Hardwire kit for A810

[GBorba]

Got the early deal on the 70mai A810 including the back camera and hardwire kit. Notice that the cutoff voltage on the hardwire kit is 11.4 Volts which makes the state of charge of the battery dangerously low, in my opinion.

Can anyone recommend another hardwire kit with an adjustable voltage cutoff or one with a fixed voltage cutoff much higher than 11.4 Volts (> or = to 12 volts) that will work on this dashcam?

Thank you in advance.

Gary

 

[lisabon_Q3]

Hi, the protection voltage in UP03 is 11.6 Volts.

Only the "70 mai hardwire kit" model UP03 and UP04 will work with the 70 mai dashcams. By the way, you can purchase "70mai 4G hardwire kit" UP04 and you will have a choice in the voltage protection threshold: 11.8 \ 12.0 \ 12.2 V. Even if you do not use online functions, the protection settings appear automatically in the controller and the application. I checked, believe me, I hope it will help you.

Good luck.

 

[GBorba]

Thank you for the information. I may look at adding a 40v 3A shottkey diode in line with the battery terminal to drop the voltage the hardwire kit sees by about 0.5 volts.

Gary

 

[Daijoubu]

It's 11.8V, not 11.6V, unless you made a typo, that's what the manual says and when I tested with a variable voltage PSU.

The problem with using a diode is that the Vf varies depending on the load.
A 3A schottky may drop 0.5V at 3A but it will be much less in parking mode where it only draws 100mA or so
A common 1N5819 that drops 0.6V at 1A only drops 0.4V? at lower current, still better to cutoff at 12.2V than 11.8 imo

Have anyone cracked their open? I noticed the cutoff only applies to parking mode, not when the dashcam is operating normally with ACC pulled high.
Does it use some opamp to compare with a vref and switch a mosfet off? Maybe it's just a matter of changing a small resistor for a voltage divider

 

[Daijoubu]

Yeah ok so I did some test, 1N5819 only drops 0.2V at 100mA, I guess 12V is better than 11.8?
I then tried with an 1N4007, that one will drop 0.8V at 400mA as well as at 100mA, which was too high, cutoff voltage was at 12.6V

I don't have other power diodes on hand to test, will have to be looking at datasheets

 

[GBorba]

Thank you Daijobu for the information. I should be getting the 1N5822 diode in today and will check it out.

What I was concerned about was the manual said the current draw of the A810 was 2A and, not knowing the current draw in standby, did not want to potentially exceed the spec of the 20V, 1A diode. If the A810 only draws 100 mA (or even several hundred mA) in parking mode then the 1N5819 may be a better choice. If the voltage drop in standby is not as high as I want then, perhaps, 2 diodes in series.

Wrote the original post before the A810 arrived. Do see in the manual where the cutoff voltage is 11.8V. Still too low, in my opinion. Really would like to see it >= 12.2V, or about at a battery capacity of at least 60%. The car is garaged and is only parked outside for a few hours when shopping or other activity so long duration recording is not really needed.

 

[Nigel]

What I was concerned about was the manual said the current draw of the A810 was 2A and, not knowing the current draw in standby, did not want to potentially exceed the spec of the 20V, 1A diode.

That will be 2A at 5 volts, so it will be under 1A at 12 volts.
Diode might get a bit warm though, so make sure it is sensibly mounted with a bit of ventilation and decently soldered.

 

[Daijoubu]

You're right that 2 in series could work in parking mode.
It was dropping 0.35V under regular operation at 400mA iirc, so it's only dissipating 0.14W, shouldn't get too hot.
Active parking mode was about 200mA?

 

[Daijoubu]

I cracked it open, vise and a tap with a blunt drywall knife, its not sonic welded, just some very strong clips

Anyone better than me at reverse engineering it?
Top is input, from left to right: VCC, GND, ACC
Bottom GND, VCC and a yellow cable, I do not have a Type-C breakout board but it would be interesting to see where the last wire goes

Edit: as per 4pda forums, 5V ACC signal goes to SBU pins

 

[Daijoubu]

Ok so at first glance, the CX8835 is the DC-DC switching IC, VIN is on pin 4 which seems to be switched by p-ch mosfet 230S with its gate pulled down with a 287k resistor
The IC marked 209601 is maybe a microcontroller?
SOT89 M5450B a 5V LDO to power the microcontroller.

the SOT23 1AM is probably a transistor/mosfet to pull the 230S mosfet high and turn it on, controlled by IC PIN 2.
Now we need to figure out how the microcontroller is reading the voltage, you'll think there's a voltage divider somewhere

 

[Daijoubu]

Ok I figured it out, R13 and R17 are the voltage divider, marked 02D and 01C, 102k/10k ohms, it is read by the microcontroller on pin 4, with 11.8V input, it reads below 1.054V and it switch off the input.

If you want a higher cutoff voltage, you can swap the 102k for a higher value (or add a resistor in series) or swap the 10k for a lower one (alternatively another resistor in parallel)

Edit: did some math, you can get about 12.2V if you put 220k in parallel with the 10k resistor or 180k for 12.4V

Edit 2: if you have 5.6k on hand, you can add it in series with the 102k to get 12.4V and 4.7k in series for 12.3V.

Edit 3: I've decided to order 0603 0.5% SMD resistors to swap out the 10k one, will do the mod for my brother as well.

