I can’t go the distance

Discussion in 'General Electronics Chat' started by Help Me, Mar 16, 2008.

  1. Help Me

    Thread Starter Member

    Mar 16, 2008
    13
    0
    I have two electric scooters that run on two 12 volt 15 AH (I assume that’s 15 amps) batteries for a total of 24 volts and 15 amps. These batteries are sealed lead acid. Each scooter has a 500 watt motor and a 24 Volt fully potted Smart Power Microprocessor with relay protection. The scooters can go a maximum of 12 miles (depending on the weight of the rider). I weigh about 200 pounds (twice as much as my son). The scooters can hold a maximum of 240 pounds. My problem is that when I go riding with my son, I can only go half the distance as he can. We have to switch scooters after a few miles so that the one I was originally riding can make it back to the starting point.

    Consequently, I’ve asked three electronic technicians that I know to give me suggestions on increasing the distance of the scooters. Two of them told me that I could use two 12 volt batteries with more amps. I was instructed to connect the two batteries in series and then connect the series in parallel with the original batteries. The other technician suggested that I buy batteries like the original ones and use a toggle switch to select the additional batteries when I need the extra power.

    Subsequently, my question is "which suggestion is better?"

    I like the suggestion of the first two technicians. However, I’m not sure what kind of 12 volt batteries with higher amps to buy. One of them suggested Lithium Ion batteries. Unfortunately, the batteries would cost more than the scooters! Therefore, I’ve been searching for less expensive batteries. I know that car batteries are 12 volts with high amps. I saw one with 12 volts and 450 amps for only $59.

    Can I use 12 volt high amp car batteries with the scooters? If I can, do I need two batteries or can I use one? The reason why I ask is because I only have room for one battery on each scooter, but I could possibly mount two. Can I connect these batteries in parallel to the original 12 volt 15 amp batteries? Can I recharge this setup with the 24 volt 1.5 amp recharger that came with the scooters? Should I disconnect the original batteries since I can’t go far with them and use only the additional batteries?

    I would really appreciate any answers and suggestions that might help me. Please keep in mind that I have very limited knowledge in Electronics.

    Here's a link to more info on the scooters that I have:

    http://www.currietech.com/html/schwinnPopup/07_S750.html


    Thank you!
     
  2. recca02

    Senior Member

    Apr 2, 2007
    1,211
    0
    HA HA your problem is more like a conundrum which one may find in competitive exams.
    I hope someone with more knowledge will help you soon.

    http://www.allaboutcircuits.com/vol_6/chpt_3/2.html
    http://www.allaboutcircuits.com/vol_6/chpt_3/3.html

    First see if those links can help you further.
    AH means Amp(ere)- hours: gives the number of hours the battery will work at that ampere...As far as I know using the battery at half the rated ampere means they will
    last twice as much
    this will give you better info...http://www.1st-optima-batteries.com/amp_hours.asp

    I think those links will solve most of your difficulties understanding the problem.

    IMO instead of letting only one battery supply the load it will be better to have to better to have two(or more) batteries in parallel supply the load.
    This will help you increase the Ampere ratings of the combination
    The load is shared equally and the more number of batteries you connect in parallel the more miles covered.(and you wont have to keep switching)

    If you will use two 12 volts batteries (and if load demands 24V) then you will need to connect two 12 volts in series to raise the voltage...this however does not increase the ampere ratings and also batteries in series does not decrease the load on them and they will only last as much as the A-h of single battery.


    Hope this helps.
     
  3. Help Me

    Thread Starter Member

    Mar 16, 2008
    13
    0
    @ recca02

    Thank you very much for the info. Only being able to go about four miles takes away from the enjoyment my son and I derive from riding the scooters. Consequently, I need all the help that I can get!

