Potential Battery issue ??

[chrisvoi]

Ok ANY advice or knowledge will be appreciated just a quick question to anyone that may know ,, I found a 48v scooter battery for sale real cheap and built it into my bike it's quite large ! Any way for the best part it's been amazing going from a real small 7 ah battery that only lasted 5 miles with voltage drop on the throttle all the way ! This one is 15ah and zero volt sagging ect and would last alday, BUT here's my (MAYBE) PROBLEM I'm pretty sure it's supposed to charge to 54.6 but seems to stop charging at 53.7 ,, this isn't a noticeable issue my journey is 4.8 mile to work and back and still has plenty left to use, after going 30+ speeds BUT my question is .. is this going to get worse, or how can I add that extra volt I'm missing on a fresh charge and if this is just deterioration from who ever had it before me , how long is it likely to last ?? Thanx in advance

 

[fill]

Sounds OK ? You cant really expect the battery to be charging to the same capacity level it was when new out of the box when bought for a good price 2nd hand Unless sold as new or near new..

it will continue to loose top end capacity and this will be related to the frequency its recharged, so if depleted and recharged daily it wont last as long as if depleted and recharged weekly..

If you continue needing it for a 5 mile daily round trip it should last a good long while..

 

[chrisvoi]

Sounds OK ? You cant really expect the battery to be charging to the same capacity level it was when new out of the box when bought for a good price 2nd hand Unless sold as new or near new..

it will continue to loose top end capacity and this will be related to the frequency its recharged, so if depleted and recharged daily it wont last as long as if depleted and recharged weekly..

If you continue needing it for a 5 mile daily round trip it should last a good long while..

Ok great thanx for quick response,, not sure if this should be done but I ride to work and then home and recharge , or sometimes I'll nip to shops and then charge again , Its never been below half way , I may charge too often ? I was always under the impression not to fully discharge them , and ofcourse I like the punchier power from a fresh charge

 

[Diggs]

Do you have another 48v charger to try? It is the charger that stops the charge and holds at a balance voltage (54.6 volts).

 

[chrisvoi]

Ok great thanx for quick response,, not sure if this should be done but I ride to work and then home and recharge , or sometimes I'll nip to shops and then charge again , Its never been below half way , I may charge too often ? I was always under the impression not to fully discharge them , and ofcourse I like the punchier power from a fresh charge

Do you have another 48v charger to try? It is the charger that stops the charge and holds at a balance voltage (54.6 volts).

No mate , I know the one I got is a 2a wit a fan and no screws to open it up ?? As I heard I could adjust the charger to go higher ? And or get a 52v charger and this will boost it up BUT as it seems to have done this from the start for 7 weeks says 53.7 on the screen also is only way to see voltage, also the controller is just 25a and I have set to 20a on the screen , but doesn't feel no difference when it's set on 1amp or 25amps ? Still have good pull and descent ISH torque anyway to improve on a budget ? Sorry I'm new to this

 

[eMark]

You've probably heard the expression - "Leave well enuf alone" which may be TRUE with your (MAYBE) PROBLEM.

That said we all like to make modifications when it comes to improving power and speed. In your case any increase in power and speed by charging from 53.7v to 54.6v is peanuts? Besides you may/should extend the cycle life of your battery by only charging to 53.7v. Being it's a used battery if it were me i would rather charge to 53.7V (4.13v/cell) even if i could charge to 54.6v Besides you say, "Its never been below half way "

Leave well enuf alone only if it agrees with your gut instinct ... assuming you can trust your gut ...

 

[chrisvoi]

You've probably heard the expression - "Leave well enuf alone" which may be TRUE with your (MAYBE) PROBLEM.

That said we all like to make modifications when it comes to improving power and speed. In your case any increase in power and speed by charging from 53.7v to 54.6v is peanuts? Besides you may/should extend the cycle life of your battery by only charging to 53.7v. Being it's a used battery if it were me i would rather charge to 53.7V (4.13v/cell) even if i could charge to 54.6v Besides you say, "Its never been below half way "

Leave well enuf alone only if it agrees with your gut instinct ... assuming you can trust your gut ...

Thanx solid advise I'll leave alone for now

 

[99t4]

And or get a 52v charger and this will boost it up...

No don't do this if the battery is a 48V.

What are you using to measure voltage?

 

[chrisvoi]

I'm just reading the screen ( sw900) , no actual multi metre , and I'm kinda over that issue , unless any new idea on the matter

 

[99t4]

Well I would suggest comparing the display voltage reading with an accurate DVOM. Displays have been known to be off.

