Running HM off of a battery (a review)


 
B

Brent Cooley

TVWBB Member
I thought I'd share my experience so far on a recent acquisition for my HM... specifically, a rechargeable battery unit.

The reason is simple... avoid having to use an extension cord to run my HeaterMeter and thus quicker setup and put-away.

The first step was to get an accurate measurement of the current draw of my HM. There was a thread on this a while back, but I figured my own measurements would be easy enough to do so I hooked up my multimeter and checked the current draw. With no fan running, it pulled 0.18 amps. With fan maxed out, it pulled 0.38 amps. Since I rarely have the max fan @ 100% and the fan isn't going all the time, I felt safe in using a 0.25 amp average.

Since I've never cooked beyond 12 hours, the battery needed to have a capacity of at least 12h * 0.25 amp = 3 amp hours, or 3000 mAh. I shopped around on Amazon and found one with a bit extra capacity - 4500 mAh which was both economical and was exactly what I was looking for. The unit comes with a plugin wall charger, albeit only 500 mAh output. This charges the battery from empty to full somewhere around ~18 hours when I did it - although that's a guess since I came home from work and it was done. The unit also comes with a male to male 2.1mm power cord which is used to run the HM from the battery. I do have to say that charging is a little counter-intuitive. You have to plug the wall charger into the in/out jack on the battery then flip the power switch to On. When plugged into the wall charger, an LED lights regardless of whether the switch is On or Off, but it will only charge when set to On.

I've had 2 successful short cooks - one 1.5 hours and the other 2 hours - both from the same initial charge. Both times it ran beautifully. When I have a chance to do a longer cook, I will report back on my results.

Here is a picture of the unit next to a HM 4.1:

battery_HM.jpg


Here is a link to the Amazon listing. Hopefully this is kosher on this site:

http://www.amazon.com/exec/obidos/ASIN/B008UKKXRC/tvwb-20
 
Nice, glad to see someone experimenting with this. I had thought long ago it would be nice to run the HM off a battery, and perhaps have a setup where the HM case would either contain the battery or clip onto the battery somehow. There were a lot of naysayers about the idea, noting the power requirement etc... I'm looking forward to more feedback from you on how long you can cook on the battery, and perhaps some data on running the servo and/or the blower on the battery. I've gotten past my need for the battery for home cooks by running a long CAT5 cable inside the house where I can leave the HM plugged into the wall and cook right through the most wicked rain storms, but a battery would still be nice for away from home cooks like camping etc....
 
Thanks for the review! I hope to be heavily involved in the same thing in the coming weeks. I'm trying to make my HM "portable" for use inside the house (monitoring oven and food temps). I'm trying to make a small enough form factor that it is not cumbersome to use.

Thanks again and I hope to here more in the future.
 
MKader said:
Thanks for the review! I hope to be heavily involved in the same thing in the coming weeks. I'm trying to make my HM "portable" for use inside the house (monitoring oven and food temps). I'm trying to make a small enough form factor that it is not cumbersome to use.

Thanks again and I hope to here more in the future.
Click to expand...

The battery doesn't need to be that big physically. For example, iPhone batteries are 1850-2250 mAh so you could get away with 3000-4000 mAh with something double the size of the iPhone battery. Just look for LiPo (Lithium Polymer) batteries on ebay, one thing you might need is a circuit to step up the 3V battery voltage to the 12V needed by the HM. There would be an efficiency factor for this step-up voltage regulator so you'd have to factor that in to your battery size calculation.
 
iPhone batteries are only around 3.7V (nominal). The current measurements above are taken at 12V, so you'd have to adjust the mAh up to 12V. Assuming 100% efficiency that's only 693mAh @12V. The OP's battery is rated for 4500mAh at 12V which would be a 14,594 mAh iPhone battery
 
I wonder if its possible to power the heatermeter using a thermoelectric generator. There is sure a lot of waste heat that could be utilized.

That would probably be the ultimate cable free experience.
 
I know there are several people interested in the battery performance but unfortunately, I’ve not had a chance to conduct a proper “long” cook, ie. 5 hours or greater.

Instead, I did a “bench test”. On my workbench, I fully charged the battery and set the HM to max fan 50% and 150 degree set point (which would force it to keep the fan running the whole time) and just let it run.

After 7 hours and 46 minutes, the HM conked out due to too low a voltage (the battery voltage drops as it discharges). I’d say when I checked it after 6.5-7 hours, I could noticeably tell the fan wasn't as loud/forceful as when fresh, which makes sense.

Since I know at least for my normal cooks, having the fan @ 50% the entire time is overkill, instead it would cycle on/off or run at somewhat of a lower percentage on average. I’d suspect an actual real-world cook would last longer. Perhaps I'll try another bench test at 20% max fan and see how it compares.
 
