Rad Power Bike Discharge Battery

[Mikes Electric Bikes]

I'm wondering if anyone has a good way to discharge a Rad Power Bike battery. I live in Minnesota and I have a new rental bike shop. I need to discharge the batteries mechanically due to the weather. Any ideas. Thank you Mikes Electric Bikes

 

[tomjasz]

I’m setting up a Grinspector. I used two load resistors last year.

Load ResistorsLoad Resistor 6.8 +US$30.00
(Link Removed - No Longer Exists)
6.8 Ohm 250 Watt Load for Battery Discharge Testing.
Weight: 0.64 kg

Grinspector - Grin Products - Product Info

We built the Battery Grinspector as a relatively inexpensive tool for ebike shops and advanced users that need to discharge test and characterize ebike battery packs. It is controlled with a Cycle Analyst running a modified firmware and allows you to charge and discharge the battery pack into...

www.ebikes.ca

 

[slayer1962]

why do you discharge them, for storage?

 

[Mikes Electric Bikes]

I’m setting up a Grinspector. I used two load resistors last year.

Load ResistorsLoad Resistor 6.8 +US$30.00
(Link Removed - No Longer Exists)
6.8 Ohm 250 Watt Load for Battery Discharge Testing.
Weight: 0.64 kg

Grinspector - Grin Products - Product Info

We built the Battery Grinspector as a relatively inexpensive tool for ebike shops and advanced users that need to discharge test and characterize ebike battery packs. It is controlled with a Cycle Analyst running a modified firmware and allows you to charge and discharge the battery pack into...

www.ebikes.ca

Thanks Tom I will look at it!

 

[Mikes Electric Bikes]

why do you discharge them, for storage?

If you don’t use the battery for a extended period of time it needs to be discharged so it’s not fully charged. The battery will then be able to go into a sleep mode.

 

[harryS]

Do they really go into sleep mode? More sophisticated bikes probably do go into sleep mode, but Rad's? Pretty simple batteries, I believe. More like, if you let them sit too long at low voltage, they shut off because of drain from the BMS and then an expert has to determine whether or not it's safe to manually recharge the cells that are too low.'

This is probably a fire hazard, but I've run packs down with a hair dryer. Connect the battery to a 110V socket. Plug in the hair dryer. This one draws about 4A at 52 volts with the heater on That's 200 watts, and an hour is 200 w-h.

A old style 100W light bulb is safer, but only draws .3 amp at 50 volts, which is 15 watts. Too low of a load to discharge in a meaningful time.

You certainly don't want to let it run down by itself. An appliance will run the pack down to LVC, and who knows, maybe the BMS will go to sleep.



Or you can go with a 500W resistor. It will get hot. Screw it to a metal heat sink. Maybe 20 ohms or 10 ohms, which will be 125W and 250W respectively at 50V. V*V/R is your formula for watts. Still have to be careful of running the pack flat. You don't need to run it flat just down to 50%.

uxcell 500W 10 Ohm Aluminium Housing Chassis Mounted Wirewound Power Resistor Glod Tone: Amazon.com: Industrial & Scientific

uxcell 500W 10 Ohm Aluminium Housing Chassis Mounted Wirewound Power Resistor Glod Tone: Amazon.com: Industrial & Scientific

www.amazon.com

 

[slayer1962]

I ride mine in winter at least once a week and charge it every couple weeks.

 

[Mikes Electric Bikes]

I ride mine in winter at least once a week and charge it every couple weeks.

When you have 25 Bikes it’s a bit hard to ride them to get the batteries down

 

[indianajo]

surplus sales www.surplussales.com/Resistors/WireWound/WW3-5025.html
has 5 ohm 225 watt resistors at $13 ea in quantity 10. Wattage is (V^2)/R Don't exceed 60% for long life. Mount on metal brackets off the floor or better, concrete pad. I cut and bend the brackets out of box fan or microwave shells. Use safety glasses with power tools.
@ 50 v 3 series 5 ohm is a 3 amp load, 2 series is a 5 amp load. One alone would draw 500 w & you shouldn't do that very long.
I use some Dale (US) 5 ohm 225 W I got from apexsurplus at $5 each for battery checking, also full power checks on PA amplifiers I repair. But that party is over: he sells on amazon now. I've got my 8 of them. Amazon shipping is too high unless you are a streaming fan. I don't need same day delivery. I'm not paying the premium for it either. Amazon drivers can be a hazard to bikers, the way Fed Ex was in the beginning.