 

[E-HP]

I'm just reading the screen ( sw900) , no actual multi metre , and I'm kinda over that issue , unless any new idea on the matter

I may be too cautious, dealing with a cheap battery with an unknown history, but I'd check the voltage of each parallel group to make sure the cells are equally degrading, and that it's not an issue with a single weak cell group. If the groups are otherwise balanced, then status quo would seem fine. If one group is way out of wack, then I'd proceed with more caution and check the groups periodically, and always monitor the charging.

 

[wturber]

Ok great thanx for quick response,, not sure if this should be done but I ride to work and then home and recharge , or sometimes I'll nip to shops and then charge again , Its never been below half way , I may charge too often ? I was always under the impression not to fully discharge them , and ofcourse I like the punchier power from a fresh charge

General charging advice for Li-Ion is to not charge past 80% unless you are going to use the battery immediately. High charge levels stress the battery. If you need full range, then top off to a full charge right before you ride.

Many people routinely charge to a less than 100% (in other words, a lower final voltage) precisely to extend battery life. I make it a point to not charge over 80% or so and top off before leaving home if I think I'll need the extra capacity.

Long term storage voltage (you aren't going to ride for quite some time) should be right around the nominal battery voltage. Not much lower or higher. Also, I'm not sure if there is data on this, but I g3enerally let my batteries "rest" a bit before. I let them sit and perhaps cool down (summer heat or heavy use) for an hour or two first.

Other than possibly checking individual cells and/or cell banks, I think the "leave it alone" approach is likely to serve you well. Of course with a used battery you really can't be sure.

 

[chrisvoi]

Well I would suggest comparing the display voltage reading with an accurate DVOM. Displays have been known to be off.

General charging advice for Li-Ion is to not charge past 80% unless you are going to use the battery immediately. High charge levels stress the battery. If you need full range, then top off to a full charge right before you ride.

Many people routinely charge to a less than 100% (in other words, a lower final voltage) precisely to extend battery life. I make it a point to not charge over 80% or so and top off before leaving home if I think I'll need the extra capacity.

Long term storage voltage (you aren't going to ride for quite some time) should be right around the nominal battery voltage. Not much lower or higher. Also, I'm not sure if there is data on this, but I g3enerally let my batteries "rest" a bit before. I let them sit and perhaps cool down (summer heat or heavy use) for an hour or two first.

Other than possibly checking individual cells and/or cell banks, I think the "leave it alone" approach is likely to serve you well. Of course with a used battery you really can't be sure.

Thanx solid advice ,, unfortunately I do pretty much the opposite, I fully charge every day, havnt really let it get past half way empty , and I ofcourse let the bike chill before charging since I got the battery I noticed on the screen it ready it just charges to 53.7 instead of the 54.6, stated but been assured that's kinda ok specially for used battery but I get no sag, and would last all day with the right riding so all is good atm

 

[E-HP]

Question to the knowledgeable:
In this scenario, is the charger charging to 54.6v, then the pack rests at 53.7v (charger cutting off charging), or
Is the BMS detecting one or more groups exceeding 4.2v and stopping the charge (so one group could be at 4.2v, and the remainder at varying voltages that average to 4.125v)?

 

[Hillhater]

Check the battery and charger max voltages with a dvm.
And if you can check those individual parallel group voltages.
I had a new ( old stock) 48v pack that showed 51.5v at max charge which i assumed was just slight capacity loss…
…but further checks revealed one parallel group was only 0.7v !!!….with the remaining groups all at 4.2+ v

 

[chrisvoi]

Question to the knowledgeable:
In this scenario, is the charger charging to 54.6v, then the pack rests at 53.7v (charger cutting off charging), or
Is the BMS detecting one or more groups exceeding 4.2v and stopping the charge (so one group could be at 4.2v, and the remainder at varying voltages that average to 4.125v)?

It will red green flash at the end and it holds 53.7 consistently but recently accidentally left on charge over night and the voltage read 53.9,, I was just curious as the battery states 54.6 , I ovb don't want it to fail but only Cost 40 pounds used and sells new on eBay for 250 but all seems good and thanx for the advice

 

[chrisvoi]

Check the battery and charger max voltages with a dvm.
And if you can check those individual parallel group voltages.
I had a new ( old stock) 48v pack that showed 51.5v at max charge which i assumed was just slight capacity loss…
…but further checks revealed one parallel group was only 0.7v !!!….with the remaining groups all at 4.2+ v

Question to the knowledgeable:
In this scenario, is the charger charging to 54.6v, then the pack rests at 53.7v (charger cutting off charging), or
Is the BMS detecting one or more groups exceeding 4.2v and stopping the charge (so one group could be at 4.2v, and the remainder at varying voltages that average to 4.125v)?

It charges up to 53.7 or 9 if I leave on all night accidentally it will hold that charge , and I really haven't got the super cheap tools that read the voltages ect , maybe I should or am I just opening a box of worms by further investigation either way it performs good, and how could I check the individual cells without busting open the battery