View Single Post
Old Jun 12, 2006, 12:38 PM
k1uhf is offline
Find More Posts by k1uhf
Del Schier
k1uhf's Avatar
Joined May 2002
73 Posts
Actually the 0.8 volt 160 A is not a limit, it is a spec.

The limit depends on ohms law. With a "perfect battery" the Juicer may do 200 amps. We do have it fused for 180 amps but a battery would be dead before you could blow those fuses at 200 amps.

We have an FET "on" resistance plus other circuit resistance inside our product. Add the internal resistance of the battery and the associated connections and by ohms law that limits the maximum current.

Below a voltage where our FETs are full on, in order to regulate the current below that voltage we will no longer be able to regulate a constant current.

Our tests with a GP 3300 160 A shows that 160 amps is a reasonable typical spec. That doesn't mean you can't pull higher current from some other cell at a higher voltage. Of course you should not exceed the 500 watt continuous limit for the system.

If it wasn't for ohms law you would be able to pull 500 amps from a 1 volt cell

BTW as soon as we catch up on orders we plan to have a kit for two amplifiers in series parallel for 1000 watts and double the current (half the resistance).

I hope this makes sense.

Thank you,

Del Schier

West Mountain Radio
18 Sheehan Ave.
Norwalk, CT 06854
tel: 203 853 8080
fax: 203 299 0232

Originally Posted by Protocooler
Hi Del, would you maybe think of possibility to get rid of the 0.9V or 160A limit, for short bursts at least ?
The point is that in some competitions like F5B, we are trying to extract as much as a cell can supply, and as you know this typically happens exactly at just half of a cell's nominal voltage. Hence a NimH cell will supply more power @ 0.6V which will likely at close to 300 Amps for the good cells than at 160A where voltage will usually be in the 0.8-0.9V range (depending on t obviously).
I understand we are talking of a niche there,but if the system would allow by pass of protections for just graphing 5 second bursts this would be just enouh to satisfy the craziest
With that we could alo see better if/where there are physical/mechanical or chemical limits to the bursts a cell can really output.

FYI current state of the art 16 cells Nimh pack have been measured @ 3600W+ / 270A at the beginning of a burst inside a F5B glider - this is a very amazing voltage for such high amps but they need to be HOT (~80-85C) ! At the end of the burst ie about 4 seconds later current was still 240A. The poor 2.1 kg "gliders" skyrocket up @ around 240 km/h with this amont of power !
k1uhf is offline Find More Posts by k1uhf
Last edited by k1uhf; Jun 12, 2006 at 04:50 PM.
Reply With Quote