Choosing lithium battery brand...

It seems that the best brand is optipower - especially with the discounts through the forum but we am just looking at the different options available. I know this has been discussed before but can't find a specific answer to this query.

What would be the downsides of buying something like this from a lesser known brand:

https://hobbyking.com/en_us/turnigy-...lipo-pack.html

or

https://hobbyking.com/en_us/zippy-co...lipo-pack.html

Does it come down to reliability, safety or performance. Note that you can buy two of the above for the price of one optipower battery. Are optipower twice as good?

Thanks again for the help.

General reply will be to go optipower. However I would much rather have 2 batteries than one etc.

Everyone has their little horror stories with each brand, I have not had sucsess with the zippy series, dead cells etc but some people have a gold track record with them. All my robots over the past 2 years have run the hobbyking nanotech series without any fail, a couple of people have had issues with them but so long as you spec your battery properly you shouldnt have any issues.

A decent charger will make your battery care much much easier too I will add.

Quote:

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Originally Posted by harry hills

A decent charger will make your battery care much much easier too I will add.

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Any recommendations for an appropriate charger and PSU for the above batteries?

I got one from hobbyking that has done me grand. 4 chargers in one although they do two charger and single charger units. Quite honestly I can't bring myself to go back on their website as it's a horrendous mess but the charger has a black body with an orange / yellow trim.

With regards to PSU, the simple answer is, one that will supply enough current. You can find many bench top power supplies that will do the job but if you are electrically minded you can convert a PC power supply for the job (it's not usually all that hard).

I use the product below for charging. Can charge all 4 batteries inside Dystopia at once, aswell as having a wide range of chemistries ect. Only issue is the interface is not the most user friendly at first, but once you work it out its pretty easy to change around the individual settings.

https://hobbyking.com/en_us/turnigy-...k-charger.html

With regards to PSU, im afraid i cant help you - mine is not longer commercially available.

Another +1 for the TQ4. I have one - am hoping to get a second once they're back in stock at my normal supplier as one is tied up with one of the businesses I work for.

I have the older HK 4*50W and the newer Turnigy Quadkore 4*20A. A single 400W makes the collection complete.

Team RCC has a few more 2*200W and 400W Turnigies in the selection.

Power supplies. A few 600W HK units (no longer available) and a 24V/12V 100A monster that never was commercial.

I'm wondering if a cheap Chinese PSu can be seen as a "battery" that can be used in series or parallel... That would give options. Those "iron" LED PSu's are cheap and dependable.

Many thanks gents. Nice to know I'm on the right lines. ;)

https://hobbyking.com/en_us/turnigy-...lipo-pack.html X4

https://hobbyking.com/en_us/turnigy-...k-charger.html

https://hobbyking.com/en_us/turnigy-...y-uk-plug.html

https://hobbyking.com/en_us/turnigy-...harge-box.html x2 (anyone tried these? are bags better?)

And a handful of https://hobbyking.com/en_us/polymax-...airs-20pc.html

Hi, having come from gel batteries to NiCad's in previous robots I found this very useful in bringing me into the 21st century, and deals with different makes....

http://www.rchelicopterfun.com/rc-lipo-batteries.html

Seems to be good and in depth advice.

Some good reading there. Thanks for sharing.

Further to this thread (and continuing my tradition of Bad Robot Ideas), could I ask how easy it is to rewire something designed to run on mains electricity to run on LiPo batteries? My present design involves mounting a 1600W demolition hammer on the robot and setting up a power supply for it (it's designed for 230V, which means 7A current is required). What kind of batteries - and how many of them - should I be looking at getting?

I'm going to go beyond the battery question and suggest that this would be a bad idea - it would be against the rules which set a maximum voltage lower than that which is required.

An entirely reasonable point. Might have to import one from the States, then, since they're on 110V over there. =]

In my defence, however, demolition hammers have been used on combat robots before - the RW Wiki informs me that a hardy beast called Roter Osche competed with one powered by an 8.5HP petrol engine back in the days of the Second Wars. Admittedly, it was a superheavyweight that weighed in at ~167kg, but that can probably be put down to '90s-era materials and build styles. =]

The other problem is that that is most likely using an AC motor which either won't run or if you're lucky may be a universal motor that can run on DC but would see reduced power and have a lot of inefficiency to start with.

