Has anyone done any testing with different batteries on the monsterborg other than rechargeable AA's?
I've got the 10 pack of 2500mAh NiMH batteries, but i really don't enjoy having to pull them off and keep charging.
I was curious of if there is any difference between say
12 V (10x1.2v) @ 2500 mAh
vs
11.1 - 12.6 with 3 x 3.7v 20a IMR's @ 3000 mAh
When it comes to the Thunderborg board and motor speed.
As long as the current draw is about what the board advertises (5A / 2 channels, max 10A) these can handle it perfect, and are pretty cheap around. Vaping is a thing here, and its a common battery for that, so easily attainable here in the states (I can not speak for cultural norms over your way). There are a bunch of 3000+ mAh batteries around $5-7 USD, and the charge boards (one per battery, chain-able) seem to be about $8 USD on amazon.
Has anyone tried this at all before I invest some time?
If no one has, I'm going to draw up a holder (which would include charging circuitry, plug, and a switch), and with the magic of my 3d printer, print one. Some quick estimates put it as possibly a little smaller than the 5x2 AA pack, and then I would not have to unzip the entire pack to spend a ton of time charging. I'm researching boards for a 3 cell BMS solution to charge on board.
I've taken a little bit of time to graph out distance to time using standardish batteries.
Remaining charge was at about 12.4v after these tests.I'm adding this here, as for any battery change, it would be good to understand if there is a performance change with that. (The ThunderBorg board looks spec'd way above what the motors can handle from your datasheet, spec sheet says 0.716A, board says it can deliver 5A per channel)
The motors seem very linear, i still need the accelerator wired in to see how long it takes to hit target speed. But I figured this would be some interesting data to start off with.
I'm using 4x 18650 batteries to give a nominal 14.8V, approximately the same as 10xAA's. I've found it possible to fit 12x18650's in the space between the motors so there's scope for different arrangements eg 8x@30V or 2x6@22V. The thunderborg controller will handle up to 30V (or is it 36V?). Beware comparing the motors rated current to the module spec 5A/channel, what you need to worry about is the stall current, a surge which occurs when the motors are stopped ie from a standing start there will be an instantaneous very large current through the controller before the motors start turning, a bit of a grey area for designers but generally you do want a controller rated much higher (eg 6x,8x,10x) than the rated current of the motors.
Regarding the charging arrangements, and you can try this at your own risk, I've found it possible to charge the 18650's as a bank in situ using a small 12V motorbike charger, although I do tend to charge them individually by preference.
The zip tie battery arrangement is one major flaw in a very good system, and it continues to haunt racers to this day with random power cuts and reboots being a major concern. I've found in the past that by using multiple rubber bands you can secure the batteries to the thunderborg board much more securely (aot to the zipties squeezing the entire battery/pi combination onto the chassis with only lateral securing) with much less risk of accidentally disconnecting them in a collision, and it also made them much easier to remove from the board when charging was needed.
I'm not sure if this forum is being monitored any more since they moved us all to the discord chatroom, so you might also like to ask the question on there. There is also a monsterborg specific forum buried somewhere on the piborg site where you might also find some answers.
That's good info, I'm glad to see someone else has played with the 18650's, so that gives some positive feedback on direction. I'm just in awe of fitting 8 of those under the monsterborg.
Have you noticed a difference in performance between the AA's and the 18650's? The rechargeable AA's are only 1.2v a piece, so i think with only 3 of the 18650's I wouldn't be missing much.
For the integrated charging I was looking at a set of TP4056 circuits, one per battery.
Thanks for the info on that there's a discord, i didn't even notice that, i'll also look around for that monsterborg forum.
Hey picos_pit_crew,
Not sure what your battery arrangement looks like, this is what I had come up with.
Triple 18650, hung off the base-plate. The blue cap just snaps on and every thing seems sturdy.(the original white one was a touch loose), so when charge time comes around, I just pop off the cover and pull out the batteries. I've been driving it around using my phone to control it (I have a java rest endpoint server running on it to enable that), and it's stayed put well even with my light abuse.
There is a vape shop near me, and I found these batteries there- They're rated for 30 amp continuous, so the stall / peak isn't a concern at all.
I'm looking forward to the summer series, I've already paid my dues, and I'm playing with hardware right now to prepare.
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