How to start the engine when the main battery is out of charge?

if it is the hybrid battery, (which i'm not sure you've diagnosed correctly) you have to go to the dealer to use their special charger. or buy the one in the priuschat shoppe for $400.

 

Do not try to start it more than a handful of times, otherwise it will drain the Hybrid Battery too low.

Charging the hybrid battery will involve a bit of dismantling the car to access the hybrid battery terminals.

Do you feel you have the skills for that work?
If not you'll want to find a mechanic who you can hire to do the work.

 

ericbecky, your advice is great but you did not continue on with what the poster can do once the terminals are accessed. I am assuming that there is some action to take regarding a charging process.

I too am curious as it may be helpful to me also.

 

Your battery is about 280 volts dc. It can kill you deader than hell. If you have electrical experience, great. If not, you may want to find another solution. Do you know how or do you have the equipment to charge a 280 volt battery?

 

If dashboard dies - your 12V battery is flat, you have 2 options: replace it or connect 12V battery charger for at least 2h or until you get about 12V on battery terminals, then (still with charger connected) start the car again, if you don't get "ready" indicator shut it down and call toyota you need charge the traction battery.
Just realized it is necromanced post from 2016, Bruce, stop digging that deep.

 

I was thinking if a battery sat around long enough and discharged, it might be possible to take off the cover and use a trickle charger on motorcycle mode to charge one module at a time, or in car mode to charge them in pairs. This would take days to get all 38 modules charged, and they would need to be balanced at the same voltage before connecting to the car. In theory it should work, has anyone tried this?

 

It is possible but not safe for someone not familiar with high voltage. For this exact purpose I have primitive charger made of diode, capacitor, light bulb, crocodile clips on one end and mains plug on other, luckily UK and EU mains voltage is just right for this purpose. Used it once when throttle body issue prevented engine from start so in result HV battery went too low, then twice to rebalance the battery, charging current is limited by bulb to less than 0.2A.

 

Basically to is have two options.

Use a special high voltage charger (like one from Hybrid Automotive) to charge the entire battery up at once.

They have clear guides how to install, and use the battery.

That would likely be the easiest and best documented, and take the least time.

Second option would be to dismantle the battery even further to charge each of 26 sections one at time. Assuming each section takes half a day, it could take a while.

 

This 5 years old topic is about gen 1, 38 modules, using cheap imax B6 clone charger you can charge 2 at once, depend on charger setting it would take 2 - 6h per pair, *19 pairs makes 38 - 114 h, practically 3 to 8 days. In my experience it is weekend job.

 

I've never done this.

I wonder if a "6 volt" or "12 volt" automotive charger would be able to get a useful amount of charge into the modules. I know the charger output voltage is higher than the nominal voltage, but I'm not sure how much higher. Each traction battery module is 7.2 V nominal; two in series would be 14.4 V. Obviously, if the traction battery is very discharged, the modules will be lower than that, which would give the charger a better chance of success. You also don't have to charge the modules back up all the way - just enough to start the car.

If I tried this, I would strongly, strongly consider disconnecting all the bus bars on one side of the traction battery pack. That way, you have 19 separate 14.4 v batteries, instead of two separate 136.8 V batteries - much less chance for excitement if something goes wrong. I would also strongly consider plugging the charger into something like an electromechanical lamp timer, instead of directly into the wall. The lamp timer would be set to shut the charger off after a couple of hours, so you could check the module voltage and manually restart the charging if needed; it's kind of a "watchdog" against overcharging the modules.

Motorcycle shops have 12-volt chargers with multiple independent outputs, like 4 or 6. They probably aren't designed to deal with anything other than independent batteries, so you'd definitely want to pull half the bus bars from the Prius traction battery to turn it into 19 independent batteries. If you don't already own or work at the motorcycle shop, it's probably cheaper to buy a "proper" high-voltage charger, though.

The fun thing is that the factory Gen1 pack has an unused connector on it, which is probably for exactly this purpose - bench charging with a high-voltage charger. I think the last time anybody looked, it wasn't possible for humans to buy the mating connector for it in quantity one, so you have to open up the pack if you want to use a commercial high-voltage charger. (I will strip wires and jam them into the socket for some things, but not for something like this that can deliver 27 kilowatts.)

 

Even don't think about it. Car chargers are designed for high capacity lead acid battery chemistry, it is totally different than just 6.5Ah NiMh. Usually car chargers don't have voltage or current regulation, it rely on properly designed transformer itself. Usually their max is around 15V which is safe for 2 packs but current can be deadly outside 40-80% SOC.