Charged battery cuts out under load

808ebike

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First post so please be gentle. Lol

I have a 48v13ah battery for my BBSHD. As soon as I throttle my battery shuts down. What I've found is as soon as this happens, The voltage from the battery is 0. When I turn off the battery and switch it back on, the battery shows 52 volts. I'm thinking the BMS is bad. Just need some other troubleshooting guidance that can help me track down the problem.

Thanks!
 
First speculative question might be to dig for amp cap in the specs on the battery. It is my (limited) understanding that batteries contain current limiters in the bms.
 
Typically usually the amp limiter in the bms will be way over the natural current draw for your system but if you're mating some random battery with a fairly high powered system the current draw might be too much. i gather the bbshd is nominally 750-1000 watts but could peak greater than 1000 watts, dunno
 
Update.... I charged the battery to 54v. All was well until the battery cut off. I had to turn the battery off and back on before I could turn the display on. I took the battery off and my volt meter read 50v. I believe I drove uphill for a mile with very little pedaling and 3 miles around my home.

I'm leaning toward the bms. It couldn't be the BBSHD programimg because I have to switch the battery off and on to get the display on.

Any suggestions on my next step?

Thanks.
 
First step would be to correctly define your battery. It is NOT repeat NOT a "48V" battery.

Next step would be to determine exactly what the LVC is set for both on the battery BMS and the controller.

Third would be to revise your thinking that it "cannot be the BBSHD programming"

Next incident, do NOT turn the battery off, instead disconnect it from the motor, wait a few minutes, then re-connect. What happens will provide valuable diagnostic information.
 
Thanks for the suggestions nelson37.

Just had some info. The battery is labeled as 48v 13ah.

I found someone with the cable and program for the Bafang motors.

I will get back with your suggestion of not turning the battery off when it cuts out, removing it, resting it for a few minutes and reinstalling battery.

I'll report back soon. Thanks.
 
If you are charging a 48V battery to 54V, something has gone horribly wrong. A 48V charges to 50.4V, a 52V battery charges to 54.6.

DEFINE YOUR EQUIPMENT OR FIND SOMEONE WHO CAN. You could burn your house to the ground.
 
This is the battery and the voltage I took. Going for a ride in an hour to do the test. Battery is on my grill incase it wants to self cook.
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Wait a minute. I see posts that say a 48v battery fully charged is 54.6 volts?
 
Ok. Rode bike until it kicked off. Voltage was .9v right off the bike. I let it rest for a couple minutes and then put the battery on. No power to the display. Turned power off and on. Display lights up. Took battery off and it shows 50.4 volts.

So my assumption is the bms is bad. Or am I missing something?
 

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Not to sound too argumentative here, but all three of my Unit Pack Power "48 V" batteries read 54.6 when fully charged, and they both work fine with my bafang controller and oatema controller which are both nominally "48V" systems. I'm not sure what the "fact" really means in this case, since we're talking about what manufacturers call the things that they sell, but suffice it to say there are SOME battery MFR's out the making batteries which charge to 54.6V and drain down to 47V min , which is a range that contains 48V, and calling them "48V" batteries.
 
Thanks for the reply, and I don't mind any input.

Yesterday I found a bike with the same battery. I used his battery and it cut off like mine. So I'm under the assumption that the controller is bad. But would that cause met to have to turn the battery off and then on to reset the battery. Anyone had this sort of issue with their bike. Am I right thinking my controller is pulling too many amps.

Btw.... we also pulled the information off of the bafang software. Setting is set on 30 amps, and cutout is at 40v.
 
Bioenno Power makes a "48V" battery with an operating range from 40V to 58.4 V (!*%^?). This is a fairly reputable company based in California with batteries about twice the price per WH as my Unit Pack Power made in China batteries.

 
808, Can you clarify? Do you mean that the BBSHD controller has an amp limiter at 30A, meaning it is supposed to not draw more than 30 amps? I would check to make sure that the BMS of the battery does not have a discharge current limit of equal to or less than 30A, as that could cause the power cut-out, and the problem would persist with another battery of the same make. Also clarify what you mean by the cutout at 40v? I thought before you were saying the cut-out happened at 52v?
 
My bad. They cut out at 50v. Typo.

We tried lowered it from 30 (BBSHD) to 25a. and it still cuts out at 50v.

Is there a way to check a BMS for the amps. cutoff?

Why would a known good battery cutout at the same voltage?
 
