I found a couple of battery 200watt battery dischargers with safety features so that you can set discharge amperage and voltage shutoff.  I haven't tried them, but the reviews seem decent.  Two friends have ordered so I hope to see how they work.  This allow for discharging unused batteries at the field and for battery break in.  On Amazon, and Ebay for some variability in price.

https://www.skyrc.com/BD200

https://www.skyrc.com/bd250

Another brand currently out of stock in US shops, but seems available

https://www.banggood.com/ISDT-FD-200-200W-25A-Wireless-APP-Control-Discharger-for-2-8S-Lipo-Battery-p-1499928.html?cur_warehouse=CN

Edit, found the ISDT here
https://www.progressiverc.com/catalogsearch/result/?q=discharger
and
https://hobbyking.com/en_us/isdt-fd-200-200w-25a-wireless-app-control-discharger-for-2-8s-lipo-battery.html