Need suggestions for a portable battery for a 250 W DC motor
Need suggestions for a portable battery for a 250 W DC motor
(OP)
Hi everyone! I need to find a portable power supply system for a specific motor and I don't know how to go about it since I have no experience in this area. My motor is a brushed DC motor from Maxon, specifically RE65 (model number 388987): voltage = 48V ; Nominal power: 250W. I want to use the motor in its "short-duration operation" mode, where I extract more power from it over a short duration of operation.
My requirements for the battery system are:
Power: 300W
Voltage: 48V
Portable
Preferably small and light
Most batteries I have researched are of the AC type. and the DC ones have very low voltage and/or power rating. Please suggest the type of battery I should research and also some companies that may supply the battery-or at least where to look. Please also suggest If I should prefer a different voltage too. The power however cannot be less than 300W. I have attached the product catalogue page for reference. Thank you!
My requirements for the battery system are:
Power: 300W
Voltage: 48V
Portable
Preferably small and light
Most batteries I have researched are of the AC type. and the DC ones have very low voltage and/or power rating. Please suggest the type of battery I should research and also some companies that may supply the battery-or at least where to look. Please also suggest If I should prefer a different voltage too. The power however cannot be less than 300W. I have attached the product catalogue page for reference. Thank you!





RE: Need suggestions for a portable battery for a 250 W DC motor
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RE: Need suggestions for a portable battery for a 250 W DC motor
Keep in mind that it might be easier to switch motors at any point in the design.
RE: Need suggestions for a portable battery for a 250 W DC motor
And it isn't a drone project. But, this pathway might be helpful for me to find the battery that I need!
RE: Need suggestions for a portable battery for a 250 W DC motor
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RE: Need suggestions for a portable battery for a 250 W DC motor
Worth mentioning, you'll need to include safety features to protect equipment and people. Those powerful batteries can bite.
RE: Need suggestions for a portable battery for a 250 W DC motor
Keith Cress
kcress - http://www.flaminsystems.com
RE: Need suggestions for a portable battery for a 250 W DC motor
My project is basically a lifting device, so it operates only for the short duration of lifting from H = 0 to 1000mm in around 15s. So cycle - wise , 300W is used per cycle. And right thereafter the device will not be used for a considerably large amount of time.
I was also looking at batteries used in electric bikes- they have adequate protection already and many of the batteries fall within my power and voltage range. Would this be a good area to look at, or is this also "overkill" ?
RE: Need suggestions for a portable battery for a 250 W DC motor
You'll see some very heavy gauge wiring being used, because providing a higher supply voltage is even more of an inconvenience than high current. It should be easy to work out the optimum voltage (and thus current, and thus necessary battery solution); just try a few options. It's likely to be a lower voltage that matches available Li-poly packs, or several packs in series.
RE: Need suggestions for a portable battery for a 250 W DC motor
RE: Need suggestions for a portable battery for a 250 W DC motor
If it's too long, I would suggest conventional alkaline D-cell type batteries. While D-cells are not specifically rated in terms of large discharge currents, they can do it. A typical AA battery can dump 10A for short durations, ~5 to 10 minutes. This is how most RC cars operate, and why they need to recharged so soon.
This sort of problem is all about margins, which is why a more complete set of requirements is mandatory.
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RE: Need suggestions for a portable battery for a 250 W DC motor
Two of those are typical packs for 12V and 24V applications and that's the 14.4V and 25.2V packs respectively.
The most commonly found Li-Ion battery is the 18650 which supplies about 2600mAhrs. You can draw about 2C from them possibly more for a short time.
If not hand held I'd be reaching for Lead Acid batteries as they can dish out a lot of current for a short while, are probably 1/5th the cost, and chargers are simple and cheap. No protection and charge balancing circuits are needed as they are for Li-Ion applications.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Need suggestions for a portable battery for a 250 W DC motor
As long as your capacity is sized for the idle time discharge, then you should be good to go. As an example, you could get: http://www.ebay.com/itm/MaxAMPS-11000mah-40C-25-9V..., which could theoretically stand idle for a 18 months and still provide at least 12 operations.
I used extremely conservative numbers:
> 40A*15s
> 50% derate capacity for high current
> 5%/month self discharge
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