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lentner3

18650 idea

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Ok so here’s the premise. I have an autistic cousin that’s obsessed with Tamiya. He has his own tt01 but can’t use it himself as he’s not able to manage the batteries and charger etc. So it got me thinking. Why not create a simple set up with 2 18650 cells in a battery holder and a simple wall charger for it like the old AA style chargers. Will these cells be able to cope

with the current draw of a 540 motor if I gear it down a little and ball race the whole thing for him. Basically try and make it like a QD chassis

I was thinking something like this

https://www.ebay.co.uk/itm/203190753855
 

and this

https://www.ebay.co.uk/itm/183061475059

Any thoughts or ideas would be appreciated. With this setup I could show one of his live-in carers how to charge the battery. It won’t need to last too long. But at least he won’t need to wait 3-6 month between bashing sessions when I get the chance to see him. No one else in his home is competent enough to do it with him so I though I’d think outside the box.

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I'm sure it will make the car go but I can't imagine those spindly wire spring terminals will pass much current and could get hot and deform the plastic holder.

What's the difference between getting his carers to charge the 18650s vs., say, an old NiMH charger where you just plug the battery pack in and press a button - 20 minutes later it beeps and you disconnect it, or easier still, the old slow chargers where you plug them in and they just trickle charge overnight? 

They usually come with tamiya connectors which are foolproof and easy to use. Obviously you are limited to using NiMH batteries but these would arguably be a better choice anyway as lithium batteries like to be treated a certain way or they degrade. NiMH batteries on the other hand can take lots of abuse in my experience. 

Edited by rich_f
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I think this is a fascinating project and for the best cause.   I'm just thinking out loud however..  How about trying to embed a charger into the vehicle where the user would then only have to plug the vehicle into the wall to charge it?

 

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I got my son a WLtoys buggy a few years back that had a dual 18650 battery pack that powered a 540 can motor. Run time was about what an old NiCd 1500 pack would do. Granted, the batteries were likely as low quality as the WLtoys car.

As a vaper, I’ve gone thru a few dozen 18650’s over the past 6 years.  Based on my boy’s car and thru vape gear, I can say that 18650 batteries have enough juice to power a 1/10 RC if the conditions are right.  

At 3.7V each you’ll have to disable the LiPO cutoff in the ESC.  Batteries with a high discharge rating will be critical from a safety standpoint.  Sony 25r batteries are regarded as a high quality battery.  MXJO, Imren or most any 18650 flat-top vape battery you find in the vape community will suffice. Most 35A 2500mah batteries are reasonably priced. Nitecore battery chargers are foolproof safe.

Battery sleds are easy to find.  I have no idea if the contacts in the sled will move ample current to run the car very long at open throttle, or if you can solder wires to the batteries without damaging them internally. If you use the 18650’s I’m very interested in the results. The potential is definitely there.

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10 hours ago, rich_f said:

I'm sure it will make the car go but I can't imagine those spindly wire spring terminals will pass much current and could get hot and deform the plastic holder.

What's the difference between getting his carers to charge the 18650s vs., say, an old NiMH charger where you just plug the battery pack in and press a button - 20 minutes later it beeps and you disconnect it, or easier still, the old slow chargers where you plug them in and they just trickle charge overnight? 

View usually come with tamiya connectors which are foolproof and easy to use. Obviously you are limited to using NiMH batteries but these would arguably be a better choice anyway as lithium batteries like to be treated a certain way or they degrade. NiMH batteries on the other hand can take lots of abuse in my experience. 

The last solution ended up with a NIMH melting through a chair! 😬 hence trying to think outside the box. They really can’t be trusted with much. Agreed the spindly wires are a bottle neck.

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8 hours ago, Killajb said:

I think this is a fascinating project and for the best cause.   I'm just thinking out loud however..  How about trying to embed a charger into the vehicle where the user would then only have to plug the vehicle into the wall to charge it?

 

I like the idea I might see if I can find a 2 cell charger that fits. Switching between discharge and charge might be tricky.

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6 hours ago, SupraChrgd82 said:

I got my son a WLtoys buggy a few years back that had a dual 18650 battery pack that powered a 540 can motor. Run time was about what an old NiCd 1500 pack would do. Granted, the batteries were likely as low quality as the WLtoys car.

As a vaper, I’ve gone thru a few dozen 18650’s over the past 6 years.  Based on my boy’s car and thru vape gear, I can say that 18650 batteries have enough juice to power a 1/10 RC if the conditions are right.  

