I'm looking for a non-working Rad controller for parts.

I have a Rad Rover 5. The controller has a main circuit board and two auxiliary boards, one for the brake light and one for the head/tail lights. I'm looking for one auxiliary board - it doesn't matter which one as they are identical. The head/tail light quit working on my bike; the board is bad.  Even if your controller is bad, it is likely that the auxiliary boards may be OK.

I suspect the same boards may be found in other Rad controllers, so if you think you have one other than a Rover 5 it may still be applicable.

The auxiliary boards are enclosed in shrink wrap (see photo).

Please contact me if you think you may be able to help.

On what battery version?

I have two versions of the Standard Rad battery. On which of these two types did you blow a fuse?
My reason for asking is that the BMS version is different in the later Standard Battery. It has three protection diodes that prevent current from flowing from the battery to the charging jack, and should prevent the fuse from blowing if the key is stuck into the charging jack. The earlier BMS does not have these.

Curiously, these diodes are not present in the new semi-integrated battery BMS

The Standard Rad battery is made up of 52 cells, with groups of 4 cells connected in parallel (to provide more current) and 13 groups connected in series (to provide more voltage). 

Cells are in balance when all cells are at the same State Of Charge (SOC) and voltage, and out of balance when at a different SOC and voltage.  The cells connected in parallel are always in balance, because they are all at the same voltage.  The series-connected groups can get out of balance, with one or more groups having more or less SOC than the others.

It is desirable to have all cells at the same SOC to get maximum performance – run time – out of the battery as a whole.

The Standard Rad battery uses passive cell balancing. Passive balancing is performed only during the charge cycle, and when the charger is in Constant Voltage (CV) mode. It does so by bypassing charge current away from cells that are already at the desired SOC and into cells that are at a lesser SOC.

Looking at the attached figures, each group of 4 cells in parallel has a shunt resistor and a switch connected in parallel with the cells. When the switch is off, all charge current flows to and through the cells. When the switch is on, up to about 40 mA (0.04A) of current flows through the shunt resistors, and not to the cells.

When a depleted battery is first connected to the charger, the charger operates in Constant Current (CC) mode. About 2A of current flows to and through the groups of cells – about 0.5A to each cell – and none through the shunt resistors, because the shunt switches are off. In Figure 1, note that Cell Group 2 is at a lower SOC than the other cell groups.

As the cells are charged, their SOC and voltage increases. After (typically) 2-3 hours, the combined voltage of all cells approaches the charger float voltage of 54.6V, and the charge current decreases dramatically.  Cell Group 2 has been charged along with the other groups, but remains at a lower SOC and voltage than the other cell groups. The Battery Management System (BMS) detects this voltage imbalance, and turns on the shunt resistor switches for all cell groups that have reached full SOC, bypassing current around the cells. It leaves the switch off for any cell group that is at a lower SOC, so that the current continues to flow into those cells. This stops the fully-charged cell groups from getting more charge current, and only the lesser-charged cell groups continue to get current. The BMS is balancing the cells. Because the balancing current is much smaller than the initial charge current, it can take several hours to bring the unbalanced cells up to the desired SOC.

The BMS will enable balancing any time the charger is in CV mode (green light) and any of the cell groups is at a lower SOC and voltage than the others. Balancing is enabled based on relative cell voltages, not an absolute voltage. There is nothing special about a 12 hour charge, other than 12 hours pretty much guarantees that the BMS will have had adequate time to balance. Once all cells are in balance, all the switches are turned on, and all low charge current bypasses the cells.

The new Rad semi-integrated battery has internal fuses that are a bit difficult but not impossible to replace.

I got a battery from a Facebook group member that refused to charge after a couple of months. She sent it to me to examine. (She got a warranty replacement from Rad.)

The new battery has an aluminum tube-like case, and is opened from the ends. To open it, you must first pry off a cover at either end of the battery to expose T10 Torx screws. Remove 4 screws at each end.

The battery is well sealed against moisture. The end caps have rubber gaskets, and all exposed connections are sealed in silicone rubber. The battery assembly itself is fastened to the case at either end with silicone rubber. This must be cut at both ends to remove the battery assembly. To remove the assembly, I pushed from the power connector end, rotating the end cap to fit through the case.

The entire assembly is sealed in shrink wrap and more silicone. The fuses are at either end. Not knowing the internal construction, I made a bit of a mess opening the shrink wrap. Now knowing where the fuses are located, small flaps could be carefully cut in the shrink wrap to expose the fuses and then reseal the shrink wrap. Another Facebook member used my information and photos to replace a charge fuse by just opening the end caps, cutting the silicone, and pushing the charge fuse end out of the case a few inches. He then cut a small flap in the shrink wrap to expose the fuse. It is not necessary to completely disassemble as I did.

