Help! considering first battery rebuild ,beginner needs advice

[minexplorer]

Hi,sorry this may be long.
ive moved this from the technical discussion forum, because it seems invisible to the main contributers who have helped me so much in the past.for which many thanks again.
So this is further to a thread i posted back in feb 2020 battery needs repair.Havent used the bike for over a year because of the failing battery.
Basically 3 an half years ago i got a bbshd kit and 52v batt from electron cycles.They advertised their samsung 30Q batt,as the best for the job. i learned much later the 30Q is crap,with issues after as little as 50 recycles.Ive verified the cells are definately genuine.After 11 months and 70 odd full recharges.I started getting battery failing to charge fully to 58.8v ,sagging LVC tripping at 47-48v usually due to an increased load,despite set at 41v. Tried maually balancing through the BMS with a mobile phone charger,but it soon got bad again.
I stored the batt fully charged and havnt re charged in a year. today the cell groups read at the BMS 6x 3.77v ,5 x 3.48-3.61v and one each 3.16v, 2.98v, 2.28v. Thats with not having recharged.

A repair back when was going to cost 400 odd.so i didnt bother. Now im thinking maybe i should buy a cheap battery spot welder thingy an make it a project to learn how to repair it myself.
It seems likely theres many good cells and perhaps some half decent ones. Its a 450 quid loss now as it stands. even if i end up with a 48v 4P from originally 52v 5P better than nothing. I was going to strip down all the cells and charge them up a few at a time,with my e cig charger,to root out the bad.

Does that sound feasible. Im puzzled over many things. Why when i understood a 52v was strings of 14 cells, i expected to see 5 parallels of 14 connected cells,yet they seem to be in sets of ten cells.These then are further connected to each other in a way i dont understand.

So i understand the sensor ,balancing wires to the BMS are 10.13,14 in number depending on 36,48,52v. Does that means they read one cell in each parallel ? ,rather than all the cells in one parallel .Or have i got that all wrong.how does that work.i thought each parallel of 10,13 or 14 cells was seperate and then joined at the batterys pos/neg output terminal. Similar to my two 36v batteries on my bbs01. A 5P and a 6P their power cables joined to work as a 11P.

Lastly i began to snip the connecting strip between two cells.Yet despite both being positive ends i got a flash of a short as if id touched the snips across a positive and negative. How on earth do you strip these down. i need to seperate all the cells dont i or connected good cells voltage will hide the bad ones ?

The cells i tried to seperate were at the top left end in the picture,i dont understand the construction.the photo is high def so can be zoomed in clearly. Much thanks to anyone that can give me some education on these things. I dont want to just go it alone with a battery construction manual. i had to remove the balancing wires after clumsilly shorting them touching the probes. Thanks Andy

 

[Andy-Mat]

Hi,sorry this may be long.
ive moved this from the technical discussion forum, because it seems invisible to the main contributers who have helped me so much in the past.for which many thanks again.
So this is further to a thread i posted back in feb 2020 battery needs repair.Havent used the bike for over a year because of the failing battery.
Basically 3 an half years ago i got a bbshd kit and 52v batt from electron cycles.They advertised their samsung 30Q batt,as the best for the job. i learned much later the 30Q is crap,with issues after as little as 50 recycles.Ive verified the cells are definately genuine.After 11 months and 70 odd full recharges.I started getting battery failing to charge fully to 58.8v ,sagging LVC tripping at 47-48v usually due to an increased load,despite set at 41v. Tried maually balancing through the BMS with a mobile phone charger,but it soon got bad again.
I stored the batt fully charged and havnt re charged in a year. today the cell groups read at the BMS 6x 3.77v ,5 x 3.48-3.61v and one each 3.16v, 2.98v, 2.28v. Thats with not having recharged.