At 3.7V each you’ll have to disable the LiPO cutoff in the ESC.  Batteries with a high discharge rating will be critical from a safety standpoint.  Sony 25r batteries are regarded as a high quality battery.  MXJO, Imren or most any 18650 flat-top vape battery you find in the vape community will suffice. Most 35A 2500mah batteries are reasonably priced. Nitecore battery chargers are foolproof safe.

Battery sleds are easy to find.  I have no idea if the contacts in the sled will move ample current to run the car very long at open throttle, or if you can solder wires to the batteries without damaging them internally. If you use the 18650’s I’m very interested in the results. The potential is definitely there.

As far as I was aware the cut off is identical to lipo. No 🤔

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This one looks a bit more robust.

https://www.ebay.co.uk/itm/133668880522

another problem I just thought of is what happens if the esc cut off works but the battery switch is left on? Will the esc still slowly drain the cell? I’ve had this with transmitters on the past when the kids have switched them on with out me realising. They cut out by there is still a slight draw on the battery. If left a day or so it ends up under voltage 

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51 minutes ago, lentner3 said:

The last solution ended up with a NIMH melting through a chair! 😬 hence trying to think outside the box. They really can’t be trusted with much. Agreed the spindly wires are a bottle neck.

Really?! With the overnight slow charger I got with my first rc, the battery never got more than warm to the touch. Even the 30 clockwork one with the dial didn't get it got enough to melt anything. 

Personally I think the batteries themselves will be fine (and yes if you wire them in series as I suspect you will, the lipo cut-off if the esc has one will be fine - necessary in fact. You don't want them to go completely flat) but the holder is the problem. 

Sure you can replace the spindly wires, but the thin spring contacts remain. They have a very small contact surface with the battery so are not ideal and could get hot. 

I'm not sure how confident you are with electronics, but you could solder up a 2-cell pack (get cells with the tabs on) and somehow wire in a USB power pack charging circuit board (you can buy them from poundland and remove the circuit board) so it can be charged using a regular phone charger. You'd have the rc power connector separate. Two 18650s are smaller than a normal rc battery so there would be room to put it in an enclosure with the USB charging socket exposed at an accessible point so that it doesn't even need to be removed from the car. Not entirely sure how this would work as you'd have the cells wired in series and in parallel, so you'd have to put in something to break the series connection when the charger is connected and break the parallel connection when disconnected, like a high current mosfet or relay. (there may be other, better ways to do this, I'm not an electronics engineer, but using a phone charger like this would be pretty simple to use if it worked)

 

Alternatively you might be able to find some 18650 holders that are rated to a higher current. 

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I’m an electrical engineer ( not

electronic 😉) so comfortable with that suggestion. The last link I sent had a better looking contact.

I really like the power bank idea. I’ve got several old ones kicking about I could harvest. The main challenge is the switching and the speed of charging. 🤔

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spacer.png

As stated you should have 12 awg silicon heat resitant cables ( thinnest would be 16awg). If uses in RC car you should also rather make a propper battery with balance cable or Balance bord (balance cable if you are about to use propper smart chargers like Sky RC )

2S 10A 8.4V 18650 Li-ion Battery BMS Protection Board | POWER GEN - YouTube

You can get all needed very cheap on AlicExrpess,  i made a 18560 3s battery with balance cable for use in my FlySky controller (so i do not need to use 8 AAA batteries). 

On picture is Shrink plastic, aws silcion cables, battery holders, Nickel plate, safty + pole tape (i also have another heat resistant tape. You can find many good (and bad) how to videos on youtube.

 

Edit: If you new to this i would see it much safer to buy Nimh battery with a propper charger for use in RC car, i believe this is not a safer solution .... 

 

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Hmm its just the same as the powerbank suggestion, so i only showed you how to build them yourself. The cables in you solution would melt with so much Current, same as i have in the picture:spacer.png

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If you want to keep these boxes what you should do is shown in this picture with thicker Silicon cables.spacer.png

This so you can charge with a propper smart charger ofc 

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The point is that the people who will be charging the batteries won't be able to use a proper rc charger, so he's looking for methods to charge that are extremely simple - it is not necessarily to use 18650 cells. This was just an idea as they are simple to charge for the layperson. 

