Where to put the battery for electric bike

I am wonder where everyone place their battery on the bike and how for electric bike conversion kit.
I personally installed a trunk in the back of my mountain bike and put all the boards and batteries inside. As a result, I can hide and lock my batteries.
However, the con is that the weight is concentrated in the back. It can be hard to control the bike sometimes.

I picked up a frog box. They mount on the back of the seat post. Unfortunately it means having the seat higher, and I can't. I'm just making a bracket that adds a second seat post to my bike, just behind the seat. Just an L shaped thing that fixes to the bikes original post.

My next pack will be a stick. Just 5Ah 44.4v. I'm using 4s hardpacks, and 3 in a row will fit inside a 2x2 square section alloy pipe. End to end the batteries are 417mm. That should fit nicely along my bottom tube with enough space spare at the end for a bms. If I build a third pack I will do the same for the other side of the bottom tube. Next I would sling one under the top tube, but the bms would be bound to it with tape, the whole lot wrapped with fibreglass tape, then resin coated. That should make a reasonable looking pack, but some bodywork skills would be required.

If I wanted 44.4v 10Ah I would just use a 2x4 tube. It is starting to get a bit bulky though. There is nothing slender about 4 inchs.

It sounds to me that you are using LiPo batteries.
frogbox you mean this ?
How are you going to lock your battery?
I am using NiMH batteries 18Ah. Yes, NiMH batteries. I know no one use it and I probably am the only one, but it is working fine so far.
I am using it to commute and and parking it right outside the subway station for all day long.

I am also thinking about the heat under the sun when parking outdoor.
Do yours get really hot when you park your bike under the sun? Is it going to catch on fire?

Thankfully a different frog box
http://www.alibaba.com/showroom/frog-box-battery.html
They come empty from a few suppliers. They are in two parts. The bracket stays on the seat post and has space internally for the more compact controllers and maybe a watt-meter or dc-dc convertor. The main body comes away when you turn the key to unlock it. I have 44.4v 5Ah with a bms in mine. D8veh has 44.4v 8Ah in his, but no bms. There fairly flexible but I'm not sure of your goal

Ideally, mount the battery around where your knees are on the bike if possible or convenient. Hard to do on FS bikes in general though. Some like a handlebar mount. I don't like that much, but will prefer that to a really bad rear mount.

My latest dirt trail bike carries the battery "wrong" on a high rear rack. Works fine because it's very small, only weighing 4 pounds. 15 pounds of more there would suck balls.

On my small wheeled bikes I like mine on the front via a frame mounted luggage block i.e. no load/effect on the steering.






Jerry

The front triangle frame is the best place to put them for handling. it makes a WORLD of different for how the bike feels. Here's where I keep mine on one of my bikes:


However, the downside is that a bag like this isn't as secure as a box on the back of the bike. Of course if you're really worried about someone stealing a battery, removable is the only surefire bet. I don't where you live, but try to walk into a mall with a bag full of bomb-looking lipos is a good way to get to know your friendly local law enforcement officers better.

edit: you live in canada. ok, you can walk anywhere you want with bomb looking things at ease. oh ignorance is bliss

The total weight of my batteries are around 8Kg, 18Ah 48V.
It would be too heavy to carry it around. As a matter of fact, I dont even want to move it.
I currently put them in the trunk.

I put together a lot of other stuff, such as my U lock and gloves, flash light in there.

When I put together my bike, I was planning to go for some longer trips.
However, I just use it to go to the subway station now. May be using a smaller 4.5Ah would be good enough for that purpose.

My next bike will probably a smaller form factor. Using a smaller bike with a much smaller battery.
The frog box from friendly1uk seems promising.

middriveebike said:

The frog box from friendly1uk seems promising.

Click to expand...

It's convenient but I've used 4 or 5 and here's one thing to note: you'll want to loctite the bolts that hold the two metal mounting bracket to the metal insert that holds the battery. Those suckers back off with vibration and if left unattended could mean your whole battery falls off and gets dragged along the ground by your power cables...

mlt34 said:

middriveebike said:

The frog box from friendly1uk seems promising.

Click to expand...

It's convenient but I've used 4 or 5 and here's one thing to note: you'll want to loctite the bolts that hold the two metal mounting bracket to the metal insert that holds the battery. Those suckers back off with vibration and if left unattended could mean your whole battery falls off and gets dragged along the ground by your power cables...

Click to expand...

Hum. May be changing the nuts to the nylon self locking nuts will avoid lots of headache later on.