Extra battery 2019 rad city

[Jimira]

Hopefully someone here can help me. I want to add another battery to my 2019 radcity. I called rad and they wanted me to get another battery from them for $650. I have looked at a lot of forums, and battery sites, and it was too complicated. It shouldn't be. The battery on the my rad is 48 volts 14ah. There is only 2 wires going to the controller, a + & -. I can get a 48 volt 13ah (0-1000) watt 2 wire on amazon for $269. https://a.co/d/9WuWnQd My plan is to mount this in my rear rack. I will run the two wires from the back up battery to where the original battery plugs into the controller. When my main battery goes dead, I will unplug it from the controller, & plug the back up battery into the controller. It would be nice if I could buy a wire harness that had the same plug ins, but if not, i will make my own. I checked around, & some guy said he had something like that, but was out of stock, and I think it was for mounting parallel. I appreciate any help you people can give me.

 

[Anton]

Welcome!

You could wire up a Battery Selector Switch to switch between the batteries:

https://www.amazon.com/CZC-AUTO-1-2-Both-Off-Disconnect-Isolator/dp/B08C7DSL84

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They are a little bulky, but they're made for DC batteries with many more amp hours than an ebike battery.

I wouldn't recommend ever switching it to the "1 & 2" position, since you are using different batteries. Just switch from "1" to "2" or "2 to 1" going through the "OFF" position first.

 

[Anton]

This toggle switch might be a better solution for you. It's smaller and it will never connect the 2 batteries together at the same time. It has 3 positions "1", "OFF" and "2".

https://www.amazon.com/Gardner-Bender-GSW-16-Toggle-Terminal/dp/B00004WLKA

Important: Before flipping the switch, pull over and power down your ebike completely. You don't want to switch the switch while riding along under power. The switch will arc if it's under a load, since it's switching DC power. This will damage the contacts in the switch over time and it could cause failure or even worse.

 

[Jimira]

This toggle switch might be a better solution for you. It's smaller and it will never connect the 2 batteries together at the same time. It has 3 positions "1", "OFF" and "2".

View attachment 5336

https://www.amazon.com/Gardner-Bender-GSW-16-Toggle-Terminal/dp/B00004WLKA

Important: Before flipping the switch, pull over and power down your ebike completely. You don't want to switch the switch while riding along under power. The switch will arc if it's under a load, since it's switching DC power. This will damage the contacts in the switch over time and it could cause failure or even worse.

good idea

 

[Anton]

You could actually try the FBC (Fusion Battery Combiner) which will allow you to run both batteries at the same time. I just saw @ozzie21 mention this device here: https://ebikesforum.com/threads/locking-down-a-battery.3021/post-19340

This unique FBC (‘Fusion Battery Combiner’) combines the power of two batteries, by allowing both to power your bike at the same time! This device works with the new series of modular wiring harnesses (sold separately), which are interchangeable with a conventional switch. The batteries can be of different Ah capacities; they will discharge in unison, once the voltage is equal between them.

FBC (Fusion Battery Combiner) — Electromotive Mods

This unique FBC (‘Fusion Battery Combiner’) combines the power of two batteries, by allowing both to power your bike at the same time! This device works with the new series of modular wiring harnesses (sold separately), which are interchangeable with a conventional switch. The batteries can be of

www.electromotivemods.com

 

[ozzie21]

I'm running two batteries together at the same time using the Fusion Battery Doodad. I've always been calling it the Fusion Battery Blender but I see the company that sells them calls them Combiner...oh well, you know what I mean. Check my posts for more explanation and pics.