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Greetings. First post and am adding a link to a YouTube segment that I believe is the lead designer of the Bolt electrical system doing a walk through of the disassembled vehicle. Starting around the nine-minute mark the videographer asks why a lead-acid and not lithium, and the response is basically cost savings (the Bolt is manufactured at total loss already based from GM interviews and explanation of offsets for other products). My information is that the Bolt will run continuous 1600 watts from the 12v system with a pure sine inverter off the 12v battery terminals (fed by the main system battery), and that the only reason lithium is not factory installed is cost. I have a Westfalia that I outfitted with lithium phosphate batteries, and the cost in Canada retail from my auto-parts supplier came in much less than half the cost of USA sources as it turns out the premium batteries I purchased are manufactured in Quebec and distributed worldwide from there. My issue is where to locate the inverter in the vehicle. I have removed all the rear seats and interior from my Bolt and have an ongoing project that will get posted in due course. Meanwhile, have a look at the YouTube video:

 

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I'd say "cost" is a pretty safe catchall for the reason why anything better isn't implemented. It has to be better at a price. A lithium ion 12v battery would require environmental regulation just like the traction battery, otherwise it would quickly degrade (possibly instantly in certain conditions).

I found it cheaper to replace my Prius battery with LiFePO4, but that's because it's half the capacity of the 12v it replaces, and doesn't require extra environmental regulation since it lives inside the cabin rather than under the hood. It isn't the solution for everyone, but a lead acid battery is.

I am new to these forums, so forgive me if I ask undeveloped questions. In context, I use my Bolt as a commercial vehicle and "cost" is not an issue for me at this point as it may have been for GM in the final build as per the engineer. I run my entire company off solar, and the Bolt is being adapted to replenish my batteries on site for cost savings. My tool batteries run $400 each, and I use up ten batteries per day already, and rather than purchase another ten batteries I am looking to continuosly charge them in the Bolt while the others are in use. My understanding from this thread is that lead batteries are an impediment to optimal transfer of energy relative to equivalent lithium, so if the engineer says that the only barrier is cost and that one could install lithium to improve the performance of the vehicle as a power supply, how does this relate to a Prius in the context of a lithium battery that already has regulatory approval in my jurisdiction for standard motor vehicle use?

 

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What sort of tool batteries are you using that cost $400, and do they even charge off of vehicle 12v power? (Very few tool manufacturers offer 12v chargers... But most also don't have batteries that cost more than $200 either...)

Lithium is better if you're routinely charging and discharging the battery, but that's not how most use cases for the Bolt's 12v battery work. If you're putting significantl loads on it, you want the DCDC power supply to be running (e.g. car is "on").

A potential issue with LiFePO4 in the Bolt as a replacement for the 12v battery is that the original Bolt battery is AGM and not wet-cell. AGM batteries typically have a somewhat higher float voltage than wet-cell, and I've seen that the Bolt's electrical system does seem to run a bit "hot" with voltages as high as 15v reported via OBD (haven't looked with a DMM yet...)

But for your use case, you want the car to be "on" and at that point, it doesn't matter much what's installed in the car.

Entropy512: please watch the video I provided in my original post as I believe the engineer who designed the Bolt system is likely correct in the figures that he presents, and also the assessment of using the Bolt main battery (which the video is really about) for continuous power is in fact practical though NOT officially recommended, and is designed to run at 1600 watts continuous; I see no reason for him to be misrepresent the data. This thread was started with the question about longterm energy use of the heavier lead batteries, and asks how much savings there might be over a period of ownership using the lighter lithium battery. The replies seem to go on to the various limitations of this and that and I thought it might be useful to have the link to the video with the engineer to resolve some of the questions that have arisen in the replies. The 12v battery is not discharged, the main Bolt battery is what is being discharged, and I am clearly not meant to be here and apologize for confusing the thread with my tangent. I had hoped that someone with a Bolt had installed an inverter, and that they might speak to the actual continuous wattage supplied by the lithium versus the lead as the engineering articles I might have misunderstood suggest the exact opposite of how I understand you determination that lead is more efficient and would likely supply the higher continuous wattage (from the main Bolt battery) approaching the theoretical 1600 watts the system designer refers to. As a bonus to having increased efficiency in the current flowing through the lithium battery, I believed the original post had a valuable point in weight reductions as I often operate near the vehicle limit. Not that it is relevant to this discussion whatsoever, but the batteries I primarily use are the Husqvarna BLi 300c and they may appear much less expensive wherever it is that you live, but in my currency in Canada they retail for $449.99 each and I have a fleet discount and tax roll that allows for a reduced cost relative to list. I do also use the Dewalt DCB606 and this is not so much an issue because only the portable compressor eats up power, and they receive light use otherwise.

