Recelled battery voltage query

[me1]

My mother recently had a bike battery recelled for her Crossfire ebike

She has since taken the bike out to test the recelled battery & has been a bit disappointed by how quickly the
battery seemed to deplete compared to the performance of the original battery when it was new
i.e. the performance does not seem that much better than the old worn out battery

She had fully recharged the battery a couple of days ago straight after the bike ride

Today I decided to test the voltage at the outlet connectors & found it was only registering 21 volts

I put the battery back on its charger & about 15 minutes later the charger went green so I disconnected it
& rechecked the voltage which was now showing what I believe is the expected 42 volts

Does anyone know why the battery would only show 21 volts only a couple of days after a full charge
e.g. are the new batteries duds ? - or is there some other explaination ?

 

[Deleted member 16246]

If it has just been re-celled, I would think the outfit that did the work should be your first port of call. Assuming that the work was done competently, it might be that some of the cells groups are well out of balance with the others. That in itself would seem to be be pretty incompetent on the part of the worker that made it, in a newly re-celled battery.

I had a battery go well out of balance over one winter. The symptoms were that the apparently fully charged battery would switch off after about three miles of use. I removed the battery cover and measured the voltage of each parallel connected group of cells. All except one were at about 4.15 volts, but one was really down around 3.2 or thereabouts. I had to charge this one up on its own with a 4.2 volt charger and then normal service was restored. That group does gradually decline in voltage though, over time unless I do balance charges every few weeks.

Take it back to where the work was done and complain. It is certainly not fit for purpose.

 

[Nealh]

Your first reading must have been faulty or wrong, often one gets this when a meter's battery is old . It is not possible for a charger to charge an ebike battery form 21v to 42v in 15 mins so something is a miss with the voltage measurement.

How does the capacity of the re-cell compare to the old battery ?
Do you know what cells were used in the old battery and the re-cell ?

Have you been conned if not a reputable company and actually still have the same old cells in the battery ?

 

[me1]

How does the capacity of the re-cell compare to the old battery ?

The company that did the recelling said the capacity would increase from 11AH to 13.4AH but given how depleted the recelled battery got after the first bike ride when compared to the original capacity of the original (brand new) battery we cannot see how thats possible

for example when new my mother said the original battery didnt go below around 40% on any of her rides but on this first ride on the recelled battery it went down to 24% & that was with some of the trip on eco mode which she never used with the old battery

Obviously the bike itself is a few years older now so possibly that might have some affect on the power drain

Do you know what cells were used in the old battery and the re-cell ?
the old batteries were Samsung INR18650-29E - 40 of them
we were told the new batteries would be Panasonic/Sanyo NCR18650BL

Have you been conned if not a reputable company and actually still have the same old cells in the battery ?
the batteries were definately replaced as they sent the old cells back to us - we used a company recommended on this forum i.e. eBikebatteries.co.uk

The company only accepted payment by either bank transfer or paypal "friends & family" so if there is an issue as appears to be the case then we are completely at their mercy as to whether they will address the problem or not

Ive asked my mother to monitor her next few rides to see if theres any improvement

 

[matthewslack]

You still have legal redress through small claims court if they are a business. They took your money - they ARE a business!

 

[Deleted member 16246]

Your first reading must have been faulty or wrong, often one gets this when a meter's battery is old . It is not possible for a charger to charge an ebike battery form 21v to 42v in 15 mins so something is a miss with the voltage measurement.

Nealth - just to say that if the battery has well out of balance cell groups you could get exactly that situation. I know you know that the BMS will shut off charging if some cell groups are fully charged even though others are far from it. It would also shut off the battery power output as soon as the weakest group fell below the lowest allowed voltage limit.

Mind you - I can't see how that would arise if a competent company was re-celling the battery. If the operator was careless, I suppose they might have just assumed that all the cells were good and make up the new battery with un checked cells. If one group had a dud cell that leaked charge, you might get the symptom the OP posted about.

 

[cyclebuddy]

Does anyone know why the battery would only show 21 volts only a couple of days after a full charge

Yes... because if the bike is pre-2019, it's a Phylion SF-06 battery with a smart BMS that puts it to sleep to save draining the cells. When that happens, what you're measuring is spurious surface voltage... You need to turn the battery on first before measuring the outermost two contacts for voltage (don't probe any of the other 4 because you can do irreparable damage to it). Yes, Phylion did use Samsung 29E cells in that pack.

 

[me1]

Yes... because if the bike is pre-2019, it's a Phylion SF-06 battery with a smart BMS that puts it to sleep to save draining the cells. When that happens, what you're measuring is spurious surface voltage... You need to turn the battery on first before measuring the outermost two contacts for voltage (don't probe any of the other 4 because you can do irreparable damage to it). Yes, Phylion did use Samsung 29E cells in that pack.

that sounds like its probably be the reason as I think I didnt turn the battery on

also thankfully I only probed the outer contacts as I knew they were the terminals

even so there is still the possible issue of lack of capacity

 

[cyclebuddy]

even so there is still the possible issue of lack of capacity

With that BMS, when the charger light first turns green there's (IIRC) still about 18 watts of energy flowing into the battery. Let it continue to charge for another hour or two, because that's where the cells balance properly, and any low cells should be brought up.

Do that again for maybe for the next couple of rides and charges. If you then still have problems, contact the receller.

 

[Nealh]

Ebikebatteries are a reputable company , we have spoken of them often on the forum and I along with many others have used their services. So no issues there with reptuability.
I went took my battery box and picked up my battery when it had been re-celled from Jimmy the owner a few years ago.

 

[Nealh]

The Sanyo 18650BL 3350mah cell ( Sanyo is owned by Panasonic) should be a better cell then theSam 29e 2900mah cell, one may just have to give it a f ew charge discharges to see how it performs first.
If it doesn't live up to the Sam29e then contact Ebike batteries with your concerns and findings , they have had nothing but praise on the forum from those of us wh have used them.

My brother had a Bosh battery re-celled by them and it had an issue with a bad buss bar weld , however there was no issue from their part in sorting it out again.

It is possible yours may have a similar weld contact issue but as mentioned see how it goes first for a few charge discharges before getting back in contact with them.

 

[saneagle]

My mother recently had a bike battery recelled for her Crossfire ebike

She has since taken the bike out to test the recelled battery & has been a bit disappointed by how quickly the
battery seemed to deplete compared to the performance of the original battery when it was new
i.e. the performance does not seem that much better than the old worn out battery

She had fully recharged the battery a couple of days ago straight after the bike ride

Today I decided to test the voltage at the outlet connectors & found it was only registering 21 volts

I put the battery back on its charger & about 15 minutes later the charger went green so I disconnected it
& rechecked the voltage which was now showing what I believe is the expected 42 volts

Does anyone know why the battery would only show 21 volts only a couple of days after a full charge
e.g. are the new batteries duds ? - or is there some other explaination ?

Normally, ou can't measure the voltage correctly on the output of a crossfire battery because it needs the controller comms to switch it on. The 21 v you measured was probably just leakage charge.

It's difficult to judge your problem without knowing what the repairer did. You'd need to look inside it for that.