how to match car lead acid battery with controller

[ash2000al]

Hi guys,
I am newbee and I want to know how to calculate which controller is need for BLT-800 from golden motor when used standard lead acid battery from the car. I am thinking of one of these greentime controllers.
http://www.aliexpress.com/store/group/Electric-Vehicle-Controller/313864_211689768.html

I like lead acid because i build cargo trike with ample space for battery, and also it is simple, cheap, durable and readily available. Standard car lead acid battery start from 50A and upwards and there is little difference between 55A 60A,65A. 75A and 100A batteries in prices. Controllers however rated above 50A double or even triple in prices. Therefore, is it possible to put together let's say two 100A lead acid battery for 24 v, which controller I would need in this case. The cheap one with 24v ($30) or more expensive one with over 100A ($150). thank you.

 

[el_walto]

You should not use car starter batteries you are talking about with an electric bicycle for many reasons. They will be very heavy, not spill proof, and they will be destroyed after a short period because they are designed to be kept fully charged. For most bikes you would need 2, 3 or 4, for 24v, 36v or 48v Car starter batteries are meant to be charged at all times or they will be damaged. If you insist on using lead acid, you need to atleast get deep cycle batteries(marine/RV). 48V will spin the wheels twice as fast as 24V, so figure out what kind of rpm you are going for.

You can use any size battery. The rating you are finding on the battery is how much capacity it has. 100Ah battery will go twice as far as 50Ah battery. It will also have double the weight. Normal ebike setup would be 2,3, or 4 7Ah-30Ah batteries.

You better research a bit more before purchasing anything. I suggest you purchase your controller with your motor so the wireing will match.

 

[amberwolf]

I am newbee and I want to know how to calculate which controller is need for BLT-800 from golden motor when used standard lead acid battery from the car.

Entirely depends on how you want the vehicle to perform, and what the motor itself can take, and how long you need it to do that. What kind of terrain? Stop and go traffic? How quickly do you need it to accelerate? How much will it weigh? How many watts will it take to do that acceleration on the flats, or take you up any hills you have to traverse? Those are all questions you will want to answer before you choose.

 

[SamTexas]

As said above, lead acid batteries are not good for ebikes. Car starter batteries are the worst for this application.

I like lead acid because i build cargo trike with ample space for battery, and also it is simple, cheap, durable and readily available. Standard car lead acid battery start from 50A and upwards and there is little difference between 55A 60A,65A. 75A and 100A batteries in prices. Controllers however rated above 50A double or even triple in prices. Therefore, is it possible to put together let's say two 100A lead acid battery for 24 v, which controller I would need in this case. The cheap one with 24v ($30) or more expensive one with over 100A ($150). thank you.

Yes they are simple and readily available. But cheap and durable they are not. You could easily kill a set of starter batteries in 20 cycles which makes them extremely expensive.

 

[Jeremy Harris]

Hi guys,
I am newbee and I want to know how to calculate which controller is need for BLT-800 from golden motor when used standard lead acid battery from the car. I am thinking of one of these greentime controllers.
http://www.aliexpress.com/store/group/Electric-Vehicle-Controller/313864_211689768.html

I like lead acid because i build cargo trike with ample space for battery, and also it is simple, cheap, durable and readily available. Standard car lead acid battery start from 50A and upwards and there is little difference between 55A 60A,65A. 75A and 100A batteries in prices. Controllers however rated above 50A double or even triple in prices. Therefore, is it possible to put together let's say two 100A lead acid battery for 24 v, which controller I would need in this case. The cheap one with 24v ($30) or more expensive one with over 100A ($150). thank you.

First off, it's worth noting that you're mixing up units here, in addition to the points that the others have already made (which are very good - car batteries are hopeless for even a very cheap electric vehicle, as they will die in just a few charge cycles).

Car batteries don't come from 50A upwards at all, even the smallest car battery will deliver several hundred amps. I think you are confusing battery capacity in Amp hours (Ah) with battery current in Amps. The two are different, one is a measure of energy and the other is a measure of current.

Controllers are normally given a current rating, in Amps. A controller has no way of knowing, or caring, about the battery energy capacity in Ah.

The controller rating you select depends entirely on the voltage and current that you wish to run at. The battery capacity in Ah makes no difference to the controller, as long as the battery can deliver the maximum current needed.

 

[ash2000al]

Thank you all for replies. I am still not confused though, how do I determine the amps (and cintroller) for my motor., The motor rating is 48V800W 1100 rpm.
so if we divide 800W/48V equals 16.66 amp. Does it it mean that I need to find controller that has rating 48V at 20 amps continue. How do I determine max amps which usually they show first for controllers.

Ok, I was going to use lead acid battery because I am newbee and would not want to destroy the lithium batteries acidentaly. You know they cannot be repaired.
With lead acid battery at least I know what I am working with and it is repairable. Importing from China is so expensive only DHL serves my country (eventhough we are neighbours) and it makes the cost of batteries from China so prohibitive. It is cheaper to go to China and buy in bulk but I need only few for now. Threfore, I want to get my foot wet with lead acid battery. We do have deep cycle batteries too. I refered to 50 AH upwards because that's what you find usually for cars. I think below that thay are usually for generator and motorcycles which are out there but not hot and almost as expensive as bigger ones such as 100A.

But I don't know what is their amp rating. 100 Aamp Hour, I thought it meant a battery can provide 12 volts at 100 amps for an hour. What am I missing? I know that voltage will be added and amps rating will be the same, so two 12v 100AH batteries added togather will be 24 volts at 100AH. Does it mean that motor will have in this case half RPM of (1,100 at 48 volts/2 = 550 RPM).