Could you not just whack an inverter on it? Or would that just increase the weight to a ludicrous degree?

An inverter large enough to power a 1600W demo hammer weighs around 5.6Kg and is quite bulky (going on a 2Kw model for a safety margin). It would be far better to fit a brushed or brushless DC motor onto the hammer mechanism.

Why bother? RC brushless motors come up to 10 kw packages in affordable* form.


Not the first roboteer that makes his own batterypowered tool from a 240V mains machine
(it's very easy to fit a 50mm outrunner in the body of a cheap anglegrinder), working that route should be a lot cheaper and inside the rules.

*affordable is a fluid term, different for everybody.

The cheapest way I see is to replace the AC motor with a series wound startermotor from a junkyard.

All excellent points. Thank you very much! I admit that my electrical engineering knowledge could be written on the back of a postage stamp in quite big letters, but my fiancée's old flatmate Tim apparently builds and flies multi-rotor helicopters (I intend for both to be team members, assuming they're willing, of course). He can handle that - I have a pronounced spasm in my right arm, which I fear will not mix well with soldering irons, TIG welders, or precision cutting equipment. =]

Thanks again for helping me out. My overall plan is to follow maddox's advice and disembowel the demo hammer accordingly, then shock mount it as well as I possibly can, The central idea behind the weapon is to couple active damage from the hammer strikes (the 230V hammer I've been looking at strikes at 2000bpm) with the sheer amount of strikes through the metal chassis of the target spreading vibrations through the bodywork and knocking stuff loose inside. Hopefully it won't also deafen everyone in the building, but who can say? =]

Perhaps look at air hammers as an alternative? Possibly from a DC compressor or even from low pressure CO2? Not sure how practical it is but cheaper and maybe lighter.... https://www.amazon.co.uk/Silverline-...rds=air+hammer weighs 735 grams....

That's an interesting idea, Yat. Given how light they are, I'm almost envisioning a bank of them on a kind of jaw-like setup, clamping onto the opponent from the top or sides (I've often wondered why more vert crushers didn't use additional horizontal clamps to properly corral their victims) and hammering away on them until something comes loose inside. I'd kinda love to see that sort of thing on Battlebots, actually - let's break Deadblow's record for most hits in a match! =]

bear in mind that if you clamp onto an opponent and vibrate away, the same vibrations will be going back through your machine. Need to design it accordingly

Indeed. I envisaged a very steep wedge at the front, say 50-60 degrees, with the horizontal clamps mounted fairly low on the robot to hem the opponent in and the multiple air hammers on a bar coming down from over head. Ideally, this would direct the vibrations down through the opponent and into the complicated, sensitive, electronicky things, of which I am assured the opponents will have several. =]

the more processes, the more batteries, wiring, power you use.. and weight, so you forfeit weight in your hammer i guess. 100kilos seems a lot in heavies, but having weighed up armour its a lot harder than you think to keep it down.

Weight was never really a concern - the moving bar (think Mousetrap rather than, say, Arnold Arnold Terminegger) was a mount for air hammers, which are fairly tiny. Like, the one linked in this thread previously weighed ca. 800 grams. The idea is much more clamp than hammer. I agree it's probably overcomplicated, but it's definitely unique - even if it is beyond my engineering skills at the moment.

The previous sentence implies I have any engineering skills; this would be what we in the trade call a "big fat porky pie". =]

Are you thinking of putting Air hammers inside each pincer !! that' be quite cool to see.

I wasn't initially, but that would work too! A couple of little ones mounted on the grabbing claws, plus ca. 5-6 on the bar coming down from the top. With that amount of vibration power, something'll probably get shaken loose... plus the paintwork'll be completely ruined. Which is of course the most evil damage it's possible to inflict. =]