Battery Pack - Rechargeabe D? 10,000MAh


#1

I'm trying to figure out if i can power the 3 brushed motors ( on the build list, LCD, and servo from 10 1.2v Rechargeable D Batteries.

I came across these: http://www.batteryjunction.com/bcqusmch4d10.html

I'm new to this power stuff, but would this help last longer while powering the unit?


#2

I guess the C NIMH would work too: http://www.amazon.com/Tenergy-5000mAh-Capacity-Rechargeable-Batteries/dp/B001AYI4IK/ref=sr_1_7?ie=UTF8&qid=1351482269&sr=8-7&keywords=c+nimh


#3

What would be the benefit to having an LCD in the ROV?


#4

Sorry, Meant LED lights.


#5

The Design of the OpenROV is running 8 C batteries. Since we know it is running 12v we know the C's are running in Series.

Thus if we look at Wikipedia: http://en.wikipedia.org/wiki/C_battery

"The voltage and capacity of a 'C'-size battery depends on the battery chemistry and discharge conditions. Alkaline 'C' batteries can hold up to 8,000 mAh, rechargeable NiMH 'C' batteries can hold up to 6,000 mAh, and zinc-carbon 'C' batteries usually hold up to 3,800 mAh."

We can figure that powered by C batteries we can expect 8 hours of 1amp draw or 6 hours of 1amp draw depending on if the batteries used are ALkaline or NiMH rechargeable.

You are asking about switching to D sized 1.2v batteries. As you already know since your planning on running 10 of them instead of 8. Since you also will be running these in series you already know your mAh @ 10,000. Your looking at replacing a 6K-8K mAh battery pack with a 10K mAh battery pack so you should have more than enough power. You will need to design your own battery packs since the D's won't fit the the space of the design (C's) and they are going to weight enough more that you will likely need more balast.

This is just IMHO on paper since I don't have a kit and am just going by the info on this site.

Also, based on your motor inquiry post I believe your planning to run brushless motors, not brushed.


#6

Thank you Dan! That really helped me get through some breakthrough in my understanding how the battery system works. Yes, You were correct, Brushless motors. I think I'll stick to the C. Since i can get more batteries that way :) I cant wait till more items come in.


#7

I appreciate these discussions. There is the other recent thread also talking about batteries, the li-ion 3.7V batteries in C form.

http://www.batteryspace.com/LiMnNi-Rechargeable-26650-Cell-3.7V-400...

There will be performance benefits to going with Li-ion? Regardless of capacity? I couldnt find current ratings for alkaline batteries, I saw that for AA it was 0.7A. The Li-ion ones linked to above are 4.0A. The motors we use certainly will appreciate that I would think.

Now as for dc-dc converters i have just a little experience playing with some 7.4V to 5V converters for some usb stuff.

From whats listed just on batteryspace, not doing a huge search, it looks like we might have to go down to six and not eight of these 3.7V cells? The upper limit on some of these small little boards is like 26V.

http://www.batteryspace.com/dc-dcregulatormoduleinput6-26voutput3-5...

this is a little bigger and max 24V.

http://www.batteryspace.com/dc-dcregulatormoduleinput6-24voutput3-5...

Will these things even fit into the electronics tube? The first one is pretty tiny so maybe? Or are there some series vs. parellel things we could do?


#8

Could the winning recipe be to wire the two 4x3.7V "series" tubes (14.8V) together in parallel? Then apply an inexpensive pcb like the following to regulate to 12V.

http://www.batteryspace.com/dc-dcregulatormodulefrom13-168vdcto12-132vdcselectable4arated.aspx

BUT the board is massive, 4" long. BUZZKILL


#9

Frank,
I was just about to bring up the LiMnNi. Power regulation is definitely an issue, but that's something we've been talking about with CircuitCo and we can figure out a solution on a small PCB. My friend Colin Ho was explaining to me how the Li batteries could essentially turn ROV into a bomb when it gets, so it needs a pressure release valve.

Also, they're heavier than alkaline batteries so ballast becomes an issue.

i think the battery/power discussion is a great one to have. I think, collectively, we'll be able to come up with an awesome and elegant solution for the next version.


#10

hmm the li-ion degassing (I guess thats what happening?) is something I wasnt aware of. Yes a little pressure release stopcock and I wonder what the p/n would be :-)


#11

I'll probably stick with rechargeable since I'll only be snorkeling with the unit. How much life do you think the unit will give with 8 5,000mah c batteries?

Thank y ou again!


#12

Depends how hard you're driving it. Anywhere between half hour to 1.5 hours.


#13

It'll be mostly surface to 10 feet since we are snorkeling.