A repair back when was going to cost 400 odd.so i didnt bother. Now im thinking maybe i should buy a cheap battery spot welder thingy an make it a project to learn how to repair it myself.
It seems likely theres many good cells and perhaps some half decent ones. Its a 450 quid loss now as it stands. even if i end up with a 48v 4P from originally 52v 5P better than nothing. I was going to strip down all the cells and charge them up a few at a time,with my e cig charger,to root out the bad.

Does that sound feasible. Im puzzled over many things. Why when i understood a 52v was strings of 14 cells, i expected to see 5 parallels of 14 connected cells,yet they seem to be in sets of ten cells.These then are further connected to each other in a way i dont understand.

So i understand the sensor ,balancing wires to the BMS are 10.13,14 in number depending on 36,48,52v. Does that means they read one cell in each parallel ? ,rather than all the cells in one parallel .Or have i got that all wrong.how does that work.i thought each parallel of 10,13 or 14 cells was seperate and then joined at the batterys pos/neg output terminal. Similar to my two 36v batteries on my bbs01. A 5P and a 6P their power cables joined to work as a 11P.

Lastly i began to snip the connecting strip between two cells.Yet despite both being positive ends i got a flash of a short as if id touched the snips across a positive and negative. How on earth do you strip these down. i need to seperate all the cells dont i or connected good cells voltage will hide the bad ones ?

The cells i tried to seperate were at the top left end in the picture,i dont understand the construction.the photo is high def so can be zoomed in clearly. Much thanks to anyone that can give me some education on these things. I dont want to just go it alone with a battery construction manual. i had to remove the balancing wires after clumsilly shorting them touching the probes. Thanks Andy
View attachment 47984

My advice is not to try and rebuild the battery, either get a professional company to do the work, or bite the bullet for a new battery, and take better care of it.
If you continue to try and repair it yourself, increase your house and contents insurance, and buy the best safety gear around for you to wear, but a new battery will be far cheaper!
Also watch the many exploding batteries/cells on YouTube e-bike videos.....See here for starters:-

https://www.youtube.com/results?search_query=Li-ion+battery+fires

best wishes
Andy

 

[soundwave]

id not bother with these things unless you know what you are doing it is not a good idea to wing it as all it take is 1 wrong connection and the hole lot will explode with a dead sort.

you need to remove the bms and then pull apart the cell groups and then strip the group of each individual cell with some plyers/ snips but do it outside as when these thigs go up you wont be able to put it out with any fire extinguisher.

 

[WheezyRider]

That looks like a real dog's dinner.

Put it somewhere outside of your house, so if it does burn it won't do any harm.

Really, you'd have to break it down to individual cells and do a few test cycles with each one to find which are good and which are bad. If there are bad ones, you will not have enough cells to make a battery of the original voltage. There's no point trying to add some new cells to an old pack, you'll end up wasting a lot of time.

I am worried about what you have done with a mobile phone charger? This does not sound good.

Welding is not trivial, I have struggled to get one that is any good.

Before you do any more damage, read up as much as you can about how batteries are put together.

 

[Nealh]

One needs at the minimun a malectric arduino welder and a quality lipo high rate pucker 3s cell pack, mine in all cost me £190 3.5 years ago and is still going strong.

 

[StuartsProjects]

Might be worthwhile reading the other recent thread on the same subject;

Same problem

 

[Nealh]

It makes no sense starting two threads the same, it was started in the correct tech forum where it belongs. The main reason for lack of responses is likely due to no one having the knowledge or experience to reply, if someone sees it they will respond.
The other thread is in the correc tplace and where I would reply with tech responses.

 

[minexplorer]

My advice is not to try and rebuild the battery, either get a professional company to do the work, or bite the bullet for a new battery, and take better care of it.
If you continue to try and repair it yourself, increase your house and contents insurance, and buy the best safety gear around for you to wear, but a new battery will be far cheaper!
Also watch the many exploding batteries/cells on YouTube e-bike videos.....See here for starters:-

https://www.youtube.com/results?search_query=Li-ion+battery+fires

best wishes
Andy

thanks for the advice mate you and all the others have convinced me to not even try.