The charge fuse is 10A, possibly because the new charger is higher amperage? I'm charging with my standard 2A charger to confirm the fix. The battery arrived depleted, with 1 of 10 LEDs lit. At present I have 3 LEDs lit. The battery is presenting about 46V at the power port, consistent with 3 LEDs. I cannot test it on my Rover 5, but I have no reason to believe that it will not work; in fact it was working fine, just not charging.

I'm sure many other than me question the decision to require such disassembly to replace a fuse. Including Rad. This inexpensive fuse cost them a replacement battery.

This post applies to the batteries on the Rad 5 and other models using the same battery.

I just finished repairing a Rad battery by replacing its faulty BMS with an aftermarket one.

A Facebook member sent me a battery that had failed with less than 200 miles on it. He had opened it up and observed condensation (despite the battery not having gotten wet) and apparent damage to the BMS circuit board. I offered to take a look at it.

There was indeed damage on both the top and bottom surfaces of the BMS circuit board. The cells looked fine and all were nearly fully charged. This was not too surprising. Battery failures are much more likely to be due to bad connectors, wiring, or switch than bad cells. If you have a battery that has failed completely to work or charge, as opposed to working but with limited range, odds are the cells are fine. Especially one with so little use as this.

Rad does not sell components such as the BMS for their batteries. Fortunately, aftermarket BMSs are available. I found a suitable replacement at greenbikekit.com for $26 plus shipping. It is much more cost- and time-effective to replace a BMS rather than troubleshoot and repair a BMS, as BMS components are surface mount (very tiny solder connections) and some components (such as the BMS chip) difficult to source.

Repair involves removing the faulty BMS, reconnecting a handful of wires (some of which require extension) to the new BMS, and making connections to each individual group of cells. The Rad BMS circuit board spans the entire top of the cell holder, making clean connections to the individual cell groups. The aftermarket BMS does require several more wire connections than does the Rad BMS. I spent a couple three hours at this, and could probably do it faster if there is a next time.

I will run his battery through a few cycles to make sure it is working well before returning it, but so far so good.

I will be providing more details on this repair.

It appears that Rad has improved battery and possibly charger design with the new semi-integrated battery as used in the Rover 6.

The previous batteries use passive balancing, which requires the charger to be left on after the Charge light turns green, to supply the trickle current necessary for the BMS to balance cells if required. The Rover 6 manual gives no instructions to balance, and the Rad Q&A states that no special balancing procedure is needed. This suggests that the semi-integrated batteries may use active balancing. I wonder.

https://radpowerbikes.zendesk.com/hc/en-us/articles/4406497553819-RadRover-6-Plus-Semi-Integrated-Battery-Q-A

This letter from the FTC in 2018 is interesting: https://www.ftc.gov/news-events/press-releases/2018/04/ftc-staff-warns-companies-it-illegal-condition-warranty-coverage
"Each company used different language, but here are examples of questionable provisions:
This warranty does not apply if this product . . .  has had the warranty seal on the [product] altered, defaced, or removed."

If you have a bad battery or controller, I'd be interested in taking a look at it. I would like to know more about these components and see if they can be repaired.

I recently got a bad battery from a Facebook member and found that it had a simple problem - a separated electrical conductor. This type of simple failure is often the case. I repaired the battery at no charge and returned it to the member for shipping charge only. Doing this while in learning mode.

Best to send me a private message.

The Rad battery pack is made up of batteries, Battery Management System (BMS) circuit board, key switch, charging port, power connector, and battery meter.

The Rad BMS uses a Sino Wealth SH367008 Li-Ion Battery Management chip. Sino Wealth is a Chinese integrated circuit manufacturer. The spec sheet for the chip is in Chinese, but Google Translate does a good job.

"SH36700X has built-in high-precision voltage detection circuit and delay circuit to monitor voltage, current and temperature to ensure the safety of the pack. At the same time, the series of chips also have Balance function to extend battery life."

The Rad battery pack has 13 groups of 4 cells each, with the 4 cells connected in parallel and the 13 groups connected in series. Because of the parallel connection, each group of 4 cells is essentially one cell with 4 times the capacity of an individual cell. Unless otherwise noted, further use of the term "cell" refers to a group of 4 parallel-connected cells. To the BMS, each group is in essence one cell.

The Rad chip uses a passive switching shunt resistor method for balancing. It does not use active balancing. Balancing is done during charging only.