Surely a 12v SLA battery is a better way to go? A 12 Ah battery would last a normal cook without being over discharged. Any thoughts?
 
Ron Webb said:
Surely a 12v SLA battery is a better way to go? A 12 Ah battery would last a normal cook without being over discharged. Any thoughts?
Click to expand...

Yes, a bigger battery like that would be the way to go for longer cooks and still maintain some portability. The reason I chose the one I did was quite simply its size, weight (or lack thereof), and included a simple charger. A 12 Ah SLA battery definitely weighs more and likely needs a separate trickle charger like a Battery Tender. You're also correct implying that deep discharging a Lithium Ion battery like mine is not ideal.

I figured since I was testing batteries, I'd hook it up to the solar-charged deep cycle boat battery I have in my outdoor shed. It's not sealed, but it's lead acid and fairly inexpensive. I think it's rated at something like 70 Ah. But, it's just not very portable. In short, it works fine running the HM. I plan on taking some pictures and writing more about it soon. Stay tuned.
 
Portable weather resistant build

I was wondering if you have any more feedback on your experience with this? Do you run a damper servo? Where did you tap/connect your multi-meter to measure current draw?

I was just looking into doing something very similar, there is a friendly low key competition coming up mid-November I am participating in. It occurs overnight at a local park here in Dallas and I would like to be able to run my heater meter on my UDS without any access to power. I also need it to be semi-weather resistant as I have no idea if I will be doing this while its raining.

My plan was to build the heater meter into a pelican 1050 case (on amazon) with (10) 18650 li-ion 3.7 volt 2600 to 2800 mAh batteries in the bottom. This is 26 Ahr at 3.7 volts, so about 8 Ah at 12 volts if I am understanding the conversion. Electrical engineering was not my best distribution requirement course in college. I was also going to get a voltage regulator battery condition/charging board that will cut the cells at low voltages and make sure they charge evenly while pushing a consistent 12 volts. Using your power draw this should get me 32 hours with 100% battery use. Most of my brisket cooks run into the 18-20 hr range and I want a pretty good buffer on this, cause nothing would be worse than losing all my meat temp information and fan power right as I need it most at the end of the cook. I figure with an hour or two buffer I am at 75-80% battery use.

Things I am unsure of right now are if various wifi adapters have different current draw. I haven't had much success with the wifi adapters(I have tried two different ones from the list) and at home I have just been running a Ethernet cable to my back porch for cooks. I am going to get the larger antennae Ralink RT5370 linked off the wiki. I also don't know if running a servo damper takes more power. My fan generally only does work at the start, and then over the last couple hours with everything in between needing only minor damper regulation (UDS's are awesome at maintaining temps). I will also need the heater meter to host the network to login to from my phone (so I can just drink beer under the tent), which is different than how I run at home.

Ideally I can keep the case penetrations down to three, one for the antennae, one for the temp probe wires, and one for the fan cable. The case could be opened to charge it at home and to switch the whole thing on 'in the field.'
 
DGetz, is there a reason you'd like to use those lithium batteries? I've done a fair amount of research for battery options in the 12v space because I go to the BWCA here in northern MN once a year to fish out of a canoe for several days. I like to bring a 12v fish finder / GPS combo but I can only bring whatever I can carry on my back and there is no electricity for charging in the wilderness. In the 12v semi-portable space, Lithium has one distinct advantage and that is weight. For high capacity on the cheap you can't beat lead batteries. If it were me and this was a one-time use thing, I'd probably just pull a car battery and use that for the day. Otherwise for more frequent use I'd get one or two small gel cell batteries like the ones I currently use for my portable fish finder. These are cheap, relatively small (but heavy), can easily be run in parallel for more capacity, and should easily be found locally. I bought my most recent one at Fleet Farm. If I really wanted Lithium for weight and better portability, I'd probably look into something like the 12v 10Ah Lithium from Rapala, or something along those lines. I'd really like to get one of those for my portable FF and they'd work great for the HM though 10Ah might be pushing a brisket cook. Just my opinion, but with the batteries you're talking about, you'd need to make a custom holder and figure out how to run them in series to get the voltage needed.
 
Yeah I'd recommend getting a motorcycle or jet ski battery or something and just using that. You don't need to feed 12V into HeaterMeter v4.2 it can be up past 20V (although the higher the voltage the harder time HeaterMeter will have stepping down the voltage for the fan). The step down power supply and blower circuit is "very" efficient and you'll save a lot of energy going that route vs stepping up 3.7V cells to 12V to get stepped back down. I've been meaning to look into using one of those 12V UPS batteries just to see how long it runs for.

