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Can the C-Max be used to jump start another vehicle?


Bill-N
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Good question.  When you push the start button on the C-Max, the battery voltage does jump up to 14+ volts.  But the question is how long does one really want to crank the other vehicle with the other vehicle's starter motor draw through the DC/DC converter.  The converter is cooled by the HV battery cooling fans.

 

From the workshop manual, the bold implies one can connect load to the battery terminals under the hood. -- "External customer loads must only be connected to the vehicle at the customer battery connection point. If an external customer load is connected at the negative battery post, the Battery Monitoring Sensor accuracy cannot be guaranteed. It is recommended that the Battery Monitoring Sensor pole clamp is not removed unless a battery replacement is required.Should the battery need to be isolated, this should be done by disconnecting the ground eyelet at the chassis ground."

 

Also, the DC/DC converter is protected by a 30 A high side fuse and can provide 145 A of low side power:  "The Direct Current/Direct Current (DC/DC) converter control module is protected by a 30 amp high voltage low current fuse located in the High Voltage Battery Junction Box. The Direct Current/Direct Current (DC/DC) converter control module steps the high-voltage down to a low-voltage (between 13 and 14.9 volts, depending on vehicle needs), providing power to the  vehicle low-voltage battery systems. Depending on the vehicle and environmental conditions, the Direct Current/Direct Current (DC/DC) converter control module is capable of  outputting as many as 145 amps to the 12-volt battery."

 

So, I don't see a problem but I'm not going to try unless it's an emergency. :) 

Edited by Plus 3 Golfer
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Good info from Plus 3. I'd add one additional thought: if you are going to jump start another vehicle with your C-Max, it might be best to use your battery to charge the other car battery, rather than using your battery to start the engine. We have plenty of juice available if delivered slowly, but not a great deal of cranking amps. So plug in the jumper cables and let the cars sit for a bit, rather than attempting immediately to start the 2nd engine.

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  • 4 months later...

I was able to jump start a my car with a bad battery to get it to the parts store to get a new one. I used my C-Max, just using the positive terminal that pokes out where a battery would normally be located. I could not see the battery per se because everything is sealed and tucked away on the compartment. Anyway, the trick was to keep the C-Max floored so that the ICE stayed on. After about 5 minutes it worked which is a long time but, that battery was d-e-a-d!

 

Long story short, it is possible and C-Max is fine.

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I was able to jump start a my car with a bad battery to get it to the parts store to get a new one. I used my C-Max, just using the positive terminal that pokes out where a battery would normally be located. I could not see the battery per se because everything is sealed and tucked away on the compartment. Anyway, the trick was to keep the C-Max floored so that the ICE stayed on. After about 5 minutes it worked which is a long time but, that battery was d-e-a-d!

 

Long story short, it is possible and C-Max is fine.

The battery is in the back by the High-Voltage battery.

 

Anyways, I jumped my Explorer, didn't require any flooring of the engine for me, but I wouldn't call it d-e-a-d either. :)

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  • 1 year later...

After reading a couple of horror stories from Prius owners getting the polarities wrong and frying very expensive computer modules, I won't do it unless it is a true emergency which I have yet to encounter.  I've told folks stranded in parking lots, "I have an electric car and have an extremely high voltage battery." which they understood as a no.  It's not the whole truth but it's not a lie either!   ;)    

 

Instead of jumping from our hybrid(s), I used a battery charger with a 10amp boost setting on our last ICE vehicle that had an occasional dead battery.

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The battery is in the back by the High-Voltage battery.

 

 

 

That's true, but there are positive and negative terminals under the hood in front of the driver.  They are probably just linked to the starting battery with 0 gauge wires. 

 

EDIT:  while washing the car last weekend I noticed the said wires are fairly thin--probably 6 gauge at most.

Edited by Adrian_L
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That's true, but there are positive and negative terminals under the hood in front of the driver.  They are probably just linked to the starting battery with 0 gauge wires. 

 

Maybe this question answers a bigger question.

 

Why does Ford use a "Starting" battery,which it doesn't need, in the Cmax?

