it is until I ask him if he would like to sell wax a few pounds at a time. He's being very kind helping me out but may want to focus on bigger markets than homebrew ebike...
  6. S

    Creative Cooling Ideas?

    I think your 20A number is right at 14 watts heating. 1/2 the heating with 4x the mass equals 1/8 the temperature rise. Instead of a my 30° rise, yours is probably 4° over the same amount of time. With the size of your trike, a 40 lb battery does sound appropriate. If it would fit and the...
  7. S

    Creative Cooling Ideas?

    Yeah, 40C would be great but my ambient is about 30C as I speak, 10° rise is probably about what my cells at 0.2C in the charger do. If I add insulation on top of that (heat shrink) and pack them more densely, it's got no chance. When my ambient gets to 40°, which happens, I'm doubly screwed...
  8. S

    Creative Cooling Ideas?

    Yes, new LG M50T 21700s. The Opus says around 4,800mAh and between about 60 and 120 mili-ohms. I would prefer lower internal resistance but it's not too bad. I'm going to do some statistics to see if any of the slots are giving results that differ too much from the other slots because I was...
  9. S

    Bitcoins

    Yep, big problems are coming and sooner than people think. I know Microsoft has a serious cold computing program that is aiming to make quantum computers with hundreds and thousands of q-bits, that will make most encryption vulnerable overnight. I'm sure Microsoft isn't the only one trying...
  10. S

    Creative Cooling Ideas?

    With typical heat shrink insulation on a battery pack, what you can feel on the outside is not indicative of the temperature on the inside. Also, there are not multiple definitions of heat. There just is not. I am currently testing my cells so I can sort them and place them in my pack for the...
  11. S

    Creative Cooling Ideas?

    Heat in the battery is unavoidable. The question is how much power can you pull out of your cells before the temperature exceeds what you are comfortable with or what the cells will tolerate gracefully over its expected lifetime?
  12. S

    Bitcoins

    I hear bitcoin is very popular in Venezuela so I think it is more like entity's forcing people on to their monetary system and cryptocurrency's popularity is a function of distrust in those governments. Trust in fiat currency is just big brother telling you what to believe when you think about...
  13. S

    Razor upgrades? Nothing crazy.

    A little more calculation, it looks like 1,100 watts is required to attain maximum speed at 27.3mph and with an 1,800 watt motor, I should be able to maintain that riding in to a 10mph head wind or up a 4% grade. A 7% grade drops the speed to about 21mph, not terrible. I probably should have...
  14. S

    Razor upgrades? Nothing crazy.

    So far, my cells seem to be testing out at around 4,800mAh according to my Opus charger and the 1A charge rate seems to give similar results to 500mA charge rate. This tells me that 0.1C and 0.2C rates are nothing for these 21700 cells. A power calculator says I should be able to cruise at...
  15. S

    Creative Cooling Ideas?

    The thing about air is you can get convection or forced air cooling, that can be much more effective than the thermal conductivity of potting compound. On the other hand, if your pack is covered in heat shrink with no air flow, that is when the air does nothing for you. Unless you have an...
  16. S

    Common pack design mistakes, how to avoid?

    My spacers create a 22mm cell spacing in a cubic pack (orange crate style), with a 21mm cell, that's a 1mm air gap, pretty small but not zero. The spacers are plastic and I am going to hot glue my cells to them with a small amount of glue but hopefully enough to really lock the pack together...
  17. S

    Bitcoins

    Crypto makes at least as much sense as any fiat currency that's not commodity backed. Personally, I like the idea of cryptographically strong tokens to guard private information and transactions but they need to be quantum resistant or else they will be garbage in a few years. Instead of...
  18. S

    Common pack design mistakes, how to avoid?

    That stacking without spacers could cause problems. I'm going to stack like that with spacers and I'm a bit worried. Also two levels of cells is going to make the interior side of each cell toasty. I think it would be great for a high capacity battery with conservative amps per cell. If you...
  19. S

    Creative Cooling Ideas?

    Thermoelectric Coolers (TECs) sound like what you remember. It's not a good solution because you need lots of power to run them and that will make your batteries generate more heat and defeat the purpose. There are Thermal Interface Materials (TIMs) which I am planning on using but more to...
  20. S

    The BEST connectors, period

    I've seen the big Anderson's get used and abused on forklifts and if you park a forklift for too long in a humid environment the contacts can get cruddy. It's probably a combo of warn housings, warn contacts and cables twisting things but they seem to always get better if you plug and unplug...
  21. S

    The BEST connectors, period

    Anderson's are good for high current but they are designed for frequent connect and disconnect. The wiping contact that makes the connection needs to be wiped. If you plug it in and leave it, the contacts will oxidize and then those heat and cable twist problems start to happen. If you are...
  22. S

    Razor upgrades? Nothing crazy.

    I was thinking about it and decided to test my 21700s. They fit in my Opus BT-C3100 so I thought I could sort them and arrange them for the best thermal performance. What I didn't think about when I started is with the default 500mA charge and discharge current, the test cycle takes about...
  23. S

    Razor upgrades? Nothing crazy.

    With a higher achievable top speed, more stability would be desirable so rake greater than stock would be ideal. I got my cell spacers trimmed so tomorrow I will begin hot gluing the cells and getting my nickel ready to weld. The hot glue will be minimal, just to keep the shape while I build...
  24. S

    Razor upgrades? Nothing crazy.

    That does look interesting. They don't list rake and I'm not sure if it is threaded or thread less. I see combos that have the fork, a motorized wheel, a disk brake and a fender but I can't seem to find the fender separate. I would need to do a wheel upgrade too. I got my spacers! Here is...
  25. S

    Big mid-drive motor, bypass IGH?

    You can try to negotiate regen, I just wouldn't count on it because even if it "works" it might not be available when you need it. Worst case it will work until it over volts the battery and starts a fire while you are trying to stop. Just treat it as entirely supplemental so you can drop it...
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