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23 minutes ago, rich_f said:

The point is that the people who will be charging the batteries won't be able to use a proper rc charger, so he's looking for methods to charge that are extremely simple - it is not necessarily to use 18650 cells. This was just an idea as they are simple to charge for the layperson. 

Ok, so then i suggest whats done in the Video and add a balance Bord with usb in, so you can charge like you would a phone.

Or as originally suggested use the 2xBattery box and change to thicker silicon cables only. Then charge in li-ion charger as Lentner first wondered and suggested, have not tested but it should work. I would also use Xt-60 plugs as in the picture and not Tamiya plugs, when we are talking safty

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1 hour ago, rich_f said:

The point is that the people who will be charging the batteries won't be able to use a proper rc charger, so he's looking for methods to charge that are extremely simple - it is not necessarily to use 18650 cells. This was just an idea as they are simple to charge for the layperson. 

Thanks for trying Rich.

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I see....you need the most elementary battery and charger system imaginable to prevent the house from being burned down.

Perhaps adapting a portable hand tool charger and battery into the car would work.  Those are rugged, simple and can only plug in 1 configuration. I'm thinking maybe a Dewalt-powered Tamiya....

 

DW.jpg

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11 minutes ago, SupraChrgd82 said:

I see....you need the most elementary battery and charger system imaginable to prevent the house from being burned down.

Perhaps adapting a portable hand tool charger and battery into the car would work.  Those are rugged, simple and can only plug in 1 configuration. I'm thinking maybe a Dewalt-powered Tamiya....

 

DW.jpg

I have thought about using something g similar. Makita do one but it making the female battery compartment to suit that fits in the chassis would be difficult.

definitely an option though. It would mean running 3 cells but I can probably work with that. Get a higher turn motor in it too.

I didn’t realise Dewalt did a 2 cell version. That’s very interesting

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On 3/4/2021 at 4:22 PM, lentner3 said:

Any thoughts or ideas would be appreciated. 

How about a different rc like the tamiya mini lunchbox but fully customize it for him. Those can run on AA batteries and he wouldn’t even need to charge it. Just get a bunch of cheap dollar store batteries.

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7 hours ago, DaveBuildsRC said:

How about a different rc like the tamiya mini lunchbox but fully customize it for him. Those can run on AA batteries and he wouldn’t even need to charge it. Just get a bunch of cheap dollar store batteries.

I’m afraid he had this same car we built together about 15 years ago and he’s very attached to it. Otherwise I would do exactly that.

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12 hours ago, lentner3 said:

I have thought about using something g similar. Makita do one but it making the female battery compartment to suit that fits in the chassis would be difficult.

Rather than make a female battery compartment in the car, could you splice in another battery connector (e.g., a tamiya connector assuming that's what's on the esc at the moment) in parallel to the regular contacts? You'd have to attach it internally and have it exiting the battery at the opposite end to allow it to be plugged into the original charger.

So the carer would charge the battery using the original contacts and original charger, and then they'd remove it and put it in the car and use the other connector to connect to the esc. 

That deWalt battery looks like it would fit in a tt01 without much trouble. Might need part of the wider end part filing off. 

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12 minutes ago, rich_f said:

Rather than make a female battery compartment in the car, could you splice in another battery connector (e.g., a tamiya connector assuming that's what's on the esc at the moment) in parallel to the regular contacts? You'd have to attach it internally and have it exiting the battery at the opposite end to allow it to be plugged into the original charger.

So the carer would charge the battery using the original contacts and original charger, and then they'd remove it and put it in the car and use the other connector to connect to the esc. 

That deWalt battery looks like it would fit in a tt01 without much trouble. Might need part of the wider end part filing off. 

Yep that would work. but I’ve looked at the charger and battery and they are quite expensive. I have a few of the makita ones spare but they are 3s which is probably too much. I’ve got some supply’s on order so I’ll post an update one way or another.

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Quick update. I’ve come up with a solution I’m really happy with. An old drill battery that had a single duff cell. (actually fine now it’s been cycled on it’s own). A simple robust cell charger and an 18650 2 cell holder. I used a modified table-02s with a resistor to create a 6v cut off which is suitable for these cells. I will do some testing to find out what voltage the charger is happy with. So far so good. Worked out perfectly from a size point of view and seems to have ample capacity. Also I’ve got 4 cells to give him. Plus Super light to boot.

many other input appreciated. 
image.thumb.png.3e831e89d5aeb4b95baa7ec9e40d3a1a.png

 

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