I bought a grid charger that does 350mA output and maxes out at 205v. As I understand the process, I was expecting the battery voltage to stop increasing somewhere between 185v - 195v and possibly oscillate a bit as individual cells reached their peak voltage. Instead the voltage just kept slowly climbing until it eventually hit 204v and the grid charger's output decreased to 300mA (I assume because it was close to max voltage). 204v would be 1.55v/cell I think!

My battery was replaced by Honda under the original drive-train warranty some 60k miles ago and is now a CA2 battery pack. It was really cold (-10F) while I was charging (if that matters). Has anyone experienced anything like this? Have I damaged my battery? Should I just try again on a warmer day?

Edit: I have a 2007 Honda Civic Hybrid

 

If you have a voltage concern, you should confirm it with alternate means.

Grid charging while very cold does cause higher voltage. In fact, I would completely discourage you from charging in those conditions unless you have no choice or use a small space heater to raise the interior temperature to above freezing.

Which charger did you buy?

 

The one from HybridAutomotive.com They had the most information on their website. I did confirm the voltage with my own digital multimeter. I didn't confirm the current.

Unfortunately I have a detached garage, so it pretty much follows the outdoor temps. So I guess I'll try with a space heater.

 

Good choice. NiMH doesn't charge for crap below freezing, and it can actually be damaged by even moderate charge rates. Once the cells warm up to about 50°F, they're good to go.

Low temp charging is also very inefficient.

At 75°F ambient, my HCH2 packs tend to peak around 195. I've had a few go over 200V, but just barely.

 

That seems to be working. With the space heater in the car the interior is holding about 65°F and the battery seems to have peaked at a stabile 186V.

 

That seems low. You're going to need at least 25 hours of charging following a discharge to ensure the battery is full.

 

I had discharged it a bit with a lightbulb between when I had charged it to 204 in the cold and when I charged it with the spaceheater yesterday. With the spaceheater I let it charge for 12hrs after it stabilized at 186v. It should be balanced now, right?

Prolong's instructions say 185v-189v is expected but I've seen you and others on the forum here often see higher. Kinda makes me wonder if I didn't cause the batteries to vent when I let it charge to 205v in the deep cold. ¯\_(ツ)_/¯ ... not much I can do about that now. But it's in the range Prolong expected, so maybe it's ok?

Before I got the charger the battery was frequently recalibrating and had little usable capacity. Earlier this month it got down to -20F and the car would only start if I forced it to use the 12v starter (by flipping the breaker or disconnecting the 12v battery for a few seconds so it forgot the IMA state of charge). We've never had trouble starting in the cold before.

 

If you're saying it held 186V for 12 hr, then yes, likely balanced.


Venting unlikely unless the battery was horribly deteriorated already to the point that the low charge rate of the HA unit is > 0.1C. Your pack would have a total capacity of < 50% rated for this to occur. Given your temps, I would be very surprised if that's the case.


The start behavior you describe is a bit odd. Did you try holding the key in the start position for 5 seconds? There is frequently a delay when the car is deciding to start off the 12V. I don't know the cutoff, but I think it's 0°F when the car will start off the 12V. Note that it's the battery temperature that matters. Car doesn't care what ambient temp is...


I recommend that you conduct 2X discharges to 106V. Use high wattage bulbs while pack is above 158V and 25-40W bulbs below that. Once you've switched to 25-40W bulbs AND the pack has dropped back below 158V, terminate charge after 7 hours (25W) or 5 hours (40W). I would wait until your temperatures are above freezing.

 

Hi Guys,
Apologies for a lame question here, but are there any grid chargers which can be bought of the shelf which do not require removal/disconnection of the IMA battery? Yes, this is a bit lazy, but I am not the most technical guy, and to have to remove the seats, and then 1 hour to try and unplug the battery (without frying myself on 180V!!!) is a bit of a hassle I would rather avoid if possible. So if there is a more "user-friendly" grid charger which could be fitted to allow for recharging with the IMA installed that would be great. Are the Prolong Chargers designed this way? https://hybridautomotive.com/collect...ant=5576553796
Thanks.

I also don't have a garage at my place, which is another slight complication...

 

You must access the battery to install the harness, but once the harness is installed, it's a "pop the trunk and plug it in affair". Their complete instructions are here:

https://hybridautomotive.com/pages/install

Judge the difficulty for yourself.

The HCH2 pack is one of the easiest hybrid batteries to replace. I can do a full swap in less than 20 minutes from park to drive away. There are a LOT of steps in the instructions, but they go very fast.