Battery indicator shows empty after short distance

johneb

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Aug 3, 2013
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Well, at long, long, last I finally had free time to 'electrify' my trike. I'd like to offer a huge 'Thank You' for all the invaluable advice given to me by members of this forum in getting to this point.

I've now been for a couple of inaugural shake-down rides (a mile at most), and on both occasions have been alarmed by the (apparent) rapid emptying of the battery. I've just returned from a half-mile run on power levels 1 & 2 and the display shows empty. The battery LED's disagree, thankfully. When it first happened, I was worried that the newly-bought battery was defective, as the LED indicator was showing 3 green and one red light (my cordless garden tools show 4 green when full). However, I've been in touch with the suppliers (Eclipse Bikes), who assure me that this is normal and one red light will always illuminate.

The throttle is connected, but wasn't used. I've checked the connections and they're all correct, so I'd be grateful for guidance on what might be the cause and solution, please.

My setup:

Motor: Q128 201 (260) rpm in 20" wheel, running at 48v
Controller: KT36/48 17A
Display: KT-LCD6
Throttle
Wuxing brake levers
No speed sensor
PAS with Dual Hall sensor
48v 12Ah Battery with Samsung 30Q Cells
 
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Deleted member 25121

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Did the display show empty all the time after the journey or only when the motor was running?
 
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johneb

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Aug 3, 2013
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Did the display show empty all the time after the journey or only when the motor was running?
It shows empty for a while after the motor has stopped, but when I return later and switch it on again, the battery level on the display shows full once more.
 
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Deleted member 25121

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It shows empty for a while after the motor has stopped, but when I return later and switch it on again, the battery level on the display shows full once more.
That would incidate a problem within the battery pack, are you able to measure the battery voltage with a DVM?
 
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johneb

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Aug 3, 2013
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Yes, thanks - I'll try another run tomorrow, then check the voltage. Am I correct in thinking it should be around 52v?
 

Nealh

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A full balance charged 48v is 54 - 54.6v (4.15v-4.2v per cell), for a minimum voltage I use 42v or about 3.23v per cell.
Don't bother with lcd6 battery meter instead use and the LCD6 voltage reading, It will give amore accurate view of the batteries SOC.

I have lcd3 and have a constant voltage reading on the screen, you may have to press the on/off button quickly for it to show on the screen.
 
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Nealh

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What is the P5 parameter set to ?
 
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vfr400

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After switching on, you can do two short presses of the power button to switch the bottom of the display to show voltage. Make a note of the reading immediately after unplugging the charger, then keep an eye on it to see at which voltage it shuts down during the ride.

I can see two possibilities that can cause your problem. Firstly, a duff battery. the readings above will show that. Secondly, something causing a very high drain on the battery. Ther are various causes for that, like a faulty MOSFET in the controller, a false positive on the phase/hall sequence or timing issues.

Did you by any chance try and fast charge the battery? Are you using a standard 2 amp charger?
 
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johneb

Pedelecer
Aug 3, 2013
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After switching on, you can do two short presses of the power button to switch the bottom of the display to show voltage. Make a note of the reading immediately after unplugging the charger, then keep an eye on it to see at which voltage it shuts down during the ride.

I can see two possibilities that can cause your problem. Firstly, a duff battery. the readings above will show that. Secondly, something causing a very high drain on the battery. Ther are various causes for that, like a faulty MOSFET in the controller, a false positive on the phase/hall sequence or timing issues.

Did you by any chance try and fast charge the battery? Are you using a standard 2 amp charger?
No, the battery is new and was delivered charged. I've just given it a couple of brief top-ups with the only charger I have - a standard 2A charger Eclipse supplied with the battery.
 

johneb

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Aug 3, 2013
88
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Thanks for the advice, all. I hope to test it tomorrow (rain permitting) and let you know the outcome.
 

johneb

Pedelecer
Aug 3, 2013
88
3
A full balance charged 48v is 54 - 54.6v (4.15v-4.2v per cell), for a minimum voltage I use 42v or about 3.23v per cell.
Don't bother with lcd6 battery meter instead use and the LCD6 voltage reading, It will give amore accurate view of the batteries SOC.

