How the Radwagon 4 should have been built w/pictures:

[SanDiego101]

Hi, The Radwagon 4 is great. Here is how it should have been built:

1) One battery is unsafe. I have run out with both kids on the back a few times and it's horrible. The range they state in not even close. I added a 52v 2nd battery. Note location in photos.
2) It's slow and unsafe stock. Added a Bolton controller. It pulls hard up hills and goes close to 35MPH. Plus the range with two is great.
3) REALLY unsafe stock brakes. I tried cable pull hydraulic , they are terrible after a short time. I added front and back Avid code 4 piston brakes with 203mm SRAM rotors
4) Trailer hitch (gas pipe) and trailer (amazon). You can carry everything needed and not get sand or whatever in your car plus park right where you camp or whatever.
5) Simple side mirror
6) true 750w Bafang Hubbody
7) extra tube, tire irons and 4 C02 (i have got 3 flats over the last year and had to call friends. Now I can fix a flat on the side of the road)
One Up rack - I can put this heavy bike on this rack and go places...

[Ddaybc]

That's a lot of mods on your RW4. I like the larger brakes as I feel the 180 mm brakes on my RW4 aren't as good as I would like. I'm not sure about how you've spaced your callipers though.
Are you able to run your bike with both batteries plugged in simultaneously or do you need to switch them when one is expended?

[SanDiego101]

That's a lot of mods on your RW4. I like the larger brakes as I feel the 180 mm brakes on my RW4 aren't as good as I would like. I'm not sure about how you've spaced your callipers though.
Are you able to run your bike with both batteries plugged in simultaneously or do you need to switch them when one is expended?

Hi,

I spaced the calipers with a bunch of washers. I guess I could have bought a caliper extension and used less washers but I got lazy. Works perfect tho. Unreal stopping power with both kids.

The RW battery is 48v and the Amazon one is 52 so I just unplug when I need the 48. It's rare that I need the second but SO nice for piece of mind.

I also just added suspention type seat LOL and suspention seat post. MUCH better as the ride is harsh.

[NaturallyRC]

I would upgrade my brakes too if my ebike went 35mph instead of 20.

[Altema]

You're basically driving a 2 wheeled truck with that load, so your upgrades make sense. The Rad motor is a true 750 watt motor (you can't measure specs by looking at it), but it has an internal RPM limiter that can't be bypassed, so it needs to be replaced to increase top speed. Congrats on the setup, and if you do want to run both batteries in parallel, you can use a DATEx2 or Battery Blender (same thing, different seller).

[SanDiego101]

You're basically driving a 2 wheeled truck with that load, so your upgrades make sense. The Rad motor is a true 750 watt motor (you can't measure specs by looking at it), but it has an internal RPM limiter that can't be bypassed, so it needs to be replaced to increase top speed. Congrats on the setup, and if you do want to run both batteries in parallel, you can use a DATEx2 or Battery Blender (same thing, different seller).

TY

"if you do want to run both batteries in parallel, you can use a DATEx2 or Battery Blender"

Even with different voltage? 48/52? Do you have a link for the DATEx2 or Battery Blender

Thank you

[SanDiego101]

You're basically driving a 2 wheeled truck with that load, so your upgrades make sense. The Rad motor is a true 750 watt motor (you can't measure specs by looking at it), but it has an internal RPM limiter that can't be bypassed, so it needs to be replaced to increase top speed. Congrats on the setup, and if you do want to run both batteries in parallel, you can use a DATEx2 or Battery Blender (same thing, different seller).

TY

"if you do want to run both batteries in parallel, you can use a DATEx2 or Battery Blender"

Got it: Thank you! https://www.sparkcycleworks.com/index.php/product/battery-blender/

Even with different voltage? 48/52? Do you have a link for the DATEx2 or Battery Blender

Thank you

[Altema]

Yes, these are smart battery management systems and allow you to use batteries of different voltages and chemistries. It will draw from the highest voltage battery until the next battery voltage matches, then it will use both batteries while the voltages overlap. Your 52v battery is from UPP (good stuff), and they turn off by themselves when the voltage gets down to 42 or 39 volts. However, you can always just turn the battery off manually when it gets down to 42 volts. A link is below, and they sell a 30 amp and 90 amp version, but the 90 amp version is really expensive.

https://www.sparkcycleworks.com/index.php/product/battery-blender/

[SanDiego101]

Yes, these are smart battery management systems and allow you to use batteries of different voltages and chemistries. It will draw from the highest voltage battery until the next battery voltage matches, then it will use both batteries while the voltages overlap. Your 52v battery is from UPP (good stuff), and they turn off by themselves when the voltage gets down to 42 or 39 volts. However, you can always just turn the battery off manually when it gets down to 42 volts. A link is below, and they sell a 30 amp and 90 amp version, but the 90 amp version is really expensive.

https://www.sparkcycleworks.com/index.php/product/battery-blender/

Just watched the video. Thank you SO much! My Bolton controller is 35A so hope that's ok.

