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ELECTRIC BIKE BATTERY GUIDE

 

Electric bike battery is without doubt single most expensive part on your electric bike. And unlike other expensive components such as motor, batteries have a life cycle. So you have to be very careful when you are buying an electric bike or replacement ebike battery.

After you read this article, you will know as much as an ebike store owner about your electric bike battery.

 

What is difference between Volt and Amp of ebike battery ?

I will try to simplify them here. I will use a watermill analogy. If water flowing in a pipe is electricity then volt will be the water pressure. Amp is the amount of water flowing through the pipe.

If you multiply both you will find watt which is the power applied to turn the watermill.

If we take two identical electric bikes one of which has a higher battery voltage, that one will go faster.

And if one has higher amp will have a better acceleration.

Amp Hours : This is different than amps. It shows basically how many amps can your battery supply for one hour.

C rate : This is something related with chemistry of your battery cell. It shows how much “max amps” your battery can supply without any problem. So if your battery is 20 amp hour and has C rate : 4. Then your battery can supply 20x4=80 amps in a safe way.

Battery suppliers such as Samsung or Panasonic produces different 18650 battery cells for different purposes. Battery used in electric vehicles need to have high C value so when needed they can provide higher amps. And these cells are generally more expensive. And they have some cells designed for electronic cigarettes which don’t need such high amp consumption and they have lower C-rate. 

Ask your e-bike battery supplier or e-bike seller what is C-rate of the battery. Because there can be two identical batteries both with 48V 14 ah values. If one battery pack is equipped with C rate 1 cells and other has C rate 4 cells, you will have two very different performance from your e-bike and battery. One e-bike battery can give as much as 14x1=14 amps on the other hand other e-bike battery can give 14x4=56 amps if needed.  (Most probably your controller will limit this).

Watt Hour: This is your battery volt x amp hour which shows your battery capacity. Basically it tells how much energy can be stored in your ebike battery pack.

If your have a 1500 wh (Watt hour) battery pack, it can deliver 500 watt power for 3 hours.

 

Ah vs Amp : Don’t confuse them. Amp value generally not advertised on batteries. If someone mentions about 13 amp battery, he means 13ah battery.

Ah vs Wh : Ah is a parameter about capacity but without Volt it means nothing. Important parameter is Watt hour (Wh). 10ah battery can have a larger capacity than a 12ah, if 12ah one is 36V and 10ah one is 48 e-bike batteries. 

36x12= 432 wh  and 10 ah one has 48x10=480 wh capacity. So please check battery wh value.

 

Does a Larger Battery Pack means Better ?

If you mean large in volume or weight then my simple answer will be no. As mentioned earlier important parameter is the watt hour of your battery. (Also check other parameters too). If one e-bike is larger in size, with similar watthour values, it is most probably because of using old technology cells.

Older generation cells have lower capacity so they need to use more of them to give same capacity.

But this extra volume or weight comes with issues too such as;

  • Your ebike becomes heavier. Heavier e-bike means slower and lower range e-bike.
  • Harder to lift your e-bike
  • Higher chance to damage your battery if it falls down.
  • Affects balance of your e-bike.
  • Larger packs generally don’t look that nice .
  • Large volume ones may affect your riding style

 

 

How to Store Your Ebike Battery ?

               Charging and discharging by using your e-bike battery is the best way to store your ebike battery. This is the shortest answer I can give.

               If an an e-bike battery stays idle for long time will change internal chemistry of battery cells and you will see big drop in capacity of your e-bike battery. If an e-bike bms isn’t sophisticated enough your battery may even not be able to recharge again. At Ariel Rider we use a very advanced and sophisticated BMS (Battery Management System) to prevent you experience such unpleasant incident. But again our biggest suggestion is try to use your e-bike at least from time to time.

 

Why do e-bike batteries detoriate by time ?

               In contrast to what you may imagine, your battery charge isn’t consumed only when you use your e-bike but also when you store them too. On average you will see a 1% drop off stored energy of your battery pack. 

               As mentioned before each battery cell has a safe range of capacity which is 3.0V to 4.2V. A single battery cell’s nominal capacity is 3.6V.  IF you combine 10in series it will be 36V and if you combine 13 in series you will have your 48V battery pack.

               Your battery management system is programmed to keep your battery pack within this range. If your cells reach 4.2V then it stops them charging and if charge drops below 3.0V it shuts them down to prevent further damage.

               So if you see your electric bike battery is “empty” on your display actually it means it reaches close to  3.0 V/cell (this is 39V in 48V battery).

               As said each month you will see a 1% drop in your e-bike battery capacity and if you store your e-bike battery for long time and let your battery charge go below this critical level, your batteries will be damaged in irreversible way. Because at this point your batteries internal chemistry is changed which we call “lazy cell” situation. Unfortunately once you experience it, your batteries will hold little charge or not at all depending on how bad their chemistry changed.

