Low High Voltage Battery Coolant Level

My 2012 Chevrolet Volt had to go back in to add battery coolant (from what I remember, it limited battery use until refilled). The dealership searched for leaks and found none. I want to believe that this was about 2 years after purchase as well. They wrote it off as air in the system when the car was manufactured. I never had any more trouble with it after that. They covered it under normal warranty service (no fees to me). Have you examined where you park your car to see if you have any leak residue?

 

@jace,

Your post prompted me to go out and check on my levels. My Clarity is very similar to yours in age and miles, and the level is fine. Thus, I do not believe it is 'normal' to lose HV battery coolant.

Although you did not mention this, it is fairly difficult to check this level. They put the darned tank in an area that is quite inaccessible. According to the manual, you look through a "window" to see the min/max level markings on the plastic tank. This "window" is maybe 1" x 1", and is viewed from the top, under the hood. I found it impossible to see the level through this window without shining a trouble light through the grill in front to illuminate the tank. it was tricky to get this right in order to 'see' the fluid. I was looking through the window while maneuvering the light in front until it was clear that light was illuminating the bluish fluid. In order to be sure, I wound up jostling the car so I could actually see the fluid slosh a little.

I presume you experienced a similar thing? Having seen this, I need to ask the dumb question as to whether you are certain you really saw an 'empty' tank? I could see how you could easily be deceived by this crummy arrangement ! Do you park in a garage? If you did have a leak, it would likely have resulted in a visible puddle along the way...

In my opinion, it is very unlikely that there is a relationship between your fluid level and the 12V battery issue you have seen. This is puzzling because when sitting with the A/C running the 12V battery should be charged as required from the HV battery. I assume you had sufficient HV battery charge when this happened? The 12V battery should not drain under those circumstances.

I have no idea why Honda obviously does not want us to add fluid other than it would normally be associated with a leak which it is probably critical to get repaired. My suggestion would be to double-check yourself to be sure you are actually seeing an 'empty' tank. It so, then definitely take it to the dealer.

 

If you frequently charge in the same spot and haven’t observed a leak, the “false reading” theory may be accurate. The coolant will circulate while charging so a leak should be apparent.

It doesn’t specify in the manual “when” to check the fluid level. While charging? One hour after charging or operating the vehicle? I don’t know if it makes a difference. I’m currently separated from my Clarity. However, the image in the manual appears to show a fill cap next to the viewing glass. I’ll leave it to each individual to determine how trained or qualified one needs to be to remove that cap and add coolant. Perhaps someone who has downloaded a service manual can help out here.

Why was it necessary to replace the tires at 15 months and presumably less than 15K miles?

 

No... Take a look in-person when you get a chance. The viewing "window" is really closer to 1/2" x 1/2".
There is NO access to a fill-cap at all - it is totally inaccessible without disassembling a large plastic cover that goes over the whole front portion, connecting to the grill, and the air filter duct. This plastic piece is held in place with the plastic pop-fasteners. I took a few out just to explore and the cover was not coming loose. I broke one and then declared defeat since I really have no reason to go there right now. Seems like a poor design, and it could have been made intentionally inaccessible if they had good reason to prevent the owners from dealing with whatever this coolant is.

 

Just checked mine for first time ever out of curiosity. Indeed looking at tank thru the car’s grille it looks deceptively empty. But looking thru the little inspection window up top and shaking the car? Fluid can be seen sloshing at a visible high level and it is obvious the empty-looking tank is actually nearly full of fluid. As Mr Fixit says, it is not especially easy to check, but once you find the inspection point it takes 5 seconds to see it’s ok.

 

Thanks. I will.

The coolant is specified in the manual as Honda Long Life Antifreeze/Coolant Type 2, mixed 50/50 with distilled water. Same as the engine coolant.

Taking a shot in the dark, I’d say that the battery and inverter cooling systems operate at lower temperatures and pressures than the engine cooling system. Typically a lithium battery will not accept a charge if temps are above ~135F. And 1-2 psi would be sufficient to circulate the coolant. That said, the system would be unlikely to leak. This could explain why the reservoir is concealed.

It’s an attempt to make it foolproof. But as Groucho Marx once said, “It is impossible to design anything that is foolproof because fools are so ingenious.”

 

Not sure I agree with this... It is the same basic coolant, but here in the specs (page 567), it looks like the HV and Inverter coolant systems use the Type 2 undiluted, while the engine uses the 50/50 mix.

 

On page 492, where the inverter cooling system is covered, it says the coolant is a 50/50 mixture. Perhaps it is a 50/50 mix in the bottle. I haven’t seen the packaging. This would mean there is nothing to do but pour it in.

