Controller and battery amps?

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rockypro1   10 W

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Re: Controller and battery amps?

Post by rockypro1 » Apr 13 2018 5:19pm

I have been looking at this battery. By the same person on ebay/amazon. But the thing I don't understand is the batteries are lithium but on the charger it says LIFePRO. will these chargers charge these lithium batteries? plus there is a difference of 57euro in price between ebay and amazon from the same seller same battery.
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rockypro1   10 W

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Re: Controller and battery amps?

Post by rockypro1 » Apr 13 2018 5:32pm

Sorry my bad there's actually a difference of one hundred and twenty two euro in price of the same batteries from the same seller. ebay/amazon.
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Re: Controller and battery amps?

Post by e-beach » Apr 13 2018 9:47pm

A LiFePO4 charger if set to charge Li-on battery's will charge them. It has to be set at a high enough voltage to activate the BMS. If the BMS does not get a sufficient voltage, it will not kick in and do it's job. If the charger gives the proper voltage then - No problem.

It does seem a bit weird though.

I have a v-power LiFePO4 charger that has been very dependable.

eBay is 55 pound difference. Also, eBay has free delivery.

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Re: Controller and battery amps?

Post by 999zip999 » Apr 14 2018 2:24pm

If a seller is selling quality cells he will proud of it and will tell you what cells are in his high-quality worth buying battery pack or else they could be cells only good enough for a laptop a laptop computer that just sits on the table and doesn't Propel anyone around. Meaning there are a lot of fake batteries generic low-quality that don't last very long we're just trying to help you not waste your money.

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Re: Controller and battery amps?

Post by 999zip999 » Apr 14 2018 2:30pm

That battery is rated for 20amps and with 20ah of capacity. That's a very low rating for a 20 amp hour battery so they may be using lower-quality cells. A good 20ah battery should put out 30 or more amps. This may be a clue or may not.

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Re: Controller and battery amps?

Post by wesnewell » Apr 14 2018 2:43pm

rockypro1 wrote:
Apr 13 2018 5:06pm
I wouldn't have a clue about what type of batteries at all. I'm going to buy a battery just know 48v and the higher the amps the better. I hope.
You got that right. My controllers are 40A and 60A. My battery packs are rated for 100A for one and 200A for the other. Your controller is rated for a max of 26A, so you need one rated fro at least 26A continuous, and the more the better. And that 26A is what the controller can draw from the battery. Has nothing to with motor amps.
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Re: Controller and battery amps?

Post by molybdenum » Apr 14 2018 5:30pm

As for name brand batteries, most ebay vendors advertize "high capacity" or "powerful", which is meaningless. I'd steer clear of vendors that state "samsung" without listing model number such as "Samsung INR18650-25R", which happens to have 2500mAh capacity per cell, and each cell has max discharge of 20A. For practical real world applications, you would never want to exceed 5A per cell max burst to preserve the life of your pack.

In short, you just don't know what you're getting if the vendor doesn't include a model number, and these companies all make batteries better suited for laptops and pocket calculators that would die an early death if used for high discharge applications.

Some cells have very high capacity (Ah) and some have very high discharge rates (A). Most are a compromise between the two. See the following table for capacity and discharge rating for commonly used brand name cells. Not all of these would be suitable for ebikes.
Battery specs.jpg
Battery specs.jpg (240.38 KiB) Viewed 1016 times
This is by no means a complete list, and misses many good cells for ebike applications. It is the best I could do on short notice.

Now for the Samsung 25R, I said the max you would want to draw is 5A per cell, but if you put 6 of these cells in parallel to make one large 15Ah 4.2V battery, your max amps would increase accordingly to 30A. In order to get a 48V battery, 13 of these parallel units would be put in series to increase the volts accordingly: 13 x 4.2V = 56.4V. Such a battery with 6 parallel groups (for 2500mAh x 6 = 15Ah) and 13 of these in series (4,2V x 13) would be denoted "13s6P, and such a battery would comprise of 78 18650 cells and weight about 4 kg.

My favorite model cells for batteries are MJ1, 35E, NCR18650PF, 30Q for high energy packs where you want a light pack but don't need something that can do 50A bursts.