If only we could use a Pi B+ it would save a lot more juice. I tried to just do a basic layout with the LCD and the Pi B+ this weekend and couldn't find a shape I was happy with.
 
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The advantage I saw was fitting it all in a fairly small case and the weather resistance. The idea of possibly having a 12 volt car lead acid battery in the rain chilling next to my smoker wasn't that appealing. I could buy a cheap plastic tub at walmart or something, but that just didn't seem very slick. If I can work out something that is quite portable, I would use it every time I smoke. The pelican case I am thinking of using is 6.31"x3.68" inside dimensions, the batteries would just fit in a 5x2 layer in the bottom below the heater meter board. 18650 are supposed to be the cheapest li-ion batteries on the planet (its what the tesla uses in bulk because of this). I think I am looking at about $60 worth of batteries plus the cost of the controller. I don't have an extra car battery and won't be able to park near my smoker.

Bryan given your info about the built-in voltage regulator I am probably more inclined to feed the thing a higher voltage and forego the secondary regulator. I might go with an 18.5 volt PCB (about $12) and wire the batteries in two banks of five. Alternatively I could go with some higher power batteries, the 18650's can be had in up to 3400 mAh for a little more cost, and go with a 4x2 arrangement at 14.8 volts.

I actually changed out an older 24volt dewalt ni-cad battery pack in a hammer drill of mine doing something similar. Cracked the case open and redid the batteries, cost about the same to go to higher capacity li-ions as buying a new NiCad version (mostly because its dewalt and a model they don't make any more).
 
I not trying to hijack the thread or anything, but I have been using heatermeters when they were still attached to Linksys routers. I also have been using them in all kinds of weather from thunderstorms, snowstorms, hail, you name it and the easiest way and cheapest way to keep rain from getting to the heatermeter, I have found is a zip lock bag. Works every time. I did not even have a case on mine for years.

I'm a firm believer of KISS, my wife though may just delete the KIS and call me just S.
 
Actual data! HeaterMeter v4.2 w/ RF module + Raspberry Pi B + RT5370 wifi adapter in client mode with servo and rotodamper. Ethernet unplugged.
Code: 
Input 11.5V blower 0%: 235mA
Input 11.5V blower 100%: 405mA
Input 12.5V blower 0%: 220mA
Input 12.5V blower 100%: 396mA (up to 450mA as servo is moving)
Input 13.5V blower 0%: 200mA
Input 13.5V blower 100%: 375mA
Input 14.5V blower 0%: 190mA
Input 14.5V blower 100%: 355mA
Input 15.5V blower 0%: 180mA
Input 15.5V blower 100%: 335mA
...
Input 20V blower 0%: 140mA
Input 20V blower 100%: 270mA
So a 10Ah "12V" battery will last about 25 hours at full blower, 45 hours at no blower. Probably a little less because the servo potentially moves every second.

Another thing I'd suggest is not cutting a hole for the wifi antenna if it fits. It will probably work 99% as well from the inside of a pelican case.
 
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John Bostwick said:
I not trying to hijack the thread or anything, but I have been using heatermeters when they were still attached to Linksys routers. I also have been using them in all kinds of weather from thunderstorms, snowstorms, hail, you name it and the easiest way and cheapest way to keep rain from getting to the heatermeter, I have found is a zip lock bag. Works every time. I did not even have a case on mine for years.

I'm a firm believer of KISS, my wife though may just delete the KIS and call me just S.
Click to expand...

For mine i just put it in a http://www.sockitbox.com/ box and it is nice and dry with the power transformer in there as well.
 
Bryan,

Thanks for the data, that makes me feel pretty good about having enough power to not run out right at the end of a cook. It sounds like an 8 to 10 Ah 12 volt battery is good to go for a nice and slow brisket cook at 18 to 20 hrs. Do you think how often the wifi is accessed will increase the power demand? Like if I leave my phone connected to the heater meter as an access point could it drain it significantly quicker?

You are probably right I should just keep the antennae inside the case. I will start experimenting with it all this weekend. Due to the magic of amazon I will have the case and other bits by then. I haven't fully settled on the battery stuff so I haven't ordered it yet. One other option I was considering was trying to run it on some li-ion tool batteries. They can be expensive, but are useful for my other hobby, home improvement projects. Dewalt 20v has 4.0 Ah and 5.0 Ah replacement batteries which is 6.7 Ah or 8.3 Ah at 12 volt. They are definitely *** on cost for what they are though.

DaveyR that is a pretty nice solution. Looks like DRi-box is the US branch of it. It looks to be more expensive than the pelican case and rubber grommet idea I had planned (about $15).

John, I had used that for one of my first cooks after seeing you talk about that somewhere else on here. Then I got into 3D printing and it was all downhill and cases from there...
 
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