Stoked

[Eric7]

First I want to say it is a very nice build.  Thanks for sharing.

I think a multiple battery connector is some diodes to make sure the batteries on the bike can only drain through the bike ports and not be charged through the bike port.  The diodes force the current to go only one way - out of the batteries.  The diode should have a breakdown voltage (or whatever it is called) high enough so that it would not fry no matter the voltage of the extra battery.  Something like 72v or 100v. 

Connected this way, regardless of voltage, or state of charge, the multiple batteries won't self balance.  Simplistically, you can connect a 100% charge battery in parallel with a 0% charge battery and, over time, it will not become two 50% charged batteries.

Another benefit is that when two batteries are running in parallel, the current draw for each battery is less so the battery lasts longer.

If the current is too high during regular bike operation, you would need a heat sink to make sure the diodes don't overheat.

I plan to build one later, when I get a second battery.  I want to build one even if it cost more so I can know exactly how it works.

[SanDiego101]

First I want to say it is a very nice build.  Thanks for sharing.

I think a multiple battery connector is some diodes to make sure the batteries on the bike can only drain through the bike ports and not be charged through the bike port.  The diodes force the current to go only one way - out of the batteries.  The diode should have a breakdown voltage (or whatever it is called) high enough so that it would not fry no matter the voltage of the extra battery.  Something like 72v or 100v. 

Connected this way, regardless of voltage, or state of charge, the multiple batteries won't self balance.  Simplistically, you can connect a 100% charge battery in parallel with a 0% charge battery and, over time, it will not become two 50% charged batteries.

Another benefit is that when two batteries are running in parallel, the current draw for each battery is less so the battery lasts longer.

If the current is too high during regular bike operation, you would need a heat sink to make sure the diodes don't overheat.

I plan to build one later, when I get a second battery.  I want to build one even if it cost more so I can know exactly how it works.

Thank you - I bought and installed the battery blender and just had it die FAR from home........ Not 100% sure what's going on? I wonder if the 35A Bolton controller is causing issues?

"I think a multiple battery connector is some diodes to make sure the batteries on the bike can only drain through the bike ports and not be charged through the bike port.  The diodes force the current to go only one way - out of the batteries.  The diode should have a breakdown voltage (or whatever it is called) high enough so that it would not fry no matter the voltage of the extra battery.  Something like 72v or 100v."

Can you show me how this is built?

[Eric7]

I can see how the battery blender died.  It probably died from overheating and it is a good thing that it did not short your very expensive batteries.

Power dissipation across a diode is the voltage across the diode X current.  For silicon diodes, the voltage drop would be about 0.7 volt.  You have a 35 amp controller. 

In engineering, you hypothesize the worst-case scenario - the batteries are uneven, one is 100% and the other is 0%.  35 amp is coming out of one battery.  35 x 0.7 = 24.5 watts. 24.5 watts is coming out of one half of the device.  That's the worst case.

In regular operation, if you have the throttle wide open, even in optimal conditions, you are drawing 35 amps and 12.25 watts is coming out of each half of the blender, a total of 24.5 watts is still coming out of both halves of the device.

So whatever blender you use would need to dissipate 24.5 watts continuously. The breakdown temperature is about 175°C.  If the blender reaches 175°C it dies.  If you add in some safety margins, you would probably need a heat sink that can dissipate 50 Watts for a 2-fold safety.

Anybody feel free to correct me if I am wrong, I just don't see how any blender device can be designed to be reliable without some sort of 50 watt heat sink.  Or maybe the margin of error needs to be bigger, like a 100 watt heat sink?  The good thing is that heat sinks are not expensive.

But there is an additional complication, this is coming out of the hot end of the battery, so your heat sink will be at 48 volts.  If you short circuit the heat sink with the frame, you may short circuit the battery. 

I have not figured out everything yet and this is not my field. Power electronics is not my thing.  For example, would the heat sink (now connected to the diode) be at 48 volts?  Or would it be at 0 volts until there is a breakdown and then be at 48 volts causing a further short when there is a breakdown?  I guess we would need to put fuses in to avoid shorting the batteries if there is a breakdown.  Is the voltage drop across a 40 amp power diode really 0.7 volts or is it higher - and do we would have to test this under high current conditions of 35 amp?  A standard silicon diode will have a voltage drop of roughly 0.6V to 1.2V but that depends on current so the more current you send, the more the voltage drop and the bigger the heat sink.  I would need to prototype before I can finalize a design because I don't know enough.  Also, now we are talking about 35 amps going through a solder joint and maybe the heat will just melt the solder joint.  Is soldering even viable? There are a lot of engineering challenges for me - probably somebody with better knowledge can solve them easily. Since I don't expect to buy a battery any time soon, I don't think I will come up with a design soon.

