Portable Power with the Stoker (Long)

I posted this elsewhere as well.

I found just a couple threads relating to using a portable power station for your stoker (or guru) when you do not have access to hard wired electric (at a competiton for example). If you don't have a generator, using a portable battery pack may be a viable option. I wanted to add my personal experience to the mix for those wondering how well it works, and what specific product I used. For a more detailed look at the amp requirements of the stoker device, I did a search at tvwbb and found some good threads that gave me an idea of what kind of power draw I could expect.

This weekend I was running a single stoker 10cfm fan at a competition. Typically our contests have power, however (somewhat at the last minute), I learned we'd have none this weekend. I did a quick feature compare of several "emergency battery jumpstart" systems to see which one would meet my needs. Specifically, I needed one with enough juice to run the system for an entire 'long slow' cook. I also required it to have an inverter with AC outlet for simple plug in without the need for an adapter. I wanted to spend no more than $100. I wanted it to be portable and self contained. Lastly, I had to be able to pick it up local rather than ordering it online because i needed it the same day.

Based on my criteria, with the "local last minute pick up" being very much the constraint, I settled on two finalists:

http://www.harborfreight.com/automotive-motorcycle/battery/5-in-1-portable-power-pack-96157.html
or
http://www.walmart.com/ip/Black-Dec...Charger-for-AC-DC-Appliances-VEC026BD/5679657

It did not take me long to convince myself that the stoker was not going to be subjected to the whims of a Harbor Freight electrical product, even though the features were theoretically more desirable.

So I picked up the Electromate 400 at Walmart, brought it home, and plugged it in for initial charging. The directions tell you to charge 48 hours on first charge. Unfortunately .... I had about 16. I am hoping the 48 figure assumes a fully drained battery. I have a couple clues that my battery was not sitting on the shelf very long, so I am reasonably sure I gave it a full charge. According to the (not detailed enough) power meter on the Electromate, mine was fully charged by the time I had to pack up and leave for the competition the next morning. Time will tell if I have a permanently weak battery on my hands. (I think it is fine).

The moment of truth: Once at the competition, I started the stoker's pit at about 10 PM, running the stoker immediately. The stoker went through the normal set up, and I breathed a sigh of relief as it operated normally right away. I turned the stoker off at about 1 PM the following day, achieving almost 15 hours of continuous use. A battery test yielded the "Recharge Now" light. I assume I would have been able to get at least 2 more hours out of it.

In conclusion, for the size of a fishing tackle box, I was impressed with the electromate, and consider it good insurance. I will probably bring it along to most competitions, even if we will have power available. It is also nice to have a portable jumpstarter (albeit 450 cranking amps), DC power supply, and compressor.

Although it is not the product I would have bought if I were not in this time cruch, I am pleased so far.

Buster Dog BBQ said:

I haven't had the success you have had. I bought one to power my Guru and FEC. Worked great about the first six months but then couldn't run the FEC for more than 4 hours on a full charge. I bought another one and similar issues. Took it back. But as far as size and power that is a good sized unit.

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Do you know how much power is drawn from a FEC? When I researched the amps drawn from a stoker, I got more comfortable with the idea because they were quite low. I wonder if an FEC draws more amps.

I am going to try and find the thread that had a breakdown on the power usage.

EDIT To Add:

This is what I located form a helpful person on tvwbb. For whatever reason, I think the estimate below is a little low.

I measured my Stoker's current usage with a Fluke clamp-on current probe.

Configured with 5 probes and 2 5CFM fans and connected Ethernet, it used:
1.05A with both fans running
0.36A with neither fan running
With a single fan, we would expect to see
0.7A with 1 fan running

At the idle current, efficiency (from the graph) is at approx 82% or 2.2 watts from the source.

With a single fan on, efficiency is at about 88% or 4 watts from the source.

Assuming a fan duty cycle of about 10% over the duration of the cook this gives a average wattage of about 2.37.

This, in turn implies an average current of about 200ma on the 12V source. Over a 18 hour cook that means battery usage of about 3.6AHr.

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Goddahavit said:

By the way, the inverter takes a lot more power, if stoker has a adapter for 12 volts, i know guru does, it helps with the longer cooks. my harbor freight model that you listed went for over 14 hours and still had most of the charge. with the adaper, with the inverter running, I ran the same amount of time, but the battery was much more depleted.

Will it work in 6 months, probably not, but I dont have it 6 months yet.

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A) I don't know what I am talking about
B) Amir, the stokerlog guy said this at one point:

An inverter has about 85-90% efficiency. The switching power supply in stoker has about the same. So in rough numbers, if you use a 12 volt battery+inverter as shown plus stoker power supply, you are in 70% power conversion efficiency range.

On the other hand, the typical solution for a 12 volt to 5 volt is a linear voltage regulator. With such a huge voltage drop, it will be very inefficient (much less than 50%). More efficient switching regulators exist but they tend to be more expensive.

So as non-intuitive as it may sound, the inverter solution may work better!

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I don't know if it referred only to an external inverter plugged in to DC, or if it also applies ot the units built in inverter. Either way, the proof of concept worked great for me.

BBQchef33 said:

^^^^^^^

I was just gonna type that.. running on DC will draw significantly less than inverting it to AC. Too bad though.. i just checks Rocks website for stoker accessories and it doesnt have a DC option. Only an inverter.

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Yeah, but it was also moot at the time (for this contest) since I was leaving the next day.

What is your take on my quote above from Amir? Am I mis-interpreting it?

Goddahavit said:

Fine, sorry to post in your thread, I guess my personal experience is wrong.

Glad it works for you. :thumb:

Have a nice day.

Edit, perhaps I read that the wrong way, sorry if that is the case. I am by no means any kind of engineer, but on the harbor freight model, the inverter also runs 2 fans and a led full time, I know the led doesn't take much, but 2 fans might account for some extra drain, dont know.

Sill glad it works.

Eric

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I think you read it wrong. I REALLY don't know what I am talking about. :thumb:

Brew-B-Q said:

I use a Duracell Powerpack 600 with an inverter that I bought for $99 on Amazon. I've used it at contests to power 3 5 cfm fans and have never had any problem. I bring it along now and use it because I don't trust the competition power and don't always want to fire up my generator. I've had it 2 years now and I guess I'll find out next weekend how it works after a long layoff. I do keep it plugged in most of the time as the manual suggests.

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This is the model I wanted to buy, but it was not available locally.