48/57 volt Battery failing or not ? need HELP

kim

New Member
My 4yr old 48 volt battery is failing on my Prodeckotech Outlaw, at least I thought it was but just because of age ..I checked the volts after a full charge @ 57.6 volts this morning,
Went for a ride (down to 10mi now) until it shut down again but the battery was still at 52 volts standing off the bike..
I thought the volts might be dropping below a threshold under load.
Having no load tester to see if the volts drop under load I tapped right off the battery connection and while riding
with my Fluke meter taped on the top tube at full throttle for the load the bike actually shuts off right at 48.0 volts.
looking right at the meter it never went below 48.I really don't understand what is going on here and need advice. Thank you
 
Your numbers are a bit high for a 48V battery. Maximum charge should be 54.6V, not 56.7V, so I suppose your Fluke's batteries are low, causing it to read a little high. Or maybe you have a 52V battery where full charge is 58.2V.

There are two low voltage cutoffs (LVC) in an ebike. First one is set by the controller looking at the total battery voltage. That would be around 40-42V for a 48V battery. Second is set by the battery BMS, and that looks at individual voltage of all the parallel cell groups. This varies by battery maker, but typical numbers are 2,5-2.8V per cell., An older battery can get unbalanced, where one cell group is off. Say at full charge most of the groups are at 4.1, and one is at 3.5, It's .6V closer to shutdown, so you could have a pack at 48V and that low group shuts down the battery. However, when a battery's LVC triggers, it usually shuts off and reads no voltage. You have to disconnect it or hit on/off to restart it, Your prodeckptech might be different. Anyway, the behavior sure sounds like an old battery.

What people try for an unbalanced battery is to leave it on the charger after the charger says it's done. Maybe a day or two. Better batteries have balance circuits, which will equalize those lower cells. I would say most inexpensive batteries do not have balance circuits.
 
Wow,thanks for all your time and this valuable info.. I had a feeling there was more than one way it could shut down..
To be more clear on the side of the battery is "51.2 volt 12Ah 614Wh LIFEPO4" but from what you said if understand it
it's likely I have a "low group" and a rebuilt battery from FTH Power or Nethers Battery will be the cure.. It's really closer to 5yrs old
so age is a main factor here from what I've read (2-4yr life) I was just baffled when it shut down at exactly at 48 volts.
EDIT: I don't think the 1-2 day over charge will work in my case. The charger is hot while charging but now with the green light on
it's cold. I'm going to give it a day and see what happens.
 
Oops, my fault for assuming you had regular lithium cells. LiFEPO4 is another variation of lithium. Its cell voltages are not the same. being little lower, and the batteries require more series groups to get a similar voltage, This results in different voltages at full charge and low charge, Its main virtue is that it's a much safer battery, less likely to blow up.

Nontheless, it can also get unbalanced and also gets old. If they lasted five years and you got good use out of them, not much more to ask for.
 
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I've been studying this mostly on youtube to understand what is going on. I opened it up to get at the Balance Connector where I found 3.6v on every pin (3.59 on one) new battery in Fluke :)
I have 58.6v total balanced that makes me think what I need here is a new BMS shutting down @10mi with 52v still in the battery
I'm hoping you can correct me if that's not the problem but these BMS are less that $20 on aliexpress.. the only place I can
find one that looks exactly like mine but it's 30A I'll try to load a pic here of my BMS and once again thanks for your time
 

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Yep. The battery is fully charged and balanced. The BMS is the right type, maybe a bit high on current, It would be convenient if the balance plug is (a) the same size and (b) wired in the same order. Not always the case. I've used an Annpower BMS in the past. It worked.

This is a tricky thing to diagnose. You could still have a failing pack. It's hard to catch voltage sag with a digital meter, especcially when riding a bike. Well, it's only 22 bucks to buy a BMS, maybe a 5 week wait for delivery, and an hour or two to install it to find out that you either have a bad BMS or worn out cells.

By the way, I've never seen a BMS go bad on an original battery. I thought I had, but it turned out my charge wire had fallen off. The original one was OK, but after taking it out, I had cut too many wires to put back. The new BMS didn't work though, and neither did its replacement. The seller jacked me around til the dispute window expired and then ignored me. That's when I bought the Annpower model.
 
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Yep. The battery is fully charged and balanced. The BMS is the right type, maybe a bit high on current, It would be convenient if the balance plug is (a) the same size and (b) wired in the same order. Not always the case. I've used an Annpower BMS in the past. It worked.

This is a tricky thing to diagnose. You could still have a failing pack. It's hard to catch voltage sag with a digital meter, especcially when riding a bike. Well, it's only 22 bucks to buy a BMS, maybe a 5 week wait for delivery, and an hour or two to install it to find out that you either have a bad BMS or worn out cells.

By the way, I've never seen a BMS go bad on an original battery. I thought I had, but it turned out my charge wire had fallen off. The original one was OK, but after taking it out, I had cut too many wires to put back. The new BMS didn't work though, and neither did its replacement. The seller jacked me around til the dispute window expired and then ignored me. That's when I bought the Annpower model.
 
After reading "I could still have a failing pack" makes me think now I want to test all the volts
after it shuts down to see if they're even. Make sense?
Also "You've never seen a BMS go bad on an original battery." Hmmm..Could this shut down @52v be the controller? Just so happens
the only part on ebay for a Prodeckotech Outlaw is the 48v Controller for $79.95 .. Did you ever see an original controller go bad go bad?
 
