ElectricMotorcycleForum.com
General Category => Electric Motorcycle News => Topic started by: Stonewolf on August 13, 2024, 04:48:20 PM
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https://www.motorcyclenews.com/news/2024/august/yamaha-working-on-large-capacity-battery-tech/
- Something actually promising, could Japan finally be following Harley's lead?
- Air cooled, boo. MCN seems bullish on it but my experience says passive thermal management wont cut it
- That diagram looks awfully familiar ... can't quite put my finger on it
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What do you think this is supposed to be suggesting? The new cells won't need heat for the winter or the riders depending on conditions will have a hot brick with fins in the center of the motorcycle.
" the patent simply describes the batteries as lithium-ion, upcoming tech advances such as solid-state lithium-ion batteries will swing the balance towards air-cooling as they tolerate a much broader range of operating temperatures than current designs."
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I think they mean that air cooling might be more viable with solid state cells since they generate less heat on charging and have better energy density which means the cells don't have to be packed in so tightly. Basicly MCN is speculating but I think they're putting too much faith in new tech.
Energica's Ego platform battery (the big one, they only offered the small one until stock ran out) has a significant thermal performance problem that can't be solved without either increasing the interface surface between the heat transfer structure and the battery or improving the dissipation surface of the structure or both but this is hampered by the fact they hit that 21.5 kWh number by jam packing as many cells as possible into a box. Looking at the patent we don't know what Yamaha are doing for the first because we don't know about the cells or the battery's stats or its internals, but we can see they're trying to address the second with cooling fins.
Ultimately the problem here is when you charge the battery it gets warm and the faster you charge the warmer it gets, this causes a number of problems:
- Default charge rate throttling to avoid overheating the battery (Energicas max out at 1.25c)
- Charge rate throttling on subsequent charges if you can't dissipate the heat fast enough (Energicas can't)
- Battery degradation due to heating the cells which causes higher resistance which increases the heat generated during charging (starts to hurt after 20k-ish miles)
Active thermal management (using either standard liquid cooling or refrigeration) is going to be necessary for BEV bikes to advance despite the weight and complexity as it hits all the bases people care about bar range. You can access significantly higher charge rates by keeping the cells cool, you can dissipate all the battery heat between charges (ideally as much during charging as possible), you reduce battery degradation by keeping the cells cool, and even as battery degradation eventually creeps in it takes a long time for anyone to notice because the cooling system is compensating for the higher resistance.
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I’m no engineer, but I always thought that even if there’s no practical way to actively cool the pack, there ought to be a way to pump heat out of the battery pack and into the motor and the AC charger, which are both liquid cooled on the Experia. The motor isn’t working very hard at steady highway speeds so there should be plenty of leeway there, and the AC charger isn’t used at all while riding.
If Yamaha has figured out a system where less cooling is needed in the first place, that would also be very nice. Other than range, battery heat issues were the #1 problem I had with my SS9 13.4 so it’s important to see an advancement here.