Lego 'Mars' rovers and battery power questions

[mooffle]

Yesterday I came across a used lego Mindstorms NXT and with all the mars rover Perseverance landing hype today decided to jump on it. My dad is coming over later to watch the live stream with my son and I while we rover up in the living room.
However the one I got did not come with the rechargeable battery module and instead uses 6 AA batteries. We also got out our much older lego RCX to rove around with (because all proper NASA missions seem to have robots in pairs) and this also uses 6 AA batteries. OOF, my battery budget may become NASA sized quick. My question is what are some good replacements for 9.6v peak power on these systems? AA rechargables might be acceptable if I have to but the peak voltage is less at 1.2v, and while the bots do work with them, performance probably suffers. I'm handy enough with a soldering iron and dremel that I have no real hesitation to mod the things but I have no idea where to start looking as far as chargers ans battery packs.
Random google image attached with the battery pack opened (this guy modded for a stationary plug) this is the space I have to work with on the RCX, NXT is pretty much the same.

 

[Funkworks]

I've used rechargeable AAA or AA in Lego bots and had no issues, so I'm not sure mods are worth it. The solution you have in mind might not be available.

 

[mooffle]

I've used rechargeable AAA or AA in Lego bots and had no issues, so I'm not sure mods are worth it. The solution you have in mind might not be available.

That's good to know, and frankly if you and others have done it then its not much of a concern. Was the battery life and motor performance degraded significantly from what you saw? I did read some forums on the subject and answers were kind of all over the place. Might have been because the RCX is 20 years old and battery tech was not what it is now though.

 

[dhbarr]

14500's fit in the same holder, check your system to see how many V it will take ( there's usually a fairly broad range ).

 

[Funkworks]

Was the battery life and motor performance degraded significantly from what you saw?

I never compared. I just use a regular set of rechargeable Energizer batteries, and I never replaced them (I remove them to recharge and put back the same ones in). Power has never been an issue.

 

[Zeus-cat]

Too bad it doesn't come with an authentic plutonium power source. I wonder how many lead Legos you would need for shielding?

 

[mooffle]

Looks like I'm overthinking things then, chart below on the 2 bottom lines show typical 1.2v rechargeables vs 1.5 regular batteries and the voltage over time is similar. In my case maybe favoring the rechargeable as the voltage starts lower but stays more constant.


Speaking of real rover power, no I don't have plutonium but I do have some solar house lights. Maybe a Sojourner/MER type build is on the bench next... Then all I need is an L2 cert to send it up in the dessert.

 

[mjennings]

How are you programming the RCX brick? I dug out mine a while back and couldn't find the cd what I found on the web was that even if I had the CD it doesn't work on newer OSs.

 

[mooffle]

I suppose I use a 'period accurate' computer. My work had an old laptop that I rebuilt and reinstalled windows 98 on. One usb port has definitely been a limitation but adds to the fun. I also work IT so fidgeting with this kinda junk is another hobby of mine. Overall I wouldn't say I recommend it.

The limitations are sort of true. The program itself apparently runs on modern OS's just fine with compatibility settings adjusted, though I haven't bothered to try it myself. The real issue is that there are no 64 bit drivers for the usb to IR tower so you really need a 32 bit system to run that, or the rarer serial tower which may work if you have a modern pc with a serial port or card.
Realistically the best way to still use these bots is to pick up an old Windows XP box with a 32 bit pentium. Basically the cheapest tower you can buy used would work. If you want I can send you the software or a link to the lego download (I'd have to find the link again otherwise I'd post it now)

 

[mjennings]

I have an old tower that still works. If you can't find the link let me know and I'll PM you an email address. Thanks

 

[mooffle]

I believe this is the link. You will probably want the RIS v2.0 iso. On win98 I have to run the program from CD still.
https://biomediaproject.com/bmp/files/LEGO/cds/Mindstorms/RIS/

 

[mjennings]

Thanks!