Fix/Replace Hail Bopp Li-Ion Battery

[jruths]

Need to figure out some options for replacing or fixing the main Li-Ion batteries in Hail Bopp.

Specs: Brammo batteries (no longer in production, company acquired by Cummins). 29.8V + 14.8 V batteries in series for ~45V total. Both with 280Ah capacity.

The voltage current sits at about 7.5V total and the charger is not able to charge the batteries.

• Kevin found this exact match of a battery set on ebay: https://www.ebay.com/itm/235603667404

  • Pros: exact configuration match, no issues with compatability
  • Cons: a 2016 battery that seems to still hold charge, but essentially offered as-is. Missing out on 8 years of possible improvements in battery technology

• LiTime and other similar companies offer new batteries that do not have quite the same capacity as the stock, but should be enough to do what we need.

  • Pros: new battery technology, new fresh battery cells
  • Cons: hard to know if compatibility is going to be an issue, matching exact voltage specs, and supporting the 6.5 kW motor that drives the drivetrain.

• Is it possible to safely "jumpstart" the batteries so they would charge again?

[jruths]

[jruths]

6.5kW Motor:

[jruths]

Found this documentation of the motor controller: https://www.thunderstruck-ev.com/images/Gen4%20Product%20Manual%20V3%204.pdf

It indicates that the working voltage range is 19.3 V to 69.6 V for the 36V/48V version of the controller, which I believe we have. So it shouldn't be very sensitive to voltage variation.

[jruths]

Seems like the DC-DC converter 48V --> 12V is a SEVCON Part# 622/11111 36/48V 300W. Or possibly a 500W version.

Discussion about the DC-DC converter:

This product can also be used as an upgrade for many 4-pin 300W Sevcon DC-DC converters. This 5-pin upgrade takes care of the number one cause of faulure on most 4-pin Sevcon DC-DC converters! The 5th pin is an enable switch. The problem is that the DC-DC converter powers the main contactor and the DC-DC stays enabled at all times. This causes the units to drain power at all times even when the vehicle was not in use. This eventually would lead to vehicle failures from either the converter burning out or from the converter slowly draining the batteries dead. The 5th pin acts as an on/off switch for the DC-DC. Jumping the 48 Volts + DC-DC input to pin five will enable the DC-DC to turn on. If a toggle switch is put in line between the 48 Volts+ input and pin 5 the toggle switch can be mounted somewhere handy to allow the DC-DC unit to be turned off when the vehicle is not in use. Such a switch could act as a vehicle Kill Switch as well. However, if Pin 5 were hard wired to the 48V positive DC-DC input without a toggle switch, the vehicle would suffer from the same problem of having the DC-DC that stayed on 24 hours a day. A mating 5-pin connector is needed.

This discussion suggests a wide operating voltages as well for the DC-DC converter: 48V (28.8V Min. – 60V Max.)

[jruths]

I realized that the new battery for the 1/3rd scale car is a lower capacity version of what I was looking at getting from Li Time. So it should be possible to test it's compatibility with the vehicle by taking out the old batteries and inserting that battery in its place. Which should be fairly doable.

[jruths]

Thinking about this battery from Li Time as the replacement. We would get two and put them in parallel to supply the 6.5kW motor. I would get the suggested bundle, that includes the charger, monitor, and bolt down kits.

[jruths]

9/9/2024 Update:

• Status: Done, created a new task for battery installation
• Next Steps: Batteries ordered 9/8/2024, so will arrive Sept 16-20?
• Projected Completion: Done
• Update:
  • Tried to slow (low amps) charge kickstart/activate the existing Brammo batteries, then follow up with the main charger. Did this twice and the main charger could never fully take over. The second time, the batteries were charged up to 25V (should be 45V), but once the power supply was turned off, the charge rapidly declined (down to 16V in about 3 min). Seems like the batteries are toast.
  • We also tested that the new batteries would work by connecting the LiTime battery from the 1/3 scale car (same voltage we would use, just lower capacity) to ensure it would allow the car to turn on and to move (only moved it a few inches).