70mai Dashcam Battery Pack - Unboxing & Review

[EricSan]

The 70 Mai battery may not be the only issue. I tested two dashcams, a Viofo a229pto and the Wolfbox Tripro. At temps below 0 oC for two days straight, they didn't accept proper current flow (hardwired) after a 10 min car warmup.

It’s got nothing to do with which brand of battery box you have. It has everything to do with what type of battery chemistry is inside the box. LiFePo batteries cannot accept a charge when temps are below 32F/0C or above 113F/45C- that’s the end of the story for them.

LTO chemistry batteries charge and discharge down to about -22F/-30C and work well up to about 130F/55C. They are a MUCH better option.

The operational question is: “Which dashcam battery company will be first to the table with an LTO battery?”

 

[ujsc]

It’s got nothing to do with which brand of battery box you have. It has everything to do with what type of battery chemistry is inside the box. LiFePo batteries cannot accept a charge when temps are below 32F/0C or above 113F/45C- that’s the end of the story for them.

LTO chemistry batteries charge and discharge down to about -22F/-30C and work well up to about 130F/55C. They are a MUCH better option.

The operational question is: “Which dashcam battery company will be first to the table with an LTO battery?”

Interesting, that is similar to what I observed. I do have a way to keep my battery supply above 0 oC even in the coldest temp. I use an extra fan to keep temp below 45C.

 

[EricSan]

I use an extra fan to keep temp below 45C.

This is an impossibility inside of the typical closed car during the summer months, fan or not. A closed car during the midday summer will easily climb to above 45c. Having a fan circulate air that is 50c will not keep your battery cool. The only option for a closed car that I am aware of is a Tesla with Pet Mode enabled for air conditioning.

 

[ujsc]

Let me explain. I had issues with 70 Mai battery. It lost charge every time temp reached 43-45+ degrees. Put a laptop fan underneath. It worked every time after that. It was reproducible espevially on long drives. Test it your self! I now have used an even larger fan platform for the bluetti. This is probably stupid as it never gets hot under standard charging or with lots device in my car. I haven't had a single issue with the power supply or any loss in charge since the summer. It has a huge fan already so this extra fan probably is most likely not needed. I have used it in subfreezing temps after warming up my car. No issues. Those are the facts and I don't have a friggin Tesla!!!!!!!!!!!

 

[Hack_man]

This is an impossibility inside of the typical closed car during the summer months, fan or not. A closed car during the midday summer will easily climb to above 45c. Having a fan circulate air that is 50c will not keep your battery cool. The only option for a closed car that I am aware of is a Tesla with Pet Mode enabled for air conditioning.

I know it sounds odd but airflow even in what seems like a hot environment can actually improve thermal performance. Remember the junction temperature you are trying to keep cool is much warmer than 45ºC, maybe hotter than 100ºC. Increased airflow over a heat sink (the metal case of the 70 mai battery) reduces the effective thermal resistance of the heat sink. Heatsinks actually have performance curves that vary as a function of airflow. I'm not a thermal guy but I remember thinking it was weird when we ran thermal tests in a hot thermal chamber that were impacted by the fan.

 

[ujsc]

I am agreeing with your results which show increased airflow in a hot environment can improve the thermal performance of the electronics.

It was such a simple observation. I clarified what type of device worked best with fans, didn't I? What I reported is common knowledge anyway but you made it a task.

Ever hear of the venturi effect creating a low pressure transfer of heat through rapid air current flow? It is analogous to fluidics.

 

[EricSan]

Please accept my apology - I didn't mean to come across that way.

Thanks you for explanation, I do appreciate it. I had an EcoFlow battery pack die on me following a few days of 95F during the summer. The specs say not to use in temps above 45c (113F) and apparently they mean it, because it stopped functioning. I see how using a fan can keep transistors cooler should they climb above ambient temps inside of a closed car. There is still the problem of the LiFePo batteries themselves (which won't generate much self-heat in our use case) not liking temps above 45c for charge and discharge.

 

[Hack_man]

It was such a simple observation. I clarified what type of device worked best with fans, didn't I? What I reported is common knowledge anyway but you made it a task.

Ever hear of the venturi effect creating a low pressure transfer of heat through rapid air current flow? It is analogous to fluidics.

If you read thru my last posts, none were directed at you except to agree with your observations.

This forum is intended for helping others.

 

[ujsc]

Please accept my apology - I didn't mean to come across that way.

