RR6+ battery

[DoomSlayer001]

I bought a RadRover 6+ a little over a year ago and now my battery won't charge, does anybody know anyone or any place in MN that refurbishes batteries.

[handlebar]

Here's a guy who knows who to fix them, but I don't know if he's in MN.
https://www.youtube.com/watch?v=Q287-kQNDsM

A suspicious person might imagine they'd designed the battery to force the consumer to pay $700 right after his warranty expired.

[Adams]

Have you checked the fuse?  What is the serial number on the battery - could then tell if it has replaceable blade fuse or the tougher soldered in one.

[philipshaw]

Sounds like a blown charging fuse. It's a 10amp mini-blade automotive fuse and I fixed one last week using the video Handlebar suggests as a guide. The battery works fine now.

[handlebar]

If a 2-amp charger blew a 10-amp fuse, I would think there must be something wrong with the battery pack or the charger that would blow the replacement fuse immediately.

That doesn't seem to happen. I think Radpower is installing inaccessible fuses with a low fatigue rating.
https://electronics.stackexchange.com/questions/251271/when-is-fuse-fatigue-a-concern

They would want these fuses to be good for as many charge cycles as a consumer would need during the warranty period.

Are the metal cases hazardous? It seems that the plastic you cut to get to the fuse is what prevents a short against the case, and a short could mean a big fire. If I replaced a fuse, I'd want to put reliable tape over the cut plastic. I don't know what kind of tape would be most reliable in this application.

[philipshaw]

The fuses can blow by anything conductive coming in contact with the charging port including moisture or anything metal. It can also happen if you leave the charger plugged in while connecting or disconnecting it from the battery. The position and design of the charging port seem to be a problem with the integrated batteries on the RR6+.
After replacing the fuse you need to reseal the blue insulated cover over the fuse. I used a very high-quality weatherproof electrical tape made by 3M called "Super 88". I believe it is rated for use underground and is waterproof and chemical resistant. The tape and adhesive are very strong. It will do the job for sure. You should be able to find it at hardware stores that serve tradesmen like Home Depot. Ask for it by name.  Of course, for liability reasons, Rad would never be able to say this can be done safely.     

[handlebar]

Thanks for the tip on electrical tape. All the 3M stuff I've used has been very good. No-name stuff that looks the same can be terrible.

It's hard to believe moisture could conduct enough current to blow a 10 amp fuse in a 50 volt circuit.

My battery and charger use a coaxial connector with the center pin live. Is yours coaxial? I don't see how plugging it in could short anything.

To me, the danger of connecting the live charger to the battery is that a little spark could pit matching surfaces so that the connector would then be troublesome. There could be a surge, but I don't see how it could be big enough to blow a 10 amp fuse.

If user error is the cause of blown fuses, it should happen most often in the first week or month of ownership. I wonder if that's the case.

If after a year of ownership, a rider blows a fuse because he ignored moisture, was clumsy, or didn't make sure the charger was off, sooner or later he'd probably do it again. I wonder if people have had to replace the replacement fuse.

If no-name electrical tape is likely to be terrible, I imagine there are terrible no-name fuses that look like the good ones. On the fuse you replaced, were there markings to show the origin?

[philipshaw]

The reasons for the fuse blowing that I stated came from someone at Rad. What you say makes a lot of sense when I think about it. Our battery was only 3 weeks old when the fuse went and we didn't do anything that would have caused it to go. So a bad batch of fuses may be it. I didn't save it, unfortunately. It was marked as 10amp but it didn't look like it was the same quality as the one I replaced it with. It looked flimsy. Like the plastic wasn't as robust. Rad did send a new battery under warranty but I thought I would attempt the fix and it worked out well. No problems with the repair.

[DoomSlayer001]

Thank you to all for the info, will take the battery apart and see what I can do hoping it isn't to much trouble to fix.

[DickB]

The charger is CC/CV (Constant Current/Constant Voltage). If you plug in to the battery first, the charger will start in Constant Current mode limited to 2A. If you plug the charger in first, it will be in Constant Voltage mode, and present 54.6V to the charge connector. If you plug that into a discharged battery, the large voltage difference between battery and charger will generate a large current spike that may or may not be sufficient to blow the charge fuse.

The charger should have protection against this type of current spike in my opinion.

[handlebar]

The charger is CC/CV (Constant Current/Constant Voltage). If you plug in to the battery first, the charger will start in Constant Current mode limited to 2A. If you plug the charger in first, it will be in Constant Voltage mode, and present 54.6V to the charge connector. If you plug that into a discharged battery, the large voltage difference between battery and charger will generate a large current spike that may or may not be sufficient to blow the charge fuse.

The charger should have protection against this type of current spike in my opinion.

Thanks, Dick. I wish I had equipment to test the surge. According to one Littlefuse chart, it takes about 100 milliseconds for 40 amps to blow a 10 amp fuse. It's hard to believe a 2-amp charger would have a low enough impedance to produce 40 amps or that the regulator wouldn't take over before 100 milliseconds.