Connect charger directly to bike controller? (For testing.)

[MrDecaf]

I have a bike with a dead 12S 2P lithium-ion battery pack. The label on the dead battery says 44.4V. I am considering replacing the 44.4V battery pack with a 48V battery pack, because 48V is more standard.

I am thinking about connecting a Cycle Satiator charger with a 48V 8A profile directly to the existing bike controller to see what, if anything, makes blue smoke. My goal is to to know what will need to be replaced before committing to the expense of a new 48V battery pack.

I know it does not simulate the bike under actual load, but does this seem like a plausible test?

 

[nickceouk]

I think the charger first checks battery voltage and then applies power at the same voltage for the constant current phase of the battery charging cycle.
If this is indeed the case it will sense 0v from the controller and likely provide no output...ie 0V back to the controller.

I may be wrong about this though

 

[MrDecaf]

I think that is what normally happens. The Cycle Satiator has a “Force Charge” feature, but might still do that, even if I do a force charge. I guess I could try it, and see what happens. If it shuts off immediately, it’s probably not a good test. Thanks.

 

[E-HP]

I think that is what normally happens. The Cycle Satiator has a “Force Charge” feature, but might still do that, even if I do a force charge. I guess I could try it, and see what happens. If it shuts off immediately, it’s probably not a good test. Thanks.

Might work, but I'd do a quick check of the controller's battery inputs to makes sure there isn't some sort of odd short first (just to make sure the blue smoke doesn't come from the Satiator).

 

[MrDecaf]

Might work, but I'd do a quick check of the controller's battery inputs to makes sure there isn't some sort of odd short first (just to make sure the blue smoke doesn't come from the Satiator).

 

[amberwolf]

The satiator should have overcurrent protection, so that's unlikely, but still good to check.


Note that if your controller is meant for a 44v pack then using it with a 48v pack means it's LVC will not engage until the battery';s BMS emergency shut off has already done so...so you will want to watch the voltage as you run down and not force the BMS to do this all the time--it's not intended as an everyday shutdown device, that's what the ocntroller LVC is for.

 

[MrDecaf]

The satiator should have overcurrent protection, so that's unlikely, but still good to check.


Note that if your controller is meant for a 44v pack then using it with a 48v pack means it's LVC will not engage until the battery';s BMS emergency shut off has already done so...so you will want to watch the voltage as you run down and not force the BMS to do this all the time--it's not intended as an everyday shutdown device, that's what the ocntroller LVC is for.

That makes sense it sounds like I should plan on replacing the controller, anyway

 

[MrDecaf]

I went ahead with connecting the Cycle Satiator directly to the bike controller, where the battery would ordinarily connect. I selected the preconfigured profile for charging a 48V battery at 7A, and I did a “Force Start.” The good news: Lights on the controller lit up; the headlight lit up; no blue smoke. The bad news: The front hub motor did not turn.

I am pretty sure the reason for the motor not turning is that the Satiator was trying to trickle charge at 0.1-0.2A. Voltage fluctuated in the 54.5 volt range. I'm not sure how meaningful that is, but those are the results.

 

[glennb]

I have a bike with a dead 12S 2P lithium-ion battery pack.

So was Frankenstein’s monster. No plans to bring it back to life?

 

[MrDecaf]

So was Frankenstein’s monster. No plans to bring it back to life?

I tried unsuccessfully to trickle charge the 12S battery pack. Opening the pack to gain access to the the cells looked impossible without destroying the BMS. I cut the cables for future use, and I plan to take the unopened pack to the recycling center.

I am undecided about purchasing a 48V battery.

 

[glennb]

Fair enough.

If you’re lucky it’s the 1st or twelfth parallel group that failed, and you can simply break the serial connection or lop an end off and have a 11S battery. Or if it’s the second or eleventh, likewise for a 10S pack.

On the assumption that each of the parallel groups are equally likely to fail (which isn’t actually a given), there’s a 33% chance that you have a useful 10S battery on your hands. They’re not bad odds.

Also, even if it’s a failed P-group centred in the pack, splitting and rejoining, or jumping, is not difficult.

You might find people willing to repurpose the pack, and save yourself a trip to the recycling center by offering it up in the classified section.

 

[amberwolf]

I went ahead with connecting the Cycle Satiator directly to the bike controller, where the battery would ordinarily connect. I selected the preconfigured profile for charging a 48V battery at 7A, and I did a “Force Start.” The good news: Lights on the controller lit up; the headlight lit up; no blue smoke. The bad news: The front hub motor did not turn.

I am pretty sure the reason for the motor not turning is that the Satiator was trying to trickle charge at 0.1-0.2A. Voltage fluctuated in the 54.5 volt range. I'm not sure how meaningful that is, but those are the results.

The satiator will only provide the current the controller asks for--it cannot force current into it.

So the low current you see is *because* the controller isn't running the motor; it's not the cause of it.

There are at least a few handfuls of common reasons the controller might not be trying to drive the motor; since the system is "dead" (no working battery) those also include fried controller, fried motor, bad wiring or connections, internal corrosion (in any part), etc.

The first thing I would try is set the CS down to the 44v battery nominal range, and retest the bike, in case the controller has an HVC that is below what the 48v charge profile outputs.

Does the bike have a display that lets you change modes? Many of these don't allow throttle operation in all modes, so if you're trying to use the throttle to test the motor, you might need to change to another assist level. Some of them have a mode zero that doesn't do anything at all, and is the default poweron level, for safety. You have to go up a level or more to get any motor assist.

Also...does the battery to bike connection have more than two pins? If so, it might be one of the few types that requires a signal from the battery to make the controller operate.


Do you want to troubleshoot the bike?

If so, and none of the other things are the problem, I'd start with unplugging and replugging every connector, examining each plug on both ends carefully in direct sunlight while they're disconnected.