    One of the diagrams found on the info that you referred me to looks exactly how a technician told me to connect the additional batteries to the scooters.

    http://sub.allaboutcircuits.com/images/05082.png

    However, I’m not sure what batteries to buy and how many to buy. Can I use this 12 volt car battery with 525 amps (click on the specs option):

    http://www.sears.com/shc/s/p_10153_12605_02830170000P?keyword=car+battaries


    From what you posted, it appears that I need two 12 volt batteries for each scooter. If I understand the Amp Hours info that you referred me to, two of these car batteries should power a scooter for about 35 hours at 15 amps. What I don’t understand is how the 500 watt output of each motor factors into the equation. Nevertheless, I found some info on a 36 volt 1000 watt scooter motor running on 24 volts at 666.6 watts:

    http://www.thesuperkids.com/10wabrmofors.html

    Scroll down to features and read the output info. The motors on my scooters are made by the same company except they are only 500 watts. If a 36 volt 1000 watt motor can run at 666.6 watts on 24 volts, I have to assume that the 24 volt 500 watt motors on each of my scooters can run on a 12 volt 525 amp car battery. If I can use a car battery, please let me know. The car batteries are lead acid like the ones that come with the scooters. I know the charger would have to be replaced. I was thinking about this one:

    http://www.amazon.com/Japlar-schaue...1UDCIDKTCW8LW&s=generic&qid=1203287009&sr=1-4

    Here’s some more info that I found on this subject:

    http://answers.yahoo.com/question/i..._vYS0dojzKIX;_ylv=3?qid=20080221033925AAEFzFY

    Any additional info is appreciated. I being very cautious because I don’t want to damage the scooters. They were gifts from this past Christmas. Furthermore, I don’t have much knowledge of Electronics.

    Once again, I would like to thank you for your response recca02.


    Btw, this site is awesome!
     
  4. recca02

    Senior Member

    Apr 2, 2007
    1,211
    0
    I'm glad you did try and learn from the links.

    That one diagram is having two batteries in series combination which would then give the required voltage and then this series combination in parallel to increase the number of hours the batteries will last.

    If your scooter worked without a problem till now on 24 volts then you should stick with 24 volts..Its now a question whether to have two 12 volts connected in series or one single 24V ..whatever is cheaper is what I will advice.Space can again be a consideration. Note that connecting in series will not increase the hours the batteries will last meaning two batteries in series do not double the hours.

    You can go with two(or more) 24 volts batteries(or the series combination of 2x12V which gives you 24 volts) then connected in parallel or you can also use the switch to change the supplies from one battery to another. Either way would be fine..I think taking out one battery for recharge either way won't cause a problem...Here connecting in parallel does not increase total voltage but the hours increase i;e having two 24 volts( or the series combination of 2x12V which gives you 24 volts) will give you a combination that works at double the time but at 24V only.

    The more Ah ratings the better(in this case longer) but just connecting more batteries in parallel is going to give you that advantage(In a way Ah of batteries in parallel add up) anyway so again whichever is cheaper and again the space considerations.

    Just see that your batteries don't end up weighing more than you and your son.:D:p

    I think I don't have any more to offer but do ask anything you wanna know.

    About the specs, trust me, in this case I'm not to be trusted.;)
     
  5. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    "15 AH" means "15 Amp-Hours." This is not the same thing as "15 Amps." It means (approximately) the battery will provide 1 Amp for fifteen hours, or 15 Amps for one hour, or some similar combination. (Actually, it's more complex than this, but this gives a rough idea.)

    To complicate things even further, the "cranking amps" listed for automotive batteries is the maximum current the battery can provide for a short time. This rating has nothing to do with amp-hours.

    I suggest shopping for batteries of the correct voltage with the highest amp-hour rating you can afford.
     
  6. Søren

    Senior Member

    Sep 2, 2006
    472
    28
    Hi,

    No, don't use car batteries, they are not rated for deep cycling (i.e. fully discharging them before recharging again).
    For your purpose, use deep cycle batteries a.k.a. marine batteries. They are more expensive than car batteries, but will last (a car battery used for this will quickly perish).

    No reason to use parallel batteries, if you get eg. two 12V 40Ah batteries (for the 24V you need), just use them alone for more than double the riding time of the 15Ah batteries you have now. That way you won't get into the situation where one battery set will discharge the other either.
     