Well it would cut out at the battery's max amp rating, regardless of voltage. I'm not necessarily thinking that is the problem, actually most likely it isn't, I just thought it's an easy thing to check.. It would be in the specifications list for the battery. It will say something like "30 amp BMS". To be clear that's an entirely different number than the amp hour rating of the battery. 13AH is a measure of how much energy is stored in the battery.

There also might be a low voltage cutoff built into the battery BMS. It will say something like "LVC" . Or you might be looking for an "operating voltage range" like "47 to 54.6v", meaning the battery charges to 54.6 and goes down to

The point is you're looking for these numbers in the specifications list. You don't need to do anything.

Sounds like it's most likely something to do with the bbshd controller. I'm not a mid drive user so I have no direct experience advise to shed there.

I do know that *some* controllers have built in low voltage cutoff i.e., if the battery drops below voltage X, the controller cuts out power. It's insurance protection for the battery, but performed by the controller. Maybe the number X is programmed in wrong?.. Or maybe 50v is the low voltage X for a "52v" battery, which would make sense, and there's a change in settings. Doesn't the bbshd operate at 52v as well?





I really don't know I'm just giving you other things to consider, stabs in the dark.
 
Battery capacity is defined by SERIES count. A 12S battery, fully charged, is 12 times 4.2V, which is fully charged voltage for almost all lithium cells. 12S gives 50.4. This is what is referred to as a "48V" battery. 13S is 54.6V and is called "52V". 14S is 58.8V and is called various things.

Notice that the numbers are NOT an average, nor any reasonable value to define a battery. They are simply easy approximations that honestly do great harm and are stupid. Many ebike fires are caused by this idiotic convention, and the end users lack of any knowledge whatsoever of what it means.

YOU MUST KNOW YOUR SERIES COUNT.

Overcharging a lithium battery is extremely dangerous.

BMS and Controller have LIMITS as to maximum amperage, but not a CUTOFF. BMS and controller have CUTOFFs for Low Voltage. SOMETIMES these are programmable, SOMETIMES they are set by a changeable menu item. This is for the controller, not so much for BMS, meaning the programmability.

If you have a 30a limit, then the controller or BMS will not put out more than that, at least continuously, but they will not shut down.

Battery BMS cutoff is reset by turning battery off and on, which also resets controller. Controller is reset by removing power. Removing battery resets the controller. Leaving battery switched on while doing a remove and replace resets the controller but not the battery. Note that there is some risk involved installing a live battery.

If you are cutting out at 50V, then your controller is set for a MUCH higher voltage than your battery is capable of.

Battery BMS LVC are almost always set up for the battery they are installed in. Controllers are not closely connected to the battery voltage when built or installed. They are much more likely to be incorrect for the existing setup.

Oh, and you have established pretty much beyond doubt that, in fact, it IS the "BBSHD programming". Did you buy this from Luna, that is the kind of mistake they make pretty often.8
 
If you are charging a 48V battery to 54V, something has gone horribly wrong. A 48V charges to 50.4V, a 52V battery charges to 54.6.

DEFINE YOUR EQUIPMENT OR FIND SOMEONE WHO CAN. You could burn your house to the ground.
This comment is incorrect. A 48v battery charged to its full capacity is 54.6v. Which is 13 parallel groups connected in series (13 x 4.2 = 54.6). A 52v battery has an extra parallel group connected in series making it 58.8v fully charged (14 × 4.2 = 58.8).
 
This comment is incorrect. A 48v battery charged to its full capacity is 54.6v. Which is 13 parallel groups connected in series (13 x 4.2 = 54.6). A 52v battery has an extra parallel group connected in series making it 58.8v fully charged (14 × 4.2 = 58.8).
The 48 volts is the batteries nominal state of charge meaning in between fully charged and flat. A lithium ion battery shouldn't be discharged below 3v or charged higher than 4.2v. Discharging the cells below 3v is causing irreversible damage to the cells. If this happens you will notice your ebike charger will not charge your battery any longer. Unless the parallel groups are all holding atleast 3 volts. You can recover the cells by trickle charging to get them back up above 3 volts and then your ebike charger will recognise the cells and charge your battery again, but damage has already been done and the cells will be at a lower capacity than what they were. If left too long below 3 volts the cells will lose the ability to be able to hold any charge and then they become useless. This is why if you're not going to be using your battery for extended periods of time it is important to store it with about 80% charge and every 3 - 6 months check the level of charge. And then if need be charge the battery to keep the cells from dropping below the 3 volts if you want to leepnyour battery in good condition.
 
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