I got a a check today that I wasn't planning on, it fits the bill for a pc680, but Im not sure of something. While the car is running, does it power the same as a large battery? For example, I have a car stereo and a water pump for my water injection. Do the small batterys work exactly same or is there no enough power to work heavy accesories?

I think its more a matter of the alternator being efficient enough to keep the charge in the battery, am I right? Thanks.

 

The only problem is starting in cold weather (cold cranking) and using when the engine is off. I run a custom stereo and air with no problems (with engine "on") but it won't start if I leave the radio on even for a few min after the engine is off. You may have the money for the battery but what are you going to hold it down with?

 

well it comes with a metal case. I was thinking to weld a bracket to it.

 

^ uhm, you mean like "L" brackets? The metal jacket is not removable. I'm not McGyver, so i'd be afraid of welding a battery. You can buy the BMK (battery mini kit) from NTech engineering. Basically the battery, a replacement metal tray and a strap to hold it down. I was using a Hockey Puck with the OEM hold down bar but it was cheesy and would work its way loose.

Oh the battery is now in my Honda and i'm using rubber straps with metal hooks to hold it down. I found those at the auto parts store. I'm not sure if it will work on the RX7 though.

 

you have a link to the NTech thing? I was thinking of ordering rotorextreme's also.

 

http://www.micromanx.com/goble/rx7/batcrane.html
http://www.odysseybatteries.com/accessories.htm
The RotaryExtreme's looks nice I Can't figure out how the battery is "held" down. It looks like a box but no strap ot tie down. http://www.rotaryextreme.com/minibattery.html

 

I think for the 235 for the n-tech I'd pay 250 and get the polished battery box from rotoryexreme. But I really thought batterymarts metal battery tray was a seperate piece. Eveyone kills my dreams on this forum

 

David,

I have the Odessey PC 680 mini battery kit. It's is held down by the battery boxc and a nylon strap that you cinch down.

The thing works fine once you get the car started. I also have a stereo with a decent 450 watt amp running and things are fine.

The only problem is that the battery doesn't have much reserve power. Meaning that if you leave it parked for more than a week, you'll need to recharge it. My Fd is my daily drivier so it'isn't too much of an issue. But don't expect to play the stereo while you work on the car with out the engine running...

John

 

where did you get yours? Does the batterymart one come with the strap or is that something that we just getto from home depot? Thanks!

 

Hey David, whatever you do, make sure the battery is securely held down. That way, you'll pass tech when I finally drag you to an autocross....

 

I bought mine used from a guy on the forum along with my M2 Lrg IC & UIM & TB(extra, for polishing). The strap isn't highly engineered. It's just a nylon strap with a buckle thingy attached to bottom of the battery box. You could easily rig one together.

 

The alternator supplies the 'power' for the electrical systems while the car is running. THe battery is just for starting, or to allow you to sit and listen to the radio/etc with the engine off (conditions where you do not have the output of the alternator).

The exception is if the electrical systems overwhelm the max output of the alternator. I don't think you'll have too much of a problem given the WI is not constantly on all the time. Of course, if you have 6 amps in the hatch....

 

The PC680 battery with the metal jacket can be removed from the metal jacket. It's glued on there. You just need to insert a metal strip and cut the hot glue loose.

My mini battery kit is attached the same way but I use high temp 500F silicone instead of the hot glue that's used on the metal jacket. It's very secured.

For the ntech battery kit, they just take the battery out of the metal jacket and spot weld a very thin bracket at the bottom of the metal jacket. One of my customers had the Ntech battery kit and the spot welds broke off so he purchased my battery box instead, which is made of thick wall aluminum and TIG welded.

For the nylon strap tie down, you can buy those from http://www.mcmaster.com.

So if you want to save some money, you can just buy the PC680 battery with the metal jacket and weld on a bracket at the bottom. The wall on the metal jacket is very thin so you can't TIG weld it the whole bracket onto the box or the whole box will distort. You can only spot weld it but then the spot weld might break off. Hope this helps.

Chuck Huang