Hi all, i have this problem: i have a 4x3 battery bank 48V-660Ah/C20 as output. I should connect this bank to a 48V/300A cc motor: how i can protect batteries from undevlotage and short circuit? I thought about a ralays or a similar solution: what do you think? Thanks
should connect this bank to a 48V/300A cc motor: how i can protect batteries from undevlotage and short circuit? I thought about a ralays or a similar solution: what do you think?
-- What's a cc motor?
should connect this bank to a 48V/300A cc motor: how i can protect batteries from undevlotage and short circuit? I thought about a ralays or a similar solution: what do you think?
Fuse will fix the short problem. What's your definition of undervoltage under what load conditions? What do you want to happen at undervoltage? Just go dark? Controlled shutdown? Early warning?
If you have a 300A load, you need bigger batteries. The issue is likely much more complex than you've disclosed.
Not to be a jerk or anything, but if you are pushing 300 amps into anything, I'd suggest hiring an electrical engineer. Your question is so basic that the task is beyond you.
I will suggest you investigate fusible links. You can't have enough protection schemes with batteries. I get mine here:
A fusible link is not a substitute for electronic protection. You need both in the event the electronics fails. Also, you put the link as close to the battery as possible so that should a short occur before the electronic protector, you have some protection. I use welding wire for the power cables. Don Rowe can supply that too if you want.
Based on what you've posted, you can't. In the absence of full specs, the 300A motor is too large for the battery bank mentioned. The initial current surge when you start a motor can be up to 10 times the running current, so we'd have to design for a 3000A surge. It's possible that by specifying "48V/300A cc" you intend the "cc" to indicate "cold cranking" - but we don't know what you have in mind. You haven't posted the cranking amps rating of the battery, so we can't assume it will survive a 3000 amp surge.
So, based on what you've said - or rather what you haven't said - it is not worth even thinking about. If you want a good answer, please post the full detailed specs for the motor, the battery bank, and the application.
Ed
I thought about a ralays or a similar solution: what do you think?
should connect this bank to a 48V/300A cc motor: how i can protect batteries from undevlotage and short circuit? I thought about a ralays or a similar solution: what do you think?
Methinks you might be solving the wrong problem. You can't drain batteries all the way flat or you'll kill them in short order. A safe number is maybe discharge them down to 75% of full capacity. That means your 660 Amp-Hr pile will only deliver 165 Amp-Hr before you have to shut down to save the batteries. With a 300 Amp load, that's about: 165A-hr/300A = 0.55 hr = 33 minutes If that's good enough runtime for your system, just install a timer and shut down after 30 minutes and be done with it.
Assorted DC contactors good for 300A and up. Bigger is better. Use a coulomb counter to calculate how much charge you've used and trigger the relay when the batteries are in danger of going below some threshold.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
should connect this bank to a 48V/300A cc motor: how i can protect batteries from undevlotage and short circuit? I thought about a ralays or a similar solution: what do you think?
If you are handy with electronics you could make yourself a power mosfet switch system. It would take a few mosfets to handle that much power however, you could switch mode the output and do a current monitor to limit the load to 20 amps..
Basically it would be a current mode switch that switches off when current goes over and comes back on with in a short period. The idea is to use the motor as the inductor. The end results should show a nice smooth output with minimum heat from the mosfets and keeping the switching freq low, it shouldn't cause much excessive heating in the motor.
Of course, I am not sure what you mean by a cc motor? Close circuit motor, like an integrated type?
If all you want to do is simply open the circuit then doing a relay with a threshold driver could work however, it'll chatter, because the battery will recover voltage when the load is removed and try again until it gets to a point where there isn't enough to trigger the threshold!
Post back when you have a clearer view of what you need.
Have a good day..
Jamie
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.