First post so be gentle

[YamaRDLC]

If this is in the wrong part of the forum please feel free to move it

I have a question about a bike i just bought off ebay, its a Carrera Vengeance E Spec mountain bike.
It is in very good condition overall but was advertised as having a dead battery and no key to remove it but does have a charger.
Got it for a cheeky bid of £175 and it was fairly local.
Got a key from replacementkeys.co.uk, highly recommended, got it the next day and only about £9
Even with the key the battery did not like coming out but got there in the end.
Watched a few youtube videos on how to check your battery and measured the voltage at just 2.26v so assumed it was unrecoverable, the charger would not charge it at all.
Took the battery cover off and connected my bench power supply, gave it 42v at 0.9a and it gradually started to charge and after 4 hours it reached 36v and i then plugged in the charger which then worked and took another 5 hours to fully charge the battery.
Measured it at 41.9v last night and it was still 41.7v this morning, what should a healthy battery measure?
Haven't reinstalled it yet as i wanted to measure it a few times.
Before i did this and assuming the battery was dead i made another cheeky bid on ebay and got another battery on the way for £60 which the seller claims is in good condition.
Cant believe the cost of new batteries or some second hand ones which can be 300 - 400 so more than the bike is worth, hopefully i will be able to recover this second battery as well.
The bike has been fitted with a throttle which i don't understand, bearing in mind i have not connected the battery back up can some one explain how this works as i thought these bikes were supposed to be pedal assist so does that not work now?
Never had an E bike before so assume i know nothing

 

[matthewslack]

Those fully charged voltages are fine, and the battery didn't catch fire, so balance may also be fine. Worth checking since you have opened it up, if you can get access to the cell group balance wires or connector.

The risk of the first part of your recovery charge is that the BMS is not doing balancing, and if cell groups are out of balance, one or more get pushed to a voltage where they fail in a fiery way. But nothing bad happened so you got away with it!

The battery has 10 cell groups, and each should measure 1/10 of the full voltage, to within a few hundreds of a volt. Verify that if you can.

If that is all in order, then the next test is to ride the bike. Sitting flat longterm can seriously affect capacity and so range. But if it works, it works.

It would be interesting to hear what happens next!

 

[YamaRDLC]

What about the throttle? how does this work and does it affect the pedal assist?
I did the first part of the charge with my bench power supply in the middle of the garden because i was wary of a battery fire.

 

[matthewslack]

I didn't know a Carrera Vengeance had a throttle!

The UK rules on throttles for EAPC ebikes allow throttle alone from a standing start to 6km/h without pedalling. Above that speed throttle is only allowed to be active if rider is pedalling, but can propel you to the full 25km/h.

Throttle only to 25km/h is allowed if you put the bike through SVA (DVLA single vehicle approval).

 

[YamaRDLC]

The bike was modded i guess, i just wondered if this removes the pedal assist.
I guess i will re attach the battery and try it.

 

[Nealh]

41.5v - 42v is that which one should see for a fully charged 36v lion battery.

 

[saneagle]

The bike was modded i guess, i just wondered if this removes the pedal assist.
I guess i will re attach the battery and try it.

Does the bike have an LCD? If it does, please show a photo. I'm pretty sure that the Vengeance E never had a throttle. Is your a normal vengeance with a kit added? Please show some photos of what's on the handlebars, the area around the bottom bracket where the sensor is and the motor.

 

[YamaRDLC]

 

[saneagle]

View attachment 63315View attachment 63316View attachment 63317

That's the original Suntour HESC system AFAICS. I've never seen a throttle on one before. There's no connection for one. I'd be interested to know how it's been done. The controller needs two signals to give power. The torque sensor arrangement gives a pulsing pedal rotation signal and a 0-5v analogue signal for how how hard the pedal is pressed. A normal throttle gives a 1v to 4v analogue signal, which would work as long as you were able to spoof the pedal speed signal. I posted about how to do that a month or so ago.

 

[YamaRDLC]

So i gave the bike its first wash and noticed a few things, first is that it does not have a throttle, i think the ebayer just copied a listing then added his own details as the title says with throttle but the description makes no mention of it, i am ok with this as it would be an added complication i don't need, it does have a grip that rotates like a throttle but it just needs an allen screw tightening up.
Haven't put the battery back on yet but rode the bike and it rides fine and gears all work and the bike is in good condition.
Info i found online says it needs 25PSI front and 30PSI rear (mountain bike tyres) but they feel quite spongy at that.
The front wheel has 2 broken/unattached spokes, are these an easy fix? something i can do myself?

 

[Nealh]

Tyre pressure is a personal thing, some like hard tyres and some like a softer tyre which can aid comfort.
It really depends on the riding one does , off road then softer may dampen the terrian . On road then a softer tyre may impede speed and mean more rider effort.
With soft tyre pressure one has to be weary of snake bite puntures if using tubes.

