TechnicSummse Posted June 18, 2017 Posted June 18, 2017 (edited) Hello :) Anyone of you got some imformations about the current limitation of the old 9V battery boxes 4760c01 ? [img=] I dont have one yet... but from some pictures i saw, it seem to have the same heat-protection-element then the 2847c01. How many amps does it supply, without kicking in the protection? Thanks for help :) Summse Edited June 18, 2017 by TechnicSummse Quote
dr_spock Posted June 18, 2017 Posted June 18, 2017 It seems like they all use the same 750 mA resetable fuse. http://www.philohome.com/batteries/bat.htm Quote
TechnicSummse Posted June 18, 2017 Author Posted June 18, 2017 The 750mA there are on PF-elements... but im am asking for the OLD 9V battery-box 4760c01 Quote
syclone Posted June 18, 2017 Posted June 18, 2017 (edited) There is no circuit. it is just ON / OFF , nothing else. I've dissasembled one because it was second hand and got some corrosion , and there are simply some metal parts bending when you press the button and nothing regarding protection. Nevermind, it looks like it has some , but can't tell what it is , will post a photo, in case someone knows about electronics... It is a weird circle between the contacts, it seems to be multi-layered. Sorry for picture quality, tomorrow better photos. look at the left wall , between metal parts: Edited June 18, 2017 by LXF added images Quote
bonox Posted June 18, 2017 Posted June 18, 2017 based on what the manufacturers suggest, I doubt you'll get much more than 0.75A out of those tiny batteries anyway. http://data.energizer.com/pdfs/522.pdf http://data.energizer.com/pdfs/la522.pdf the lithium one shows a capacity value using a 1A draw, but if you're pulling that kind of current you won't be playing for very long. Quote
aeh5040 Posted June 19, 2017 Posted June 19, 2017 Indeed, in my experience these 9V batteries themselves are not suitable for high-current applications. I once tried running a buggy motor powering a pneumatic compressor from one - I seem to remember the battery was dead in a minute or so! Quote
mocbuild101 Posted June 19, 2017 Posted June 19, 2017 5 hours ago, LXF said: a weird circle between the contacts, it seems to be multi-layered. That is the current limiter, it's the same as the one in 2847c01. Quote
IstakaCiti Posted June 19, 2017 Posted June 19, 2017 4 hours ago, aeh5040 said: Indeed, in my experience these 9V batteries themselves are not suitable for high-current applications. I once tried running a buggy motor powering a pneumatic compressor from one - I seem to remember the battery was dead in a minute or so! Yes, driving a motor from 9V battery will drain it quite fast. Somehow, technology has ignored 9V batteries, they are still the same as they were decades ago. Quote
Marxpek Posted June 19, 2017 Posted June 19, 2017 Hey @TechnicSummse welcome here ;) this box has one of the worst thermal protectors around (kicks in very fast), this has a older version of the thermal protection, a plate that bends when hot, breaking contact. Since i already know what you want to do here: i will say it again, buggy motors can ONLY be powered fully by the rc-unit, nothing else can bring out their full potential (unless you cheat with the thermal protectors) not even the battery boxes that came with the buggy motor expansion pack or the yellow batterybox (like on 8421) can handle the current needed. Besides that: 9 volt batteries that can deliver that kind of current are rare, since they are moslty made for low power consumption. Quote
TechnicSummse Posted June 19, 2017 Author Posted June 19, 2017 Thank you for tthe answers so far. Does anyone have any hard facts? I would like to see like: "it can support 200mA for 5 min, then it kicks in". If I understand you correctly, this old protection depends on time+current? So, you could take for example unlimited time (until battery is empty) like 100mA, because the protection element cools down faster, then it heats up at this current. But if you take for example 1000mA it would kick in within less then a second? And if taken 500mA it will last for like 1 minute? Do I understand this in the right manner? If so.... are there any values you could deliver to me? ... like time*current=xxx Again thank you for the help. @Marxpek Well i need fresh ideas... and i like to think outside the box ;) Quote
