Motor 5292 - Battery Problem?

[Frootloop]

Hello fellow Eurobricks-Users,

this is my first post here, after i revived my interest into lego. I recently got hold of 2 of the fabolous rc buggy-motors 5292 (resp. 8287) for 27 euro each. Judging by their exterior, both seem to be in good shape.

Because so far, I only had the 9398-power functions, I could connect the motors only to an old battery box from the set 8287 with an 5306bc015 cable i got from amazon. So, the connections fit, and i have put 6 1,5 V AA Batteries (fresh from the store - no AAA) into the box and was looking forward to the amazing rpm-speed of the motors.

Unfortunately, both behaved similarely: They started to spin for a second and then the speed decreased for another second; then they came to stop. I tested them separately. Although i do know about the huge power drain these 5292s have, I was pretty disappointed and thought that they were out of order. But I did get them from different sources (one seemed to be from a buggy-set and one came with the 8287-box), and they behaved similarely. Also, other threads for the 5292s provided info about the relatively good endurance these pieces have over time.

Now, as I am new (again) to this field, I suspect that the failure may be the power from the batteries (maybe I should take the best and freshest ones?), but I exchanged them for different ones (from the same brand).

Any clue or hint would be welcome!

Thanks,

Frootloop!

[Carsten Svendsen]

This is because there is a current resistance component in your battery box. You would need to get a hold of some old battery boxes or the RC Unit for it to work properly.

Also take a look at this thread: http://www.eurobricks.com/forum/index.php?showtopic=87319&hl=battery

[Frootloop]

Thank you very much for the diagnoses and the links and tipps. I have several questions as a follow up and would appreciate replies for

1. These old battery boxes ... do they have a "lego chiffre", just like the 4x4 offroader is the 9398?

2. In the thread that you have linked, the bridging of the thermal swith (is it this current limitation component?) was mentioned by youself: "bridge the thermal switch on box A (Just solder a small wire from one end to the other on HL5L)". Does this work fine resp. safely, and would it replace my need to find the "old" battery boxes or the rc-component? The soldering-effort seems to be pretty low which is why I would prefer this way.

3. What is this "lipo mod" about which you were talking about in the thread?

Thank you very much for your patience?

[Frootloop]

There is another disturbence, that I sensed within the ... logic: I did use the very battery box provided in the 8287-set: http://www.philohome.com/batteries/bat.htm says, its 54734, and it wouldn't work. Would the set require, that the the motor and the box are able to work properly together?

[clarkdef]

Thank you very much for the diagnoses and the links and tipps. I have several questions as a follow up and would appreciate replies for

1. These old battery boxes ... do they have a "lego chiffre", just like the 4x4 offroader is the 9398?

2. In the thread that you have linked, the bridging of the thermal swith (is it this current limitation component?) was mentioned by youself: "bridge the thermal switch on box A (Just solder a small wire from one end to the other on HL5L)". Does this work fine resp. safely, and would it replace my need to find the "old" battery boxes or the rc-component? The soldering-effort seems to be pretty low which is why I would prefer this way.

3. What is this "lipo mod" about which you were talking about in the thread?

Thank you very much for your patience?

So this battery box can't run one motor? That would be strange considering it was packaged with 5292...

What kind of setup are you thinking of running? Are you going to use PFunctions? If so there are two roadblocks that prevent full use of even one of these motors.

I thought about starting a thread on how to do the lipo mod, or what batteries to use, but I didn't because it can be dangerous there are a few things to go over. The lipo mod is also only useful if people already have the equipment to charge the batteries, if you were to buy the stuff it may cost you as much as the lego lipo, except of course you would have a more versatile setup for future applications. So PM me if you are interested in knowing.

[Frootloop]

So you understand my irritation? I bought it as a used component, and probably either the battery box (yes, it is the box for which you have provided the image) or the battery aren't alright. For the beginning, i wanted to try directly coupling the motor to read axes, then later couple them with pf-xl-motors. But the very first thing needs to be: get those pieces going one by one.

Before I would consider you taking much time to explain the lipo-mod by PM, there is another question: The Lego LiPo has only 7,4 V power output, but the 5292 requires 9 V ... is this the reason for the need for a Mod?

And I'd like to take up the question nr. 2 from my earlier post: Would bridging the thermal switch component solve the problem with the 5292 as well (but only for the case of AA-batteries)?

[clarkdef]

1. No the Lipo mod I have done is also 7.4v. The average Lipo could power 8 buggy motors at once it is the best battery in any situation, because it is also light weight, though to power 8 motors you would have bridge the thermal sw, becareful because shorts can lead to instant fires.

