Greentime Controller 15 Fet Regen Stops working at top of charge

[cloudy]

I've setup regen on my Green time controller using a reed switch and magnet mounted on my hydraulic brake calliper. It works great while pack voltage is below 58V. Above 58V, there is no regen. Can anyone tell me how to modify the controller to enable regen at around 60V?

I'm running a 14S8P 18650 (with BMU) in series with a 1S8P booster pack made of plastic cell holders to get 15S. I check the Boost pack periodically to ensure it's balanced with the other cells. Usually I Bulk charge the 15S around 60V.

This is the controller:


Reading the forums, i think regen stops working at higher voltages because the LVC on my controller is set too low for 15S (currently LVC=40V). I think LVC should be increased to around 15x3= 45V.

Is it just a matter of shorting the terminals marked 60V on the circuit board to increase LVC and improve the Regen? Is there any way of knowing what the LVC will be if I were to do this?



The Tabs for 60, 64, 72, 80 V are currently not used on the board (no resistor or short)

 

[john61ct]

The whole point of regen is you need a depleted battery.

Otherwise it cannot accept high-current charge without getting damaged.

An alternative is to burn the energy off to braking resistance

 

[cloudy]

I suppose I thought there would still be room in the battery given I usually stop charging at 4.0V/Cell. In hindsight, the title of my post is a bit misleading.

 

[john61ct]

Discharge the pack down to say 50-60% if you want to get much regen.

What is your reason for wanting regen?

 

[cloudy]

I like regen because it saves on brake wear and gives a little extra range.

 

[E-HP]

Split your piggyback pack to two 4P packs and test out 16S and see if you get the same results.

 

[cloudy]

Can you help me understand what adding more voltage would achieve as a test? I've already noticed regen stops working above 58V, wouldn't adding another series group ( going to16S) just stop it working all of the time? In other words, what am I missing?

 

[E-HP]

Can you help me understand what adding more voltage would achieve as a test? I've already noticed regen stops working above 58V, wouldn't adding another series group ( going to16S) just stop it working all of the time? In other words, what am I missing?

Seeing if the controller only recognizes standard voltages, 48V, 60V, 72V for various settings. I figured if they're in cell holders, it might be easy to try.

 

[cloudy]

Thanks for clarifying. I assumed the settings would be fixed and it would not recognise different voltages, but now realise this might not be the case so maybe worth a try to go higher voltage. Unfortunately there is very little information available on this controller.

 

[E-HP]

Thanks for clarifying. I assumed the settings would be fixed and it would not recognise different voltages, but now realise this might not be the case so maybe worth a try to go higher voltage. Unfortunately there is very little information available on this controller.

The way I looked at it, is the 40V LVC seems to correspond with 13S, but the 58V regen cutoff seems to correspond with 14S. So, maybe with 15S, the controller still thinks it's in 14S mode. Just guessing, so thought it was easy enough to try 16S.

 

[cloudy]

I've bridged the pads marked '60V' in the photos of my controller and this has enabled regen over a wider range of voltage that suits my 15s battery.