Philo Posted June 19, 2017 Posted June 19, 2017 42 minutes ago, TechnicSummse said: Thank you for tthe answers so far. Does anyone have any hard facts? I would like to see like: "it can support 200mA for 5 min, then it kicks in". If I understand you correctly, this old protection depends on time+current? No, it's very hard to tell... These devices are thermal protections, whose resistance value increases rapidly with temperature. So exact time to trip depends on current, but also initial temperature and on device itself (they have fairly loose tolerances). To get a better idea, look at the trip time curve of the component. For example, this is the datasheet of the resettable fuse in PF devices http://www.bourns.com/docs/Product-Datasheets/mfr.pdf?sfvrsn=24, curve is on page 4. Note that exact model of older battery packs is not known (no marking on the component). Quote
Marxpek Posted June 19, 2017 Posted June 19, 2017 41 minutes ago, TechnicSummse said: But if you take for example 1000mA it would kick in within less then a second? And if taken 500mA it will last for like 1 minute? this is not how a thermistor works, it has a certain setting, lets say a 1 amp thermistor will pass through any current up to 1 amp, if you go over that it will kick in within a second or so, but if you pass 500mA it will never kick in, a thermistor should always kick in within a few seconds of overload to prevent melting wires and shorting/burning wires. The previous best (tested) batterybox can pass 800mA, will trip the thermistor within a few seconds when attaching a buggy motor with some load, there are small differences in the thermistors production making some go to 900 mA and others to 700mA. The newer AA batterybox with the brighter green led, has a higher setting then 800mA, but this has not been tested for exact data yet (as far as i know), but from my own experience: one new batterybox can still not fully power a buggy motor, there are reasons the buggy motor was discontinued, this is one.. Quote
syclone Posted June 19, 2017 Posted June 19, 2017 (edited) Hop[efully these will be useful. As far as I can see the protection can be removed without soldering. (click to enlarge photos) IMG_8715 by Alaxaf, on Flickr IMG_8717 by Alaxaf, on Flickr IMG_8714 by Alaxaf, on Flickr Do I have NASA's 9v batteries or something? Edited June 19, 2017 by LXF Quote
Marxpek Posted June 19, 2017 Posted June 19, 2017 18 minutes ago, LXF said: Do I have NASA's 9v batteries or something? What is the discharge rate on these? they say "high drain" but how high is that? Compared to a normal 9V battery anything over 200mA discharge I consider highh, but a 1000mA is not nearly high enough for a buggy motor. But when i look at the "normal charging time" on the battery that is pretty slow, and this normally correlates to the discharge rates. does it give a fast charging time for it and a C-rating? can it trip a thermal resistor when stalling a motor? Of course you are still only getting 8.4 volts from them, lowering the speed on the motor and also lowering the current being drawn. @LXF and somewhere you are being scammed with the info they provide, there is no way in hell this battery can contain 2000Mah @ 8.4v, most (trusted) battery brands have a value of 150mah up to a maximum of 500mah, my guess is they did some fancy numberwork here and you actually have a 285mAh battery at 8.4v. They went creative with numbers and most likely did something like this: 7 cells @ 1.2v each with 285mah = (7x285mah) 2000mah.. Did you ever do some measurements on these? it is highly unlikely that they will contain the same energy as a battery box filled with rechargeable AA batteries of the same quality..it is just a size thing.. Quote
Marxpek Posted June 19, 2017 Posted June 19, 2017 @TechnicSummse and of course removing thermistors is cheating, but i still do not believe 9v batteries can power a buggy motor.. Quote
syclone Posted June 19, 2017 Posted June 19, 2017 (edited) 12 minutes ago, Marxpek said: @TechnicSummse and of course removing thermistors is cheating, but i still do not believe 9v batteries can power a buggy motor.. I have no idea about discharge rate of these, but I'll build a MOC with them for test. For now, I tried stalling the fast output of a buggy motor withoput success, it just kept slowly rotating The only thing I accomplished is to burn myself ... Edited June 19, 2017 by LXF Quote
