Hi,
I wanted to add some lighting to my Rad Rover that could operate off the battery voltage, and there are a number of motorcycle lights set-up to do that that draw maybe 15W or so. I thought that I could perhaps access the battery terminals through the charging port, and just run my accessories from there. But I think there must be some kind of series resistance, because a small load pulls the terminal voltages there down to 3V.
So, I was wondering if anybody has found a clever way to tap into the battery terminals. Some kind of a splitter that mates to the factory connections somewhere?
Thanks!
The recent Standard batteries have diodes in the charger circuit which prevents current from flowing from the battery to the charger. (I know this from reverse-engineering my Rover 5 battery.) I don't think that earlier batteries had these diodes. The diodes do allow minuscule current to flow, which is why you can get a higher voltage reading at the charge port with a multimeter.
Use care with motorcycle batteries, as they may not be able to operate with the high battery voltage (up to 54.6V).
I don't have a plug-and-play solution, but minor disassembly of the battery tray would expose the connector and permit additional wiring to be added.
Thanks DickB!
I don't intend to use any motorcycle batteries--was exactly just looking for some plug and play--I thought maybe folks that run batteries in parallel might have a source for a splitting arrangement--and maybe instead of a second battery, I could use those terminals to interface to the motorcycle lights I found on amazon that can run on the battery voltage.
Sorry, I meant to say motorcycle headlights.
Because of the way that the connector is integrated into the tray, and because it is Rad specific, y connectors are not readily available.
I realize it's a nice thought to add a second headlight powered off the bike's battery, but I wouldn't do it. Why risk the bike's circuitry, especially the controller, when there are so many rechargable headlight options out there?
Quote from: Radding Along on December 26, 2021, 06:34:27 AM
I realize it's a nice thought to add a second headlight powered off the bike's battery, but I wouldn't do it. Why risk the bike's circuitry, especially the controller, when there are so many rechargable headlight options out there?
There is no risk to the controller. It is much more convenient to not need to recharge a light separately.
Did you read what he is proposing? He wants to gain access through his charging port. For someone experienced in electronics, maybe they can pull it off. But other people may eventually read this thread, who may not have a lot of electrical knowledge, and introduce an electrical issue. Why risk your bike's electronics because you want a more convenient light?
Quote from: DickB on December 26, 2021, 06:41:55 AM
Quote from: Radding Along on December 26, 2021, 06:34:27 AM
I realize it's a nice thought to add a second headlight powered off the bike's battery, but I wouldn't do it. Why risk the bike's circuitry, especially the controller, when there are so many rechargable headlight options out there?
There is no risk to the controller. It is much more convenient to not need to recharge a light separately.
DickB has exactly stated the point. I already have a battery on the bike that I recharge. I don't have to remember to place and replace and check the state of charge on a second device. I think people who are considering Rad Modifications (the name of this thread) can make judgements about their competence and the risks. Use of the charging port was an approach I had read somebody doing elsewhere, and it is remarkably convenient, if it were possible with the modern battery. But DaveB clearly pointed out with his circuit model that it is more complicated.
DickB,
I too, have a RadRover5. So, where the battery plugs into the bike there appears to be a 5 pin connector, but on the bike side, there are only two electrical terminals used (these are the largest two pins.) Since you have done some reverse engineering-- Do you know if/how these three terminals are connected on the battery side, if at all?
Bob
Quote from: DickB on December 24, 2021, 03:46:16 PM
The recent Standard batteries have diodes in the charger circuit which prevents current from flowing from the battery to the charger. (I know this from reverse-engineering my Rover 5 battery.) I don't think that earlier batteries had these diodes. The diodes do allow minuscule current to flow, which is why you can get a higher voltage reading at the charge port with a multimeter.
Use care with motorcycle batteries, as they may not be able to operate with the high battery voltage (up to 54.6V).
I don't have a plug-and-play solution, but minor disassembly of the battery tray would expose the connector and permit additional wiring to be added.
The 3 pins are not used.
Sent from my LM-K500 using Tapatalk
I am throwing this out in case you are concerned about range and run time. I have two phone mounts. On one mount I mounted my phone. On the other mount I mounted a portable battery. Wires connect the two so my phone battery is always 100% charged. The battery in my arrangement can be wired to constantly charge rechargeable headlights. This may give a rechargeable headlight with enough range for your needs.
Just an aside. I've ran over some giant potholes in my life in the dark that have destroyed my bikes and destroyed my car tires. Think about whether it is worth it.
Here is a video I found about adding lights brake lights and turn signals to a radrunner. If you look in the description there is a wiring diagram that you can download.
I have not done any of these mods.
https://youtu.be/ORh76YoUEZg
https://youtu.be/MwKxOy7e498
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You can access the main battery output by removing the battery mount and soldering in an extra connector to the two large pins (numbers 1 and 5). You should use a fuse so that any shorts in your accessory wiring does not damage the bike battery, even though that has fuses as well. For motorcycle headlights you'll need 12 volts, and a converter that works well is listed below (output 20A @ 12V). 15 Amps of current is a lot of power, so I suspect the light you are looking at is incandescent. You may want to see if they have an LED version which will use far less power and be longer lasting. The stock Rad headlight and taillight draw 0.135 amps (about 7 watts), while a 15 amp 12V headlight would be about 180 watts. That's going to impact your range.
https://amzn.to/3t14jP8