Mini 0803 capacitor version

[mr_milo]

Yeah, I was still in "prototype mode" and was really only trying to see if it would work at the time. I didn't get too complicated with it, just used some 1/16" heat shrink on the leads of the capacitor, 3/32" heat shrink on the solder joints.
I was then going to just double stick tape it to the case of the mini BUT the bright green case of the capacitor pack bothered me so I added some 3/4" heat shrink over the whole thing first.

For my purposes it works and really doesn't look too bad mounted since most of it is behind the mirror or transponder. Obviously this wasn't done for mass market but works for the hobbyist. I'm sure I could come up with a cleaner solution but it works so I'm not really inclined to mess with it.

 

[inimeg]

Sorry for digging out such old topic, but recently I've done the same kind of mod and I have a bit of an issue with my cam now.
What I did is basically the same as OP but instead of using a few smaller caps I have one Gold Cap 5,5V 4F capacitor like this one:

My problem is that the camera acts like there's no power source at all when i pull out the usb cable or switch off ignition in my car. There's no chime and the screen goes immediately blank. I can't turn it on without connecting external power. What is even more interesting, the last file is saved but the last 10 seconds is missing. When powered up the camera blinks red/blue when recording and charging like it did with battery on board. When it stops blinking red the voltage on capacitor is around 4.1V. I've tried using two capacitors, which gave me total of 8F, but there was no difference.
Am I doing something wrong? Or maybe the capacitor I'm using is not suitable for that kind of use?

 

[Nigel]

Or maybe the capacitor I'm using is not suitable for that kind of use?

I think the coin cell ones can only provide 1 milliamp at most due to internal resistance, you need something like 400 milliamps...

 

[mr_milo]

inimeg - Unless your firmware is modified for immediate shutdown 4Fs aren't going to do it for you. Unless you made a calculation mistake like I had done, the 8Fs should work OK.

I have 7.5F and it works OK if I drive everyday and don't do any short cycles of the ignition. However if I leave the car for the weekend or a long weekend, chances are the first recording won't have the correct time/date since the caps will die. Although it will correct itself once the GPS syncs. Also if I short cycle the ignition and the camera tries to start, it's game over and it will also loose the time & date.

The red light blinking is normal but the caps will really charge for a bit after the light turns off to reach full potential.

As far as the type of Caps, Nigel is probably correct. Look at the datasheet and see what it says. Here are the datasheets for the family of parts I used: Single 2.7V caps & Dual 5.4V caps

 

[inimeg]

I think the coin cell ones can only provide 1 milliamp at most due to internal resistance, you need something like 400 milliamps...

That's what I was afraid of. I didn't find datasheet for my type of capacitor assuming it will be capable of providing such current and I was apparently wrong.

inimeg - Unless your firmware is modified for immediate shutdown 4Fs aren't going to do it for you. Unless you made a calculation mistake like I had done, the 8Fs should work OK.

Yep, I'm running stock FW20140901 V1.0 firmware.
I have the basic 0803 version without internal memory and GPS. I assume it requires a bit less energy to properly shut itself down.

Thanks guys. I'll change the capacitors and report back.

 

[Nigel]

However if I leave the car for the weekend or a long weekend, chances are the first recording won't have the correct time/date since the caps will die. Although it will correct itself once the GPS syncs.

What are the consequences of the caps dying?

Just wondering if it is feasible to run a cam without any battery or capacitor if you don't mind one incorrectly timed file after each engine start, or are there other problems?

That's what I was afraid of. I didn't find datasheet for my type of capacitor assuming it will be capable of providing such current and I was apparently wrong.

Look up memory backup super capacitors which is what the coin cell ones are normally sold for and you will find they tend to have very low current ratings. I assume it is just due to the way they are constructed as there is no point making things difficult or expensive to construct or use extra materials if you know that it will only be used to supply a few micro amps.

Also remember that the bigger super capacitors can supply huge currents to the point that they can be dangerous.

 

[inimeg]

What are the consequences of the caps dying?

Just wondering if it is feasible to run a cam without any battery or capacitor if you don't mind one incorrectly timed file after each engine start, or are there other problems?

My cam is now acting like there's no power source beside the external one. Only problem I get is the last 10 seconds of currently recorded file are missing. If it's ok for you, then go ahead and try it out yourself.

