Help me find the perfect Dashcam

[kamkar]

if you have the room in your car you can put a #2 car battery in it, and have it isolated from the original battery so it only get charged when driving and you cant discharge your original battery.
This is what i would prefer, but to do that is a bigger job than i can handle, not least with no access to a welder as i would have to put in a #2 tray for the #2 battery in the engine bay, but other than that my little Suzuki have room for another battery, due to it being a bottom line model and so don't have any AC, and the lack of that in the engine room are why i have the room for a second battery out there.
I can even replace the original 45Ah battery with a 80 - 90 Ah one, but again this will need tools and materials i don't have access to, but other than that i could do that too no problem.
I would not go lower than 12.2 V for cut off value, and really lead acid batteries you don't want to deep discharge,,,, but you can get other types of car batteries that will handle deep discharge much better, but with a very low on voltage battery you can not start your car, but for a #2 battery only feeding a camera or something else that would be nice.

Yes i believe the 12 V to 5 V happen in the little box on the hard wire kit, the cut off just work on the 12 V side of things inside that little box.

I remember my Mitsubishi L200 pickup had 2 batteries, one for starting i assume and the other one for all other things, and i assume the 2 was split up in a way discharging the #2 battery would not mean doing the same to the start battery.

 

[Ormy]

Thanks for the helpful info and ideas Kamkar. I did consider using an additional lead acid battery, however there I found a few drawbacks when I was looking. Mainly that lead acid batts cannot be charged as quickly as lithium. Sometimes I drive for 15 mins and then leave the car for 24 hours, a lead acid would not be able to charge much in 15 minutes, fast-charging a lithium could give it a fair amount of charge in just 15 mins. Secondly, lead acid is big and heavy, I could probably find space in the boot somewhere but I'd still be concerned about the weight affecting handling and fuel economy. The battery in the car is already a 80Ah unit.

I would not go lower than 12.2 V for cut off value, and really lead acid batteries you don't want to deep discharge,,,,

Yes that's right lead acid doesn't like to be dishcharged very deeply. I have however done some testing and my car will start happily even when the battery voltage is as low as 11.6V. This is because its a new-ish battery (3 years old), and my engine is light (1.8L petrol) and well cared for. I will leave the cut-off switch at 11.8V (the lowest setting) because it gives me the longest recording time. If it means I have to replace the battery in 2 years time instead of 4 years that is an acceptable trade-off for me.

 

[kamkar]

If winters are gentle to the UK like it have been to Denmark the past 2 years then a sub 12 V might not be a problem when it come to starting a cold car engine, but you will be hovering just on the edge i think, which might be a issue if you rely on the car bringing you to work.
I do think a car charge on a car battery pretty hard if it have been depleted some, otherwise it of course just trickle charge.
Some lipo batteries you can also charge hard, normally on my RC batteries i only charge with 1 C so a 3000 MAH battery i charge with 3 Amps, now i could do that much faster but really i see no reason for that with those batteries.
BUT ! lipo batteries are also a fire hazard, and they should not be stored or charged too hard in cold or too hot environments, the dedicated dashcam batteries you see on the market are also not using lipo batteries but lion instead, and only charge with 13 A or so max when hardwired.

 

[Nigel]

If winters are gentle to the UK like it have been to Denmark the past 2 years then a sub 12 V might not be a problem when it come to starting a cold car engine, but you will be hovering just on the edge i think,...

The easy answer to that is to replace the standard battery by an AGM battery which are far more tolerant of deep discharge and not being filled frequently and also charge much faster, especially when half empty. You only need to replace it once you have killed the standard battery.

Remember that lead acid, and AGM batteries do need to be filled to 100% occasionally, if you don't do trips of many hours then you should use a battery charger at least once every 3 months.

So my next job is figuring out how to extend the recording time of the dashcam whilst parked, probably using a separate battery pack. Dashcam battery packs seem ridiculously expensive for what you get (who pays 3-figures for a rechargeable battery pack?), by comparison a similar capacity power bank designed for charging a mobile phone is much cheaper, can anyone explain the difference? Is it just that the dashcam battery packs are 12V and the phone charger ones are 5V? Is it the high-temp tolerance? Is it fast-charging capability?

