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Quick weatherproof camera box.

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Re: Quick weatherproof camera box.
« Reply #60 on: 03 / September / 2013, 08:57:58 »
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OK, time for taking risks with one of my SX220hs.

This morning I made a dummy battery so that I could connect 3-way and 4-way battery holders with PP3 connectors.
The SX220hs uses a 3.7V LiIon battery.

The results with NiMH cells are as follows :-

Three cells, 4.2V off-load,3.85V on-load, camera indicates 67% capacity.
Four cells,5.2V off-load,4.47V on-load, camera indicates 100% capacity.



David

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Offline ahull

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Re: Quick weatherproof camera box.
« Reply #61 on: 03 / September / 2013, 12:13:54 »
 :blink:.. and no magic smoke... I must admit I would be more likely to be tempted to parallel up a bunch of 3 cell packs (with in-line schottky diodes so they don't start charging each other up), to get the extra capacity, rather than risk four cells.

Having said that 4.47V *just* squeezes outside the acceptable limits for LiPo cells, so you will probably be safe.
 
 
« Last Edit: 03 / September / 2013, 17:24:54 by ahull »

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Offline ahull

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Re: Quick weatherproof camera box.
« Reply #62 on: 03 / September / 2013, 17:25:21 »
Actually having thought about that a little more, if you stick with the 4 cell packs, and protection diodes that might just be perfect. You end up with 4.47 V minus one typical schottky diode forward voltage drop of approx 0.45V which gives you a good clean 4.02V  ... Spot on for our purposes.

If we use something like a 1N5822 which is good for 40V and 3A (we probably need about 2A max for even the most demanding camera), they are really cheap from the usual suspects as they are used a lot in solar panels and similar applications. In fact I just bought 50 for 2.58 GBP, which is less than the cost of one from a certain well known UK electronic component retailer, lets hope they arrive a little quicker than the missing mosfets. 

Theoretically this could be scaled up to as many packs as you want all in parallel. 
« Last Edit: 03 / September / 2013, 17:34:25 by ahull »

Re: Quick weatherproof camera box.
« Reply #63 on: 03 / September / 2013, 17:33:32 »
Thanks for the diode information.
The four-cell pack was not fully charged so potentially could be 0.4V higher.
Even though the designers will assume the maximum voltage is the maximum voltage of the 3.7V LiIon battery, you would think there is built-in over-voltage protection with whatever IC they use.

My Springtime A620 time-lapse enclosures used IN4001 diodes to allow hot-swapping of the SLA.
The 1A rating was not high enough, they tended to blow.

« Last Edit: 03 / September / 2013, 17:36:28 by Microfunguy »


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Offline ahull

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Re: Quick weatherproof camera box.
« Reply #64 on: 03 / September / 2013, 17:47:22 »
I suspect the 1N4001 also looses you quite a bit more in forward voltage drop. If you actually need the voltage drop, then something like a 54 series 3A silicon rectifier, say a 1N5401 would be better.
« Last Edit: 03 / September / 2013, 18:13:14 by ahull »

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Offline ahull

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Re: Quick weatherproof camera box.
« Reply #65 on: 03 / September / 2013, 18:03:52 »
Thanks for the diode information.
The four-cell pack was not fully charged so potentially could be 0.4V higher.
Even though the designers will assume the maximum voltage is the maximum voltage of the 3.7V LiIon battery, you would think there is built-in over-voltage protection with whatever IC they use.

The maximum voltage from a well behaved LiPo is 4.2V, and this is fed directly to various places, for example the flash circuit in the PowerShot SD630/DIGITAL IXUS 65/IXY DIGITAL 80 is shown as connected to vbat (through a small SMD fuse for protection), so there is a slight risk of boiling the camera's brains in new and interesting ways if you exceed this by too much.  I have replaced one of the 2A SMD fuses on one of my ebay Ixus 60s, so they do sometimes get popped. The main DC power supply chip is probably a bit more robust, but bear in mind most of these camera components are very small components, and there may be equally small tolerances associated with them. I would tread carefully, it is impractical to replace almost any of the individual components on a board the size of an Ixus main board, they are simply too small and closely spaced.  Having said that, I can pick up a dead screen or dead lensed Ixus 60 for next to nothing, which is why I am willing to risk leaving them out in remote locations.
« Last Edit: 03 / September / 2013, 18:11:50 by ahull »

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Offline ahull

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Re: Quick weatherproof camera box.
« Reply #66 on: 04 / September / 2013, 15:33:27 »
I managed to find a few minutes to hack together the RC plug and the "Gold Solar Charger 2600mAh". The plug is just a fraction too large to hide under the solar panel, so I put some long tails on it and will have it clipped to the side of the charger.

The result still requires a little refinement with the Dremel, and perhaps some bright yellow heat shrink tubing to cover the blue electrical tape but here is what I have so far.



Now I should be able to power direct from the LiPo, measure the current drawn by various cameras, and should the mosfets ever arrive, place an inline electronic switch between the lipo and the camera. I should also be able to see if that little solar panel ever has a chance of charging the LiPo.