For higher power, you usually have to compromise on capacity, and the Sony VTC3, VTC4, Samsung 25R would be better choices, and you wound build a higher capacity pack to allow higher safe amp draws.

I hope this helps clear up some of the mysteries surrounding cell choice. IMO, most of the ebay and amazon vendors are crooks selling misadvertised junk, and it is difficult to separate the wheat from the chaff. This is why we recommend dealing direct with vendors that actually construct the cells such as EM3EV.
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Alan B   100 GW

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Re: Controller and battery amps?

Post by Alan B » Apr 14 2018 5:55pm

It takes a LOT of nickel to handle 30A, so just because they have good cells doesn't mean the wiring and BMS is up to it either.

Bottom line - you need a reliable battery supplier, and a way to get the battery serviced. It is not uncommon for a battery to need maintenance - replace a few bad cells, replace the BMS, etc. Buying overseas is very risky. Many packs do not live their full life before they need attention, so they get tossed early because there's no good way to get service.

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rockypro1   10 W

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Re: Controller and battery amps?

Post by rockypro1 » Apr 17 2018 4:53pm

Hi,

Thanks so much guys. Thats some great information I never even knew there are so many types of batteries you can use that list is crazy.
I'm looking at a few batteries on ebay but looking with caution.
Hey take a look at this :shock:
https://youtu.be/OIs7C5tXERo

Thanks again Sean
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Re: Controller and battery amps?

Post by 999zip999 » Apr 17 2018 10:56pm

Em3ev talk to Paul great batteries great support. No ebay No Alibaba.

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rockypro1   10 W

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Re: Controller and battery amps?

Post by rockypro1 » Apr 18 2018 10:06am

999zip999 wrote:
Apr 17 2018 10:56pm
Em3ev talk to Paul great batteries great support. No ebay No Alibaba.
I'll have a look, thank you.

My daughters boyfriend lives the UK. He says he knows a guy near him is into e-bikes. Says he will ask him about a battery and bring it over next time there over. Sounds good to me. Saves me a lot of hassle.
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rockypro1   10 W

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Re: Controller and battery amps?

Post by rockypro1 » Apr 18 2018 10:54am

I am in the process of making the connections and here is what I've done.

I have an inline fuse holder and I'll be using a 20amp fuse. Do I need this? Plus are these wire connectors ok to join the wires?
Image

Also I'm using a kettle lead to connect/disconnect the battery, the gauge of the kettle wire is a lot thinner than the other wires is this ok?
Image

Is it ok to disconnect and reconnect the kettle lead as I only have a push button on the throttle NOT KEY and I'm afraid someone could just push the switch and you know yourself.
So would I need a switch between the battery and controller or will the kettle lead be ok?
Image

Just to have it ready for a battery thanks
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rockypro1   10 W

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Re: Controller and battery amps?

Post by rockypro1 » Apr 22 2018 7:13pm

Hi,

Not going to use the kettle lead as the wire gauge is to low.
I'll be using the connection that comes with the battery
Image
Yes I got a battery no sorry two batteries which are the very same. :D .
I bought them on ebay from good sellers, brand new 48 volt 20ah each. Got one waiting on other in the post. I tested it and its perfect.

Here's my new battery.
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I'll be using wire connector blocks for the connections and a 20 amp inline slow blow fuse.
I'll also be using ferrules to make a good connection.
Image
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This is when I got my bike first, It was just a frame.
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This is it now. Just have to do a few more bits and add batteries.
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I bought a trailer on Amazon that's one of the reasons I built a 2wd e-bike.
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See my dog tiny in the window he'll be going in the trailer also :)
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Here's me and my bike and my new bike trailer.
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Here's the bike all light up and my unicycle lit up as well :)
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rockypro1   10 W

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Re: Controller and battery amps?

Post by rockypro1 » Apr 22 2018 7:17pm

Oh forgot this is the reason I'm using the block connectors.
They seem to pass the hot test. Have a look.

https://youtu.be/2uYD8e7idnY

https://youtu.be/os66cID30Ek
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