 

Page 490 is somewhat ambiguous to me. It specifically states that the engine coolant is 50/50 in the side bar.
Yes, the inverter and HV is [kind of] in the same section, but...

I would defer to the spec's on page 567 which seem clear that the engine is 50/50, and the inverter / HV is 100%

WAIT - You may be right...Page 488 states:
"This coolant is premixed with 50% antifreeze and 50% water. Do not add any
straight antifreeze or water"

Maybe it is all the same, 50/50 ?
Poorly written to be sure...

 

Agree. The engine coolant spec could be misinterpreted as the 50/50 coolant should be mixed 50/50 with distilled water. Yes there is a warning to not add anything with an exception for operating in temps below -31F.

I wonder if Honda would consider hiring a moderately fluent English speaker as a work at home proofreader for their manuals?

Does anyone know how to get an email response from Honda that isn’t AI generated?

 

I could only buy 50/50 diluted Honda Long Life Antifreeze/Coolant (Type 2) when I purchased some at my local Honda dealer after I purchased our Clarity in 2018(I like to keep the right fluids handy even if sometimes I do not think I will need them). I think that the 50/50 coolant goes in all three systems. It is easy to check the inverter coolant if one has a hygrometer. If no one else does this, I might give it a try.

LeoP

 

First, one needs to use a hydrometer (density of liquids) rather than an hygrometer (humidity of a gas, etc.) as I mentioned (mea culpa). Second, curiosity got the better of me and this morning I used my coolant hydrometer to measure the inverter coolant density. The coolant in the reservoir appears to be a 50/50 dilution. I will not make the effort to get at the traction battery coolant tank but I would assume that coolant to also be a 50/50 dilution.

LeoP

 

Nice job... Thanks for doing the test and reporting back on this. I think the evidence is clear that all three (engine coolant, inverter coolant, and HV battery coolant) simply use the Honda Long Life Antifeeeze/Coolant (Type 2) straight out of the bottle (and it is inherently a 50/50 mixture). I would prefer a concentrate, but only because you are essentially paying double the cost with the pre-mix. It seems they don't sell a concentrated version (at least, not the Honda brand).

Personally, as the OP was questioning, I would not hesitate to top off any of these coolants. The only caveat would be if there is evidence of a leak (either because you had to add a lot of coolant, or, if you see any telltale puddles where you park).

Hydrometer, Hygrometer, Thermometer, Barometer, Anemometer... whatever it takes !!!

 

I had no idea there was a separate coolant thank for the battery coolant.

I was only aware of this one, but apparently that’s just for the inverter coolant:



Just found the other one, and mine looks OK:



That's with a bright flashlight shining through the grill.

I'd say Honda kinda cheaped out on the design here. Should be easier to monitor and to add fluid when necessary,

As an aside, has anyone else found this site to occasionally be almost unusably slow and laggy when trying to post from an iPad running Safari? On mine, sometimes a lag of almost 5 seconds between keystrokes and them showing on the screen. I just gave up and came upstairs to post this on my Mac, where it runs just fine.

 

Yes, occasionally slow to post using an iPhone. The other bug I’ve experienced is that, occasionally, it won’t allow a sentence or two, to be selected and added as a quote. It’s either, quote the entire post or nothing at all.

 

My Mac is 8 years old and it does the delayed keystroke thing too. This site uses more resources than old computers have. I don't know why it has to be this way.

 

There is always the possibility of an internal leak in the battery pack. The Volt has a plug similar to a drain plug, to check for coolant laying in the battery pack.

 

I had noticed the same regarding the third coolant tank level, and made mention of it during a subsequent PM service. Honda's service advisor informed me that (allegedly) the coolant level has to be observed while meeting certain conditions (e.g., 15 minutes after engine shut-off, etc.) in order for the visual check to be representative and accurate, and that otherwise the systemic distribution of the gross coolant accounts for the seemingly deficient volume. I have no idea how much of this explanation is actually authentic, nor why none of this was mentioned in any of the vehicle documentation.

 

Having kept an eye on the coolant tank in question through the "eye hole"...I never noticed it change regardless of when it was checked. The Clarity I drive displayed a level below the "max" line but slightly above the "low" line every single time it was checked...before a drive, after a drive, 2 hours after a drive etc.etc.etc.

Suffice it to say...today, when I added some coolant to the tank clearly visible inside the engine bay (overflow tank I'm guessing)...the level of the coolant tank visible through the eye hole now reads to "max" fill line.

Only variable that has changed is temps are generally cooler by 5-10 degrees.

Could be totally a coincidence...dunno.

Go figure.

Hope this helps.