               So try to charge your batteries from time to time. During your ride if you see your charge goes very low or your battery is fully drained, charge your battery once you go back home as first thing to do.

               If you are going to leave your electric bike abandoned for a long time due to trip or seasonal reasons, check it’s charge level and charge it if you feel charge level is too low.

               DON’T FORGET YOUR E-BIKE WILL LOSE 1% OF IT’S CHARGE EVERY MONTH EVEN YOU DON’T USE IT. 

               This 1% is an average value and there are many factors affecting it such as what kind of cells being used, bms system and external temperature. We tested several batteries from different suppliers and see that cheap “no name” Chinese batteries tend to lose 3% month which is scary and surprising. Just like other things cheap components need higher maintenance. This can give you idea how some e-bikes can be very cheap but they come with so many problems that you will need to deal with.

              

SHALL I STORE MY EBIKE BATTERY FULLY CHARGED?

               Keeping your battery fully charged for long duration is also not adviced. Because once your battery is fully charged your batteries will have stress internally. And once they are subject to such stress for long duration of time, they can get damaged (Not a major one). 

               Based on our talks with Samsung executives and our tests we see best rate to keep your batteries for long periods is 70%. Try to store them at this rate and try not to go below 30%, in this way you can use your e-bike battery for longer periods without seeing major drops in your range.

              

DOES HEAT AFFECT THE BATTERY PERFORMANCE ?

               Batteries work on electro-chemical reactions and as we know from our high-school chemistry courses heat affects all chemical reactions. Certain reactions occur faster in hot conditions and certain reactions stop happening in cold temperatures.

               Safe temperature to keep your e-bike is between -10 Celcius and 40 Celcius.

               This February Ariel Rider were invited to Samsung battery cell factory and engineers of Samsung instruct us certain things which are parallel to our experience with e-bike batteries.

  • If your battery is subject to temperatures over 45 Celcius degrees for more than 5 hours you will see drop in your battery capacity. Don’t leave your e-bike at the back of your van for long durations or subject to direct sun light in summer for long period of time.
  • If your battery cells reach -20 Celcius for longer than 24 hours then they may have irreversible damages too. So if you have long cold weathers try to keep your battery inside your home or garage to prevent your battery subject to such damage.

 

Humidity is also not a good friend of your battery. Try to keep it in dry environment. At Ariel Rider we spend lot of effort to prevent humidity to penetrate inside your battery pack.

You can see our packing. After batteries are packed then they are covered with anti-static film and on top of that an anti-humidity film is covered. In this way we can protect battery cells from humidity, dust and other things that can damage your e-bike battery.

 

IS IT DANGEROUS TO LET MY BATTERY CONNECTED TO CHARGER OVERNIGHT ?

               Most of the electric bike batteries have smart and sophisticated BMS on them. This BMS will prevent your battery being overcharged or over discharge. Besides that most chargers also have smart control system to prevent overcharging the battery. 

               So in theory you can leave your battery connected to charger indefinitely and there is no major harm to your e-bike battery life cycle. But after your battery is fully charged and you keep on it connected to charger will consume electricity. It has no benefit to you and costing your money and our natural resources. So after you see green light on your charger which means your e-bike battery is fully charged better disconnect it.  

               For this smart BMS and Charger, I can’t generalize for each e-bike brand. Unfortunately I see many companies try to cut cost and using very simple BMS on their batteries. And they are inadequate in keeping your e-bike battery safe and healthy. It is hard to understand what kind of BMS an e-bike is using unless you are an experienced person in this field. So buy an e-bike from a company you can trust with.  Check if they know what they are doing. If they can’t answer your questions right a way then most probably you need to be more cautious..

 

 

 

 

AFTER LONG TIME OF STORING CAN I IMMEDIATELY RIDE MY E-BIKE ?

               Basically yes you can. Li-ion battery cells don’t have memory affect so they can be charged at any point without affecting the lifecycle of your e-bike battery.

               But as your e-bike battery has been waiting idle for a long time (we are talking about over 3-4 months at least), there can be some issues with cell balancing. So If you charge your e-bike battery for a little while is advised. So your BMS and charger will balance the cells. This will ensure you to get the most range from your e-bike battery in your first ride after storing your battery for long period of time.

 

TRANSPORTING YOUR E-BIKE WITH BATTERY

               You can but for safety reasons we advice you to take off your battery from your e-bike. You can follow these steps;

  • Inside the car put your battery in a place where it won’t subject to direct sunlight.
  • Take off the key from your battery. So the key won’t brake inside.
  • You can use terminal covers for extra protection.

 

 

CAN I CLEAN MY E-BIKE WHEN BATTERY IS ON IT ?

               Sure you can as our electric bike batteries are designed to be used in humid or rainy weather. If you plan to wash your e-bike with pressure water or water jet, take off your battery.

               Also don’t use a steam Pressure washer for your cleaning your e-bike battery.

               Generally wiping your battery with a moist cloth is more than enough in terms of cleaning.