Shunt resistors are switched in to equalize the voltage of each cell by dissipating the energy from higher-voltage cells down to the lowest cell voltage. Resistors are connected in parallel with each series-connected cell through semiconductor switches. The switches are controlled by the Sino Wealth chip.

The shunt resistors draw only a small amount of current and would be ineffective at high charge current. Balancing must take place at the end of the charge cycle. This is almost certainly after the Rad Charge light has turned green. To balance cells, Rad instructs that the charger be left on for 12 hours, long after the green Charge light. I have observed the charger continue to supply current to the battery pack after the green light illuminates. If an aftermarket charger cuts off current at charge complete, the pack may not be balanced.

The circuit board has semiconductor switches to disconnect the battery under both charge and discharge conditions as a whole pack. There is no provision to connect or disconnect individual cells or groups of cells. The pack is disconnected under charge overvoltage, discharge overvoltage, charge under voltage, discharge under voltage, short circuit, and high or low temperature.

With the key switch in the Off position, the semiconductor switches are off. Turning the key switch on "wakes up" the chip and the discharge switches are turned on presenting voltage to the battery power connector. As long as the key switch is on, the BMS is active and drawing current, albeit small, from the battery. The key switch does not disconnect power directly, but basically tells the chip to do so.

Construction of the battery pack is high quality. The mechanical construction is very good, with a plastic holder for the cells that is very well secured, as is the circuit board. Battery connections are direct to the circuit board with welded straps. Components and connections to the circuit board are all environmentally protected (think humidity) with conformal coating - the blue stuff that you see in the photo.

In my quest for more information on the Rad battery and charging, I ran an experiment to plot the battery voltage discharge profile and note the accuracy of the Rad battery meters.

For the test, I ran full throttle only on a straight, quite level road (Florida!), stopping every 2 miles to check battery voltage and meter readings.  The meters were read per Rad instructions, with no pedal assist and no throttle, about 60 seconds after stopping.

My test shows that the Rad meters are a bit optimistic.  The LCD meter reads Full at 70% charge. One would expect to see 4 bars. At 50% capacity, the meter shows 4 bars, which you might interpret as 80% remaining.

Li-Ion battery life can be extended significantly by not charging the batteries to their full capacity. For example, charging the battery to 100% capacity, one can expect 300-500 discharge cycles. Charging to 80-85% capacity , one can expect 850-1500 discharge cycles. (Source: batteryuniveristy.com.)

If you are not using the full capacity of your Rad battery when riding, you can take advantage of this characteristic and extend the life of your Rad battery. I typically ride 10-12 miles per day, with minimum level (1-2) assist, and my battery capacity drops only about 20% on the battery meter. On trips into town, I ride about 15 miles at higher assist (3-4), and then use about 40% capacity. Clearly, I could charge to only 80% capacity and have ample reserve capacity at the end of my rides.

The Rad battery charger will on its own charge to 100% capacity.  You can charge to a lesser capacity with it by simply disconnecting the charger before it has completed a normal charge cycle - that is, before the CHARGE LED turns from red to green. But how do you know when to do this to achieve an 80% charge?

I have developed a simple smart switch to do this.  It plugs in between the Rad charger and Rad battery, and monitors the charge. When the battery has been charged to 80%, the smart switch disconnects the charger from the battery. (The CHARGE LED will turn green, just as it does if you unplugged the charger from the battery.)

I have been testing my smart switch for several days now, and so far it is working as expected. I will continue testing to fully validate the design.

I would like to emphasize that this smart switch does not alter the Rad charger or charge characteristics at all. It simply disconnects the charger as if you had unplugged it. Rad even recommends charging to only 75% when storing the battery for more that two weeks (although they offer no way to determine when this level of charge has been achieved!), so it is a perfectly legitimate thing to do.

I am an electrical engineer. I have developed and marketed several add-on electronic devices for automotive and other uses. I use a professional circuit board fabrication company and quality components from a major electronics distributor. If there is interest, I will market my smart switch for Rad users. The cost of the smart switch will be about $50. Considering the cost of a replacement Rad battery, I think it is a wise investment.

I would appreciate any feedback on interest in such a smart switch. I welcome questions.

I like the mounting bracket but found that even a short Polar bottle hit the handlebars. A simple mod fixed that, and put the bottles at a handier angle.

Pinstripes to accentuate the fender.

I've found that the speedometer and odometer accuracy can be improved by changing the tire size from 26 to 28 on the controller display. 28" is closer to the actual size of the fat tires.  To change, power on the display, press and hold both up and down arrow keys, then use the up arrow key to set 28". My speedometer and odometer are now near identical to GPS.