Inside the Rad battery and BMS

[DickB]

BTW since my first post I have identified the BMS chip in the Rad Standard battery and studied it's spec sheet, as well as reverse-engineered much of the BMS circuit, so I have learned more about how the BMS works.

[JillGat]

Happy New Year, everybody!

I keep reading - from various sources - about battery maintenance and charging; some very specific recommendations about when, how often and how much to charge, etc.  Sometimes there is a difference of opinion (though I trust the knowledge of people on this thread.)  I am still waiting for somebody to tell me that none of it matters, that ebike batteries are designed to compensate for any charging "mistakes" owners make.  My guess is that the majority of ebike riders out there just go out and ride and then leave the battery on the charger until it's full or even until they go out for the next ride.  Or just charge it when it runs out. 

My biggest question is why the advice about balancing the battery is not included in the owner manual, or even on a separate sheet of paper when you receive your bike.  I happened to see it mentioned in the forum somewhere before I got my bike and then had to dig a little bit to find the instructions on the site. 

[DickB]

Balancing information is included in the Owner's Manual.  Which model Rad do you have?

Proper charging does matter if you want to get the most performance and longevity out of your battery.  The thing is, many riders are using only a fraction of battery capacity, and won't notice a degradation in capacity. For example, I ride 12 miles a day PAS 1 -2, and use only about 15% of battery capacity. If improper charging reduces my battery capacity say 20% over six months or a year, I'll never notice it. If I take long rides at high PAS levels, I will notice a 20% reduction in capacity. It depends upon how one rides.

[dan26ntn]

This is kind of a late reply , but may be helpful to someone eventually.  First off, I've been into just about every nook and cranny of my RR1 and I've come to the conclusion that Radpower put a lot of thought into their designs. Yes , there are lower cost parts in places, but in those places, it makes sense . They absolutely put quality and safety in places where it matters most. The battery is a good example. It's not over engineered, but it's designed to not go up in smoke the first curb you hop off of. The cells used are the Samsung 35E as mentioned before. I know a lot of people want faster charging. This cell is one of the best on the market IF you charge it slow. It'll last 1000+ charge cycles in the right conditions. .2C is your best bet if you want it to last as long as possible. That's about 3 amps . The upper limit I would go would be 6amps . Some very thorough testing shows this battery will be "shot " quick if charging above .5C or 6.8 Amps.

[Gizmo]

How come I did not get a Samsung or Panasonic battery on my rad 6+ as they advertise on there website, instead I received a DLG battery, when I called rad they tried to tell me that was the container Co for the battery total BS!

[dan26ntn]

How come I did not get a Samsung or Panasonic battery on my rad 6+ as they advertise on there website, instead I received a DLG battery, when I called rad they tried to tell me that was the container Co for the battery total BS!

Have you opened it and looked at the individual cells? If they're the purplish-pink color they're most likely Samsung's . There's nothing outside the case that indicates which cells are inside that I'm aware of.

[Veggyhed]

Companies buy the cells from Samsung and assemble their own packs. They're almost as never an indication on the external case of the battery pack. This method is industry standard.

Sent from my Pixel 3a using Tapatalk

[flaco1801]

Hello Dick...I have a 2020 Rad Mini 4.....I can use the battery on peddle assist 1 and 2....I get near the house and use the throttle and the bike dies...The group has been very helpful and many are saying its the BMS....some times i can lift the battery out of the cradle and the display will go back on when i set it back down...I will roll into the garage after it dies and the Fluke says 52 volts....sometimes i roll in and it says 25 volts...The battery will go to 54 volts to 25 volts in a heartbeat...Is there anything i can do short of buying a new battery...I can get a reading of 25 volts put the charger on for 5 mins. and get a reading of 52 volts....researching the pros and cons of an aftermarket battery to save money is a chore...Thanks,Jeff

[DickB]

Hello Dick...I have a 2020 Rad Mini 4.....I can use the battery on peddle assist 1 and 2....I get near the house and use the throttle and the bike dies...The group has been very helpful and many are saying its the BMS....some times i can lift the battery out of the cradle and the display will go back on when i set it back down...I will roll into the garage after it dies and the Fluke says 52 volts....sometimes i roll in and it says 25 volts...The battery will go to 54 volts to 25 volts in a heartbeat...Is there anything i can do short of buying a new battery...I can get a reading of 25 volts put the charger on for 5 mins. and get a reading of 52 volts....researching the pros and cons of an aftermarket battery to save money is a chore...Thanks,Jeff

I can guess, but a few tests are in order to determine if it is bad cells, bad BMS, switch, connectors, or wiring.

I got a battery from another member and it was displaying similar symptoms. One of the cell groups was bad - low voltage. The bike would work for a few seconds, then shut down. The BMS was fine and doing its job - shutting down under low voltage conditions which were aggravated by high current draw.

On the other hand, a multimeter will read about 25 volts if the key switch is off. This is because a very small leakage current flows with the key switch off, and the resistance of the multimeter drops the voltage that it sees. If your key switch is intermittent, that could be the problem. Your 25V reading is a strong clue, so I would start there. I would bypass the key switch (one way is to unsolder the wires on the key switch and solder them together) and use the throttle. Or just try turning the switch off and on a few times when you see 25V.

Next I would test the cells.

To test the cell groups, open up the battery, connect a voltmeter across each opposite pair of terminals in turn as per the photos. You'll be making 13 connections and measurements.  On the circuit board you will see B- or B0, B1, B2 etc. Test B0 - B1, then B1 - B2, etc. You should see the same voltage within a tenth of a volt on all cell groups.

Be careful. If you short out any pair of conductors to each other, bad things will happen - sparks, very high current, heat, melted conductors.

[Omidia Ramin]

Since you have already taken the battery apart, in great detail. I'm curious to know: is there any slack space inside big  enough to say hide an Artag in? Thanks!!

[DickB]

Yes.

[mr.ed]

Great post and thanks very much Dick. 

About the YZPower charger that Dick cited earlier:  Has anyone purchased this and did it work OK?  I would like to have a fast charger with me for long rides when I need to give the battery a mid-ride charge.  The 2A charger from Rad takes about 2 hours for each hour of riding and I would like to double that and get at least an hour of riding for an hour of charging.  So I'm looking for experiences with the YZPower charger.
Thanks,