Rm1 battery size??

Hector Fernandez · Posted: Sat Dec 15, 2012 6:26 am Post subject: Rm1 battery size??

I have a early Rm1 and need to buy a battery.. Anyone know the correct battery size??

Thanks in advance..

Russell Stevens · Joined: 15 Oct 2012 Posts: 100

I didn't know what an RM1 was, so I looked it up. Double check the size of the battery box, but seeing how it's a Rotax DD2 it should be a (Rotax universal battery) Yuasa YT7BS (or equivilent), or really any 7-9 Ah sealed battery that you can get to fit. The Shorai 9Ah lithium is reletively inexpensive, and is so tiny it can be mounted anywhere. I believe the DD2 is lacking a charging system, and the battery will need to be recharged between runs. Also check the Aprillia RS125 engine out for parts if you aren't running a sealed Rotax class. Same basic engine, and occasionaly some of the bits and pieces are less expensive.
Rusty

Hector Fernandez · Posted: Sat Dec 15, 2012 11:05 am Post subject:

I checked the size of the battery shelf and the yt7bs seems way to skinny unless it's supposed to be laid on its side then it would fit n the box..

Can anyone confirm this..

Should the battery be laid on its side in a RM1??

Thank you

Russell Stevens · Joined: 15 Oct 2012 Posts: 100

Unless you are doing a concours restoration it doesn't really matter. Lay the sealed battery on the side, right side up, however it will stay in the mount without grounding out the leads. You can check with CRG America, they seem to carry RM1 parts (first hit on a google search). Laying the battery flat would lower the CG of the chassis, so it's not a bad idea. Either way you are talking about a couple of tenths for a pro driver, who wouldn't be using a Rotax "Spec" chassis from a few years back. From your posts you are not a pro driver, and just bought a kart from the left coast. The Shori I put into the stock mount of my Kosmic T-11 / Rotax Sr. kart changed the distribution by ~.1% according to the scales. It weighs a significant amount less then the lead battery that was there previously. Worry about fresh tires, tuning (if you are running the engine sealed, and cannot use the adjustible main jet), and conserving speed by picking the optimal line. Battery position won't make as much of a difference, and the karts are not that finicky for those of us in the amature ranks. Enjoy the drive, and learn to tune the powervalve. Mmmmmm that 7500RPM whoosh!
Rusty

Hector Fernandez · Posted: Sat Dec 15, 2012 5:14 pm Post subject:

Thanks Russell .. I have spoken with Dave at CRG .. Great guy..But thought this question could be anwered here..No Im not doing a restoration..lol But im not sure if you are aware the start /shutoff button is integrated into a cover that goes over the battery.. If I don't get the correct battery I would have to Find a way of securing the battery as well as the cover with the buttons... I think it would be easier to get the correct battery so I can use the system it was designed for..

Thanks again

Russell Stevens · Joined: 15 Oct 2012 Posts: 100

No I did not realize that the RM1 chassis had that cool battery box. Finally found a video of one showing the original box, most resources that I have found show the standard rotax button on the nassau panel. It looks from the limited glance I could get that the cover has a latch and a screw that holds it down? Does the box just have a space for the battery, or do they use the battery to hold the top on somehow? It would be wierd for a spec Rotax chassis to require something other then the spec Rotax battery (no?). if it all fits with the battery sideways then that is likely how they intended it to go together. If you get a battery that is (physically) too small you can always pad the box to make it snug.

Have you contacted BRP USA to see if they know for sure?

Nathaniel Dewitt · Joined: 02 Dec 2008 Posts: 109

I'm pretty sure the battery does lie on the side on a RM1.

Hector Fernandez · Posted: Sun Dec 16, 2012 5:44 pm Post subject:

Russel ..I do think it's the correct battery and it needs to go on its side...
Will be visiting CRG America tomorrow will get a battery there... And hopefully confirm how it sets up..

Thanks guys appreciate all the help..

Russell Stevens · Joined: 15 Oct 2012 Posts: 100

Good luck, toss some pictures up when you get it set up.

Nick Weil · Posted: Mon Dec 17, 2012 6:57 pm Post subject:

The battery is the same as EVERY Rotax battery. However, if you don't insulate it with some foam, vibration will likely kill the battery very quickly, especially if you buy the under $60 batteries.
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Nick Weil
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2004 Team USA Rotax Worlds Finals DD-2 Driver

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