Waking up an e bike

[HPW]

Hello, advice needed, please. I have a Carrera Crosscity ebike. I only rode it twice - long story! - so battery still had charge, when I had to stop. Just tried to use it today, and getting no power. Instructions manual says it will have gone into deep sleep mode and I need to hold down the power button on the battery for several seconds, but that makes no sense as the power button is a simple click on or off - you can’t hold it down. Am I missing something? Thanks for any help after a very frustrating morning!

[Graham]

How long has it been unused ?

The stored energy will drain away over time, at a rate depending on the battery chemistry.

Would it not be best/simplest to plug the charger in to replenish the battery ?

[HPW]

Thanks, David. Have plugged the battery into the charger but the LED is green, indicating it is charged. Left it charging for a while anyway... It’s several months since I’ve ridden it.

[hemo]

Some batteries do have a sleep mode and need a long depress to reactivate the BMS.
Check the battery output voltage with a meter to accertain if the battery is balanced or not, some times after long inactivity cell volatge can bleed off unevenly and the battery cells can become unbalanced.
Batteries should not be left stored at full voltage as this leads to ageing of the cells, ideally 38.5v storage voltage is good for periods of inactivity and better stored in a cold place.

[HPW]

Thanks for reply. Took it back to Halfords. My charger was a dud. “Not a another one” I heard... So they got a fresh one out of the box and that did’t work either. (Got them to try chargers on both my bike and their showroom model.) Then they used the charger they use - and still nothing on my bike. Asked me to leave it with them to give it a longer charge. Still not heard anything. I paid £80 when I bought the bike for extended warranty as I could see the battery was the weak point and by far the most expensive component. Not sure where this will go....

[squeaker]

I paid £80 when I bought the bike for extended warranty as I could see the battery was the weak point and by far the most expensive component.

Looks like a good call! Hope you get it sorted to your satisfaction, but do let us know how you get on.

[Chrissie2309]

Hi, hope you get this, am not very good with these sites. I read your post and thought to myself I have the same problem. I bought bike from Halfords in Nov 17, and due to repeated illness in 2018 it wasn’t used a lot. I was ill all through 2019 and have only just got bike out to use. And I found battery was dead despite green light on, can you give any info on how far you got with rectifying your problem . Buying a new battery is not really an option at the moment, they seem to be around the £350 mark which I can’t afford. Any info would be gratefully received. I bought this bike being only 4’ 10” and all the rest were too big a frame for me.

[hemo]

Some batteries have a sleep/hibernation mode. If it has a button to press for switching on, try depressing it for 10 - 15 seconds.
Owning an ebike also means ownong a cheap (DVM) digital volt multi - meter about £5 - £10 on ebay or electronics outlet.
With a DVM it is easy to check voltage output of the charger and usually a battery to see what is occurring.


A 24v battery has a 24v nominal voltage of 24v and will charge to 29.4v (100%) and around 22.4v (0 -10%) discharged.
A properly functioning charger will read 29.4v on the charge pin when plugged in to the wall.

A 36v battery has a nominal voltage of 36v and will charge to 42v (100%) fully charged and around 32v (0 - 10%) discharged.
A properly functioning charger will read 42v on the charge pin when plugged in to the wall.

A battery that has not been used/serviced often over a couple of years may be ok, though likelihood is that a cell group or two may have self drained to below 3.2v, the internal electronics by the way of the BMS (battery management system) a matchbox size pcb only allows charging to take place if the cells are within a voltage of 3/3,2v- 4.1v.
A cell group that is low voltage wise may be possible to recover if a very low current and voltage is applied, I have done just this using a 500ma 5v phone charger and a DVM a few times.
A battery not charging most companies won't touch or bother with as it is time consuming to investigate and most will not have a clue where to begin, mostly it is ebike enthusiasts/amateurs who have the knowledge/skills to fault find and test batteries.

[Stradageek]

Had a chat with an ebike shop proprietor today on exactly this topic, my friends having experienced this issue.

Simple answer, if you leave a ebike for an extended period, with a low battery plugged into the bike, it will discharge and irrecoverably die.

He says they see it all the time because so many people buy and ebike, use it for a bit, ignore it for the winter then come back to find it dead in the spring .

If there is a way of recovering these batteries I smell a real business opportunity out there

[stodd]

I read on Pedalecs forum of special chargers to recover over-discharged batteries. I can't find it now. I think it involves an expensive specialist charger, and isn't at all certain even them.

p.s. more on https://www.pedelecs.co.uk/forum/thread ... ost-184501

[hemo]

Stodd you have been reading posts by Andy Prat who talks a load of crap, his last one was we have all got out rotors back to front because manufacturers don't know what they are doing. He just can't be taken seriously and is basically trolling mistruths with gobbledygook.

[stodd]

Yes, thanks. Didn't notice the d8veh signature ... (I usually qualify my references from here to Pedalecs with a comment that there is lots more expert advice, but some that NOT so expert).

Are there any reliably references to reviving an over-discharged battery?

[hemo]

Had a chat with an ebike shop proprietor today on exactly this topic, my friends having experienced this issue.

Simple answer, if you leave a ebike for an extended period, with a low battery plugged into the bike, it will discharge and irrecoverably die.

He says they see it all the time because so many people buy and ebike, use it for a bit, ignore it for the winter then come back to find it dead in the spring .

If there is a way of recovering these batteries I smell a real business opportunity out there

As I mentoined most techinically don't know much about battery constuction and testing/fault finding.

If a battery is left for a year or two fully charged then cells will die and lose capcacity, any lithium battery should NEVER be left fully charged for more then a few days. They should be left in the 50 - 80% SOC range and only charged about 12hrs before use, if used daily full charge is ok as the cells don't sit to long.

For anyone with a battery that has been left there is nothing to hard in taking readings (voltage) with batteries if good sound advice is followed though you need a DVM to carry out these tasks. The hardest part is patience and opening and closing a battery/pack back up.
Some fairly simple voltage readings can usually pin point where ab issue may lie.

I build and diagnose batteries as part of my ebiking interest/past time.

[mattheus]

It feels like e-Bike batteries are going to become rather like car batteries in practice - despite the different chemistries (which are not THAT different deep down, arguably).

Lead-acid car batteries are consumables. Their lifespan is highly dependent on how you use them and maintain them.

Hopefully owners will quickly learn about these foibles and they won't impact the popularity of e-bikes. If people realise the similarity with car batteries, that should help. (I guess that for many it will be like owning a fair-weather vehicle, like a motorbike or classic car.)

[hemo]

Yes, thanks. Didn't notice the d8veh signature ... (I usually qualify my references from here to Pedalecs with a comment that there is lots more expert advice, but some that NOT so expert).

Are there any reliably references to reviving an over-discharged battery?

You have probably crossed my alias on here with the Pedelecs one ?

Generally only ref's appear on forums like ES (USA) , Pedelecs or Pedelecforum.de. There are some posts in the search area of pedelecs from d8veh aka vfr400 and maybe a couple of others as well as myself.
Ebike sellers/battery sellers very rarely go to any lengths because it isn't very profitable, so much easier to sell a new expensive battery.
As long as you have a DVM and are confident in opening/prying inside a battery then most issues are pretty staright forward to check. Recovering low cells depends on their start voltage usaually above 2.5v they can be coaxed back up using any std old 5v phone charger of <500ma charge rate, it is the low charge rate that is critical to gently coax a rise in voltage so not to stress cells any more. Charging back to health can take hours and steady monitoring every 10 -20 minutes until they are at a good level of charge.
A phone charger needs a slight mod at the charge outlet and a use of a solder iron and a couple of pcb pins from a pin strip.