 

WILL MY E-BIKE CHARGER GET HOT ?

               If you plug your charger to your battery for long period of time, it will get hot. So don’t put your battery or charger in places where it may cause a fire.

               Our chargers and batteries are equipped with temperature sensors but there are some chargers which don’t have those functions. So if you don’t know features of your charger or battery, try to be on the safe side as much as possible.

 

HOW TO CHARGE ELECTRIC BIKE BATTERY?

CAN I SHIP MY E-BIKE BATTERY ?

               We all want to bring our e-bikes with us where we go. Unfortunately most of the airlines won’t accept you to bring your e-bike battery or ship them via air transfer. Even they let you, they will ask many paper works and in the end they have right to reject your cargo.

               My best advice and cheapest one is to ship it via ground shipment if possible

 

Maybe you have heard about some stories of hover boards getting fire. The main reason is they using cheap low quality li-ion cells, poor assembly of pack and cheap BMS. That is a very dangerous equation which can cause fatal results. If you or your family members have a hover board or you already have an e-bike battery which you can’t be sure about the quality I will advice you to use this fire-resistant bags for e-bike batteries. (https://www.amazon.com/gp/product/B01DPZ49YY/ref=as_li_qf_sp_asin_il_tl?imprToken=jRyrURf2UwFuu4Mo8aBB2A&slotNum=0&ie=UTF8&camp=1789&creative=9325&creativeASIN=B01DPZ49YY&linkCode=w61&tag=ebrcta-20&linkId=QCUG6G2DS4ZV3WK5)

 

How long does an Electric Bike Battery Last ?

               First of all electric bike battery life is calculated by charge cycles not days or months. A good battery can be used for for 500 700 full charge cycles. So you can expect to use your e-bike battery for good 3 to 5 years if you take good care of your e-bike battery.

 

What happens when my e-bike battery reaches to max. number of charge cycles ?

               It is not the end of the world for your e-bike battery. When it reaches max. number of charge cycles your battery capacity and range will show a major drop. But it depends on you to replace your battery or not. If you don’t commute for long distance you can keep on using your e-bike battery. But if that dropped range is being an issue for your commute, then you can invest for a replacement battery. Maybe you can consider to buy a bigger capacity one too.

 

Is it ok to leave my e-bike battery in rain ?

               Yeah it is ok but not advised. If you need to ride your e-bike under rain or need to park outside on a rainy day, you can do it. But if you have chance to keep your e-bike or at least e-bike battery in a dry place, better do it. Don’t take risk and test limits of your e-bike battery.

 

How many cells are in a 36 volt battery ?

               It depends on ah (amp hour) of battery. But in general they have 40 cells or 50 cells. It will be packed with 10 series 4 parallel or 10 series 5 parallel.

 

How much does it cost to charge an e bike ?

               If your e-bike battery capacity is 500Wh it needs 0.5 Kwh to charge your e-bike battery. On average it costs $ 0.12/kwh in USA so it will cost $0.06 to charge your e-bike battery. So for 6 cents you can expect to ride your e-bike for 40 miles.

 

Do electric bikes charge themselves ?

               Only direct drive hub motors have chance to charge themselves as they don’t have internal gear. This is called regen function. In order to charge your battery you also need a special controller for it.

               This can sound so tempting but now comes bad news. The self charging you will have is negligible. Besides that Direct drive motors are heavier and inefficient so amount of energy you get from self-charging is going to be much smaller than extra energy consumed because of inefficiency of a direct drive hub motor.

how much is a battery on an electric bike ?

               Generally it costs around $450 - $ 750 to buy a new e-bike battery. But it depends on capacity of your e-bike battery, brand of cells and brand of e-bike too.

 

When Should I charge my e bike battery ?

How long does battery last on electric bike ?

Depending on battery cell brand, bms and how it is packed it can go around 500 fully charge cycles up to 1500 full charge cycles. After that your battery will continue to work but you will see sharp drop in performance. Your range will go down.

This full charge cycles depends on how you keep your battery and how heavily you use them. 

Some people worry to charge 10-20% when they take their e-bikes to office for example. As they think such charging is considered as full charge cycle. Good news is it isn't a full charge cycle. If you charge 20% for 5 times then your battery considers it as a full charge cycle. (Actually it is more complicated as there are other factors, so in reality 20% charge times 4.73 is considered full charge but for simplicity you can consider as 5 times).

How often should you charge your electric bike Battery ?

You can charge your e-bike battery as often as you want. As they don't have memory like old generation batteries which are advised to charge less frequently. So after basically a 5 mile ride you can still charge your e-bike battery. 

It is advised to keep your battery full but don't keep 100% full for extended period of time.

Do you need fully charge an Electric Bike Battery for the first time ?

If you have a NiCaD ebike battery then you will need to fully discharge and charge them. But Lithium Ion batteries don't need it. Lithium Ion batteries don't have charge memory so it doesn't need deep discharge or full charge when you buy your e-bike battery.