I have lcd3 and have a constant voltage reading on the screen, you may have to press the on/off button quickly for it to show on the screen.
Ok, Just fitted in another test ride. P5 is set to 12. Starting voltage (after top-up charging the battery) was 53.6v on the display, confirmed with my voltmeter. Rode for around 1 mile on flat and gentle incline, using level 2 assist. The battery level indicator on the top of the display was showing full until I stopped, when all the bars promptly disappeared. The voltage was down to 52.8v. After leaving it for a few minutes, I switched back on and the battery level indicator was once again showing full and voltage 52.9v.

I realise I have to give it a much longer test, but before venturing further want to establish if I actually have a problem with my setup.
 

Nealh

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It appears that the meter reading isn't reading the voltage level accurately if the battery meter disappears from the display, it should be pretty constant. As long as the voltage reading is constant then that is the better gauge of battery then the meter with 4 or 5 bars.
Try playing with P5 setting using the other values it won't do any damage doing so, try lower and higher until hopefully you find one that gives a more stable meter reading. Does the voltage meter indicate a saggy battery ?
If your battery is saggy then the meter might not be able to keep up with it properly and takes a while to gauge a stable reading.
 
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johneb

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Aug 3, 2013
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It appears that the meter reading isn't reading the voltage level accurately if the battery meter disappears from the display, it should be pretty constant. As long as the voltage reading is constant then that is the better gauge of battery then the meter with 4 or 5 bars.
Try playing with P5 setting using the other values it won't do any damage doing so, try lower and higher until hopefully you find one that gives a more stable meter reading. Does the voltage meter indicate a saggy battery ?
If your battery is saggy then the meter might not be able to keep up with it properly and takes a while to gauge a stable reading.
Thanks Nealh. What readings would indicate a saggy battery? (The voltage was fairly constant during my ride, just dipping briefly on a short, steep slope).
 

Nealh

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If voltage is reasonably stable then no saggy battery, saggy battery would be 2-3 volts depending on PAS level or current drawn. All batteries will sag on climbing as usually more current is needed.
 
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vfr400

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It sounds like your battery is OK to me. If it wasn't, the LCD would go off. Check the bullet connectors for the motor on the controller. Make sure they're nice and tight. Also, check that the connector near the motor is pressed all the way in to the line.
 
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Nealh

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I should have also mentioned a saggy battery will show it self up better in lower PAS levels where current demand is less.
My 5 year old 29E 36v cells are saggy, ok to use in PAS 1 or 2 and can still manage 30+ miles. Use PAS 3 or more they sag badly and range in PAS3 is only about 18 miles.
I could get rid and have something better but for my commute/errand bike they are plenty good enough and can see them going another 2 - 3 years, even in PAS 2 acceleration is spritely with 20a controller and PAS 2 draws about 4a current.

Horses for courses if the battery suits your needs and does what you want it to then it is still capable and pointless discarding.
 
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johneb

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Aug 3, 2013
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It sounds like your battery is OK to me. If it wasn't, the LCD would go off. Check the bullet connectors for the motor on the controller. Make sure they're nice and tight. Also, check that the connector near the motor is pressed all the way in to the line.
Thanks vfr. The bullet connections on the battery were incompatible (different diameter) with the ones on the controller, so I soldered extensions to the controller wires (correct gauge) and fitted an Anderson Connector.
 

johneb

Pedelecer
Aug 3, 2013
88
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Have the cut-outs stopped now then?
It wasn't cutting out - I was just concerned about the (apparent) extremely rapid depletion of the battery. I have mobility problems and will be dependent upon the electric assist on longer rides. I particularly need to know when to head home whilst still having more than half battery capacity remaining, hence the worry about the display indicator showing empty. Now I know how to monitor voltage instead, I feel more relaxed. I plan to look at the parameter settings (more postings on the forum coming up!), and gradually build up the length of my rides.