mxxc Posted July 8, 2020 Posted July 8, 2020 I got a 42099 recently and was kind of disappointed by the slow speed of the 6x AA nimh batteries (7.2V), so I made this 8x AAA battery box (9.6V, or 12V if you use alkaline). The speed boost was tremendous. The fully charged 8x nimh batteries could reach almost 11.5V, but the voltage drops quickly. In theory it should be stabilized at 9.6V. 6x AA battery box. The downside is 8x AAA will have less playtime than 6x AA. I don't know exactly how long you will get from this setup. I took the offroader to a park over the weekend and played 30 minutes without issue. Quote
mkbryant Posted July 8, 2020 Posted July 8, 2020 29 minutes ago, mxxc said: so I made this 8x AAA battery box (9.6V, or 12V if you use alkaline) Did you make the battery holder or happen to find one that conveniently fit? Where did you get it? Do you have instructions? I would love to use this mod for the 42099 that I just put together. Quote
kbalage Posted July 8, 2020 Posted July 8, 2020 That looks very cool, would love to see more details about it! Quote
howitzer Posted July 8, 2020 Posted July 8, 2020 I see you're using Eneloop batteries, which are high quality but expensive. Apparently Ikea sells the same batteries, branded as their own but for much lower price. Quote
ScT Posted July 8, 2020 Posted July 8, 2020 They are called "Ladda" in IKEA. AA are 2450 MAH, and AAA are 900 MAH. 3 hours ago, mkbryant said: Did you make the battery holder or happen to find one that conveniently fit? Where did you get it? Do you have instructions? I would love to use this mod for the 42099 that I just put together. Second this - we need to know more! Where did you get the battery holder? Can we get it somewhere ourselves, etc. Quote
dr_spock Posted July 8, 2020 Posted July 8, 2020 Neat idea. Looks a standard 8x AAA holder you can get off ebay with some metal tabs attached to it. Is that what you did? Quote
mxxc Posted July 8, 2020 Author Posted July 8, 2020 1 hour ago, dr_spock said: Neat idea. Looks a standard 8x AAA holder you can get off ebay with some metal tabs attached to it. Is that what you did? Close enough, I actually glued 2 4x AAA battery holders together. The conductor pieces were made from a soda can. I will update some instructions later. Quote
2GodBDGlory Posted July 8, 2020 Posted July 8, 2020 Do you think the higher voltage would eventually cause problems in the circuitry? I once hooked up a hobby 9.6V cell to a PF receiver, and the receiver didn't last long. Lego motors are supposed to take up to 12V (I have heard), but I don't know about control systems. If the PU hub can take it, though, that could be a very interesting high-performance solution! Good ingenuity! Quote
JaBaCaDaBra Posted July 8, 2020 Posted July 8, 2020 6 minutes ago, 2GodBDGlory said: a hobby 9.6V cell to a PF receiver, and the receiver didn't last long Must have some other cause, less than 10% should not be a problem. Quote
pleegwat Posted July 9, 2020 Posted July 9, 2020 If you're concerned about 9.6V, you could also put in 7 AAA cells which should stabilize at 8.4V. Quote
dr_spock Posted July 10, 2020 Posted July 10, 2020 On 7/8/2020 at 5:13 PM, 2GodBDGlory said: Do you think the higher voltage would eventually cause problems in the circuitry? I once hooked up a hobby 9.6V cell to a PF receiver, and the receiver didn't last long. Lego motors are supposed to take up to 12V (I have heard), but I don't know about control systems. If the PU hub can take it, though, that could be a very interesting high-performance solution! Good ingenuity! Absolute max voltage for the LB1836M motor driver in the V1 PF IR receiver is 10.8V and allowable operating voltage is 9V at 25 deg. C. DRV8333 driver in the V2 PF IR receiver has 10.8V for operating in the spec sheet. Do the Power UP hubs also use the LB1836M motor driver? Quote
2GodBDGlory Posted July 11, 2020 Posted July 11, 2020 On 7/8/2020 at 5:22 PM, JaBaCaDaBra said: Must have some other cause, less than 10% should not be a problem. Perhaps it had something to do with the fact that I was running nine motors off of it at once--A Servo, four Ls, and four XLs! Quote
Philo Posted July 12, 2020 Posted July 12, 2020 (edited) On 7/10/2020 at 11:37 PM, dr_spock said: Absolute max voltage for the LB1836M motor driver in the V1 PF IR receiver is 10.8V and allowable operating voltage is 9V at 25 deg. C. DRV8333 driver in the V2 PF IR receiver has 10.8V for operating in the spec sheet. Do the Power UP hubs also use the LB1836M motor driver? Yes they do use the trusty but voltage limited LB1836M chip. So going above 10.5V means taking risks! Screenshots from the datasheet: Edited July 12, 2020 by Philo Quote
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