●●● edited to add more info ●●●

[SanDiego101]

I can see how the battery blender died.  It probably died from overheating and it is a good thing that it did not short your very expensive batteries.

Power dissipation across a diode is the voltage across the diode X current.  For silicon diodes, the voltage drop would be about 0.7 volt.  You have a 35 amp controller. 

In engineering, you hypothesize the worst-case scenario - the batteries are uneven, one is 100% and the other is 0%.  35 amp is coming out of one battery.  35 x 0.7 = 24.5 watts. 24.5 watts is coming out of one half of the device.  That's the worst case.

In regular operation, if you have the throttle wide open, even in optimal conditions, you are drawing 35 amps and 12.25 watts is coming out of each half of the blender, a total of 24.5 watts is still coming out of both halves of the device.

So whatever blender you use would need to dissipate 24.5 watts continuously. The breakdown temperature is about 175°C.  If the blender reaches 175°C it dies.  If you add in some safety margins, you would probably need a heat sink that can dissipate 50 Watts for a 2-fold safety.

Anybody feel free to correct me if I am wrong, I just don't see how any blender device can be designed to be reliable without some sort of 50 watt heat sink.  Or maybe the margin of error needs to be bigger, like a 100 watt heat sink?  The good thing is that heat sinks are not expensive.

But there is an additional complication, this is coming out of the hot end of the battery, so your heat sink will be at 48 volts.  If you short circuit the heat sink with the frame, you may short circuit the battery. 

I have not figured out everything yet and this is not my field. Power electronics is not my thing.  For example, would the heat sink be at 48 volts?  Or would it be 48 volts when there is a breakdown causing a further short?  I guess we would need to put fuses in to avoid shorting the batteries if there is a breakdown.  Is the voltage drop across a 40 amp power diode really 0.7 volts or is it higher?  I would need to prototype before I can finalize a design.  Since I don't expect to buy a battery any time soon, I don't think I will come up with a design soon.

Thank you for your time Eric. It turns out that the Blender killed my Bolton (I had a second to test) screen. Both batteries are fine and the Bolton controller is fine. I'll return this Blender and just plug in each battery separately when they die. I follow what you're saying but don't have the knowledge to execute.

[Tree]

Hi, The Radwagon 4 is great. Here is how it should have been built:

1) One battery is unsafe. I have run out with both kids on the back a few times and it's horrible. The range they state in not even close. I added a 52v 2nd battery. Note location in photos.
2) It's slow and unsafe stock. Added a Bolton controller. It pulls hard up hills and goes close to 35MPH. Plus the range with two is great.
3) REALLY unsafe stock brakes. I tried cable pull hydraulic , they are terrible after a short time. I added front and back Avid code 4 piston brakes with 203mm SRAM rotors
4) Trailer hitch (gas pipe) and trailer (amazon). You can carry everything needed and not get sand or whatever in your car plus park right where you camp or whatever.
5) Simple side mirror
6) true 750w Bafang Hubbody
7) extra tube, tire irons and 4 C02 (i have got 3 flats over the last year and had to call friends. Now I can fix a flat on the side of the road)
One Up rack - I can put this heavy bike on this rack and go places...

definitely a cool set up, but one of the lures of Rads are their relative affordability, and with your set up, that bike isn't staying under 2k.

I would definitely love an extra battery set up on my Rad Rover 6+, but I'm too afraid of burning something out.

[ericwn]

Hi, The Radwagon 4 is great. Here is how it should have been built:

1) One battery is unsafe. I have run out with both kids on the back a few times and it's horrible. The range they state in not even close. I added a 52v 2nd battery. Note location in photos.
2) It's slow and unsafe stock. Added a Bolton controller. It pulls hard up hills and goes close to 35MPH. Plus the range with two is great.
3) REALLY unsafe stock brakes. I tried cable pull hydraulic , they are terrible after a short time. I added front and back Avid code 4 piston brakes with 203mm SRAM rotors
4) Trailer hitch (gas pipe) and trailer (amazon). You can carry everything needed and not get sand or whatever in your car plus park right where you camp or whatever.
5) Simple side mirror
6) true 750w Bafang Hubbody
7) extra tube, tire irons and 4 C02 (i have got 3 flats over the last year and had to call friends. Now I can fix a flat on the side of the road)
One Up rack - I can put this heavy bike on this rack and go places...

definitely a cool set up, but one of the lures of Rads are their relative affordability, and with your set up, that bike isn't staying under 2k.

I would definitely love an extra battery set up on my Rad Rover 6+, but I'm too afraid of burning something out.

It would be cool if Rad had these items as options when placing an order, so you'd get them mounted on the frame before it ships.

So far I've added the small basket, a suspension seat post, a better saddle, the caboose and Conestoga, Tannus armour, hydraulic brakes, new grips.