A couple days ago I got a GX CS2. I bought it from GX and used their 10% off code to get it for about $250. I like filling from my bottle which I fill using my Yong Heng. But it won't last forever and isn't very portable. I've taken the bottle to the range but it's pretty big. Anyway, I am not sure exactly what I will do with this so I got the normal CS2 to have 120V and vehicle power to use it. But I also wanted to be able to power it with my 18V Milwaukee tool batteries. So I bought a 18 to 12 V 240W step down converter from Amazon with a Milwaukee battery dock. I was a little worried it was only 240W but I done a dead head test and filled a gun with it and it seems to work fine. I thought about integrating it with the CS2 but decided, at least for now, to just have this little power unit I can clip to and use without modifying the compressor.
Battery power for my GX CS2
- Thread starter JimD
- Start date
Does the battery adapter have a low voltage cutoff built in to protect your batteries? If it doesn't I highly recommend at least one of the watt meters for rc to monitor your overall battery voltage(it will also show you current draw and Ah used) you can even calculate how many fills per battery so you can plan to bring more batts if you have as many as i do.
The way the Milwaukee battery monitoring circuit works it will show a full charge being 3 bars when you over draw or hurt a cell (first and last cells in series get measured 2 times iirc there's a whole writeup about the design flaw online)
I built a 50ah lifepo4 battery in a 50 cal ammo can with xt60 connectors on the face to run my pellet grills, portable fridge or compressor and it's been pretty rad, also cost less than a 6.0 m18. The large capacity m12 and m18 have treated me so bad in daily use that I switched to yellow for 18v and retired an impact price tag worth of tools.
Tldr; watch your level of discharge to save money
. Nice to see a fellow traveler with "the knack" keep up the great work and I look forward to hearing how you like it!
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After building an m18, and a 20v dewilt (18v) like yours I went a little harder. 13.6v charged 12.0 discharged
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Thanks for the suggestions. I've been using a 6 ah battery and two gun fills only dropped it to three bars. But the battery level indicator started flashing so I'm not sure if it doesn't like this load or if it might not have been in great shape. I'll try a different battery, probably a 8 amp hour. I plan to recharge the battery well before it gets fully depleted - does that address your under voltage concern? The first battery was at 18.9 volts when it started flashing which seems to be about right for 3 bars. I charged it back up to full which is over 20V (which may be why DeWalt calls theirs 20V). The compressor seems to run fine on the battery. I did a dead head test with 120V and with the battery before charging a gun and they took the same amount of time (about 25 seconds).
I have a big Milwaukee battery pack that supplies 120V and will run the Yong Heng and all it's extras. But it weighs 50 lbs and would just further make transporting the YH a challenge. The little CS2 with even a big 18V battery would still be less than 20 lbs.
I have a big Milwaukee battery pack that supplies 120V and will run the Yong Heng and all it's extras. But it weighs 50 lbs and would just further make transporting the YH a challenge. The little CS2 with even a big 18V battery would still be less than 20 lbs.
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The blinking usually means an over current situation which goes in a counter intuitive direction. My experiences have been that the highest capacity batteries don't like to be drawn too hard for current. The two near instant failures I had in factory tools was the 8.0 m18 and 6.0.m12. It gets into the nuance of lithium ion cells and how they like to be worked. Typically but not always, lower capacity batteries are more tolerant of regular high current draw.
A workaround for your current issue could be another battery adapter and feeding your voltage converter with 2 batts in parallel.
My next concern is the bms circuit and how it works, this I can't speak definitively on, but i think that the tool and battery "talk" back and forth on what the battery can deliver and what the tool can demand. I can't recall if it's red or yellow, high or low voltage that has the issue. Esc to bms talk COULD be the low voltage cuttof recipe that I was preaching an abundance of caution about.
Charging them straight away is a good idea, the lvc is just there to prevent you from bricking the battery and having to do a sketchy "bump charge" to bring it back up to a voltage that a normal charger will allow it to proceed as normal. I do, and will do these things but stressing lithium cells can lead to a very energetic failure and losing the money for those pricey batteries or burning down other things. I haven't seen lion outside of ev applications do it or lifepo4 yet, but I've burned down a handful of lipo batteries. (like what dewalt just put on their power stack batts).
I dig what you're doing here I just wanted to pass along some of the costly errors I've made over the years. Like jumping my truck with one and bricking a 4.0 battery.
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I filled my Avenger from zero to about 4100 psi using the 8 amp hr battery. I stopped before 300 bar because the compressor seemed to slow down slightly. It is still testing at 19.65 V so it is not badly discharged, should show 3 bars, but if I push the check battery button it flashes instead of showing bars. I ran the fan of the compressor 5 minutes after shutting it off and the fan sounded normal. It's a high load but so is my big hammer drill. I don't remember trying to check the charge status after using the hammer drill. Wouldn't normally use the drill for 8 minutes straight either.
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I tried filling with my P35-22 still in the rest this morning. The little CS2 and battery are so compact nothing had to move. Voltage after the fill was 18.94. From what I read a low 18V battery is 15V. Under voltage protection kicks in at about 12.5V. I ordered a volt meter so I can monitor the battery. I plan to recharge when the battery is at 18V. Right now I'm using a multimeter but the gauge will simplify checking it. Seems like that will give me about 6 gun fills. It's a nice flexibility to just move the compressor to the gun. I may use this more than I thought.
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Hopefully, it's not to late to add a comment?
It could be worthwhile to monitor the battery voltage while the compressor is running. That will warn that the draw is too great for the battery to sustain.
That applies to virtually any type of battery. I use that as a warning that the draw (current flow is too high) not that the draw is safe for the battery.
