GM Volt Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
As the battery nears full charge the amp draw decrease. When the draw reaches a certain minimum the battery is declared "full".

Does anyone know of a curve of %full vs Amp Draw.

Reason I ask is at work 2 of us charge on a 110V, 20AMP (presumably, the breaker is not accessible to me). One day we tripped the breaker soon after plugging in. I was on 12A and we believe she was on 8, equaling 20A and I believe we both had empty batteries. From that point forward we both only charge at 8A.

Say my battery is half full and I charge at 12A, would I really be only drawing 11A. Or when I'm 90% full am I only really drawing 2A?

Thanks
 

·
Moderator
Joined
·
8,680 Posts
The Volt doesn't charge very fast or very close to the top, so I don't believe you'll ever see a curve, aside from a little bit of cell balancing at the top where it keeps pulling a little power after reaching the target percentage.

Even Tesla barely shows one on AC power - when pulling 80A/20kw, they show a taper from about 96% on up if I remember right.
 

·
Registered
Joined
·
5,782 Posts
A 20amp breaker will pop if the continuous load is > 18amp.

I haven't seen much taper (although I don't pay that much attention) with either '13 Volt or '14 ELR. I seriously doubt it falls to 2amps at any point. However, voltage has a large effect. I gain 1/2 hour @248v vs 228v.

Maybe it would be better to try serial charging at 12amps. Whoever gets there first charges for 4 hours and then the other at 4 hours.

I'm sure that some engineer on this site has tracked taper. Might be difficult to find though.

edit: here is an early thread discussing 240v taper.
http://gm-volt.com/forum/showthread.php?6816-Has-anyone-actually-monitored-a-full-recharge-using-the-240v-Voltec/page3
 

·
Moderator
Joined
·
4,851 Posts
Here's a charging profile report for the 2013 Volt:
https://avt.inl.gov/sites/default/files/pdf/phev/2013ChevoletVoltChargingReport.pdf

There are similar ones for other makes/models.

In the past I linked to several EVSE's that were tested in a similar manner. They usually used a Volt as the vehicle to test the EVSE's.

The site was very insightful because it also provided standby power draws. SInce the EVSE is powered 24/7, this can be a non-trivial amount of electricity usage, in addition to the efficiency of the EVSE during charging.

EDIT: I found the EVSE testing data! It's actually the same site, haha.

https://avt.inl.gov/evse-type/all-evse-types

Here's an example of the old 240V Voltec EVSE charging a Volt. This EVSE has one of the lower power consumptions when not actively charging a vehicle, between 2-3W:
https://avt.inl.gov/sites/default/files/pdf/evse/EVSEVoltec.pdf

It shows a nice zoom in of the taper at the end on a 2011 Volt.
 

·
Registered
Joined
·
1,992 Posts
Does anyone know of a curve of %full vs Amp Draw.
With the data I collected, the amp draw is at its maximum until the last ~20 minutes of the charge as it balances the cells and runs cooling system. During that time it ramps down and fluctuates a bit depending on the need.


From that point forward we both only charge at 8A.
On a 20A circuit you both should only charge at 8A each.

Say my battery is half full and I charge at 12A, would I really be only drawing 11A. Or when I'm 90% full am I only really drawing 2A?
As mentioned, it will draw at the maximum of the EVSE throughout the charge cycle. However, that maximum may also fluctuate a bit depending on the available voltage. And as mentioned it will drop during the last ~20 minutes of the charge cycle.
 

·
Registered
Joined
·
5,782 Posts

·
Registered
Joined
·
3,945 Posts
With the data I collected, the amp draw is at its maximum until the last ~20 minutes of the charge as it balances the cells and runs cooling system. During that time it ramps down and fluctuates a bit depending on the need.
Which make sense, because the Voltec system never has to deal with a fully charged battery or a nearly-empty one. All the tapering that charge curves normally seem to address is out in the last 5-10% at the ends.
 
1 - 8 of 8 Posts
Top