I added a few more pictures to the build gallery including a closeup of the wiring on the pcb. You can find them all here.
« Last Edit: 04 / September / 2013, 17:52:18 by ahull »

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Offline JvdP

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Re: Quick weatherproof camera box.
« Reply #67 on: 04 / September / 2013, 16:25:25 »
You could of course have used something smalled than the XT60 plug. That one is unnessecarily big. But I suppose it will do if you are having a "scramble parts together" project  :D

Anyway, thanks for the battery advice earlier. I have a lot of left over LiPo's that I don't use anymore. They are in pretty OK shape and I'm thinking of using them in parallel. They are 3S though, so I need to use one of my voltage regulators.

Another plan is to buy some beefy 1S (3.7V) LiPo's. Something like this Zippy 6200mAh. Or maybe go even more DIY (and cheaper) with this naked 5800mAh cell. If I would take 3 in parallel, I would get like a solid 18Ah and that should have my 240HS running for some days.

You were talking about the Schottky's, so I ordered 50x 1N5822's on eBay. But do I just put on each plus (+) wire of each battery and then put all batteries together?


By the way, have you seen this Solar charger circuit from Adalight? Of course it is more expensive but also better quality than the chinese versions on eBay, but is it the same functionality?

I liked your referral to the magic smoke  :P ;)


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Offline ahull

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Re: Quick weatherproof camera box.
« Reply #68 on: 04 / September / 2013, 17:36:32 »
You could of course have used something smalled than the XT60 plug. That one is unnessecarily big. But I suppose it will do if you are having a "scramble parts together" project  :D

The idea with the XT60 was to use standard parts, the size was of secondary consideration, but I thought it might just squeeze in to the case (it probably would with a little effort), but having it on a flying lead actually makes life easier. I am trying to keep everything modular, I'll use the same connectors on the PIR switch, a regulator module and a modified Ikea alarm clock. It should all just snap together in a Lego like fashion. The XT60 is pretty common on all sorts of battery configurations, (and is an open source design SFAIK), so using this as my standard made sense.

Anyway, thanks for the battery advice earlier. I have a lot of left over LiPo's that I don't use anymore. They are in pretty OK shape and I'm thinking of using them in parallel. They are 3S though, so I need to use one of my voltage regulators.

3S gives approx 12.5V which will give you better efficiency from the regulator, than trying to drive it from 3.7V

Another plan is to buy some beefy 1S (3.7V) LiPo's. Something like this Zippy 6200mAh. Or maybe go even more DIY (and cheaper) with this naked 5800mAh cell. If I would take 3 in parallel, I would get like a solid 18Ah and that should have my 240HS running for some days.

That would certainly do the trick for reasonably long shoots. Running them in series with the regulator on the output is another option.

You were talking about the Schottky's, so I ordered 50x 1N5822's on eBay. But do I just put on each plus (+) wire of each battery and then put all batteries together?

The diodes allow you to parallel up cells or sources without having to balance them. Highest voltage wins, when it discharges and is no longer the highest voltage, the next  one takes over. The diodes ensure  they don't discharge into each other. Any diode with a high enough current rating will do, but schottky ones have less of a forward voltage drop than traditional vanilla silicon rectifier diodes, which matters when you are dealing with low voltages as we are. I'll provide a circuit diagram it you want, but you probably get the idea, its pretty much as you describe. As previously stated, this is a good arrangement if you want to hot swap the batteries and/or other power sources without powering off.

By the way, have you seen this Solar charger circuit from Adalight? Of course it is more expensive but also better quality than the chinese versions on eBay, but is it the same functionality?

I saw that too. I uses one of these. and is probably quite effective.  Theoretically it looks like it would cope with up to 1A charging current, so good for a fairly small set up.

I liked your referral to the magic smoke  :P ;)

 :D
« Last Edit: 05 / September / 2013, 08:58:37 by ahull »

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Offline JvdP

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Re: Quick weatherproof camera box.
« Reply #69 on: 05 / September / 2013, 15:41:19 »
3S gives approx 12.5V which will give you better efficiency from the regulator, than trying to drive it from 3.7V
Yes, but I driving it from 3.7v directly (no regulator) gives me even better efficiency. The only thing I'd use is a over-discharge circuit to prevent the lipos from being fully drained.

That would certainly do the trick for reasonably long shoots. Running them in series with the regulator on the output is another option.
Again, I want to eliminate the need for a regulator.

Can I get your opinion on RC LiPo's by the way? I am aware of the risks and I can live with that. But I'm just interested why some people advice against RC lipo's, like here on Adafruit. But I think that if you use protection circuits, it should be safe enough for our type of projects.

As previously stated, this is a good arrangement if you want to hot swap the batteries and/or other power sources without powering off.
Yes, I liked that idea.


By the way, I noticed that All-Battery.com has the perfect circuits for battery protection. So I was interesting in buying there, untill I noticed that shipping to Norway cost a whopping $100! I searched eBay but no luck. Do you know anywhere else they sell these kinds of battery protections?
« Last Edit: 05 / September / 2013, 15:43:48 by JvdP »

 

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