 

[mr_milo]

With out a battery or cap I would assume the last file, before shutdown, gets corrupted, but I could be wrong.

I also still haven't tested the other capacitor I had found and posted about here. Although after looking at the datasheet more closely, due to the comments I had received, I'm not sure that it will work. Basically the same kind of problem.... ESR is too high so it will charge and discharge too slowly.

EDIT: Just bench tested the Vishay cap and it's not going to work.

 

[rtsam]

Trying to use less capacitors.... could I use 2 15F 2.5V caps in series?

Thinking these... HB1325-2R5156-R

 

[jokiin]

you need 2.7v caps, for 5.4v total

 

[rtsam]

So 2 of these.... HV1325-2R7156-R 15F 2.7v

That would give me 7.5F 5.4v... and I am good to go.

 

[jokiin]

So 2 of these.... HV1325-2R7156-R 15F 2.7v

That would give me 7.5F 5.4v... .

correct

 

[Nigel]

you need 2.7v caps, for 5.4v total

Why do you need 5.4 volts?

They are connected to the lipo battery connector, the maximum voltage for a lipo is 4.2 volts so the camera shouldn't be charging it above that and for long battery life in a dashcam a bit less than that is sensible, it's not going to be more. No harm in having a higher rating, especially when connecting them in series without any balancing but 20% spare should be enough?

 

[jokiin]

Why do you need 5.4 volts?

They are connected to the lipo battery connector, the maximum voltage for a lipo is 4.2 volts so the camera shouldn't be charging it above that and for long battery life in a dashcam a bit less than that is sensible, it's not going to be more. No harm in having a higher rating, especially when connecting them in series without any balancing but 20% spare should be enough?

well you're working with a hacked solution so it may not behave as expected, the correct way to do it isn't anything to do with a battery charge circuit, it does need more overhead though as they don't have the long reserves of a battery so I would still go with the 2.7v caps

 

[mr_milo]

I did go with 5.4V on the caps I used but from my testing and info I made in this post, I think 5V would be fine. But then again, why not 5.4V? It can't hurt and can only help.

 

[vagner]

mr_milo,
I like your work. But I have some doubts: you put 4 caps into case solded in séries and more two external in parallel? Can I find this caps on aliexpress, for instance? Or can I put any
electrolytic caps with almost the same F, like this?

 

[mr_milo]

Hi Vagner - The caps inside the case were my starting point hoping that I could make an internal super cap solution, however that was not possible without a much needed "immediate shutdown" mod to the firmware. Therefore I just continued adding capacitors until I got a solution that worked with the current "delayed shutdown" firmware.
As for the caps, the internal ones were all single 2.7V caps and therefore two of each size are placed in series to get to the desired 5.4V working voltage. The external cap(s) were a 5.4V cap which was essentially a factory build series of two 2.7V caps. Then all three sets of 5.4V caps (3F, 1.5F, 3F) were placed in parallel to get my 7.5F solution.
If I was to do it again I'd probably just add the Rev. 1 set of 3F caps internally and a 5.0F 5.4V cap on the outside (Eaton Bussmann P/N: PHV-5R4V505-R) which would yield 8F and be easier to complete. Alternately you could just add a 3F and 5F set on the outside and be done. It all depends on aesthetics you desire.
The part numbers and links I provided previously and above area all from Digikey, but also available at Mouser, Newark / Farnell and a few other shops which I think sell to Brazil. The problem with the Aliexpress parts is no datasheet that I can find and no Manufacturer's part number, therefore I don't know the specs. They might work but might not too, since you need caps with a low ESR or they won't charge quickly enough and won't work. One possible option would be to use three sets of the super caps for the Mobius camera. I believe those are 2.7V 5F caps in series so three sets in parallel should give you the same 7.5F I am using. No guarantees but I think that would work and might be cheaper than my solution.

Hope this helps!

 

[jokiin]

Larger caps is a workaround to cure shutdown issues but is also a negative for startup, when the product isn't designed for it though there's not a lot of choice

 

[kajmac]

I found this one on aliex : ultra capacitor 7.5F 5.4V. I will need 3 of them in order for it to work? @jokiin @mr_milo

http://tinyurl.com/nkcf94z

 

[jokiin]

the product wasn't designed for it so whether it will work reliably or not is hard to say