R17 value
9.42k = ~12.5V
9.53k = ~12.4V (confirmed)
9.65k = ~12.3V (hard to find value)
9.76k = ~12.1V
10k = 11.8V (stock)

 

[Daijoubu]

Ok so I performed the mod, soldering 0603 was a little tricky, 9.53k is just perfect, cutoff voltage at 12.4V
Basicaly as soon as the MCU reads below 1.054V, it cuts off the input

 

[safedrivesolutions]

Hi, the protection voltage in UP03 is 11.6 Volts.

Only the "70 mai hardwire kit" model UP03 and UP04 will work with the 70 mai dashcams. By the way, you can purchase "70mai 4G hardwire kit" UP04 and you will have a choice in the voltage protection threshold: 11.8 \ 12.0 \ 12.2 V. Even if you do not use online functions, the protection settings appear automatically in the controller and the application. I checked, believe me, I hope it will help you.

Good luck.

I have the UP03 and 70mai A810. I can confirm there is no selectable voltage anywhere on the unit. It shuts off at 11.8 volts instantly.

Got the early deal on the 70mai A810 including the back camera and hardwire kit. Notice that the cutoff voltage on the hardwire kit is 11.4 Volts which makes the state of charge of the battery dangerously low, in my opinion.

Can anyone recommend another hardwire kit with an adjustable voltage cutoff or one with a fixed voltage cutoff much higher than 11.4 Volts (> or = to 12 volts) that will work on this dashcam?

Thank you in advance.

Gary

I can also confirm that the Viofo hardwire cables would not support parking mode. Very interesting as Viofo USB C cable works fine for a Red Tiger dash cam putting it in and out of parking mode.

The Vantrue VP03 cable works and has a 12Volt shut off switch. confirmed on my bench. Same hardwire cable that is used for N4Pro.

 

[Daijoubu]

I did some research on the Viofo HK3-C/HK4, as per this post

HK3-H hardware kit arrives! (Viofo is not going to be happy about it)

Thank you for your feedback and input guys! Below I'll try to comment on some of the points: Thanks for heads-up! I was planning on setting it to 60 seconds but this will be an easy programming fix if I need to make the delay longer or shorter for any reason. Actually planning on having own...

dashcamtalk.com

Viofo/Red Tiger use pin CC (A5/B5) to carry the 5V ACC signal whereas 70mai/Vantrue uses SBU (A8/B8) pin

Also, it seems like the Viofo HK is a little janky, from my reading, it appears to use a cheaper n-ch mosfet to switch off the output GND and disable the DC-DC converter, and you can have weird voltage 9V on the VCC and 6V on the ACC output lines, I would be wary of plugging it in another brand dashcam in case the dashcam.is being grounded elsewhere, it could fry it.

See the comments in this video

 

[safedrivesolutions]

I did some research on the Viofo HK3-C/HK4, as per this post

HK3-H hardware kit arrives! (Viofo is not going to be happy about it)

Thank you for your feedback and input guys! Below I'll try to comment on some of the points: Thanks for heads-up! I was planning on setting it to 60 seconds but this will be an easy programming fix if I need to make the delay longer or shorter for any reason. Actually planning on having own...

dashcamtalk.com

Viofo/Red Tiger use pin CC (A5/B5) to carry the 5V ACC signal whereas 70mai/Vantrue uses SBU (A8/B8) pin

Also, it seems like the Viofo HK is a little janky, from my reading, it appears to use a cheaper n-ch mosfet to switch off the output GND and disable the DC-DC converter, and you can have weird voltage 9V on the VCC and 6V on the ACC output lines, I would be wary of plugging it in another brand dashcam in case the dashcam.is being grounded elsewhere, it could fry it.

See the comments in this video

I have used an HK4 4 times on Red Tiger. Have had zero issues to date. It functions completely normal.

Customer did not have a parking mode cable so I tested and found out about it by fluke.

It is very weird how so many things are not standardized.

 

[Lucky_Day]

Ok so I performed the mod, soldering 0603 was a little tricky, 9.53k is just perfect, cutoff voltage at 12.4V
Basicaly as soon as the MCU reads below 1.054V, it cuts off the input

Any chance you have an after photo of the mod? I may reach out to some local electronics repair shops and see if this is something they can do.

 

[Daijoubu]

I swapped the SMD resistor so it looks just like stock, only difference is the resistor value.
Were you going to install it yourself or have someone install it? Because it will probably be cheaper for you to buy the Viofo HW kit and splicing in 3 wires by cutting off the USB-C cable

 

[Sila]

I have the UP03 and 70mai A810. I can confirm there is no selectable voltage anywhere on the unit. It shuts off at 11.8 volts instantly.

In the latest firmware 1.3.72ww8 there is a choice of turning off the voltage (3 stages). screenshot in Russian

 

[Daijoubu]

In the latest firmware 1.3.72ww8 there is a choice of turning off the voltage (3 stages). screenshot in Russian

Isn't this only for the UP04 4G kit? UP03 voltage cutoff is done in hardware, not user selectable

 

[Sila]

Isn't this only for the UP04 4G kit? UP03 voltage cutoff is done in hardware, not user selectable

This is a screenshot of a DVR that is connected to a PC (usb port) without a UP03\04 cable