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More Details..balance check
I did a ride starting with 57.6v total with 3.6v on all 16 pins of the balance connector..(one 3.59)
Had shut down @9.4mi with 52.2v and home checked 3.26v on 13 pins but (1)3.25 (1)3.24 (1)3.157v
Is that 3.157v enough out of spec enough for the shut down?
One more bit: My throttle has the green/yellow/red lights that used to stay green
when I used full throttle for the first 10mi or so, now the green goes off full throttle right up front with 57v at the battery..
Thanks for looking.
 
The throttle goes off green because of voltage sag. It doesn't care about the BMS. The throttle circuitry says the battery voltage is down about half,. That's a type of a load test. I'd say your battery is not meeting it.
 
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From my first post remembering how a failing car battery can show 12.5v and as soon as you hit it with the starter 200amps it drops
to 8-9v my first thought was a load test, I thought the volts dropped below a threshold that makes it shut down but not at 48v.
"Having no load tester to see if the volts drop under load I tapped right off the battery connection and while riding
with my Fluke meter taped on the top tube at full throttle for the load the battery (with the 52.1v left where it shut down) riding reset actually shuts off right at 48.0 volts. (2.1v drop at full throttle) looking right at the meter it never went below 48." (48v green light off)There is some very mysterious stuff going on with these components and I'm afraid I'm going to pay $600+ for a rebuilt battery and it's
not going to fix my bike. .. I also read during this crash study course LiFE batteries last 2-3yrs maybe 5 at best but LiFEPO4 cells last 10yrs..
 
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This is when it's good to temporarily try out a known good battery, You could buy a wattmeter. Put it in between the battery and controller. It will tell you the minimum voltage it sees, along with the max current, although not whether the two are aligned.

Check for frayed wires, bad connectors, or anything that might be adding an ohm of resistance. That's a 10 volt drop at 10 amps,

When you bike shuts down, can you power it back on again? A low battery sgutdwob usually allows a restart. A BMS shutdown often requires the battery to be turned off or disconnected, anything to to take the load off.

 
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The bike restarts every time I turn the key off and back on and can even help me get home as long as I pedal
and bump the throttle easy .. Also the voltage drop was my very first thought and why I put wires on the blades of the battery connector when I slid it together to my meter. Under full load on the restarted battery at
51.2v it shut down at exactly 48.0v.. I was looking right at my meter and did it 3 times.EDIT:Another light just flickered in my brain,are you thinking there is a possible voltage drop on one cell group or even one cell that doesn't show up on the total output that is causing this ?
( I checked that 9v meter battery when I put the new one in my Fluke and it was a little over 9v)
The amp watt checker looks great, thanks for sending the link.. I read your post in "Battery % Readings"
From day one I wished there was more battery info than the 3 idiot lights on the throttle.The only thing the lights tell me now
is the green light goes off at full throttle with a full 58v battery where it didn't do that before until 10-15mi down the road.
The thing that made me think it might be the BMS or Controller is this 25mi per charge down to 10mi happened all of a sudden.
It's so nice of you to stick with me on this.. thanks so much.
 
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One more question here so they aren't all bunched together in #14
I also watched this youtube says I can reset the BMS by charging through the out port or by disconnecting the Balance Connector
and plug the charger in and reconnect the connector while the charger is running.
Hmmm? I'm asking you first..thanks
FF to 3:30
 
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When a cell under load goes under the minimum voltage, the BMS shuts off the battery, If this is a transient condition, the BMS will turn the battery back on when the load is removed. If the cell does not recover, the battery is bricked. No output, and cannot be charged, I've never seen a bricked battery happen because of a load situation, but have seen one brick because a few cells discharged to zero over the winter.

I believe the above video is specific to Biktrix batteries. They assume that the cell is just barely under the minimum, and applying voltage thru the output port, coupled with turning off the BMS, will allow the battery to restart. The Biktrix battery must not have an on/off switch, as that often resets the BMS. If the reset doesn't work, it means the affected cells are still below the minimum level. At this point, safest thing to do is to recycle it.

None of this applies your battery. It's not bricked.
 
"bricked" I have a new word. With all I put you through here is it your opinion I should just have this battery rebuilt?
I'm not getting into that but on that note FTH Power replied to my email :
"Your battery has a data line that communicates with your bike’s control board. Unfortunately the information on the data line is not available from the original manufacturer. And we will not be able to obtain a part needed for repairs.
At this time we are not able to repair or replace these model type of batteries."
 
re: 25 mile range suddenly becoming 10 miles....

Did it suddenly turn cold where you live? That reduces range. How about tire pressure? The latter makes a big difference.
 
Yes, 40F is winter Cape Canaveral.Thanks for considering that. Riding the last 2 days we dress like we're going skiing. We keep our batteries inside though at 75F and I think we're back before the cold soaks in but I did loose one more mile yesterday down to 9.5 so I could be wrong there.
When this started it was warm though, and tires are surely up especially because I might need to pedal home but with this I make sure I'm on our street by the 10mi mark. It's 9 now..I used to get 20-30mi because it's all flat here.
What do you think of the reply I got from FTH post #17?
 
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