LegoTT Posted June 19, 2017 Posted June 19, 2017 Removing the thermistor is cheating, however blocking it with a bush is still 100% LEGO... According Philo the 5292 motor can handle 3.2 A so if a 9V battery can discharge 0.2 A we can sum up 16 9V battery with various cables to prevent heating and go for a 60 secondes round of incredible mechanical power. Which is nice, for a lightweight TT in a small race. Despite the running time, the subjet is interresting for me ! ____________________________________ English is not my native language Quote
Marxpek Posted June 19, 2017 Posted June 19, 2017 4 minutes ago, LXF said: I tried stalling the fast output of a buggy motor withoput success, it just kept slowly rotating It doesn't not need a lot of current to burn your fingers ;) can you attach a wheel or something to the output? when you can trip the thermistor inside the buggy motor that would mean the battery delivers enough power. (but you will need a shunted box, but since you suggested it, you probably have one) Just now, LegoTT said: 16 9V battery with various cables Just now, LegoTT said: lightweight TT These 2 do not really combine ;D Quote
LegoTT Posted June 19, 2017 Posted June 19, 2017 (edited) I have in mind this category of builds (from Paave), with the maximum of work on the mechanical power/weight ratio, regardless the autonomy. I can imagine quick stop like in F1 races to switch battery and beat the chrono. ____________________________________ English is not my native language Edited June 19, 2017 by LegoTT wrong link Quote
Marxpek Posted June 19, 2017 Posted June 19, 2017 10 minutes ago, LegoTT said: Removing the thermistor is cheating, however blocking it with a bush is still 100% LEGO... This is creative, but but I do not agree, you are placing a part somewhere that was never intended to have any parts, even worse, you are blocking a safety measure, especially designed for that purpose, so i do not consider that 100% Lego (solutions), since TLG will never approve this. Quote
syclone Posted June 19, 2017 Posted June 19, 2017 (edited) @Marxpek Just did it, put some lights on the battery box for proof , uploading video. Yes , I cheated the protection already Sorry for sound, but my phone's microphone doesn't work Edited June 19, 2017 by LXF Quote
LegoTT Posted June 19, 2017 Posted June 19, 2017 I think I can understand your point of view, people use cheap pneumatic hoses, Sbrick, Buwizz or RC tires with fantastic results but we can't really argue if it's still LEGO because the limit is different for each person. I cant tell for other but mine is there : you can replace or repair a lego part to the same, you can misuse a lego piece if it is not destroyed. ____________________________________ English is not my native language Quote
Marxpek Posted June 19, 2017 Posted June 19, 2017 (edited) @LXF I oversaw something here... your battery is protected itself... it has probably the same protection built it... and that might kick in here and still provide enough power for the lights, still not prooving anything, all those damn safety-precautions ;D maybe attach a other motor which you do not stall in stead of the lights? that should draw alot more power then the lights (as far as i know the thermistor never really full breaks the circuit just raises the resistance a lot, but correct me if im wrong) Edited June 19, 2017 by Marxpek Quote
LegoTT Posted June 19, 2017 Posted June 19, 2017 Just now, LXF said: I cheated the protection already I'm very interested by these tests. How soft are the wires now ? If they are, maybe it is a good idea to add some another wire. Does the 9V battery is very hot ? Do you smell a scent when you open the BB ? ___________________________________ English is not my native language Quote
Marxpek Posted June 19, 2017 Posted June 19, 2017 @LegoTT Don't forget the motors are protected for overheating as well, in theory this should not be able to melt any wires or do any damage (until you connect something wrong) the RC unit delivers this (and more) power over the same wire without problem. But by these rules of using a bush to block the old thermal resistors, you could also bypass the thermistor in a new battery box by twisting up the legs and put a Lego rubber band on it (or something similar) and then say: it is 100% Lego. to me it is all cheating, fine to do it for a private moc or something. but not in contests or in my case: speed records. Quote
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