Cycling UK Forum

Just bought second hand carrera vengeance ebike fully charged battery and went out today did 12 mile mostly flat ground and the battery has dropped to one bar I was running g it on full most of the trip new to ebike so not sure if this is correct

Yep par for the course with a used/2nd hand battery on full power. How old is the battery/bike ?

Driving on full assist will really get through battery fast, and that bike has quite a low capacity battery. That could easily be what you get even if the battery is in good condition. Many (I think most but ...???) ebike users run on lowest but one setting most of the time, increase by one for hills, and rarely use full power.

Make sure your tyres are well inflated, your brakes are not rubbing (easy not to notice rubbing brakes on an ebike) and the chain is clean and well lubed.

Just a footnote about batteries, all the good ones consist of Lithium-Ion cells fastened together in batches (even in electric cars), Generally the weight of a conversion kit battery demonstrates the Ah capacity and thus the maximum distance on one charge. Our 15Ah batteries are about as heavy as the complete front motor wheel. The bikes use about 1.5amps on the lowest power setting and so the simple maths of 15Ah divided by 1.5 gives a time of 10 hours. At 10mph this represents 100miles which is the max distance I have achieved. Note that the power settings roughly double the amps for each click and so on setting No5 the power used is over 20 amps. This gives about 0.75 hours of riding !!!

The 0.75 hours of riding in Tony's calculation above was for a 15aH battery, the Vengeance has 316Wh / 8.8Ah; so that comes to 26 minutes at top power. Actually I don't think the Vengeance will draw as much as 20amps even in top power so not quite that bad, but you get the idea.

Thanks all any where I can get a bigger capacity battery that is compatable

Pedalecs tends to be a better site for questions like that. See for example
https://www.pedelecs.co.uk/forum/thread ... ike.35105/
Post a new thread there; there might be some updated information.

Recelling (by Jimmy? https://bga-reworking.co.uk/product-cat ... batteries/) might be worth looking at.

8.8ah/316wh is good for about 30 miles in low assist in benign conditions, high assist will put that battery/cells under duress in constant use so the 12 miles is about right. Most cheaper ebike batteries aren't able to cope with max power at a constant.
Some people tend to buy them as cheap use and use them like a moped on full power, this doesn't work.
Ebike batteries can deliver higher power but should only be for the occasional use with inclines hills if you want range/distance from the bikes use.