Hi all, I have joined the forum because i need some help with a problem that has just arised this afternoon. I have a Z6 electric mountain bike with a LCD880 display, which i got last July, and i love it, untill this afternoon when I decided to go for a nice bike ride. I like to keep it in assist level 3 and use the gears. After about 2 miles and just riding along in top gear and level 3 the power just died and i had no assist, the battery is fully charged. I switched the battery off and on again and it was back to normal, but after a couple of hundred yards it went again. I have noticed that the higher assist you go the quicker the power loss. Any one any ideas please.
Power loss
- Thread starter Ronos
- Start date
It sounds as if your battery is worn and beginning to lose its capacity to deliver higher current - eg: when going up a hill or harder acceleration. When you demand more from the battery than the cells can still cope with the voltage drops rapidly ("sag") and the battery cuts out ("LVC"). When that demand stops, the voltage springs back to a higher level.
Ultimately the battery (or at least some of the battery cells) are failing. You can only tell for sure if you open the battery and measure.
Ultimately the battery (or at least some of the battery cells) are failing. You can only tell for sure if you open the battery and measure.
Hi, thanks for the reply. The battery is fully charged and just over 39v when tested with a volt meter, but that's under no load, and has less that 150 mile on the clock, so do you reckon when it's put under a heavy load the voltage is dropping that far . When I switch the battery off and then on again it shows full charge.
A healthy 36v battery should measure better than 41.5v when fully charged, fresh off the charger. Yes, a worn battery will sag to 30/32v when placed under heavy load, cut-out, and the voltage then spring back to measure a higher voltage level when relaxed.
From the web the Z6 uses a bottle battery - 36v, 9Ah? You could wire a wattmeter in series with the battery and watch the voltage collapse as you cycle, or use a dummy load to place a drain on the pack and see how long it keeps going before it cuts out.
A bottle could be 18650 cells or pouch packs. If 18650 cells, sometimes you can bump up a string if the battery has become unbalanced. I had one with pouch cells; one had gone puffy. I just chucked the whole battery as a new one was quite cheap - it wasn't worth the hassle to repair or have it repaired.
A bottle could be 18650 cells or pouch packs. If 18650 cells, sometimes you can bump up a string if the battery has become unbalanced. I had one with pouch cells; one had gone puffy. I just chucked the whole battery as a new one was quite cheap - it wasn't worth the hassle to repair or have it repaired.
Assuming its a 36 volt battery, that is too low at fully charged, no load.
I would guess that last winter it was not charged for a long period, and many cells are now damaged.
A 36 volt battery in top form, with a good charger, would show 42.0 volts, or very close to that, usually above 41 volts....
Have you checked the charger output voltage?
Cyclebuddy got it right I would think.
regards
Andy
PS. Have you had your meter checked for accuracy against a known good one?
Yeah I know what you mean, I use 3s,4s,and 6s lipo batteries in flying RC aircraft ,and if one cell goes down or one becomes puffy its in a
Hi, the battery was stored over winter at full charge, and the volt meter is good reliable one. I did check the voltage of the battery, 39.7v, after I got back after the short bike ride, so it would have used a small bit of charge. Sorry I misled you in a previous post about the voltage. It wasn't 39v fully charged, that was when I got back home, sorry.
Last edited:
Null Problemo, as Alf always said on German Childrens TV, many years ago!
I still think that your battery has some bad cells.
Was it stored where frost could get at it?
Most e-bike users, when storing a battery, store it where its cool, but not ever under 4°C.
They also store it at a middle voltage (generally much discussion for this level here!), usually around 34 Volts, but never fully charged.
They measure its voltage say once a month, and do a half charge, using time as a reference, if it is getting close to 31 volts.
Any meter, needs to be checked against a known accurate meter.
regards
Andy
Before I went to work this morning, I thought I would just check the battery voltage with my multimeter, (I took it off the bike last night and it was still showing 39.2v) well, it was down to 14v ,checked and double checked, so it looks like it's caput.
Just seen this and CB is spot on.
The battery is knackered and 39v fully charged means it is either seriously out of balance or the cells or a cell group is knackered, any 36v battery not attaining 41.5 - 42v fully charged is not well.
The battery is knackered and 39v fully charged means it is either seriously out of balance or the cells or a cell group is knackered, any 36v battery not attaining 41.5 - 42v fully charged is not well.
Hi Nealh, yes I will agree, have you read my last post this morning, it's near discharged it's self over night.
The self discharge is pretty fatal and likely down to BMS failure unless the cells are fake/crap ones used.
I had a 48v battery die on me last year before last, panasonic PF cells all died after the BMS failed. It was ok one month when I checked SOC and then the next check dead as a dodo.
I had a 48v battery die on me last year before last, panasonic PF cells all died after the BMS failed. It was ok one month when I checked SOC and then the next check dead as a dodo.
One last thing you can check with a reading of 14v is the internal battery fuse, if the discharge fuse has failed then one can expect a silly reading.
Some batteries have an external port for the fuse to hide behind.
Some batteries have an external port for the fuse to hide behind.
Last edited:
If no external port then one has to open the battery case to find the fuse on the discharge side near the discharge port.
electribikescootercar.co.uk isn't a registered domain, so emails to that domain can't be delivered.
If it's faulty, I hope you can get this battery replaced. It should be covered by a 12 month warranty.
Related Articles
-
MTF Enterprises announces acquisition of EMU Electric Bikes- Started by: Pedelecs
-
Wisper 806T folding bike wins Which? ‘Best Buy’- Started by: Pedelecs
-
Sustrans calls for protected cycle lanes- Started by: Pedelecs
-
Amazon launch their first UK e-cargo micromobility hub- Started by: Pedelecs