How has your project progressed?
It could be worthwhile to monitor the battery voltage while the compressor is running. That will warn that the draw is too great for the battery to sustain.
That applies to virtually any type of battery. I use that as a warning that the draw (current flow is too high) not that the draw is safe for the battery.
How has your project progressed?
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I actually added an inexpensive digital volt meter and have used the compressor a few times since. My batteries start out at over 20 volts before I turn on the compressor. Even the fans drop voltage a little. But the whole load only reduces voltage about 1.5 volts. I look at the voltage when I turn the compressor off and if it is under 18V I recharge the battery. That seems to give me 6 or 7 refills on a 8 amp hour battery. I used a 6 amp hour on the last run and it didn't seem to respond much different. When I put the 8 amp hour on the charger it still showed 2 bars so it was not overly depleted. It had refilled my Avenger from zero to close to 300 bar and refilled P35s 4 times. I will recharge guns a few more times on a 6 amp hour and probably then go back to using my 6.8 liter bottle. I have been a little surprised that the ~3 minute gun refill time doesn't seem very long. Bottle is faster but the CS2 is so small it can sit closer to where I park the airguns so I don't have to do anything to get in position to refill and that pretty much offsets the bottle's speed advantage. I do not trust the auto shut off on inexpensive compressors anyway so not having one is no problem on the CS2. It is a very viable "only" compressor in my mind, especially if set up for 120V, car power, and battery power.
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What is the battery voltage while the compressor is running? I am wondering how much that load pulls down the battery voltage. How do your other batteries compare, i.e. 6-amp-hour versus 8-amp-hour?
I also find it more convenient to use the compressor than a bottle/tank. One positive for the compressor is that unlike the bottle/tank, it doesn't require refilling when returned home.
While the tank can be a bit faster to fill, one has to be more watchful while filling to avoid over filling. My compressors have automatic shut-off.
I am also concerned about potential diesel ignition if a tank valve is opened too rapidly. People often misunderstand this effect as ignition of oil and other materials because of high pressure.
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The battery voltage drops about 1.5V when the compressor is running. I've only done a couple gun fills with the 6 amp hour so I don't know how many it will do yet. I think the GX battery powered comes with a 5 amp hr. My research indicated 18 V batteries sometimes are allowed to go as low as 12 or 13V so I am stopping mine well short of that. The only thing that is a little goofy is the battery charge indicator won't work plugged into the converter. I don't think it's hurting the battery but this load seems to affect the charge indicator.
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Don't they sell the CS2 equivalent in a battery operated version? I wonder how that works compared to the CS2.
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Yes, GX has a battery powered version. On Amazon (not the cheapest place to buy it) the battery powered model is $60 higher. It also uses a Makita battery. I have half a dozen or more 18V Milwaukee batteries and no Makita. I also wanted to retain the option to use 120V and a vehicle to run the compressor. Nothing wrong with the battery version that I know of, I just saw some reasons to go a different way. It cost me about $30 to get the battery dock, step down converter, and voltmeter. So a little cheaper but not a lot. Main advantage as I see it is the versatility. Another option I considered was getting the GX battery powered version and a battery converter so I could plug in my Milwaukee batteries. Lots of ways to do this.
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I think I've used the 6 amp hour for 3 refills of one of my P35s and it's voltage while not connected to a load is still over 18V but under 19V so I plan to use it one more time - but I think one more refill will drive it below 18V resting. I'll also keep an eye on running voltage which I'd like to keep above 15V.
I think I understand better why the charge indication bars do not work when using a milwaukee battery to the drop down converter and compressor. Milwaukee has used a proprietary technology in their battery protection system for around 10 years. I think it is called red lithium technology. They advertise that it is tools and batteries communicating but there are other views of what is occurring. But it is part of the battery protection technology and is not expected to work when the battery is not connected to a non Milwaukee tool. So no charge bars. My monitoring of voltage takes the place of that protection technology (at least in my mind) so I plan to keep on using my Milwaukee batteries. The 8 amp hour recharged fine and I think this 6 amp hour will too. But from what I read DeWalt and Makita 18V batteries do not have a similar circuit. So they may be better batteries to use in this application (and the GX is reportedly using a Makita battery). I think the same thing would happen if I put one of my Milwaukee batteries into a converter so it could be plugged into the GX battery powered compressor. The tool works but there is reason to be concerned the battery protection may not work.
I may reduce my use of the battery power for my GX soon not because I am not confident in it but just because I'm shooting from home and my bottle or the 120V power supply for the GX are both available. But if I have any issues I will update this thread or otherwise make it known.
I think I understand better why the charge indication bars do not work when using a milwaukee battery to the drop down converter and compressor. Milwaukee has used a proprietary technology in their battery protection system for around 10 years. I think it is called red lithium technology. They advertise that it is tools and batteries communicating but there are other views of what is occurring. But it is part of the battery protection technology and is not expected to work when the battery is not connected to a non Milwaukee tool. So no charge bars. My monitoring of voltage takes the place of that protection technology (at least in my mind) so I plan to keep on using my Milwaukee batteries. The 8 amp hour recharged fine and I think this 6 amp hour will too. But from what I read DeWalt and Makita 18V batteries do not have a similar circuit. So they may be better batteries to use in this application (and the GX is reportedly using a Makita battery). I think the same thing would happen if I put one of my Milwaukee batteries into a converter so it could be plugged into the GX battery powered compressor. The tool works but there is reason to be concerned the battery protection may not work.
I may reduce my use of the battery power for my GX soon not because I am not confident in it but just because I'm shooting from home and my bottle or the 120V power supply for the GX are both available. But if I have any issues I will update this thread or otherwise make it known.
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