When you use XR as an adventure bike, you will probably notice, that there is no battery and you can't charge equipment after the ride. So, today I'll show you how I've solved this problem.
The charger
The charger I've used is powered by 12V DC and it outputs 5V DC to charge any USB device. It's a so-called quick charger, so the output voltage may be bigger. Thanks to this, an USB device will be charged much faster. But during the process, the charger may consume as much as 20W of power.
When the phone's battery is full in 50%, the charger is charging at rate of 2.63A and 6.61V. It consumes 1.6A from the motorcycle at 12V.
The battery
I've used 2,8Ah Ni-MH battery from a cordless drill, because
- It is much safer than lithium battery (no risk of fire/explosion, no need of special charging and controlling unit)
- It is more compact than Pb battery (less weight, more capacity)
- Fully charged Ni-MH voltage is 15V (Pb 14.4V), so it should work instead of Pb battery.
- Safe charging current is 1C, so it is almost 3A (in case of XR400 it probably never happen because stator is too weak)
To protect the battery, I've wrapped it in a couple of layers of an electrical and fabric tapes. It should be waterproof and dustproof.
Additional components
To charge the battery, we need a voltage rectifier and a regulator. I've used one from a 125cc motorcycle and mounted it inside an air box, at the top.
To protect the electrical system during a short circuit, I've added fuses.
I've added one 3A fuse on the wire going from the battery to the front and one 3A fuse to limit current drained from the motorcycle (it acts also like a battery charging current limiter).
The wiring
On this wiring diagram, you can see it better how everything is connected:
I've connected my new electrical system to the bike using a factory plug.
Normally there is AC regulator connected for the headlight.
In this plug you can see two wires: the green one and white one. Green one is common ground for all devices and systems in the bike. White one is a phase wire.
I've unplugged this plug and connected both connectors to my new charging system.
Basically it connects the new rectifier and voltage regulator in the same way as the original AC regulator, but no wire cutting or soldering is needed.
Testing
Here you can see battery voltage measured while the engine is working.
I've measured 13.6V, but battery was out of the box. It should increase when it will be fully charged.
I've also connected an amp meter to measure the current drained from the motorcycle by my new electrical system.
I've noticed that the headlamp is influencing that current — that seems obvious.
When the light is off, then more current is available for the accessories and for the battery charging.
I found out there is only 200mA difference between situation when light is on or light is off.
This bike uses a LED headlamp, but power consumption is very similar to factory the H4 bulb (35/35W, not 55/60W!)
After some more measurements, I've prepared the following table.
Data in the first two tables is not looking good, because the battery is discharging in both cases.
But keep in mind that the phone was charged by a quick charger and it was consuming 18W. Common charger should consume 5W (5V and 1A) or 10W (5V and 2A).
The second set of data considers fully charged phone, with started navigation, screen brightest 100%, GPS and data connection on. In this situation, the battery was charging properly.
Summary
I plan to add the same setup for my XR400, but with some small changes - mainly in the fuses part. I will make an update, when it will be ready.
The setup above will be tested by my friend.
Luckily for now he is happy and there were no issues so far during few weeks.
You can also check the video:
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