Midday figures suggested a turnout of just 38 percent to choose a new parliament, provincial assemblies and local councils, according to the elections management agency ANGE.
Election officials in the upmarket district where the president's family and ruling dignitaries live put voter apathy down to the "cold weather".
But opposition parties have urged Chad's eight million voters to shun the election, the results of which they say had been decided in advance.
They "have all stayed at home following our call, that is, the overwhelming majority," Succes Masra, leader of the opposition Transformers party, told AFP.
The boycott leaves the field open for candidates aligned with President Mahamat Idriss Deby Itno, who was brought to power by the military in 2021 and then legitimised in a presidential election in May that opposition candidates denounced as fraudulent.
"I urge all my compatriots on the electoral roll to come out and vote en masse," Deby posted on Facebook, alongside photos of himself casting his ballot on what he called a "historic day".
'Nothing's been done yet'
On Saturday, Masra had said: "The fabricated results are already in the computers."
Herve Natouingan, 28, a construction worker turned motorbike taxi driver due to a lack of job prospects, said it was "pointless" to cast a ballot because "there's no real voting in Chad".
Patrice Lumumba Deoumoundou, an unemployed 39-year-old, told AFP he had voted Sunday morning in the hope of "change across the board" -- more jobs, fewer price rises, "more justice" and "more equality".
"Nothing's been done yet," he said.
As in previous elections, soldiers, police officers and nomads voted on Saturday for logistical reasons.
Chad's election management agency said there had been "record" turnout, with more than 72 percent in the army and 54 percent among nomads.
"There is a lot at stake locally in these elections," it said.
"The nomads came to ask the people who will be elected tomorrow to improve their living conditions," said sheikh Djibrine Hassabakarim, one of the community's representatives.
He said climate change had made life hard for his community, killing livestock, triggering clashes with sedentary farmers and making it hard for them to feed their families.
Transition to democracy
Polling stations, which will remain open until 6:00 pm (1700 GMT), are being monitored by around 100 foreign election observers and representatives of political parties.
On Saturday evening, the opposition Democratic Party of the Chadian People (PDPT) said more than a thousand ballots intended for the sub-prefecture of Bongor had disappeared.
It called for "vigilance" to "thwart the fraud networks" it said had been set up by the ruling MPS party.
Voting is taking place against a backdrop of recurring attacks by the jihadist group Boko Haram in the Lake Chad region, the ending of a military accord with former colonial master France and accusations that Chad is interfering in the conflict ravaging neighbouring Sudan.
The government has presented the elections as the final stage in the transition to democracy.
Deby took power in 2021 after the death of his father, who had ruled the Sahel country for three decades.
