Will I make it home? 48V 12AH... 25km.. --- NO ---

[Animalector]

Hi there,

I rode into work for the first time today - my first ever e-bike commute, and it was the fasted trip into work I have ever done (including by car), 25km, 33mins, average a smidge over 40kph.. This is with a 48V 1000W Conhismotor kit (stock). I was pedalling hard up every hill and hard off the line at lights only letting the motor do 'all' the work for flats, and throttling off down hills. I don't have a CA so don't know my consumption.

So my problem. I got into work and plugged in the 'slow' charger they supplied and after about 30 seconds - 'Pop' complete with smoke Before i started charging I measured the battery and got 52V across the terminals.

Will I make it home? I have a confident feeling I will if I pedal hard again. plus there are more down hills than up this time still it is 25km.. I would like the opinion of others with similar power setups... 1000W, 48V pack, 12Ah battery.

Thanks champs
Andy

P.S I will be ordering a CA online NOW!!!!

[Ykick]

It's possible to dramatically stretch range by not using any more power than what's needed to overcome the drag and weight of the system. Hard to do manually but I've had a couple "Oh Shit" moments and managed to stretch a battery much, much farther than usual WOT riding.

A power meter, preferably CA, is tremendously helpful for keeping track of system health.

What chemistry battery are you using?

[Animalector]

lIfe3po4 battery

I really did pedal hard.. so I am hoping for the best but prepared to pedal the last 3... 5.... maybe 10km home hehehe

Cheers

Andy

[ElectricEd]

It looks like you may be running pretty close to the limit. I run a 48V 15AH Ping battery on a 408 on a 27Km commute which regularly gobbles up 1000W on starts and hills even with me adding my bit. I hardly ever leave it to the motor to do all the work as It feels too stupid to not be pedalling. The route has a 200 metre altitude drop with quite a few ups and downs in between that add up to around 400 metres. A return trip takes a bit more than 12AH so I charge it up at work, knowing that there will be enough to get home. As the route is mostly downhill next morning I don't have to be too worried about running out, so "the man" often pays for the commute.
I had the same problem with the cheap plastic 2A chargers, they always blow up the main FET sooner or later. In my case it was less than a week for 3 different cheapy chargers. The aluminium case chargers sold by Ping seem to be bullet proof. Often on eBay you'll find people selling the same type of charger, so I bought a 6A charger for home, a 3A charger for work and carry the 2A Ping charger on the bike. So far they have all worked perfectly for over a year now.
You need to factor in the loss of capacity as the battery ages and most important of all, get a Cycle Analyst. My first battery was a 48V 10AH LiFePO4 and I cooked it in the first few weeks by pulling as much as 45 Amps when starting. You must be gentle for the first dozen or so cycles. When I got the CA and realised how much the battery had been abused it was too late. The capacity had dropped to about 8AH and in less than 1 year dropped further to 6AH. It takes 6.5AH to get home with a lot of assist and keeping the speed down, so a new battery was required.
For the first 2 weeks on the new battery the CA was set to 10A max. It is now set to 20A max.
I hope this helps.

[Animalector]

is your commute 27 total or each way? --- EDIT --- just read your sig.. 27 each way.. nice one..

I already did 25.. have another 25 to go... Excellent report on the rest of your experience thanks heaps for that. I have been cautious not to pull WOT without significant assist from pedals and never 'mash it' taking off I always ramp up the throttle..

either way I am gong to get home even if I have to carry the bugger the last 'x' km..

on a side note how does the CA control the current? on a standalone system with the shunt, and throttle override?? can;t be throttle otherwise top end speed would be .... well it wouldn't be top end !

Cheers again

Andy

[ElectricEd]

Hi Andy,
Yes, I was infected by the "grin" and just loved the woosh. It's easy to get carried away.
The CA senses the current through the shunt resistor and controls the total current by over-riding and limiting the throttle voltage. It's a bit soggy with the control due to the sampling time, so you can occasionally draw more than the set limit. But this doesn't matter too much as it only exceeds by a few amps on the odd occasion.

[Animalector]

got 9.5 km in and throttle cut... the trip in is more like 23km not 25.. so anyways managed to 'conserve' for a couple of km to help with some hills, but basically had to pedal the last 15km home which was a bit of a pain, but good exercise. might have to carry the charger in with me next time

Cheers for the comments guys,

Andy

[dogman]

One thing that has happend to me, is the charger being carried around on the bike damaged it, then you plug it in and Pop.

So if you have to carry a charger, at least carry it in a bag or pack on your body. Attached to the bike, it will get rattled around possibly damaging it.

So a second charger kept at work is how I started doing it.

[Animalector]

I had considered putting it in the box with the rest of the electrics, but might just back pack it until I get a second one.

Cheers

Andy

[snellemin]

I believe you can make it home. I get 40 mile range out of 8Ah when I baby my setup at 18-19mph.

[Animalector]

that was the problem I didn't baby it on the way in (with every expectation I could recharge at work).. I pedalled hard but still 45 - 50km/h 100% most of the time. if I had have stuck at 35km/h you're right I think I would make it, but the thumb throttle is pretty twitchy, and I don't have a CA to set the throttle % for me.

It all charged up ok last night, so no damage to the BMS or battery thank goodness.

Cheers
Andy