Review of the Cell Spy

[Finless]

Here is a little gizmo I just got at my local hobby shop Rob's RC Hobbies.
I thought it was pretty cool for 13 bucks and thought I would share it with you all.

Review of Common Sense RC's Cell Spy Battery Checker (20 Megs) (http://video.helifreak.com/?subpath=finless/other&filename=battchecker.wmv)

Enjoy!
Bob

[Two Left Thumbs]

Pretty cool Bob, thanks for the review.

[ahperson]

That,s nice! I could leave my voltmeter home.

BTW, I thought you broke down and bought a swash plate levelling tool.



Andre

[Finless]

BTW, I thought you broke down and bought a swash plate levelling tool.
Andre

NO way! Where did you hear that! :thumbdown:

[rcboosted]

Neat. Are those pins spaced for an Align balance connector? (common JST type) Also, I think you can do more than 3S, just off set the pins when you plug it in. With 4S, plug it in flush with first pin, and you get cells 1, 2, 3. Take it off and plug it in flush with the last pin, and you get cells 2, 3, 4. You can pretty much do any size pack.

[Big Fil]

That's sweet. I've been thinking about an item just like that for a couple of months now. I really love the way I can keep my blinky in my case and it's just quick and easy to use. This thing is small and compact way of getting the voltages. I'm definately getting one. Now if only common sense or Astro would make a blinky type balancer with a little display like that, it'd be perfect.

[Finless]

Neat. Are those pins spaced for an Align balance connector? (common JST type) Also, I think you can do more than 3S, just off set the pins when you plug it in. With 4S, plug it in flush with first pin, and you get cells 1, 2, 3. Take it off and plug it in flush with the last pin, and you get cells 2, 3, 4. You can pretty much do any size pack.


VERY TRUE! Good Idea.... :thumbup:

Bob

[Two Left Thumbs]

I have not used one, but what is wrong with a swash leveling tool???

[Common Sense RC]

First of all I want to say 'thank you!' to Finless, that is one of the most imformative and useful reviews I have ever seen.

Secondly, another product that we recomend for your workbench is this nifty little tool that adapts your DVM to a plug that works with most balancing plugs. It works basically the same as the CellSpy, but using your DVM. We recomend the CellSpy for your field box and the DVM adapter for your workbench :thumbup: There's a picture attached but you can also see more at http://www.commonsenserc.com/product_info.php?cPath=32_39&products_id=330

Thanks,
Common Sense RC

[BarnOwl]

I have not used one, but what is wrong with a swash leveling tool???

Nothing if it's useful for you, just an old vendetta that's been going on between Bob and swash levelling tools. Don't worry about it......:wink:

[emag remrofni]

Sounds cool. Where can I get one?

[Pinecone]

Neat. Are those pins spaced for an Align balance connector? (common JST type) Also, I think you can do more than 3S, just off set the pins when you plug it in. With 4S, plug it in flush with first pin, and you get cells 1, 2, 3. Take it off and plug it in flush with the last pin, and you get cells 2, 3, 4. You can pretty much do any size pack.

Probably, especially since the instructions tell you to do that. :)

[Hi-Tec]

Sounds cool. Where can I get one?
HiTecHelis carry's Common Sense products http://www.hitechelis.com and has both the Cell Spy & Volt Meter adapter plus the Battery adapters.

[BikeNBoatN]

After seeing Finless Bob use one of these out at the field, I thought it was a pretty nifty gadget and got one myself. But after using it a while, I realize it does have its limitations.

The Cell Spy works good if you only use it to check if your battery has been used or is still full. But don't trust the readings to tell you if your cells are balanced. That was a little disappointing, especially since the instructions even claim you can use it to tell if your cells are balanced because it reportedly has 0.01 volt accuracy.

Mine reads about 0.01-0.1 volts difference from cell-to-cell when connected to a perfectly balanced pack. Also, I notice the numbers gradually change as it warms up. Unsure if I had a bad one, or if they all do that, I went back to the LHS I got mine at. As luck would have it, Bob was there, so we did a little checking on the other Cell Spy's they had in stock.

We checked several of these units connected to a perfectly balanced pack. We verified the cell voltages with a separate DVM and confirmed the pack was balanced within 0.01V. I wasn't too worried about the Cell Spy's accuracy. But I was hoping the cell-to-cell precision would be fairly good. Unfortunately, it's not. We noticed that none of the Cell Spy's would read the same voltage from cell-to-cell.

In other words, if each cell actually measures 3.90V, but the Cell-Spy reads it as say, 4.10V, I'm ok with that, as long as it reads all 3 cells at 4.10. Then I'd just have to remember that I have to subtract 0.20V from the readings to tell me actual voltages. Unfortunately, none of them we checked would do this. If each cell on the pack measured 3.90 with the DVM, the Cell Spy would say cell-1 was 3.81, cell-2 was 4.07, cell-3 was 3.95, or some similar set of values. They were all within about 0.1V of each other, but none read all 3 cells the same. Equally disappointing was that the values would gradually change the longer it was left plugged in.

So like I said at the top, the Cell Spy works great to tell you if you have or have not flown a pack. A full pack will be somewhere around 4.1V per cell, whereas a flown pack will be something much less. But that's about all you can reliably expect out of it.

[BikeNBoatN]

In the interests of fair play, I thought I'd post an update to my comments made earlier about the Cell-Spy. I got a chance to talk to Bruce Sund from Common Sense RC at the RCX show last weekend (4/19/08). I asked him how accurate the Cell-Spy should be and told him how far off mine was. I basically repeated what I said in my previous post. He said that was definitely not the way they should be, gave me his business card, and told me to contact him after the show. I emailed him a few days later, expecting to have to return my defective Cell-Spy for an exchange. This is his reply:

Hi Brent,

There's no need to return your original Cell Spy, we'll just send a new one out for you. Just tested one out - first two cells are within 0.01V of what my voltmeter shows, third cell is dead on. I'll ship this one out to you today. We're sorry you had a problem with our product, and if you need anything else, just let me know.

Thanks,
Bruce Sund
Common Sense RC
21744 Devonshire St.
Chatsworth, CA 91311

So to make a short story long, they sent me a free replacement, it's actually very accurate now, and so it actually works as advertised.

Great customer service, Common Sense RC! Thanks a bunch!

[RcSuperSales]

yeah mine was always right on the money. I did get a bad one the first time. It is a nifty little thing to have. i am jsut starting to take them with me flying for people that want to snag one. I love the cell spy! :) It would be cool if they made one with enough pins to just plug a 6 cell right in without having to disconnect. I will ask them about that. Just make things quicker. I do notice on mine I let it go one or two readings before it gets it right. The first one is always a little off for me, but by number 2 or 3 it is good to go.

Kyle