CMAX uses 12v batt. to get the electronics and computers going and HVB to start the car. If you can't get electronics going you can't start the car, that is why it only needs that small 12v batt. to get the ICE going. :)

 

Paul

Edited by ptjones
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Maybe this question answers a bigger question.

 

Why does Ford use a "Starting" battery,which it doesn't need, in the Cmax?

 

 

CMAX uses 12v batt. to get the electronics and computers going and HVB to start the car. If you can't get electronics going you can't start the car, that is why it only that small 12v batt. to get the ICE going. :)

 

Paul

 

My point exactly, why not use a "Deep Cycle" 12v, it would go A LONG WAY in hiding the DEAD 12V problem.

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My point exactly, why not use a "Deep Cycle" 12v, it would go A LONG WAY in hiding the DEAD 12V problem.

Don't need a deep cycle battery if everything is working as it should,  mine has had no battery problems in almost 2 years since new.

Let's not cover up the real problem with a bigger battery, instead find the culprit that is drawing excessive power and fix the problem.

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The 12V battery in the Volt is an AGM battery, not sure if it's deep cycle or not. I noted it is rated at 60Ah which is quite a bit higher than in our cars.

 

Volt_12v_Battery.jpg

 

That picture was actually posted in a Tesla forum as they have to replace their 12V batteries often as well. In their case it's because the computers take a lot of power and are left on all the time, so periodically during the day it will recharge the 12V battery from the HV battery, resulting in many charge-discharge cycles.

 

In our case it appears the problem is normally that although the computers in ours are supposed to shut down into a very low power state - sometimes they don't.

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My point exactly, why not use a "Deep Cycle" 12v, it would go A LONG WAY in hiding the DEAD 12V problem.

I posted a thread" Possible Solution for Dead Battery Problem"   where I showed how to add another small 12v battery to storage compartment to increase 12v battery capacity by half again to minimize the possible dead battery problem. I tried find a larger battery for CMAX but couldn't find one that would fit.

 

Don't need a deep cycle battery if everything is working as it should,  mine has had no battery problems in almost 2 years since new.

Let's not cover up the real problem with a bigger battery, instead find the culprit that is drawing excessive power and fix the problem.

I agree this doesn't solve all cases or root  problem for some people but might help until FORD finds all the possible problems. :)

 

Paul

Edited by ptjones
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The owners manual is mum on this point.  Anyone tried it?  Any gotcha's?

 

My sense is that if it were not OK, there would be warning messages at the terminals of the battery and the engine compartment and in the manual and it would be fuel for bad reviews by reporters, not to mention source of warranty service and potential loss of customer good will.

Edited by obob
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I posted a thread" Possible Solution for Dead Battery Problem"   where I showed how to add another small 12v battery to storage compartment to increase 12v battery capacity by half again to minimize the possible dead battery problem. I tried find a larger battery for CMAX but couldn't find one that would fit.

 

I agree this doesn't solve all cases or root  problem for some people but might help until FORD finds all the possible problems. :)

 

Paul

It's possible Ford already found and fixed the problem by dumping Microsoft, doesn't help those with current cars though.

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Don't need a deep cycle battery if everything is working as it should,  mine has had no battery problems in almost 2 years since new.

Let's not cover up the real problem with a bigger battery, instead find the culprit that is drawing excessive power and fix the problem.

 

Yeah, and warranties and insurance are both a complete waste of money if everything is as it should be.

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Yeah, and warranties and insurance are both a complete waste of money if everything is as it should be.

Ok, but I won't comment on that since that is not the topic. I hope folks with persistent battery problems will search for a dealership with technical experts interested in getting to the root cause and not give up on getting their problem fixed.
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My sense is that if it were not OK, there would be warning messages at the terminals of the battery and the engine compartment and in the manual and it would be fuel for bad reviews by reporters, not to mention source of warranty service and potential loss of customer good will.

Agree.

 

I've jumped my Nissan with my C-Max using the under hood terminals - just used normal jump starting procedures except C-Max was put in "ready to drive" mode (ICE not running).  No issues. 

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