36 VOLT POWER SOURCE

[ElCo69]

Hello all, I just joined the board hoping to have a question answered. I recently bought an electric-bike that did not come with a battery. It requires 3 batteries for a total of 36 volts. My question is will any 36 volts work or do I need to watch out for any other type of specs? amps? Also, I want to use a 36 volt power supply while working on the bike.. something like this: http://www.powersupplydepot.com/36-volt-power-supply,-4-2a,-150w,-switching,-hengfu/16034+PS/?gclid=COqh3Nufu7UCFWhyQgodRA4Apw.

Is it safe to use a 36 volt power supply or any type of 36 volt battery? Thanks a bunch..

 

[Drunkskunk]

Basicly, Yes. 99% of the time. There are bikes out there who's battery is propriatary, and contains a chip so that the bike will work with only that brand battery. Thats a Bionx, and just about every thing else should be fine.

However, you need a battery capable of producing the amps needed. If your bike has a 20 amp controller (a common size) you need a battery capable of producing 20 amps output.

Not all batteries are created equil. a common size SLA batter is made up of three 12 volt 10AH(amp hours) batteries. That 10AH is a measure of the battery's capacity, not it's output currrent. a 20 amp output from a 10Amp hour is measured in "C" (capacity), and in this case would be 2C (that means it can output at 2 times capacity).

That size battery is common for UPS and other backup batteries in alarms and telcom equipment. Unfortunatly, many of those batteries are rated for a maximum of as little as 0.1C, and couldn't be used to power an Ebike.

If you tell us what bike you have, we can probably recomend a battery for you.

That power supply might or might not be usable with the battery you end up with. Its only adjustable 10%, so it wouldn't be usefull for charging Lithium batteries for example.

 

[ElCo69]

Thank you for the response Drunkskunk. The bike is a Chinese made bike and it says Electric Bicycle Corp of America.. bought from a guy locally here in SF, CA for a good price - I think. I have been eyeing these batteries here: http://www.monsterscooterparts.com/36vobapa.html, but not sure which 3 pack I will need. My bike apparently also came as a three pack.

 

[d8veh]

All those batterys are 12v, but they have different physical sizes, so you measure the space you have and see which size batteries fit. You want the biggest ones that fit. Once you've got your new batteries, never leave them discharged. Always put them on charge as soon as you get home. Try not to discharge them any further than you have to, so charge after every ride if you can. Whichever ones you get,make sure that they're for electric bikes/scooters. The cheaper ones are for burglar alarms etc, and will soon give you problems.

Using a power supply to turn the motor is OK as long as you don't put the motor under any load unless it can provide at least 15 amps. I've sometimes used the battery charger for testing, but, of course, if there's anything wrong with your wiring, you could blow the charger. Whichever power supply you use, you should protect it with a fuse rated less than the max from the power supply.

 

[dogman dan]

Getting the same size as you have now makes sense, so if you have 3- 12v 12 ah batteries in it now, chances are excellent that the same size will fit your batery box perfect.

Lead batteries are economical to buy, but are heavy and short in range because idealy you'd only use 6 ah out of a 12ah battery before stopping to charge. If you have some money, it could be worth it to you to buy lithium. You almost must, if you want more than 10 miles of range.

As for the original question about the power supply, I wouldnt spend any money on one just yet. But you will need a 36v charger for your batteries when they come, if you don't have one already. Some chargers would require a ps to run them, but not likely a 36v one.

 

[ElCo69]

Thanks guys for all the great tips and suggestions. Don't have any batteries for it so don't know what they are suppose to look like, but I do have the charged and will use that to test the bike and how well it spins and works. Thanks again..

 

[dogman dan]

If possible, hunt down the battery size by looking up the bike on the internet.

The charger gives you a clue as well, a 36v sla charger means it didn't come with a lithium battery. You could test the motor with any three 12v lead batteries connected in series for 36v, but don't make the mistake of buying 3 lawnmower starter batteries because they are cheaper.

One option for testing the motor is to spend 30 bucks on a motor/ throttle/ controller tester. Find em on ebay, or some of the vendors in our for sale section have them.

Some older ebikes have brushed motors. If your controller says brushed, you can test the motor with one 12v battery. If it runs when the two wires are connected to a car battery, it's good.

 

[Drunkskunk]

You may not be able to test with the charger. Some SLA chargers give a simple rectified DC output. That works fine for filling up an SLA battery, but it's "dirty" power, switching off and on with each change in phase of the AC power, and the controller won't work.

Worth trying, but failure doesn't mean it's broke.

post some clear pics of what your battery space looked like and someone here can probably tell you what filled that hole, and what other options you may have.

 

[dogman dan]

He's got a dilemma for sure. Don't want to spend a lot on a battery, only to find the motor is no good.

At 30 bucks, the motor/ controller/throttle tester is a good cheap way to test it out easy. But there are methods for checking your motors halls that should be in the ES Wiki by now. Checking a direct drive motor for shorts on the phase wires is easy. Spin the wheel, it should resist but not a lot. Now short two of the large phase wires, it should resist a LOT more now.

I've never had to learn how to test a controller without the tester tool though. Worth the 30 bucks for the time that tool saves you, over and over and over. Got a problem, do the quick tests, and you confirm that your problem is likely just the battery or the wiring harness plugs making bad contact.

Oh, just in case it's brushed. Don't buy the motor controller tester if you have a brushed motor. The testers are for brushless stuff.