deckard9 Posted March 31, 2013 Posted March 31, 2013 Hello, I am an idiot, when it comes to electric. I am building a MOC right now (http://www.eurobricks.com/forum/index.php?showtopic=80259) and have two problems. I have 10 XL motors in the Hubs of my wheels. To have enough juice ready, I need to have 5 controllers and 5 Battery packs which power 2 motors each- as far as I could figure out. I know that the receivers cannot handle a lot of power, so I split the motors to several receivers. My problems: The receivers dont always get the same command. One might be blocked from the IR signal and so 8 Wheels spin, but 2 are not. Is there a way around this? The other problem: sometimes, when negotiating an obstacle, the front wheels get blocked and drain the battery pack. So after a few tours the front wheel are out of juice and get dragged along, while the other wheels still have power. My question now: Is it possible for an electric noob to link the receivers and the battery boxes? So 1. all motors get the same command and 2. all motors get the same power? Or is there an other easy solution? Thank you for any help. I am lost on this. Quote
efferman Posted March 31, 2013 Posted March 31, 2013 (edited) what is with one receiver which is powering a servo. and the servo moves electrical direction reversers which connecting the XL motors with the battery boxes without an receiver in between. this should make sure to every motor get the same signal at the same time Edited March 31, 2013 by efferman Quote
deckard9 Posted March 31, 2013 Author Posted March 31, 2013 Hi, Great idea. That way I am loosing the proportional power setup thou, that I am aiming for. The truck is massive and I try to reduce stress by powering up slowly. But I think it could be rigid enough anyway. If proportional doesn't work out, I will surely give it a try. Thank you very much! Quote
hrontos Posted March 31, 2013 Posted March 31, 2013 Battery boxes can be linked using 8871 extension wire. Just make sure you switch on all of them in the same direction to avoid short circuit. You will need 4 of them to link all 5 boxes. You should get one huge 9V BB that will be able to give you 5x more power than standard BB. Quote
deckard9 Posted March 31, 2013 Author Posted March 31, 2013 (edited) And that doesn't raise the voltage? Don't I get 45 Volt then? Sorry, if the question is stupid, but I have no idea of anything electric... Edited March 31, 2013 by deckard9 Quote
hrontos Posted March 31, 2013 Posted March 31, 2013 Co And that doesn't raise the voltage? Don't I get 45 Volt then? Sorry, if the question is stupid, but I have no idea of anything electric... Connection is parallel not serial. This means, that voltage stays 9V but power will sum up and you will be able to draw 5Amps at once from this big battery box and not about 1Amp as is common for the standard BB. This means, that you could theoreticaly power a motor that need 5Amps. Standard BB cannot power device that need more than 1Amp. Just make sure you switch them on in the same direction. BB has protection against short circuit which activates automatically, it better to prevent it. Quote
deckard9 Posted March 31, 2013 Author Posted March 31, 2013 Thanks a lot, hrontos! That's a perfect solution. One more question about Effermans Servo-Switch solution: Is one switch fine with 5 Amp of power running through it (one switch for all motors) or do I need 5 switches? Quote
redoak Posted March 31, 2013 Posted March 31, 2013 I'd use 5 switches to be sure. the switches were surely not made for 5 Amps. Quote
deckard9 Posted March 31, 2013 Author Posted March 31, 2013 (edited) OK, thank you. Sorry, I got one more question: The 8871 cable - which by coincidence I have at home - only has a bottom connector on one end of the cable. The other end just can be connected on the top. I can't think of any combination that would make it possible to link two BBs since a BB can only be connected by a bottom connector. Or is there a trick? Edited March 31, 2013 by deckard9 Quote
hrontos Posted March 31, 2013 Posted March 31, 2013 The 8871 cable - which by coincidence I have at home - only has a bottom connector on one end of the cable. The other end just can be connected on the top. I can't think of any combination that would make it possible to link two BBs since a BB can only be connected by a bottom connector. Or is there a trick? I am sorry, you are right. I knew that 8886 has this limitation and did not know that also 8871 have it. You could possibly overcome it by an old style 9V extension cable, but it will not work in combination with PF switch or receiver until you will use solution like this which is probably more than you originaly intended. Quote
deckard9 Posted March 31, 2013 Author Posted March 31, 2013 (edited) I see... What if I link all the BBs to a brick like this (http://www.bricklink...Item.asp?P=4758) with 8886s. Then the brick would be the powerbackbone from which I could then take the power to the switches by just pluging them in on top.. Should work, shouldn't it? Edited March 31, 2013 by deckard9 Quote
hrontos Posted March 31, 2013 Posted March 31, 2013 I see... What if I link all the BBs to a brick like this (http://www.bricklink...Item.asp?P=4758) with 8886s. Then the brick would be the powerbackbone from which I could then take the power to the switches by just pluging them in on top.. Should work, shouldn't it? Yes, that would act as a powerbackbone. But you have to connect input cable of the PF switch to BB and output from the PF switch to powerbackbone. And then connect PF motors using extension cables to powerbackbone. As you said, you will need 5 PF switches, all of the operating in the same direction they will supply the powerbackbone by 9V, 5Amps max. It is not possible to connect PF switch input to powerbackbone, since 8886 cable connects only 2 of 4 wires to old 9V system parts and unfortunately PF switch need on input those other 2 wires. Output of the PF switch can be connected to old 9V system parts. Quote
Luke_likes_Lego Posted March 31, 2013 Posted March 31, 2013 I am an idiot, when it comes to electric. Your opening statement (the one I've quoted above) is all wrong. To ask when you're not sure, is not typical of an idiot, especially when it comes to electricity. Good luck with your build :-) LLL Quote
deckard9 Posted April 1, 2013 Author Posted April 1, 2013 Thank you. All your help is highly appreciated. The power issue was the biggest problem and that is solved now! :) Quote
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