  7. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Soeren gave you good scoop - don't use automotive batteries. Automotive batteries are designed to provide large, short bursts of power (as in starting the engine), and then expect to be promptly recharged. The plates in auto batteries are much thinner than marine (deep-cycle) batteries.

    For safety, you should strongly consider SLA (Sealed Lead-Acid) batteries. They won't emit hydrogen and oxygen like marine batteries will, nor will they leak acid if you take a spill (unless the case gets cracked, of course). SLA batteries are designed for deep-cycle type loads. Here's one that's 12V 35ah, but weighs 25lbs:
    http://www.batterywholesale.com/battery-store/proddetail.html?prodID=380

    You do need to keep in mind the maximum safe load for the scooter, and of course the size of the batteries.
     
  8. Help Me

    Thread Starter Member

    Mar 16, 2008
    13
    0
    Thank you very much recca02, thingmaker3, Soeren, and SgtWookie for the responses. I have been convinced that car batteries are not a practical solution to my problem.

    @ Soeren

    If I understand you correctly, you are suggestion that I disconnect the original batteries and use only the new batteries because the original batteries will discharge faster and draw power from the new batteries….

    I appreciate the Marine Battery suggestion, but this type of battery is out of my price range because I need at least two = $227.90 (below is the cheapest Marine Battery I could find at this time):

    http://www.apexbattery.com/mk-8au1-agm-marine-battery-group-u1-marine-batteries.html

    However, if I find a brand that’s within my price range, I will seriously consider it.


    @ SgtWookie

    From one former Marine to another, “Semper Fi….” I was in the Corps almost 25 years ago (I’m getting old).

    Thank you for link to the battery—it’s definitely within my price range. The only problem as you’ve suggested is the weight. The limit for the scooter is 240, and I weigh 200. Consequently, two of these batteries will not work.

    Therefore, does anybody know of a simple way that I can increase the voltage output of a single battery? Or can I use one battery knowing that the scooter will not be able to reach its top speed? I assume that the output of the motor would drop from 500 watts to 250 watts, but I would be able to go further.

    If anybody has any additional suggestions on increasing the distance of this scooter, please share your suggestion in layperson’s terminology.

    Thank you.
     
  9. nomurphy

    AAC Fanatic!

    Aug 8, 2005
    567
    12
    No, you can only use larger amp/hr batteries or add more batteries for the same effect (power vs. weight). Anything else will be inefficient and waste power as heat.

    However, there maybe another way of looking at this ...improvise, adapt, overcome:

    http://www.consumerdietreview.com/?gclid=CKTiyojIlJICFQeqggodFWtq_Q

    :p
     
  10. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    When you reduce the voltage to half, then the current also becomes half. Then the power is one-quarter.

    Are you one of those people who drive with their brakes on all the time? I wonder why they waste so much fuel? I wonder why their brakes don't last very long? I wonder why one (or both) of their brake lights is always burned out?
     
  11. Help Me

    Thread Starter Member

    Mar 16, 2008
    13
    0

    LoL.... Believe it or not, I’ve loss almost 15 pounds since I got the scooters.



    Thanks for the humor and the additional info.
     
  12. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Semper Fi, Brother - it appears our service dates overlap ;) I was in the high-speed, low drag department @ MCAS Beaufort :D

    Well, how much do the original batteries weigh? If you replace them with the new batteries, you can deduct the weight of the originals from the new batteries! If the old ones are a combined 10lbs, you will then be right at the weight limit.

    I'm afraid that "lard-keister" has gotten to you and me both. :rolleyes:
     
  13. Help Me

    Thread Starter Member

    Mar 16, 2008
    13
    0
    Thank you for the response Audioguru.

    I’m sure you’re right, but please explain how this website has a 36 volt 1000 watt scooter motor running on 24 volts at 666.6 watts (I'm just trying to understand all my options so please be patient with me):

    http://www.thesuperkids.com/10wabrmofors.html

    Scroll down to features and read the output info. The motors on my scooters are made by the same company except they are only 500 watts. Consequently, if a 36 volt 1000 watt motor can run at 666.6 watts on 24 volts, then I incorrectly assumed that a 500 watts motor would run at 250 watts on 12 volts.
     
