Battery advice for new Tamiya Bruiser

[s4n1ty 1]

I recently got back into R/C cars and picked up the re-release of the Bruiser I could never afford as a kid. After doing some research I chose a Futaba 3PM-X to get the 3 step switch to control the gear box and 2 Futaba S3010 servos. Not sure if one was necessary for the gear box vs a standard servo. I locked the rear diff and left the front unlocked since I'm probably going to be running mostly in low 4WD or low 2WD. For the ESC I chose a Novak 1835 Eiger 2S/3S Crawling Brushed ESC. I'm leaving the stock motor in for now which is a 540. The last things I need are the battery packs and a charger. I'm not exactly sure what my options are based on my setup. My super old Tamiyas used to run Nicd batteries I believe. I'm interested in getting decent run times longer than 10-15 minutes.

[MetBoy 22]

Your story sounds strangely similar to mine, only mine re-started 15 years ago, and has stretched to quite a few models since then. (Don't tell my wife!)

I would be in the same position as you only an original Bruiser came along and is stealing my attention away from my re-re.

You have an excellent setup, I approve of it all! Great radio, servos cannot be too big in my opinion. ESC should give you scope to move to brushless (not sure you would want too), and can easily drive some high wind crawler motors should you want some more torque.

If you want runtime then you have to go with Lipo, and given you are sticking with 540, 2S will be fine, not sure the 540 would take a 3S, I guess it would. (2s = 7.4v, 3s = 11.1v)

The re-re Bruiser has a tray for a standard NiMh/Nicad stick pack, like you would have used back in the day, if you want to leave that unmolested, just measure it and head to HobbyKing and get the highest capacity Lipo you can that will fit in the space, stickpack shaped lipos are harder to find and not always exactly the same size. To be honest, I am planning on using a soft pack lipo in mine, it will only be getting some gentle running, and I am not worried about it, 5000-6000mah or more should fit. Should give you plenty more than 10-15mins. I have heard of people opening one side of the tray to allow larger packs in. The more mah's the more runtime.

High C rating packs will not hurt, but probably not strictly necessary. It represents the packs ability to deliver current, small would be 20C (20 x packs mah rating, so for a 5000mah, that is 100A constant current) and big would be 90C, that is a lot of current!!

Chargers are breeze these days, a reasonably priced 6A four button Lipo charger should keep you out of trouble, might take a while to charge larger packs. Sky is pretty much the limit from there, there is always a bigger and better charger. Really cheap are worth avoiding, but really expensive is not necessary either. My opinion anyway.

You will need to make sure the ESC is set to the correct low voltage cut off for whatever battery voltage you choose as over discharging is one of the guaranteed ways of killing a Lipo. I run my 2s lipo's to 6.6 volts, a good rule of thumb is never to discharge below 20% capacity, so only use 4000mah of a 5000mah pack. Takes a few charge cycles to work this out, the chargers tell you how many mah it puts back in.

Of course you can always go back to NiMh batteries if you wish, as infrequent as lipo fires are, they do happen, looking after your batteries does reduce the risk. A 3000mah 7.2v NiMh batteries are still easy to get, runtime will not be as good obviously. Back in the original Bruiser days, many would piggy back two 7.2v packs to achieve similar. You could easily get 6000mah of NiMh joy, assuming two stick packs would fit on top of each other on the re-re, though not sure this would work.

This reply is getting wordy, most important thing, have fun building it and have fun driving it!

Look forward to hearing how you go.

Cristian..

[Nitomor 2122]

Congrats on the Bruiser, it's an awesome build.

The Core RC lipo fits perfectly in the tray and is a good spec too. Some round stick lipos like the HPI don't on account of being a couple of mm too long.

If you're in the UK, Modelsport sell them here;

http://www.modelsport.co.uk/core-rc-4000mahr-7.4v-30-60c-2s-lipo/rc-car-products/388538

I use it in mine;

ps. Good choice using the 3 position switch for gearchange, I think that is definately the way forward with this, pay attention to the EPA (end point adjustments when you set it up) so the servo isn't buzzing still after changing gear.

Also there isn't low 4wd and low 2wd, the option is 4L, 4H and 2H. If you're looking to do crawling type activities, you may want to consider the optional beadlock wheels and slipper clutch. I left both the diffs open on my shelfers but I plan to have a good play with the runner when I build it! I am going to be running an Axial Crawler ESC on that one when it eventually arrives from being on back order!

[s4n1ty 1]

Thanks for the info. I picked up a Tenergy TB6B charger and a Venom 2S 7.4V 20C 4000mah Lipo battery to start with.