2. Hard to say, depends what batteries you are using, some AAs are high drain some are not. the batteries you are using may of caused the slow down if they are low discharge, but im gonna say it was the thermal switch slowing progress, bridging this will help your cause, but if you then go through an IR and remote then that also has current limits.

[Frootloop]

Thanks for the tipps, so far. I'll try different batteries as well but will eventually switch to LiPo.

So for the theory:

According to Philohome.com, the thermal switch cuts in at a minimum of 750 mA, having a capacity of 1100 mAh with 7,4 V. In the Lego LiPo. the current limitation cuts in at 1000 mA, although the same resettable fuse in included. Nevertheless, according to http://www.philohome...s/motorcomp.htm the 5292 has a current under load of about 1,4 A; no-load current is 160 mA. So how is it, that the Lipo may power up to eight 5292s?

But also, comparing these numbers and given the fact that I used the battery pack suplied with the 8287 without putting load on the motor, there seems to be a problem with the pack (thermal switch kicking in to soon; or pack itself is damaged) or the motor (such as: mechanical problem that leads to higher internal friction and thus to higher current flows which prompt the thermal switch to kick in). In any case, I will definitely try other battery packs as well as soon as the extension cable for the 5292 (= cable adapter) arrives. If that won't solve the problem, I will contact the retailer.

Anyway, I am defnitely interested in the LiPo-Mod and will PM you, thanks!

Edit: Crap, I can only PM after 10 messages...

Edited October 8, 2013 by Frootloop

[aol000xw]

You could take a mobile phone charger for example, in the range of the 5-10 volts and capable of 1.5+ amps and wire it to the motors just to verify they work well. Probably they do, I think the battery pack is suspect here.

A Lipo battery can provide plenty of current, it depends on its specs. The Lego one can power one 5292 at full power, but that's all, it trips at 1.5 amps.

I myself got a PF battery pack moded to use Lipos,

• 3s2p
  
• 9.6 volts
  
• 1400mAH
  
• 10C continuous / 20C Pulse
  
• 14 amps max sustained current draw
  

So my pack can power 10 5292 motors. .

[clarkdef]

Thanks for the tipps, so far. I'll try different batteries as well but will eventually switch to LiPo.

So for the theory:

According to Philohome.com, the thermal switch cuts in at a minimum of 750 mA, having a capacity of 1100 mAh with 7,4 V. In the Lego LiPo. the current limitation cuts in at 1000 mA, although the same resettable fuse in included. Nevertheless, according to http://www.philohome...s/motorcomp.htm the 5292 has a current under load of about 1,4 A; no-load current is 160 mA. So how is it, that the Lipo may power up to eight 5292s?

But also, comparing these numbers and given the fact that I used the battery pack suplied with the 8287 without putting load on the motor, there seems to be a problem with the pack (thermal switch kicking in to soon; or pack itself is damaged) or the motor (such as: mechanical problem that leads to higher internal friction and thus to higher current flows which prompt the thermal switch to kick in). In any case, I will definitely try other battery packs as well as soon as the extension cable for the 5292 (= cable adapter) arrives. If that won't solve the problem, I will contact the retailer.

Anyway, I am defnitely interested in the LiPo-Mod and will PM you, thanks!

Edit: Crap, I can only PM after 10 messages...

Sorry I confused you, 8 motors can be powered using the lipo mod I have done, IF the thermal is bridged, NOT going through an IR, NOT the Lego lipo . My lipo can also be charge to 8.4v not to sure about the Lego lipo

My lipos are 750mah at 35c, so working out how many amps they can supply is easy, 750mah as you know is the capacity and the C is how fast they can be discharged.

.750x35=26.25 so that means 26 amps can be drawn from the battery, so that works out to be around 8 5292's, the battery will go flat very fast lol and the Lego wires would need to be doubled, tripled up otherwise they will burn out. Not that anyone would do this it's merely an example man.

So my pack can power 10 5292 motors. .

Except when they need to go up hill

[Frootloop]

You guys are pretty helpful, when it comes to what could be done.

First of all, the problem has been solved: Fortunately, the extension cable came in the afternoon and as soon as I connected the recent battery packs to the motors, they were fine - high rpms etc. Although I do know that the pack has limited output, I consider it good news as I now know that the motors are fine. So, indeed, you were definitely right.

@Clarkdef: aah ;) but if the LipoMod is directly attached to the motor ... which thermal is to be bridged?

The whole discussion indeed has led me to the conclusion that trying out a lipo mod could be a good idea. After a little research on the specs and searching for examples on youtube, I seem to understand the general idea and general way it is done. But I wonder: With how many motors can the LipoMod can be attached SAFELY? (e.g. your one, ClarkDef)

PS: A general thread on LiPo-Mod is appreciated :-)

[clarkdef]

You guys are pretty helpful, when it comes to what could be done.