Spokes yes most people should be able to fix them, one may need to tease the spoke in and then manipulate the spoke to match the cross pattern of the wheel.
Removing a brake rotor may be necessary on the LHS if a spoke is broken there.

If unsure of spoke length then best to remove a good spoke to get it correct, replacement is best done with tyre and tube removed but with experince one can replace spokes with tyres mounted.
For spoke tension pluck a few spokes for ping test and tighten new ones likewise using the plucking method.

 

[thelarkbox]

Welcome, and fingers crossed for your battery, the revival seems to have worked well, regardless of the Very low initial voltage. If it sustains a workable voltage under load (on the bike) your real world testing will reveal.

Set the tyre pressure to suit your mass and comfort, and by all means roll up your sleeves and fix the few bust spokes, you tube is your friend for visual walk throughs and guides aplenty the tricky bit can be getting the correct size
spoke (length) 14g is the cycle spoke default diameter/size afaik. you may find a £10-12 amazon next day delivered full set cheaper than an odd spoke or two from a specialist.

a couple of bust spokes shouldnt hamper your testing of the bike, check the brakes are good and responsive and when you have set an appropriate tyre pressure plug in the battery - This is worse than a discovery tv program where they take an hour to repeat the same 3 mins of info..

enjoy the new e-bike (pedelec)

 

[YamaRDLC]

Just plugged the battery in and gave it a first test ride, all good though its a weird sensation.
Front wheel is buckled slightly so needs trueing as well as 2 spokes replacing.
Is the 5v output on the LCD for lights/trip computer?
Have put 38psi front and 40PSI rear now.

 

[Ghost1951]

It depends where you initially measured the battery voltage, but I am sure the 2.75v or whatever it was, is not what the true battery voltage actually was. The BMS would have disconnected the battery when one or more cell groups fell below the safe low level, so unless you measured inside the actual case you would get an inaccurate reading.

When I have done something similar to you in the past, it did not take long at all for a 2 amp charger to raise the very low voltage groups to a level that allowed the BMS to switch on for normal safe charging.

And you were right to take a cautious approach. In some circumstances, as you obviously suspected, directly charging a battery with a defect can lead to fireworks.

When I did it, I used a low current charger and I monitored voltage the whole time and as soon as it had risen to about 30 volts, I reverted to the normal charge process. That battery was revived at least two years ago and this morning my partner and I rode out on our bikes and had a great ride around by Vindolanda in a very hilly area. That old and once neglected battery is still very good and has a range of about 25 miles which is about all you might expect in a good battery of that size. I think it is about 10 ahr and is on a Pendeleton Somersby.

I hope your battery does as well as this one, and that you get good use out of it.

What a bargain you got there!

 

[YamaRDLC]

Just noticed that the 2 spokes have sheared off level with the top of the nipple, is there an easy way of getting the remains out?

 

[thelarkbox]

Probably easiest to remove the tyre and just shake them out, new spokes will work better with their new nipples anyway and you wont need to bend the new spokes to fit either.

 

[YamaRDLC]

Any idea how much a bike shop would charge to fit 2 new spokes and true the wheel?

 

[thelarkbox]

Not 100% sure but £50 has been suggested in the past but that could have included the wheel build (lacing all 36x spokes etc) edit labour only pre vat etc...

May i ask whats the barrier to diy? - I urge you to watch at least 1x youtube- how to true a bike wheel vid..
I am kack handed- I loose skin off a knuckle just by looking in the direction of tools, I built and trued a wheel in an afternoon a year or so back primed only with a couple of well informed utubes..

Your revival of your battery displays competence in following a methodology, and turning a spanner/check/repeat cycle is easier to follow.

You may even be able to (probably will) true your wheel perfectly even with the 2 x spokes missing, and the only tools needed are a few cable ties and spoke spanner.. though a comfy stool also helps - either the missing spokes will be at crucial points or they wont be but as long as not side by side those spokes either side of the missing ones should be able to compensate.. - even if they are at crucial points- finding out will necessitate improving the wheel so its still a win win

 

[YamaRDLC]

Its because of where the spokes have snapped i will have to remove the tyre, inner tube and tape because i can't get the remains of the spokes out of the nipples.
And probably the disc as well.

 

[matthewslack]

I broke some spokes out on a long trip far from home, lucky to find a good bike shop and replacements for £1 each plus a bit more for the nipples. I took the broken ones in and they were able to work out exactly the right length.

You can sometimes get away with making a hole in the rim tape to get the nipple out and patch with a carefully sized piece of duct tape or Gorilla tape, just make sure it doesn't interfere with the tyre bead and rim flange.

Just replacing the spokes and tensioning them might sort out the truing.