Matt's BGT Battery Upgrade

This thread is detailing a battery upgrade on an Evolve BGT .

Basic concept is to

• replace Evolve BGT stock battery with a 10S6P 18650 pack for increased range and reduced voltage sag.
• New ABS enclosure for battery pack
• Retain Evolve ESC and BMS fitted in new enclosure

I will be doing this in parallel with another DIY board project ( see New Ground Up DIY for Mark ) leading to some time saving and cost sharing benefits

 

MJ1 Cells and lots of other stuff has arrived and battery pack construction has commenced

The battery will be a 10S 6P configuration.
First thing is check voltage of all cells - all are within 3.5Vto 3.6V so all good.

Has some spare 18650 cell heatshrinks so used that on outside cells in eack pack ( for additional inter-pack insulation).

Then hot glue 3 cell packs together.

Then 3 cell cardboard insulators on all +v ends.

Ready for nickel strips to be added

 

Hi Skaterboy58, how’s the battery build going?

 

Coming along - all 10 cell packs glued together and first layer of nickel strips completed

 

Battery pack building continued - photos show:

• each 6 cell pack wrapped in Kapton hi-temperature tape and then with fibreglass tape
• mock up of series connection with 2x 12 awg flexible silicon wire and showing current sharing on packs
• additional insulation for inter-pack cell outer skin insulation
• packs taped together to form 2 x 5S blocks

ready for final nickel strip welding and series wire connections

 

Looking good mate! thanks

 

continued with building battery pack . Series connections are 2 x 12awg silicon high temp flexible cables . Final wrap in neoprene foam for protection and heat shrink for moisture/dust protection.

 

First charge up pack at 2A to 41.7 V
Then a discharge test using an eight ohm 100W resistor hanging over a fan. This provides approx. 4.5A load ( varies with voltage)
The discharge test objective is to confirm cell capacity ( Wh and Ah) from full charge to 30V
Discharge test took four hours with data checked every 30 minutes. Results were identical to discharge test for Marks pack using identical MJ1 cells
Final readings at discharge test conclusion were
30.0V
690Wh
18.5Ah
with a cells within 0.1V

These are slightly better than estimated ( Ah capacity of 18Ah and Wh 648) - so cells are all good.!

 

ABS Enclosure was sourced as a special order from psychotiller in California USA . Comes in two halves and used special ABS glue to glue together. ABS is ideal for enclosures as it is tough yet flexible and forgiving for scrapes when bottoming out .

 

Next - Enclosure and battery pack were given to Matt for enclosure deck mounting and ESC fitting.

In this build - the Evolve ESC and BMS are being re-used in the new set-up.

Following on from ideas from my recent DIY builds - utilising an aluminium plate in enclosure for mounting ESC and BMS and as a mass heat sink for ESC.

Plate is bolted to rubber strips ( for vibration dampening) and rubber strips are glued to bottom of enclosure with ABS glue.
We are using and XT-60 socket/plug for fitting a 40A fuse and to provide physical isolation from battery +ve ( for piece of mind and safety when being stored)

 

Battery pack is fixed to bottom of enclosure with two full length velcrose strips - don't want battery pack moving under acceleration or braking!

and all enclosure bits fitted

• XT60 external 40A fuse and isolator ,
• on/off switch ( from my old BGT )
• charging port
• two holes at rear for motor grommets

 

Next is to build a BMS harness to connect from Evolve BMS to battery balance socket (green one)
I always fit in-line fuses on BMS balance leads ( under the black heat-shrink in picture) as these connect directly to battery pack cells with approx. 150A potential current available to feed a fault
.
Without fuses , a short on the BMS board could melt the balance wires , start a small fire and could cause the whole battery to go-up.

Harness is spliced into Evolve BMS plug wiring

 

BMS is fixed to gear tray with velcrose tape - all wired up ready for fitting to board

 

For weatherproofing a stick on rubber protrusion ( from Clark Rubber) is stuck onto bottom of deck - and holes drilled to align with enclosure holes

 

Motors connected and all set for test run - Evolve remote pairs OK ( eventually! ) and motors spin - so all good