Sur Ron Battery “Mod” BMS direct discharge Service


Downtube Electric Bike Battery Repair 36V – 48V-52V



Sur Ron Battery “Mod” BMS direct discharge Service

You will only see performance gains when used with an after market controller the ASI BAC 2000/4000/8000

For more in email:

We do not recommend this modification being undertaken by the inexperienced individual as risk of fire.

The Sur Ron battery has been designed to have a massive amount of “Redundancy” or “A lot left in the Bank”

Sur Ron built their standard battery with a cell type and configuration to handle a restricted 60 Amps standard,  but the set up with restriction removed  can actually handle 110Amps (The cell manufacturers data sheet  states 11 x 10 A =110Amps).

The battery has a management system known as a “BMS” (Battery Management System). This has various functions: Evenly “Balance” charge the individual cell series that make up the battery. Restrict the output of the battery and stop the battery from being drained to low “LVC” (Low battery Cut off). It simply does this by cutting off the power.

Our ASI controllers are programmed to cut off power before the battery gets too low and not take more power than the battery can handle.

Bypassing the BMS for discharge can make full use of the available power from the Panasonic cells. These individual cells have a combined manufactures continuous rating of 110 Amps. In other words they are designed to handle this amount of power until they go flat. However, they can still handle higher power safely for short periods. We have set the bigger ASI 4000 and ASI 8000 to have a burst of 125A in the “Battery Bypass Mode”. The ASI 2000 can only maintain 90 Amps continuous, within the cell manufacturers 110A.

This may have confused you, but think it like this. A motorbike has a rev limiter: Normal band, yellow band (just for a few seconds), red band (dont enter except for a split second) The motor can rev up just up before in the normal zone without issues, on the Sur Ron  modified equivalent of 110Amps.  Yellow would be up to 125 Amps. Red – the controller wont allow it! Sur Ron have restricted the battery by nearly 50% from 110 Amps to only 60 Amps.

Our work is of the highest quality using copper ring connectors both crimped and the soldered. High quality  silicon 10 AWG cable (x3) to hold the additional load,  Special insulating silicon based sealant (not he stuff you use in your bathroom!) to insulate the connections or high heat tube, doubled and tied. The main join is soldered and not just crimped and everything done is a working environment to stop mistakes or secondary damage from solder drips etc.

The benefits of removing the discharged restriction:

Free up restricted power for aftermarket controller (ASI BAC 2000/4000/8000 or nay controller set to max 110DC Amps
Power (watts) up by 50%
Balance charging
Significant improvement in acceleration and top speed

Negatives of removing the discharged restriction:

Dangerous to undertake modification.
Must have a modern upmarket controller that can monitor low voltage shut off and DC amps set no higher than 125A.
May void warranties.

Your fuel gauge percentage will be inaccurate. Use your volt reading for accuracy 67v full, 60v half  54V go home, 48V about to stop.

Sur Ron “Recovery” charger for Bypass mod – Flat battery

The Deal:

buy this service.

we send you a shipping address.

send your battery to us , (we will recommend a courier service for you).

We do the bypass and send  it back  with the courier 48hrs after receiving your battery
We guarantee to have your battery back with you within  3-5 working days from receipt of the battery. Normally much faster.
Our price includes the cost of all parts, labor and return postage.
Please understand that this modification, once completed is very safe but damage may occurs to your battery if you continuously run it at full power.

To Clarify:

Your BMS Will still balance charge BMS

Power comes direct from the battery missing out the bms

Your controller is independent and will manage the low voltage cut off (if bought from us definitely)

The gauge of the battery is no longer accurate but your voltage on your controller display or voltammeter will tell you when its empty. (minimum voltage under load is 48V but may not chrge wit the standard charger if below 54v – we recommend using our “recovery” charger to gain a much bigger battery range))



This is an aftermarket unofficial modification undertaken by a UK professional battery builder. We can not however take any liability ensuring from this modification. You undertake this service at your own risk and understand that your battery will be changed and not used as designed by the manufacturer. Any Lithium Battery is a risk to fire and this modification will not increase that risk and must not be used in a court of law or any other public announcement to suggest that any ensuing fire or damage was caused by this modification. That Electroncycles and its employees or agents will not be held for any liabilities from your use of this battery. By making this purchase you are agreeing to waver all indemnities and liabilities.

Buyer releases Electron Cycles or any person trading on or behalf of the business known as Electron Cycles from any liabilities, therein known as Electron Cycles (expressed or implied, arising by law or otherwise) that may occur from the use of products sold by Electron Cycles and purchased by Buyer. These products are being sold for “Off Road/Competition Use” only and may be used only on two wheel vehicles (bicycles, electric bicycles, two wheel electric powered vehicles) used solely for “Off Road/Competition” (off-road being defined as a private land with land owners permission and not public highway or byway). The Buyer also recognises that Lithium batteries are classed as hazardous and should not be: stored, used, charged in place, facility any area that is not fire proof or safe to do so. That batteries should not be taken into the family home, office, workplace or school place. No other applications are intended or implied. The Buyer of product sold or provided by Electron Cycles acknowledges and agrees that Seller disclaims any warranty and expressly disclaims any liability for personal injury or damages or any damages to vehicle, expensed occurred, personal property or third persons. Electron Cycles will uphold the warranty of the manufacture of the product sold for a minimum of six months from date of purchase from manufacturer defect. In the event a manufacturer’s warranty exists, it is agreed and stated that Under no circumstances shall the seller or manufacture be liable for any labour charged or travel time incurred in diagnosis for defects, removal, or reinstallation of this product, or any contingent expenses.

Lithium batteries by nature are considered hazardous items and should never be brought in to the family home or any other structure where fire may cause risk to: life, injury or possession. Batteries should always be charged and stored in a safe fireproof place. While being used, the safety to others and others property must be considered and is the direct responsibility of the purchaser. Any harm to the purchaser or other third parties or property is not the responsibility of Electron Cycles or any person trading on or behalf of the business known as Electron Cycles and   hold no responsibility either implied or otherwise for mechanical, electrical or other failure when using any products or any costs or damages resulting from these items purchased or otherwise obtained from Electron Cycles or any person trading on or behalf of the business known as Electron Cycles

Additional information

Weight 14 kg
Dimensions 50 × 30 × 30 cm