How do I calualte my amps rating needed for controller given motor specs with lead acid battry?
thank you

 

[SamTexas]

The power rating of a motor (800W in your case) means that the motor is capable of accepting 800W continuously without overheating. But it does not need 800W to function. It will take anything from zero to 800W, or 0 to 16.7A at 48V as you have figured out. It can also easily take twice as much power for a short time or 1,600W in your case. So if you want a fast bike you can choose a 30 to 40 amp, 48V controller. But you risk overheating your motor. That risk is relatively small for a direct drive hub motor. At 48V, 40 amp, your bike could be travelling around 40mph (64kph). Or you can choose a 20 to 25 amp controller which should be well matched to your motor. At 48V, 25 amp expect around 48kph top speed. You can even use a 15 to 20 amp controller and have a top speed of around 32kph.

If you insist on using lead acid batteries, make sure you DO NOT buy STARTER batteries. Starter batteries are those you find in every car and every motor cycle. They are designed to do only one thing: to start an engine. That means very HIGH current (100 to 500 amps) for a very short time (5 seconds max). They are designed so that no more than 10% of their capacity is used (5Ah for 50Ah battery), and they need to be kept fully charged all the times (by the car's alternator or the motorcycle's generator.)

Buy SLAs (Sealed Lead Acid) that are designed to be discharged for long time at a slower current. They are commonly called deep discharge batteries. Use only 1/3 (0.333) to 1/2 (0.500) of the battery's capacity if you want them to last reasonably long. For example: use only 10 to 15Ah of a 30Ah battery.

Here's how deep discharge lead acid battery capacity is rated: A 12V, 20Ah battery means that it can provide 1A for 20 hours. A 12V, 40Ah can provide 2A for 20 hours. A 12V, 100Ah can provide 5A for 20 hours. Note the common "20 hours". They are designed for very slow discharge. On ebike, the common discharge time is 1 to 2 hours or 10 to 20 times faster discharge rate. Capacity is drastically reduced at higher discharge rate (Peukert effect).

Also keep in mind that all SLAs battery manufacturers recommend a maximum of 50% discharge. That means only half of the capacity is available for use at the same 20 hours discharge. Add the Peukert effect for much faster discharge on ebikes and end up with around 33% usable capacity.

Good luck and enjoy you ebike.

 

[el_walto]

Ash, you have a lot of things correct. If you check out this simulator it might help you understand relationships between controllers etc. Too bad it is only for hub motors though.

http://www.ebikes.ca/simulator/

Ah rating on battery is capacity, like how much gas you have in your tank.

Likely you will want 36V or 48V of batteries. 20Amp controller will have less torque than a 40Amp controller.

 

[spinningmagnets]

As others have already stated, the starter batteries are the worst choice. Several reasons, (we are not trying to screw with you), but the biggest reason for me is that the plates inside are very thin. Electric wheelchairs and lake-fishing trolling motors (labeled "marine") are specifically labelled "deep cycle". Every time a lead-acid battery is deeply discharged and then fully recharged, some of the plate material melts off.

The classic symptom of a lead-acid battery that has been well used and cannot be used anymore is that its voltage (when topped off) is getting lower and lower. This is because the plates have melted away enough that there are holes forming in them, and this results in less plate surface area to provide the chemical reaction.

Starter batteries have many thin plates to provide a burst of very high amps for a few seconds. Deep cycle batteries have thick plates to provide adequate volts and amps for a long time.

edit: even when using deep-cycle batteries, when the capacity that you have used reaches around 50%, the voltage will sag badly.

 

[dogman dan]

If you want to use lead for whatever reasons, that's fine. Just don't try to use ordinary car starting batteries is all we are trying to say. You need the thick plates found in EV batteries.

Idealy, get sealed lead acid batteries designed for EV use. In other words, batteries intended for power wheelchairs. 12 amp hour size will be enough, but for wheelchairs 20 ah is common. Even the smaller 12 ah ones, if they are EV grade, will power up to a 40 amps controller ok. However, a larger battery will do it with less voltage sag when you open the throttle, so a good size to aim for would be 20 ah. Or if the 12 ah batteries are more avaliable, get enough to paralell them into 24 ah.

Match your voltage to the voltage marked on your controller, so 2 batteries in series for 24v, 3 in series for 36v, etc.

Which controller are you looking at? None of them are the one I would recomend for your application. 48v would likely make a trike too fast for good controll. But the 36v ones on the page are too weak in amps. I would recomend that you find a controller of 36v 20 amps. Those big 45 amp and more controllers will need not only lithium, but very very good lithium.

 

[kentlim26]

that was close near missed.. i had nearly wanted to buy lead acid batteries , use water n lead acid water to pour in. the shop seller told me " he cannot understand why so many people used seal lead acid for ebike. it is not intend for that use. is for stand by power UPS power supply only. the amount you pay for a lithium battery 20c , you will sure find your fun is always there.

 

[DAND214]

Ok with the batteries. Are you sure that motor is 1100 rpm? If so 24v wil be about 50% or 550 and you need a 24v controller not a 48v controller or the LVC will not allow it to function. Also as said the controller doesn't know or care if you had a 1,000 AH sitting there it's only going to take what it needs up to the rated amp draw it's designed for. So 24v 20 to 30 amp controller will work fine. Is there a lot of hills you might want a higher power one like 40. In any case you can run from 115 to 300 amp controller if you want and the motpr will take what it needs to funtion which would be probably less than 40 amps in any case.

If you plan on running 24v system why not get a 24v motor with the matching controller. i have a couple 24v500w golden/Conhis hub motors and they are still alive running 60v. And they run like a scalded cat.

dan