Regulated power supply question

[broken ed]

In short; would a regulated power supply replace the function of a battery?

I have a 24 volt, 350 watt DC motor that runs off of two 12 volt (in sires, 24 volts), 20 amp hours, deep cycle sealed lead acid batteries. Could you, for example, run an 110 volt, 1000 watt, generator with 20 amp regulated power supply to power the motor?

Watts / Volts = Amps, so 350 Watt motor divided by 24 volts equals 14.58 Amps.

Back in the 1970s we would connect car stereos and CB’s radios to a RadioShack 12 volt regulated power supply, never had a problem. We where always told to use “regulated power supplies.”

This is on a mobility scooter and wondered if you could increase the range this way.

Thanks in advance for any thoughts or help.

 

[Trebor English]

Yes, but . . .  

The Radio Shack power supply was probably 13.8 volts.  Twice that would be 27.6 volts to simulate fully charged batteties.  Twice 12.5 is 25 volts.  That might be better.  

Motor starting currents can be high.  My fridge uses 4.5 to 6.5 amps 12 volts into the inverter normal running amps.  I have measured the starting surge at up to 80 amps.  My 20 amp power supply not only doesn't start the compressor, it shuts down.  

A mobility scooter has a variable speed drive.  Usual starting surge considerations probably don't apply.  It is probably different.  If the power supply is only 24 volts the control circuits might give a low battery warning particularly if high current pulses drop the voltage.  

I have seen people carry a generator on a golf cart and hook up the charger when the battery runs down.  This is crazy bad for battery life to run it till it won't go then hook up the charger and keep on driving.  

With a particular power supply there is one way to find out.  Try it.  You don't know and can't find out anything about the surge intensity and duration characteristics of the scooter or the power supply.  

Keeping the battery in the circuit and using the power supply to maintain a float level would leave the surges to the battery but the long term running current would come from the power supply.

 

[John61CT]

The function of a battery is to store power, accept charge now and let you use the energy later.

A power supply gets power from shore and converts that higher-voltage AC to low voltage DC.

So one does not replace the other.

Seems to me you're asking

> Can I use a power supply without a battery in place **as** a buffer?

And the answer to that depends on the specific load device's characteristics, and those of the specific model power supply, (or RV "converter" or high-amp batter charger, all of which have very similar functionality) which you are asking about.

It would probably help if you can fill us in from a "big picture" POV what exactly you're trying to accomplish, why you would want to avoid putting a battery in the circuit, and maybe the context wrt boondocking vs mains availability.

 

[broken ed]

Wow - thanks Trebor English. You given me a lot more to to consider. I've measured voltage across these batteries and yes, 13.8 each fully charged. I wouldn't do RadioShack, Amazon has 24 volt regulated power supplies. And I hadn't considered leaving the batteries connected to the system. I thought I would install a cut-out switch or just remove them, but what you have said makes sense and like it better. The batteries could become kind of a reservoir.

There is a speed controller for the motor, near as I can figure, not unlike speed controllers in electric bicycles. This motor, unlike electric bikes, is a brush motor and wondered about continuous running beyond normal range. Starter motors in a car, for example and I was thought, gets it's cooling from none use.

I don't drive anymore and can't ride a bicycle. My two modes of transit are a walker and my mobility scooter. Mobility scooter(s) range are very limited. I've seen folding solar that appear (just) small enough to carry on the back of a scooter and have controllers that provide 24 + volts. Solar would be more desirable because of noise and pollution of a generator, but with the size solar I could carry I'm sure it would take all day in full sun to charge batteries that would only take me 5 miles.

Thanks again

 

[John61CT]

Yes solar would take a lot of area to get enough amps for fast charging.

Lithium batts hold a lot more usable energy per pound, but are expensive and can be complex to care for.

A gasoline powered scooter may be best, or keeping several sets of batteries charging and rotating between them.

 

[tx2sturgis]

Thinking outside the box! I like it....

But....

Adding a power supply and a generator would be fairly heavy, and possibly somewhere around the same weight and bulk as 2 more batteries. Plus you would have to listen to that generator, which might be an issue indoors or at night. 

My suggestion would be to add 2 more batteries in a series/parallel configuration to approximately double the range.

Or, you could install a battery switch (A/B) so that you would have the equivalent of a 'reserve' to get you back to your starting place. You would need to double up on the charger capacity (or double the charge time) to replace what you have used.

 

[broken ed]

Thanks for your feedback  John61CT,

"what exactly you're trying to accomplish"

Increase the range of a mobility scooter from 5 miles to at least 25 miles, with preferably the ability to do it all over again the next day.
--------------------------------
Specs;
Current range is 5.5 miles on two 12 volt, 20 amp hour deep cycle, sealed lead acid batteries connected in sires for 24 volts.

Motor is bushed, 350 watts, 3.5 Amax, 3600 R.P.M., H Class

Charger output is rated at 24 volts, 2400 mA (overnight charge)

The mobility scooter has a hitch and could (rated) to pull a trailer with an additional 100 to 150 pounds
-------------------------------

Base on my math and testing, every 20 amp hours will get you travel of five miles, so an additional two 100 amp hour batteries connected sires for a total of 120 amp hours at 24 volts should get to 25 miles. This of course is in ideal temps, batteries in good health and does account for increase weight.

I guess if I had all that, a generator could recharged 120 amp hours overnight, but I thought if a regulated power supply would work, bypass all that.

I had considered Lithium batteries, but could the same charger for the lead acid batteries to used to charge Lithium? I've search many times for gas power mobility scooters, and they're just not out there. There is a one mobility scooter that has batteries and generator. But they don't specify what brand generator and I'd rather buy a Honda 1000 watt. Your idea of rotating batteries may be the best rout, I could use trailer to keep everything going, away from the mobility scooter. The more I write about this, the more I'm thinking it's just not realistic.

Maybe the question should be, whats your plan if you couldn't drive or ride a bicycle anymore? I'll post that question in Miscellaneous Vehicles.

thanks

 

[tx2sturgis]

Maybe the question should be, whats your plan if you couldn't drive or ride a bicycle anymore? I'll post that question in Miscellaneous Vehicles.

I like this topic, and while I have no experience with these scooters I know someone here locally who rides her electric tricycle all over town. 

I don't know the exact setup, but it is long and stable for driving legally on the local roads, and yet narrow enough to fit in the doorways at stores so she can ride in and do her shopping. 

It has a canopy over her head, a tall flag and flashing lights and beepers, and a basket for carrying groceries. I would only be guessing, but I assume it has a range of at least 10 miles...maybe more. 

She can walk but only with extreme difficulty, and only for a short distance with a helper, or a walker or cane.

Possibly an electric tricycle might be your answer, with room on board for bigger batteries.

 

[John61CT]

Key question is, what is your charge source going to be?

The other is, is you desired range from the van, straight out then back, or in the vicinity of the van.

If the van is on shore power then more/bigger batteries swapping out during the day would work.

A generator will only get the batts to 80-85% full in the first few hours, at least 3 hours more to get truly full, but very low amps, solar is the better solution for that part.

Leaving a genny running unattended won't work.

You will need a much more powerful charger either way, but select your batteries first.

Big batteries, if lead, are *very* heavy. Enough that may be difficult to handle, slow down the scooter too.

Googling does show gas powered scooters, but I dunno squat about that.