That only will help if the battery voltage significantly drops under heavy load.to give a power boost when needed.
It shouldnt matter as the Caps will have a voltage charge, 20-40 volts higher than the battery voltage and feed to the motor only, which is why I need to isolate it from the controller. *There are you tube vids out there that show using a Super Cap bank instead of a battery to start a motor. Thats the kind of power Im looking for, but need specifics on how to set it up for my 60 volt config. as a booster.That only will help if the battery voltage significantly drops under heavy load.
Have you determined that it does?
Thanks for this awesome input. Any ideas on Diode selection .... *tips for installation?Tentative theory (simulated):
15 Farads appears suitable. It might last for ten seconds giving 1000 W initially, declining to 700 W.
Current draw is over 16A therefore it should be a gang of capacitors in parallel, say each carrying an Ampere. Each wire should be sized large enough to carry its share of current.
22 gauge for 1 Amp.
10 gauge for 17 Amps.
My simulation shows a capacitor alone providing power. Not shown is the battery pack.
View attachment 190074
Do you mean you are going to put the 60+(20V) across the "drive and motor"...the motor must surely be a BLDC, and so you cannot just put voltage on it...the voltage has to go through an inverter drive, then to the motor.it shouldnt matter as the Caps will have a voltage charge, 20-40 volts higher than the battery voltage and feed to the motor only
Ebike circuitry starts to border on automobile specs. The diodes I once saw installed in our car alternator were 'top hat' shape, something like 50 Ampere rated. The mechanic pounded the old ones through holes in a heat sink and pounded in the new ones.Thanks for this awesome input. Any ideas on Diode selection .... *tips for installation?
The battery is actually fine. During a fast acceleration take off, or a take off with heavier load, the amp draw goes way up and the battery shows less available power for those few seconds. What Im trying to do is likened to hitting the nitrous switch on an ICE engine, extra power for a short burst. Any ideas on how I can better achieve this is welcome and appreciated.Ebike circuitry starts to border on automobile specs. The diodes I once saw installed in our car alternator were 'top hat' shape, something like 50 Ampere rated. The mechanic pounded the old ones through holes in a heat sink and pounded in the new ones.
2 Watts is expected heat dissipation in your case as a diode carries 17 Amperes. Depending on length and frequency of use you might only need minor heat sinking.
If your battery pack is declining, then trying to draw that much more power from it shortens a charge. Maybe you can manage in that case. (I would want to try to extract as much power as the batteries hold).
Now the idea of adding 'a few volts' to battery voltage implies a revision in your goal, to add a boost or buck-boost converter.
An Ebike store would want to sell you new and more powerful batteries, but they also might have advice about modifying your present hookup, because it's taking a chance of doing something wrong.
You have the idea. Im kind of following what you are saying. Any chance of a one line drawing for what you explained? Thanks a ton !You could put a voltage sensor on the main battery...then when it drops in voltage as you draw extra power.....
One way may be to have a second battery of some 100V or so....then when the voltage sensor reports low battery volts on the main batt,
(becuase of the extra current being drawn)
you get an
ON/OFF controlled buck converter (output current controlled) to shovel say 20Amps into the main battery output bus.
It would have to clamp at 20A (or whatever is appropriate), and obviously not overvoltage the main batt.
It must be clamped to the Amp ratings of your circuit otherwise it'll smoke.
On/off controlled because this is cheap, simple, and can respond instantly to the need for extra power...and wont overshoot in its
current delivery.
If Im reading your drawing correctly, what you are showing is a voltage sensor seeing the 30V and switching automatically, or is that a manual switch situation. The 7 and the 3.6 are resistance values? Forgive my ignorance. Also, would a shotsky (sp?) Diode be the best fit for this?You can keep a capacitor charged from the battery during normal running, then reverse its connection so its voltage adds to a drooping supply voltage. The extreme load receives a 'boost' just when it needs it. To do this you press a switch at a critical moment of your choosing.
10 F might yield a ten second 'boost' if you add the drooping battery voltage. You must let up the switch after those few seconds. After the battery resumes normal running voltage, it takes a minute for the cap to charge back up.
View attachment 190092
OK I found this on a you tube video (not my drawing) . This would simplify alot, although I do like your drawing. In this case the caps always go thru the controller, in which case I would need to match the cap voltage to 60v (60-66% range). Most 10F super caps are 2.7v so I would need to series 23 caps together. If I do series them, the output is still 10 F ? is that correct ? Do you think this will work ?You can keep a capacitor charged from the battery during normal running, then reverse its connection so its voltage adds to a drooping supply voltage. The extreme load receives a 'boost' just when it needs it. To do this you press a switch at a critical moment of your choosing.
10 F might yield a ten second 'boost' if you add the drooping battery voltage. You must let up the switch after those few seconds. After the battery resumes normal running voltage, it takes a minute for the cap to charge back up.
View attachment 190092
I takes about 10 seconds to reach full speed. However, the Amp draw is high on a fast take off (sometimes a fast take off is safer for entering busy traffic) and the batt charge meter will drop from 100 to 25% if I max the throttle from a full stop. It recovers after about 10 seconds of letting off. A few times I have had the breaker trip after running it for a while (30 mins plus) then doing a fast take-off. I would be looking for the Cap bank to take the load for the first 5 - 10 seconds to smooth out the draw from the battery.How long does it take you to reach full speed? What was it new?
What would do you need it to be? In seconds.
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