INDIANAPOLIS — The IndyGo electric buses are already showing signs of trouble as the temperatures plunge. It's a problem Call 6 Investigates first exposed in March, and now it's happening.

Once the temperatures took a dip below 50 degrees, the electric buses began having problems holding a charge.

The city's Red Line system is under pressure to keep its promised schedule of buses showing up on time. It's a challenge as Indy's weather is getting colder.

In the past two weeks, as the thermometer hit 50 degrees and below buses which left the garage fully charged fell victim to the cold.

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Their 'SOC,' which stands for 'State of Charge,' became too low to complete their route, and they were pulled out of service to be recharged.

The buses are manufactured by China-based 'BYD,' which stands for 'Build Your Dreams.' Other cities have returned BYD buses, and yet IndyGo seemed committed to the bus manufacturer company.

"At the end of the day, we have a contract," Bryan Luellen, IndyGos VP of Public Affairs, said. "They have promised to deliver a solution that will work for our application. If we were to make a decision to send those buses back, that means we would have to stop at Red Line service. And we are committed to providing Red Line service, and the company is committed to holding their part of the deal in the contract."

Call 6 Investigates obtained information which shows at least nine buses unable to keep a full battery charge since November 1, and requiring replacements to take their place on the Red Line:

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IndyGo says its been aware that this was going to happen.

That's why the bus manufacturer BYD is offering to install two charging stations to help address the problem.

IndyGo says BYD will spend $4 million on that project at no cost to taxpayers.

"So, each time the bus reaches this en-route charging station at the end of the road, it will charge for about ten minutes, and that will basically allow that bus to operate and definitely out there on the road for up to 15 hours, potentially," Luellen said.

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The new charging stations are expected to be installed in January, which on average, is the coldest month in Indiana.

"We're not going to pay a discounted price, but each of these buses out there in the marketplace, this is new technology," Luellen said.

"As the technology continues to evolve and we look at placing our next order, we will make some tough calls," Luellen said. "We will have to look at whether we exercise existing options with BYD or whether we go out to bid (and) have another manufacturer provide these vehicles."

Each one of the Red Line buses is $1.2 million.

IndyGo is waiting for the buses to pass federal inspection before paying the bill.

IndyGo submitted the following statement to Call 6: