deVries
100 kW
I now have a bit (really, a lot!) of information overload and over-my-head reading I've been doing here since I found this ES-forum a few weeks ago, and I thank everyone for providing me with these challenges to understand just enough to know... I've got a long way to go... Rats! I wish I was an electronics geek... At least I did get my ham radio operators license at age 12, WN5BHQ, and loved Heath Kits. In here it's dit dit dit dah dah dah dit dit dit LOL.
But, I want to get started on my first build now, before I'll ever have time to "geek myself", and I need some expert advice. I want to avoid making major mistakes, if possible... Ha!
I bought an EV-Tech BMC motor rear mount 26", and I'm going to use a "custom controller" from Knuckles/Crazyman once I know my battery set-up.
I'm considering going with the Milw.28v to get a 56v (54v real?) with 8 battery packs for a 12ah (10ah real?) set-up. (2s4p?) I may build it as a 6ah 4 battery (2s2p) that i swap-out on longer rides with the other 4 swap-packs I carry along. Though it may be better to just use an 8 pack, so I don't wear out the batteries as fast by doing a lower avg. "drain cycle" per cell battery/pack. Correct?
1) I read about all the problems with the DeWalt BMS, balancing & cell death w/o good LVC cut-off, so I'm wondering if I can avoid these problems by going with the Milw BMS packs instead? What can I do to avoid the balancing issues with this battery pack & still use its built-in BMS? Is there a better charger(s) $100-200 to choose that will work much better than others for the Milw? I think I'm ok with the amp draw, since each Milw battery pack can handle 20amps, so with 2p or 4p I get 40amps or 80amps off the BMS, correct? Do I have a limitation on what AMP controller limit I could use for the amp pull w/throttle? Perhaps another reason to go with 4p for the extra 40amps over 2p. What about burst AMPs on the Milw BMS? Should I use a CA?
Or, is the Milw BMS going to still have the same balancing problems as the DeWalt BMS??? I did read this from GaryG: "It's been awhile since I've played with eMoli cells (we used to rip out the 7 cells in Milwaukee tool packs, and use them in our RC helicopters, before the a123 packs came out...), but I think the optimum CC/CV cutoff voltage is 4.1V, instead of the 4.2V used by Lithium-Cobalt-based LiPoly packs. As Bob points out, the crossover point for the shunts can be adjusted via an on-board pot, but the adjustable range can be modified by simply changing one resistor.
There are single cell 4V chargers that are isolated, but these ae typically limited to about 1.5A-2A. With this BMS you can use a single higher power charger or even a regulated supply, like the Mastech units, or like the the 0-60V/0-15A HP supply that Bob found for me on ebay (it was $125...). The shunts in the BMS act like individual cell CV chargers. Once the cell voltage gets to the crossover point (3.65V for LiFePO4 cells, or 4.1V for emolis...), the shunt clamps it there. The current the cell can accept then tapers off, but what ever it doesn't need/use gets bypassed so that the next cell in series can have all of the current available, if it isn't at the cutoff yet."
Tricks, tips, workarounds, or best ideas or suggestions are most appreciated for help regarding using the Milw BMS packs intact w/warranty.
POOR MAN"S DEWALT...
If I bypass the 15amp & do the resistor/connector mod, will I still have major balancing issues with the DeWalt BMS *IF* using 6 packs in parallel only? ~13ah set-up at ~34v. Someone wrote the DeWalt instructions said to leave the pack on charge overnight to "rebalance" the pack when needed. Is there a better charger or method to still be able to use the DWBMS in just a parallel set-up, or do I really need to go with the new "ES board BobGary designed" Gary-kits? What specifically should I use?
Tricks, tips, workarounds, or best ideas or suggestions are most appreciated for help regarding using the DeWalt BMS or trashing it for a POOR MAN'S DEWALT parallel set-up?
Fechter, Docbass, BobM, GGoodrum, Knoxie, Ypedal, etc., etc. you're awesome here with all your contributions!
Thank you everyone!!!! Cheering & Applause...
But, I want to get started on my first build now, before I'll ever have time to "geek myself", and I need some expert advice. I want to avoid making major mistakes, if possible... Ha!
I bought an EV-Tech BMC motor rear mount 26", and I'm going to use a "custom controller" from Knuckles/Crazyman once I know my battery set-up.
I'm considering going with the Milw.28v to get a 56v (54v real?) with 8 battery packs for a 12ah (10ah real?) set-up. (2s4p?) I may build it as a 6ah 4 battery (2s2p) that i swap-out on longer rides with the other 4 swap-packs I carry along. Though it may be better to just use an 8 pack, so I don't wear out the batteries as fast by doing a lower avg. "drain cycle" per cell battery/pack. Correct?
1) I read about all the problems with the DeWalt BMS, balancing & cell death w/o good LVC cut-off, so I'm wondering if I can avoid these problems by going with the Milw BMS packs instead? What can I do to avoid the balancing issues with this battery pack & still use its built-in BMS? Is there a better charger(s) $100-200 to choose that will work much better than others for the Milw? I think I'm ok with the amp draw, since each Milw battery pack can handle 20amps, so with 2p or 4p I get 40amps or 80amps off the BMS, correct? Do I have a limitation on what AMP controller limit I could use for the amp pull w/throttle? Perhaps another reason to go with 4p for the extra 40amps over 2p. What about burst AMPs on the Milw BMS? Should I use a CA?
Or, is the Milw BMS going to still have the same balancing problems as the DeWalt BMS??? I did read this from GaryG: "It's been awhile since I've played with eMoli cells (we used to rip out the 7 cells in Milwaukee tool packs, and use them in our RC helicopters, before the a123 packs came out...), but I think the optimum CC/CV cutoff voltage is 4.1V, instead of the 4.2V used by Lithium-Cobalt-based LiPoly packs. As Bob points out, the crossover point for the shunts can be adjusted via an on-board pot, but the adjustable range can be modified by simply changing one resistor.
There are single cell 4V chargers that are isolated, but these ae typically limited to about 1.5A-2A. With this BMS you can use a single higher power charger or even a regulated supply, like the Mastech units, or like the the 0-60V/0-15A HP supply that Bob found for me on ebay (it was $125...). The shunts in the BMS act like individual cell CV chargers. Once the cell voltage gets to the crossover point (3.65V for LiFePO4 cells, or 4.1V for emolis...), the shunt clamps it there. The current the cell can accept then tapers off, but what ever it doesn't need/use gets bypassed so that the next cell in series can have all of the current available, if it isn't at the cutoff yet."
Tricks, tips, workarounds, or best ideas or suggestions are most appreciated for help regarding using the Milw BMS packs intact w/warranty.
POOR MAN"S DEWALT...
If I bypass the 15amp & do the resistor/connector mod, will I still have major balancing issues with the DeWalt BMS *IF* using 6 packs in parallel only? ~13ah set-up at ~34v. Someone wrote the DeWalt instructions said to leave the pack on charge overnight to "rebalance" the pack when needed. Is there a better charger or method to still be able to use the DWBMS in just a parallel set-up, or do I really need to go with the new "ES board BobGary designed" Gary-kits? What specifically should I use?
Tricks, tips, workarounds, or best ideas or suggestions are most appreciated for help regarding using the DeWalt BMS or trashing it for a POOR MAN'S DEWALT parallel set-up?
Fechter, Docbass, BobM, GGoodrum, Knoxie, Ypedal, etc., etc. you're awesome here with all your contributions!
Thank you everyone!!!! Cheering & Applause...
ask!