So I'm considering wiring up my own solution either using 12V or 5V packs of LiPo batteries, a relay for charging on when ignition is on, a charging circuit (will likely buy an off-the-shelf charger, easy to find for 5V but harder for 12V, or building my own charging circuit from scratch is a possibility). Has anyone got any experience with this and might have some advice?

The phone chargers are cheap because they charge far too slowly for dashcam parking mode use and also are mass produced in huge numbers. They are a good source of cheap lithium cells for a DIY powerpack.

Some of the USB powerbanks can now be charged at 45W using USB PD, of course they cost a bit more, and that is still half the speed of a Cellink Neo, but if you can charge three of those in parallel using 3 12V to USB PD 45W chargers then you can charge faster than the Neo and then you just need a way to share the load between the powerbanks during discharge - best to tap directly onto the cells, share the loads via low voltage drop diodes so that they discharge together, and power the dashcam via a 3.7 - 5V step up converter (as used in USB powerbanks), and don't forget a low voltage cut-off to protect the cells (https://www.pololu.com/product/2868 ).

 

[Moon]

Where are all the latest offerings by Dash Cam manufacturers in the last 12 months?

Where are all the new exciting improved Brands/models using the latest tech to outdo a 3 year old VicoVation OPIA2 as the best quality (day) video in the business (imho)?
Why aren't there new players bringing us the latest and the greatest ? Where are the new Cams that have forum members buzzing?

 

[Ormy]

The phone chargers are cheap because they charge far too slowly for dashcam parking mode use and also are mass produced in huge numbers. They are a good source of cheap lithium cells for a DIY powerpack.

Makes sense. If I do DIY a lithium powerpack I will likely use 26650 cells though as I have a loads around for powering my torches.

Some of the USB powerbanks can now be charged at 45W using USB PD, of course they cost a bit more, and that is still half the speed of a Cellink Neo, but if you can charge three of those in parallel using 3 12V to USB PD 45W chargers then you can charge faster than the Neo and then you just need a way to share the load between the powerbanks during discharge - best to tap directly onto the cells, share the loads via low voltage drop diodes so that they discharge together, and power the dashcam via a 3.7 - 5V step up converter (as used in USB powerbanks), and don't forget a low voltage cut-off to protect the cells (https://www.pololu.com/product/2868 ).

Thanks for info, using this I've narrowed my options down to two solutions.

1.) Build or buy (any recommendations?) multiple 3.7V (5V input) charging circuits. Power them via 12V->5V buck converters (DC-DC voltage converter) and use them to charge 3.7V 26650 lithium cells. Attach the cells to the load (dashcam) in parallel and use a 3.7V->12V converter as you suggested. As each cell gets its own charging circuit the total input/charging current can be quite high depending on how many cells I have. My only question about this setup is; if the batteries are connected to the load in parallel, how do I make sure they are electrically isolated when charging whilst still keeping the load powered? Circuit diagrams would be most helpful if anyone has a solution. I could solve by attaching the cells to the load in series but then no balancing, not sure whats the best way here?

2.) Buy a 4S (14.4V) LiPo battery pack designed for RC use (approx 10000mAh or more) and a balancing charger that accepts 12V input. Connect the battery pack directly to the load. Benefits here are simplicity, no voltage converters, the cells are balanced automatically during charging so no need for any load sharing during discharge. Probably slightly more expensive, and more difficult to expand if I decide I need more capacity.

In both solutions above I would use a relay (activated by Acc) so that charging only occurs when the ignition is on and I am in the car. Also a fuse and a cut-off switch.

A feature I would like to implement is to have a switch so I can toggle between super-fast charging (e.g. 2C) and slow charging (0.5C). I would only use the fast charging when I know I'm doing a very short journey and then leaving the car unused for a day or more, for normal and longer journeys I would use the slow charging mode. However I'm not really sure how to implement this feature into either of my above solutions. In solution 2, some balancing chargers have a selectable current limit so I guess that could work?

Also, I'm strongly considering upgrading to an AGM battery (I found a 100Ah model that should fit) before trying either of the above solutions. Its a bit more expensive but by far the simplest to implement and will likely solve the problem altogether. Thoughts?