Tuesday, July 21, 2020

Heavy duty Ridekick adapter for bike kid trailer

Warning: Build and use this adapter at your own risk!



Dee from Ridekick has transferred me the following adapter picture made to hook a bike kid trailer onto the Ridekick or other kind of trailer: (Dennis Mount?)


My initial thought was that it was easy to build and light but it would perhaps make the frame of the ridekick a bit fragile by drilling large holes into the small metal tube of the frame, so i came up with an alternative that should not void the warranty as it leaves the frame of the trailer intact.


I use a steel bar (2 inch wide, 3/16 inch thick, 3 feet long before cutting, from common hardware store) that i bent on a vise with a heavy hammer in order to fit the curvature of the rear part of the ridekick. The hammering is quite intense with such a thick steel bar. Start from the left side as it need a sharp bent to fit the frame and continue to the right progressively. On the right side the steel bar can be cut to fit easily.



Leave a space between the metal bar and the plastic of the box to prevent damage with the bolts holding the L shape hook support in the back of the steel bar.

On the left side, the bent metal bar is bolted onto the part directly soldered to the rods of the frame from the motor/chain mount. On the right side, the metal bar is bolted with 2 separate custom bent 'U' shaped metal hooks.


One is V shaped while the other is flat in the middle to accomodate the shape of the frame vertical tube at the T soldered junction of the ridekick. (steel bar, 3/16 inch thick 1/2 inch wide)  


It is a bit tricky to get the bolts in place (i used 5/16-24 threaded bolts of various length, prefer lock nuts) through the U shaped hooks but with the right length, it fits. (pass the steel hook first, place it at an angle, insert fist bolt, flip it the other way and push a bit on the plastic case to have a bit more space).


Nicely, the 2020 version has the rear window for the flashing LEDs lower than the previous versions, so the steel adapter does not hide it at all :)


I use an electric pipe hook as a safety attachment for the nylon rope.

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V1 : The first version of the hitch system is low, but it works as long as you do not need to pass over any sidewalk edges.





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 V2: The hitch attachment allows to have the hook system at 13 inch from the ground, which is the same height as it stands when the hitch is bolted on my bike axle.



This adapter is just a plate with drilled holes to accomodate multiple hitch positions. It bolts on the original steel plate.
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Annoyingly, our kid trailer has a third swinging wheel attached close to the hook. i had to move it to be able to make sharp turns with the kid trailer hooked on the Ridekick. Perhaps the L shaped trailer hook support needs to be a bit longer, at the expense of having a stronger bending angular moment.


Time to build: 1-2 h in the evening for 5 days.
Cost: Steel bars and bolts if you have the tools...
Building fun: Maximal.
Riding performance: amazingly easy and stable at 25km/h.



--------------Bigger Battery--------------

In order to go further than 40 miles on a charge,
I got a 50Ah / 24 V LiFePO4 battery with BMS (1200Wh) on ebay (560$ + shipping) ( 12.9 in. x 6.6 in. x 8.5 in. dimensions). It is only 11.6 kg or 3kg heavier than the stock 12Ah/24V Pb battery but just fits in the trailer compartment :)

PS: the provided 2A/29.2V DC LiFePO4 charger provided with the battery is a joke... it took 25 h to fully charge the battery when it arrived new. 

The green wire is 10 gauge Cu filaments (NOT Al covered with a copper layer), compared to the stock 12 AWG wire connecting to the ESC. The wire is clipped into a copper terminal (3/8 inch or M10 hole) on one side and soldered to XT60 female connector on the other side.

The ridekick ESC XT60 connectors are short, and i hot glued them on the box to avoid vibrations to damage the soldered connections...


The overall power is amazing with this setup, i won t ever pull the kids without the Ridekick. At this time the 12Ah Pb battery holds very well with the kids trailer! we did a 12 mile (19 km) trip with the kids (not going too quick with bumps, pedaling a bit, etc) and it used 80 % Pb battery power.

yet to determine the range with the 50Ah battery...

---------- Adapter for the bike hitch --------------

One of our bike has an Al frame and is not having a large frame space to lock the position of the hitch in place. The ridekick original hook has an array of holes to place a small bolt and lock the hitch in place. (or it seriously turns all over the place when the trailer pushes)

so  i made a small piece of metal (inverted L shaped with a 4mm hole to accomodate the bolt on the hitch plate). That should lock it in place...



Thursday, June 04, 2020

Cheap high power DC power supply modification for ISDT Q8 battery charger - swap a resistor!

Disclaimer: try at your own risk! understand what you are doing.


I did not feel the need to get the 100$ ISDT T8 (42V/30A input max.) but baught the 60$ ISDT Q8 charger instead, which is limited to 34V/20A input power.

However, a DC power supply for this Lipo battery charger ISDT Q8 can not be found at a reasonnable price.
As listed below in the specs, the charger can only take a maximum of 34V. It is pretty hard to find a power supply with high power and less than 34V AND more than 30V.



ISDT Q8 Specifications: www.isdt.co

  • Charging Power: DC 500W
  • Charging Current: 0.1A-20.0A
  • Discharging Power: 15W
  • Discharging Current: 0.1A-1.5A
  • Input Voltage: DC 10-34V
  • Ouput Voltage: DC 1-34V
  • Support Battery:
    • LiFe,Lion,LiPo 1-8S
    • LiHV:1-7S
    • Pb: 1-12S
    • NiMH: 1-16S


i found this beast DC power supply for LED strips on ebay:
1000W AC 110V-240V To DC 36/48V LED Power Supply Driver Adapter With Switch

Specifications:
Wattage: 1000W
Output: DC36
Input: AC110-240V 50/60Hz
Working Temperature: 0~40℃
Storage Temperature: -20~60℃
Working Current: 27.8A
Safety Compliance: CCC/ FCC / CE  (China Export?)
Ambient Humidity: 0~95% Non-Condensation
Protections: Overload/Over voltage/Short circuit
Compatible With: 3528, 2835 ,3014, 5050, 5630 ,5730 Led strip lights

However again, the voltage of this power supply can only be adjusted in a limited range of 38 - 34.1V, which is likely to fry the ISDT Q8 charger (i chickened out and did not try).

Also, there is a safety issue on mine, i did not really understand where it comes from, the ground is not well isolated and triggers the GFCI safety fuse... 8 volts AC on the ground pin. i will have this mounted in a wooden or plastic box just in case!



The power supply is opened with 2 screws to change the AC power input, and the board can be easily removed from the box after carefully removing a few other screws hidden behind the sticker (this voids warranty - btw what warranty? on ebay, it costs 60$ : 16$ of power supply and the rest of express shipping from china, or if you got it on amazon : 16$ of board and the rest of profit for amazon).
The variablre resistor aside the green led light is connected to a 3.9 kOhm 1/4W resistor. the latter is the voltage range limiter. i replaced it with a 4.7 kOhm 1/4W resistor to obtain a voltage range of 36.0 - 30.1V ~27Amperes.

i chose to adjust the voltage to 33.0V to prevent temperature voltage drifts to go outside specifications, noxious for the charger...

this is a pretty easy modification and charger works at full power (550W)

hope it helps someone...