First of all, the problem has been solved: Fortunately, the extension cable came in the afternoon and as soon as I connected the recent battery packs to the motors, they were fine - high rpms etc. Although I do know that the pack has limited output, I consider it good news as I now know that the motors are fine. So, indeed, you were definitely right.

@Clarkdef: aah ;) but if the LipoMod is directly attached to the motor ... which thermal is to be bridged?

The whole discussion indeed has led me to the conclusion that trying out a lipo mod could be a good idea. After a little research on the specs and searching for examples on youtube, I seem to understand the general idea and general way it is done. But I wonder: With how many motors can the LipoMod can be attached SAFELY? (e.g. your one, ClarkDef)

PS: A general thread on LiPo-Mod is appreciated :-)

There's only one thermal sw on the PF battery box to bridge, it's HL5L, and then ya you could power a lot of motors. You would have test it because each motor has internal resistance, each motor added would divide the resistance on the circuit, so it all depends on what resistance the battery could handle as a load on itself, I don't know. You will have to try it, but also consider that the battery would have to be kept cool so use good judgement as the PF battery box doesn't have vents. So that should answer question 1 and 2.

I will look at making a thread.

[clarkdef]

Here's some pictures

I should of spent a little more and bought some connectors too, so I could easily take the batteries out

Here is how I charge this setup, it's not too convenient, so ya connectors would of been a good idea

This was just a simple experiment to see how they go in PF, I will redo this but next time I will use one 7.4v battery and just gut out the battery box so it fits and I will make sure that I get some plugs, also a volt alarm so they don't drain down too low as that kills them, the biggest issue could be accidentally leaving the box on which is exactly what I did with the first trial.

If you want speed I think the best idea is to do two of these boxes and put them in series with each other http://www.eurobricks.com/forum/index.php?showtopic=77490&hl=%2Bseries+%2Bbattery That way you can leave all the circuit protection in, it will still work out lighter than one AA battery box.

[Frootloop]

Do these Lipos have to have specific specs in order to be integrated into the pf-battery box?

Thanks for the pictures!

[clarkdef]

Do these Lipos have to have specific specs in order to be integrated into the pf-battery box?

Thanks for the pictures!

Only physical size and of course voltage. Battery can't over amp a motor, the motor draws what it needs, you can over volt a motor though, running it on less volts is always better for it, but they can handle a 100% volt increase.

[Frootloop]

And what's it with all these mentionings about explosions and spontaneous fires with Lipos?

[Carsten Svendsen]

Those warnings are only for people who don't know how to charge a battery properly.

[Frootloop]

Please consider myself as someone, who doesn't know how to charge a Lipo "properly". Does it mean, you should pay attention to not overcharge it resp. charge it not beyond its C, voltage, etc.?

[zux]

Those warnings are only for people who don't know how to charge a battery properly.

I read some time ago that people having experience in electronics and interested in RC models still had fires while charging their LiPo batteries. There is no wonder why there are special bags and boxes for LiPo batteries, where these should be kept while charging.

Please consider myself as someone, who doesn't know how to charge a Lipo "properly". Does it mean, you should pay attention to not overcharge it resp. charge it not beyond its C, voltage, etc.?

I'm not good at electronics, but at least I'd keep LiPo in closed saucepan durig charging process. Edited October 10, 2013 by zux

[Philo]

also a volt alarm so they don't drain down too low as that kills them, the biggest issue could be accidentally leaving the box on which is exactly what I did with the first trial.

Something like this?

[clarkdef]

Something like this?

No an alarm to tell you when the battery is draining too low, as you know if lipos get too flat they die. Something like this http://www.hobbyking.com/hobbyking/store/RC_PRODUCT_SEARCH.asp?strSearch=lipo+alarm

And what's it with all these mentionings about explosions and spontaneous fires with Lipos?

You do have to hang around the battery while it's charging, lipo batteries charge very fast, these little ones maybe 30min. The charger is a smart device it will not over charge, you can do many things with it. Most people are just over dramatic on the lipo subject. A great idea is too change in a pot.

Rules

- When the battery is new do a full chage 4.2v then drain to 3.8v with the battery charger, do this 5ish times, this will run it in

- When charging, doing it in a pot/saucepan is a good idea

- Never charge while un-attended

- Keep cool in high drain situations

- Never leave it in storage at full charge otherwise it will puff and become un-usable (most chargers can drain it to 'storage mode')

- Never drain the battery below 3.4v otherwise it will puff and become un-usable (That's why common sense or a low voltage alarm is a good idea)

[Frootloop]

Well, i think that we have collcted quite an information source for others. I am hoping for a dedicated lipo-mod thread and will definitely continue to hang around. Thanks guys