If you are interested in or a user of decentralized finance on the Tron blockchain, you probably know JustLend.

JustLend is a TRON-powered coin market protocol aimed at establishing fund pools whose interest rates are determined by an algorithm based on the supply and demand of TRON assets. There are two roles within the protocol, namely the supplier and borrower. Both of them can directly interact with the protocol to earn or pay the floating interest rate.

You can earn interests there by supplying TRX, USDT, SUN, JST, USDJ, WBTT, WIN and BTC, ETH trough smart contracts.

See here for more details. I will not develop more it is not my point here.

At the bottom of the page you can see a comment:

Unfortunately Patrick didn't get any answer from JustLend, i can say what happened:

All his TRX have been burned in a failed transaction, because smart contracts costs a lot of energy.

If you look here on the tronscan of JustLend JTRX contract, you will see that there are many failed transaction, due to lack of energy.

If you look closely at the characteristics of the contract, you will notice that the energy cost is 100% paid by the user.

The energy cost of the smart contract is very high ( 66271 here) and if dont have enough, an amount of your TRX ( 9.27794 here) will be burned for energy. That's not a good deal for this 70 TRX transaction. (Link)

If you don't have enough energy, nor enough TRX to burn for energy, the transaction will fail and your TRX will be burned trying to provide energy but failing, that's what happened to Patrick, here is an other example: ( 5 TRX lost for nothing)

So unless you have a lot of TRX frozen for energy, stay away from JustLend smart contracts, they will cost you more than you may earn.

It is a waste of energy and TRX.

I think JustLend should give more information on the energy or TRX cost of its smart contracts.

You can check here how many energy you can get by freezing or burning TRX: https://tronstation.io/calculator

You need 2200 TRX to be frozen for a 66.171 energy cost of a TRX lending smart contract on JustLend, and no transaction fee.

All the smart contract adresses of JustLend can be found here for the other altcoins (BTT, SUN ...) https://www.justlend.org/docs/justlend_api_en.pdf

You can paste them in https://tronscan.io/#/ to have more informations, check the energy ratio and see all transactions.

If you plan tu use https://justswap.io/ to convert tokens or https://just.tronscan.io/ to wrap TRX or BTT be aware that it will cost you a lot of energy too !