Memo5378

Lithium or alkaline?

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Hello all! So this was probably answered before, but I can’t find a clear answer and I am still pretty confused. Today was the day I updated one of my trains (a moc) with a PU Hub and motor. The install went pretty smoothly, but I was only able to run it for about 10 minutes with 6x new alkaline batteries. After that, it simply died is place. I tried with another 6 new batteries, and got a similar outcome.

So, I think the alkaline is not the way here, so what should I use, Li-Ion?, Ni-Mh?. Please note that I do not which to fiddle with the hub, I prefer to stick with standard sized AAA. 
 

Thank you!

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Do you have a battery tester to check that those alkalines are actually good?  10 minutes seem kind of short for good new batteries.

The easy thing is to use rechargeable NiMH AAA batteries. I get one to two hours out of them running at train shows.

batty.jpg

If you have access a 3D printer, you can make an adapter to use 9V style Li-Ion batteries with the PU hub.

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Can we have more information about the technical construction of the moc?
I had such problems when I installed a Lego PU City Hub (the small one with 2 sockets) and 2 Legp PU L motors in a moc: Batteries are immediately empty and rechargeable batteries have a very poor performance. The PU L-motor sucks a lot of current and 2 of them immediately overload the City-HUB.

Thomas

 

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10 hours ago, dr_spock said:

Do you have a battery tester to check that those alkalines are actually good?  10 minutes seem kind of short for good new batteries.

The easy thing is to use rechargeable NiMH AAA batteries. I get one to two hours out of them running at train shows.

batty.jpg

If you have access a 3D printer, you can make an adapter to use 9V style Li-Ion batteries with the PU hub.

I did test the batteries. New ones show 1.56 to 1.68 volts, whereas spent ones fall at about 1.35 volts. So this morning, I tried again with new alkaline batteries from a fresh batch. The train ran for about 60 seconds at full power, then dropped to half speed. It eventually stopped dead after about 3 minutes of running time. The batteries tested after the train stopped still show over 1.5 volts for some reason.

For reference, the train is a moc based on 10219 (6 wide), with 3 well cars. The engine weighs 605 grams, while the cars weighs 350 grams each. All together , the trains weighs 1.6 kg. It is motorized with 88009 hub and 88011 motor. I also checked to reduce friction as much as I could, but I can only do so much as I use Lego standard curve tracks.
 

Would adding a motor to the engine help, or is it just a matter of power?

Edited by Memo5378

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Have you used this specific hub elsewhere on different trains and with different motors?  You may want to check the difference (if any) there as from what you’ve said it’s starting to sound to me like a faulty hub in itself.  If that’s the case, you should contact TLG and obtain a new one because I’m fairly confident they’re meant to last more than 3 minutes.  10219 in total weighed 1922g.

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3 hours ago, Memo5378 said:

For reference, the train is a moc based on 10219 (6 wide), with 3 well cars. The engine weighs 605 grams, while the cars weighs 350 grams each. All together , the trains weighs 1.6 kg. It is motorized with 88009 hub and 88011 motor.

This HUB/motor combination is usually completely problem-free (except too fast^^) and the train is definitely not a heavyweight. This should work together without any problems and I believe here also a defect. In any case, this is not normal.
Most of my locomotives use this HUB and motor.

Ps: I mainly use rechargeable batteries, but they are weaker than batteries and that should not be the cause here.

Thomas

Edited by Ts__

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I am quite shocked to hear that the alkaline batteries last so little.

https://www.batteryequivalents.com/aaa-batteries-size-chemistry-types-and-replacements.html#:~:text=Alkaline AAA batteries are practically,capacity of 850 - 1200 mAh.

Based on this table, the mAh capacity of alkalines is quite comparable to NiMH, though the terminal voltage is higher (1.5 V compared to 1.2 V). This should give a higher motor angular velocity at each PWM setpoint since the average voltage applied across the machine winding should be higher, resulting in more current and higher back-EMF. Anyway, that's just an irrelevant technical detail.

Assuming constant current draw, the actual current should be 6 A (6 A = 6000 mA , 6000 mA * 1/6 h [10 mins] = 1000 mA/h as per the table below). That's a lot of current for these tiny cables.

If I am not mistaken, do PU Hubs have overcurrent protection?  It has been a while since I looked into it.

My guess is- busted batteries.

Chemistry Common Name Rechargeable Typical Capacity (mAh) Voltage
Zinc Carbon R03, 24D No 500-600 1.5
Alkaline LR03, 24A Mostly No 850-1200 1.5
Li-FeS2 FR03, 24LF No 1100-1300 1.5 (1.8 max)
Li-ion 10440 Yes 350-600 3.6 - 3.7
LiFePO4 IFR10440, IFR10450 Yes 250-300 3.2
Li-SOCl2 (10450) No 600-800 3.6-3.7
Lithium - Yes 400-600 1.5
NiCd KR03, 24K Yes 300-500 1.2
NiMH HR03, 24H Yes 600-1300 1.2
NiOOH ZR03 No 1000-1200 1.5 (1.7 max)
NiZn - Yes 500-700 1.6 - 1.65

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4 hours ago, Ts__ said:

This HUB/motor combination is usually completely problem-free (except too fast^^) and the train is definitely not a heavyweight. This should work together without any problems and I believe here also a defect. In any case, this is not normal.
Most of my locomotives use this HUB and motor.

Ps: I mainly use rechargeable batteries, but they are weaker than batteries and that should not be the cause here.

Thomas

Allright. So I did a few more tests with different hub/motor/engines. So I turned back to power functions only to realise that the batteries would drain quite fast as well. So I doubled my motors and voilà!. My dual motor (power functions) moc cargo train ran for about 90 minutes.

i tried the powered up setup in my older 60052 with nimh batteries and it wouldn’t pull the load. However, when coupled with a lighter load, i.e, two « standard » lego city wagon, it moved without problem, and went strong for over an hour before I stopped it.

So, is my problem really the batteries, or is the PU motor simply not strong enough? Should it be strong enough to pull my 1.6kg load? 
 

I reach out to customer service and they agreed to replace my motor, no problem. I just don’t know at this point if I want to use the PU system or stick with PF, be it only for it ease of use.

 

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the pu motor should be the same motor in theory just with a different cable, connector and ofcourse those id resistors to make the hub know what is connected. if you like pu id go pu.

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Working better with 2 motors sounds you might be kicking in the over current protection with single motor.  One way to find out is hook up an amp meter and see what's going on. 

It's possible to run two PU train motors by creating your own profile for it in the Powered UP app. 

 

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On 11/2/2022 at 8:17 AM, Memo5378 said:

For reference, the train is a moc based on 10219 (6 wide), with 3 well cars. The engine weighs 605 grams, while the cars weighs 350 grams each. All together , the trains weighs 1.6 kg. It is motorized with 88009 hub and 88011 motor. I also checked to reduce friction as much as I could, but I can only do so much as I use Lego standard curve tracks.

At least part of your problem was probably the mechanical design of the 10219 unpowered trucks. The wide spacing between the axles, the use of technic axles, and the rubber bands on the wheels all create A LOT of resistance (respectively: binding in curves, high friction no matter what, and wheels on opposite sides fighting to turn at different rpm while both having good traction).

Simply replacing that truck with a second motor (forgetting about the added power and only thinking of the removed drag) probably saved you a ton of resistance.

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