 

[minexplorer]

It makes no sense starting two threads the same, it was started in the correct tech forum where it belongs. The main reason for lack of responses is likely due to no one having the knowledge or experience to reply, if someone sees it they will respond.
The other thread is in the correc tplace and where I would reply with tech responses.

quite correct nealh prob not something others have any input to give. much thanks for all the time you spent on giving me such an informative reply. im going to pass on the idea after reading everything that you and other members have posted.

SIGH 450 quid for a years use,euphoria to despair in 11 months. by comparison my 3 36v batteries of lower spec samsung cells ,all still good at 5-6 years age.
i did alot of research on the best cell for a bbshd at the time and the 30Q was deemed a winner. electron cycles touted it as the best for bbshd.

i cant understand why there arent tons of 30Q batt owners in the same boat ,if its as bad as ive since learned.
Prehaps as i said back then, running it always to the LVC, hammering it a great deal on full power. And the biggi, electron cycles battery care instructions omitting to say it must be turned ON to enter balancing mode. 11 months of never balance charging inc they state an all important balance charge before first use.
guess its a bin job now.

 

[minexplorer]

That looks like a real dog's dinner.

Put it somewhere outside of your house, so if it does burn it won't do any harm.

Really, you'd have to break it down to individual cells and do a few test cycles with each one to find which are good and which are bad. If there are bad ones, you will not have enough cells to make a battery of the original voltage. There's no point trying to add some new cells to an old pack, you'll end up wasting a lot of time.

I am worried about what you have done with a mobile phone charger? This does not sound good.

Welding is not trivial, I have struggled to get one that is any good.

Before you do any more damage, read up as much as you can about how batteries are put together.

thanks mate im throwing in the towel after everything ive read. obviously not as easy as the teckie nerd teenager on a utube vid i saw years ago , made it seem. job lot of used laptop batteries transformed into a huge ebike battery wizzing around at 40mph

 

[Nealh]

A lot of users will opt for checking other resources like ES forum for info on cells, there are a few mentions of 30Q self discharging on that forum.

 

[AntonyC]

> guess its a bin job now.
I'm sure that was just a turn of phrase but a failed e-bike battery has to be taken to a recycling depot. Quite how I'm not sure because if they get cross they're almost impossible to put out. By wheelbarrow perhaps?

 

[Andy-Mat]

thanks for the advice mate you and all the others have convinced me to not even try.

I have been in electrics and electronics since 1955. I earned a good salary working for both the RN after school, then afterwards for 4 different US Computer companies, and I want to remain working with my original 8 fingers and 2 thumbs, whilst watching with both eyes......
What you don't know can be highly dangerous.
You made a good decision.
regards
Andy

 

[Andy-Mat]

> guess its a bin job now.
I'm sure that was just a turn of phrase but a failed e-bike battery has to be taken to a recycling depot. Quite how I'm not sure because if they get cross they're almost impossible to put out. By wheelbarrow perhaps?

A good question, my advice would be a non metallic dustbin, filled with water to just over the top of the battery, to keep things cool.
But someone else may have a better idea, wait up!
regards
Andy

 

[WheezyRider]

thanks mate im throwing in the towel after everything ive read. obviously not as easy as the teckie nerd teenager on a utube vid i saw years ago , made it seem. job lot of used laptop batteries transformed into a huge ebike battery wizzing around at 40mph

Best thing would be to put it on eBay. Someone may come and pick it up from you. If you take it to a recycling centre, it will most probably end up in landfill. Only a small percentage of lithium cells are recycled at present.

I don't want to discourage people from building/re-building their own packs. However, you need to know what you are doing and make sure you have mitigated the risks. I am worried that if there are many fires from home builds/re-cells, we will end up with legislation where you can only use a battery from a commercial supplier, even though a home made one, done properly could well be better.

 

[minexplorer]

Best thing would be to put it on eBay. Someone may come and pick it up from you. If you take it to a recycling centre, it will most probably end up in landfill. Only a small percentage of lithium cells are recycled at present.