  14. nomurphy

    AAC Fanatic!

    Aug 8, 2005
    567
    12
    Generally speaking:

    W = V * I
    W = 24V * 15A
    360W = 24V * 15A (for 1 hour)

    or 20.8A = 500W/24V (max power)
    or 20.8A = 250W/12V

    or 27.8A = 1000W/36V (max power)
    or 27.8A = 666.6W/24V

    Obviously the power rating of the motor should be oversized in order to be robust.
     
  15. Help Me

    Thread Starter Member

    Mar 16, 2008
    13
    0
    Thanks nomurphy for the very enlightening explanation. The help that I've received here is greatly appreciated!
     
  16. Help Me

    Thread Starter Member

    Mar 16, 2008
    13
    0

    ...until I Die, Brother

    I was stationed at the MCAS in Yuma Arizona. My MOS was a HAWK Operator. We were considered the Grunts of the Air Wing because that was the only MOS that had to go to the field. The Motor T Divers that dropped us off in the middle of the desert, a few cooks, and a Navy Med. person also went to the field with us. I was on the 50 Cal. and NBC teams in addition to my MOS. Wearing those NBC suits in the heat was unbearable. However, I was in the best shape of my life. Unfortunately, age has caught up with me.

    Since Soeren and you have suggested that I eliminate the current batteries on the scooter, I will do it. I will probably be right at the limit. I'll mount both batteries on the part of the scooter designed for placement of your feet. This will allow both tires to evenly support the additional weight. I plan on modifying the scooter next week. I will post my results.

    Once again, thank you all. Furthermore, additional suggestions are appreciated.
     
  17. rwmoekoe

    Active Member

    Mar 1, 2007
    172
    0
    IMO, just go with the old batteries, plus the 2 new ones (in series), paralleled to the old ones.
    or, use an alternate switch (it's up to you, the difference will take effect in practice, imagine that you have one larger fuel tank, compared to having one additional reserved fuel tank with a reserve valve. which one of the systems you'd prefer?).

    as with the weight limit, i think it'll be ok. you don't exceed it by far.
    what should be taken in precaution may be the landscape on which the vehicle's going to pass to prevent hard bumps. also the way you ride (pull on the accelarator steadily and not breaking too much) for the energy conservation.
     
  18. Help Me

    Thread Starter Member

    Mar 16, 2008
    13
    0
    Thanks for your suggestion rwmoekoe. However, if I use the same kind of batteries that I already have, I’ll only increase my distance by about 4 or 5 miles. The battery pack will cost me about $90. For that price, I can pay a little more for better batteries and get a lot more mileage and enjoyment for my $$$.

    http://www.thesuperkids.com/cuexbapaforb.html


    I will definitely take this into consideration when riding.
     
  19. Help Me

    Thread Starter Member

    Mar 16, 2008
    13
    0

    Since I liked the above suggestions, I put 50-pounds of my weight set (that was collecting dust and cobwebs) on my scooter because using two of the suggested batteries will total the same weight. I didn’t feel comfortable with the extra weight. I also realized that the scooter would be unable to pull me up an incline—which it can barely do now.

    Consequently, I thought about this idea again:



    I thought of a way to use only one of the 12 volt 35 amp batteries that SgtWookie suggested and increase the voltage to the 24 volts that I need. However, I’m not sure if my idea will work so please tell me what you think of this:

    I would use one of the suggested batteries connected in series with a 12-volt bicycle light generator:

    http://www.amazon.com/Generator-12V-Bicycle-Light-Power/dp/B000OBWMGK/ref=pd_sim_sg_title_1

    This should increase the total voltage to 24 volts. If I’m not mistaken, one battery should be all that I need. I’m also trying to locate a more powerful bicycle light generator. Nevertheless, can someone tell me if this idea will work?

    Thank you.
     
  20. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The bike generator is only 6W. You need hundreds of Watts. The little generator will fry but the scooter won't move.


    Besides, something must use a lot of power to drive a generator. It gets hot so it actually uses more power than it provides. So it wastes power instead of increasing the power.
     
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