 

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The video is the person who designed the system himself, with the car completely apart and giving the system specifications and tolerances, how could that possibly be a waste of your time compared to getting your information from here? Once again my time is wasted and I apologize for attempting to participate in another hostile forum environment.

 

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I own a 2017 premier and I can tell you that I used the referenced video as guidance. Got a Xantrex PROwatt SW 2000 watt inverter and connected it to the 12 Bolt battery. I posted this on another thread sometime back. As I recall the Bolts 12v battery couldn't handle much a load for any period of time if the Bolt was not running. Knowing from the video that 1600 watt max can be pulled I limited the AC load to 1500 watts and could run my refrigerator with no issue. I used a Kilowatt meter to make sure I didn't pull more than 1500 watts from the Bolt. So empirically I I know it can be done cause I did it . But know I didn't max it out, didn't want to take any chances.

Thank-you for the relevant information on my area of query, and appreciate the input from a member who has invested their own money and time to test this theoretical installation I am considering. The referenced video was the closest thing to actual fact that I have found until now, and I will look to the Xantrex product you have experience with. Many thanks again for giving me useful direction based on facts and direct experience.

 

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It doesn't matter who the person is, YouTube videos are a fundamentally inefficient form of communicating technical data.

Since I couldn't sleep and woke up early, I figured I'd indulge you by watching that video, which would normally take 1/4-1/3 of my entire morning time budget for "personal spare time" (emails, forums, etc.). I sometimes get more time during the day to check a forum while waiting for a compile job, but YouTube is a no-go there, same for during lunch breaks because mobile data pricing sucks.

The content first 4 minutes of the video could be read in less than a minute with a properly written spec sheet or technical article. In fact, there was an Electrek article in the past that covered the Bolt's battery. 288 prismatic cells in a 96S3P configuration, yadda yadda, nothing new in the video that isn't already known.

The only information given regarding the 12v system is a lead-acid battery (already known) and a 125 amp DCDC (already known).

For the purposes of this discussion, there are two key specifications:
1) 125A - this is the maximum capacity of the DCDC. This was covered in the video (given as wattage, but 125A at that output voltage is about 1600W) - and as we already established, this was a known specification without needing to spend 11 minutes watching a video with 1-2 minutes of content.
2) 50 Amp-hours - this is the capacity of the AGM battery, which isn't even covered in the video! (but already known from other sources)

Let's say you want to draw 50A from the system.
If the car is off, you'll flatten that battery in an hour. Do it more than a few times and it'll be sulfated
A LiFePO4 won't sulfate, but it's gonna cost you $575 just to match the capacity

In short, you NEED the car to be turned on and the DCDC active for your application. The built in battery type or capacity just doesn't matter at that point.

As far as how much inverter you can put on the system, people have been putting 1500W continuous-rated inverters on, but keep in mind those were for emergency power systems used rarely, not daily like you seem to be intending.

The DCDC's power budget is 125A (1600W) and you need to take into account that the same requirements for turning on the DCDC also mean that the vehicle is going to be using 12v power to run various things (like the infotainment system, etc.) - I'm not sure if this wattage can be seen by OBD, but it's likely to push the total power budget beyond the capabilities of the DCDC.

The DCDC isn't going to fail hard in this scenario, but it'll go into soft current limiting and the excess power will be drawn from the battery (as I've said multiple times before, its primary purpose is to absorb transients to make the DCDC's job easier, and to make power sequencing a bit easier for the engineers before the DCDC is active. Running a DCDC at very low loads is inefficient, so it likely winds up actually more efficient to periodically light it up to recharge the 12v battery than to leave it active at very low load.)

For a daily usage application like yours, I'd be careful about exceeding 750-1000W continuous load.

If you want more than this off of the 12v system you'll need to figure out how to make the Bolt's control electronics happy with the DCDC from a Volt, which is rated 165A.

One important question would be: Is the DCDC active in accessory mode? In a normal car, this is served by the alternator, which won't work if the engine isn't spinning. In an EV, it could be active in accessory mode, but is it? Oh yeah... That fairly important/useful piece of info isn't covered in the video either.

I am sure you are an interesting person. The link originally provided starts at 9:08, and the video is 11:37 in total length, and I stopped reading when you talked about the "first four minutes" as the math does not add up. I do not have the time to continue with this relationship as I run two businesses, have dependants, and have already gathered the information from the other good members here who stayed on point and answered my query directly (Thank-you!). I wish you well with your exploration, and recommend you stick to "indulging" yourself rather than look for empathy on forums. To help you, I will abandon this forum so that you can have the experience you are hoping for with others who write and read more efficiently than myself, and are less likely to cause you bouts of indulgence than my meagre contribution seems to have.