I don't want to discourage people from building/re-building their own packs. However, you need to know what you are doing and make sure you have mitigated the risks. I am worried that if there are many fires from home builds/re-cells, we will end up with legislation where you can only use a battery from a commercial supplier, even though a home made one, done properly could well be better.

to be honest all that happened was the battery started to have reduced range and not fully reaching 58.8v. after advice here i checked the cell voltages at the bms. 6 of the 14 were down. advised how to manually balance these with a mobile charger fitted with two pins. this worked ,brought them up but not quite to 4.2v. they varied around 4.05-4.1v. the battery still worked,just reduced milage,cutting out well above the LVC. at first it did restore the range reasonably well and start reaching the LVC,but it didnt last,wld go out of balance again after a cpl re charges.

the seller electron cycles neglected to mention in their battery care leaflet .that it had to be switched ON to enter balancing mode. so for the entire 11 months i was using it ,it never had a balance. didnt discover this til i started having issues.

Im considering re attaching the balancing wires ,giving it a full balance charge, bringing the low ones up manually to see if they have got worse and just accepting the reduced range if they still reach a reasonable voltage . i know they must be in the right order.

The only reason i removed them is because i clumsily touched the multimeter probes and a few now need to have some shrink wrap put over the melted sheath,or replaced with new 24awg wire.

Anyone think thats a Good /bad idea to try

 

[Nealh]

Without balancing attached one always risks an unbalanced battery unless one has the option to keep an eye on any cell drift. On could attach a seperate set of balance wires with jst and route to the pack exterior for manual checking.

 

[WheezyRider]

Good quality cells should not go out of balance, even after 100 or more cycles.

You could try putting it back together, but do so somewhere where you will do no harm or damage to you or your house if the worst happens.

You could do what I did, add some tapping points for the balance wires so you can monitor the cell banks after each cycle:

Charging pack to 41V experiment

Some people think it's a good idea for cell longevity to only charge to 4.1V instead of the normal 4.2V. However, when you have a pack of cells, only charging to 41V may cause balance issues as the BMS in many cases does not start balancing until about 41.5V. Anecdotal evidence from some on this...

www.pedelecs.co.uk

 

[minexplorer]

Without balancing attached one always risks an unbalanced battery unless one has the option to keep an eye on any cell drift. On could attach a seperate set of balance wires with jst and route to the pack exterior for manual checking.

thanks nealh.so those balancing wires i need to repair. and wish id only snipped the 4 damaged ones ,going to be a real her working out which goes on what solder spot.are just that balancing and not what actually delivers the current to the cells during charging then. so i can at least charge the battery up as its very low now.is that right. just need get some juice in before any more damage.

 

[WheezyRider]

thanks nealh.so those balancing wires i need to repair. and wish id only snipped the 4 damaged ones ,going to be a real her working out which goes on what solder spot.are just that balancing and not what actually delivers the current to the cells during charging then. so i can at least charge the battery up as its very low now.is that right. just need get some juice in before any more damage.

It shouldn't be too hard. Think of it like rungs on a ladder, going from cell bank 1 upward. Put your meter common electrode on the battery negative and keep it there, then put the positive on the opposite positive electrode, first of bank 1, then 2 then 3... each time you should see a jump in voltage equivalent to adding one more cell bank. Where you see a jump in voltage of one cell bank, you need to put a balancing wire. Don't solder the wires on straight away, do a test run with tape on the ends of the balance wires so they can't short anything. Then tape each balance wire on the electrode where it should go and make sure they are all used and in the right place. When you do come to solder, disconnect the balance wires from the BMS, to make sure you don't accidentally damage it. Then when you have soldered all the wires, CAREFULLY go along the connector with your meter and check you see the same stepwise increase in voltage at the connector going into the BMS, before you plug it in.

It's simple stuff, but you have to be careful, systematic and check multiple times! Quite often it helps to make a scale drawing.