Thanks you for explanation, I do appreciate it. I had an EcoFlow battery pack die on me following a few days of 95F during the summer. The specs say not to use in temps above 45c (113F) and apparently they mean it, because it stopped functioning. I see how using a fan can keep transistors cooler should they climb above ambient temps inside of a closed car. There is still the problem of the LiFePo batteries themselves (which won't generate much self-heat in our use case) not liking temps above 45c for charge and discharge.

Thank you for the kind explanation. Stuff like that does feel personal due to the cost. I fully understand. We are all in this together. If you put the battery pack in a cooler (insulated, kind you use for picnics), perhaps this will insulate it from extreme temps when not in use.

 

[ujsc]

If you read thru my last posts, none were directed at you except to agree with your observations.

This forum is intended for helping others.

We are all in this together. Sometimes comments like that can discourage discussion. I over reacted and tried to remove anything derogatory. Let's move on. No issue here

 

[ujsc]

I am agreeing with your results which show increased airflow in a hot environment can improve the thermal performance of the electronics.
I guess I didn't explain it very well 🤔

I would appreciate it if you deleted the one reply where I said friggin. Don't want to set a wrong example to follow. This is a great forum which is truly appreciated by all who use it.

 

[onkasongbi]

I just received the 70mai battery pack the other day and installed it yesterday. So far it seems to be working as intended. However, I opted for the cigarette lighter (12V socket) to charge it since my car is still new and I don't want to risk the warranty by messing with the fuses. That said, I know that the cigarette lighter option charges slower. My work commute is about 30min each way which seems to be sufficient to keep the camera (Viofo A229 Pro) charged for the day. However, I'm concerned about my days off when I'm not commuting...

...is there a way to manually charge the battery at home? Do I just need to order another cigarette lighter charging cable? But what power adapter would I need to get to mimic the 12V charging at home? Thanks.

 

[ujsc]

You could buy an ac to dc inverter but you would have to remove the monitor to charge at home

 

[GPak]

...is there a way to manually charge the battery at home? Do I just need to order another cigarette lighter charging cable? But what power adapter would I need to get to mimic the 12V charging at home? Thanks.

As @ujsc mentioned, you can use an AC-to-DC converter.

Here's the first possible option:
It outputs about 12.8VDC without a load, and the voltage drops to about 12.4V under load, which should be sufficient for charging the 70mai battery.
https://www.amazon.com/gp/B0CY293K6G

The second option is actually a LiFePO4 battery charger, which in your case will also work as a converter.
It outputs about 14.6VDC without a load and can charge a little faster, but you will need to buy a cigarette lighter socket extension, as linked below, to use the cigarette lighter cable included with the 70mai battery.
https://www.amazon.com/gp/B0FHPV1PL3
https://www.amazon.com/gp/B0DFH9Y58L

I have both options, and they work for charging Ecoflow River portable power stations and my DIY LTO batteries.
Many other similar converters are also available on Amazon.

 

[Kuya]

...is there a way to manually charge the battery at home? Do I just need to order another cigarette lighter charging cable? But what power adapter would I need to get to mimic the 12V charging at home? Thanks.

Aside from what was already suggested. I've thought about this and I wonder if a lifepo4 battery pack like an ecoflow river would work for this purpose. You'll just need to remember to keep this one topped up as well.

 

[Hack_man]

As @ujsc mentioned, you can use an AC-to-DC converter.

Here's the first possible option:
It outputs about 12.8VDC without a load, and the voltage drops to about 12.4V under load, which should be sufficient for charging the 70mai battery.
https://www.amazon.com/gp/B0CY293K6G

The second option is actually a LiFePO4 battery charger, which in your case will also work as a converter.
It outputs about 14.6VDC without a load and can charge a little faster, but you will need to buy a cigarette lighter socket extension, as linked below, to use the cigarette lighter cable included with the 70mai battery.
https://www.amazon.com/gp/B0FHPV1PL3
https://www.amazon.com/gp/B0DFH9Y58L

I have both options, and they work for charging Ecoflow River portable power stations and my DIY LTO batteries.
Many other similar converters are also available on Amazon.

I was curious about what makes this charger specific for LiFePO4. Is it because it charges in 3-stages- CC Stage -CV Stage- Full Charger Stage ? I assume Full Charger Stage simply means it stops charging.
interesting it goes CC to CV.

 

[TonyM]

Aside from what was already suggested. I've thought about this and I wonder if a lifepo4 battery pack like an ecoflow river would work for this purpose. You'll just need to remember to keep this one topped up as well.

There's a separate thread dedicated to that subject:

Thread 'Parking Battery-Power Station, 3X capacity and 3X cheaper than dedicated options + extra functionality'

Oct 27, 2023

First, thanks to the members of this forum for posting great reviews and comments to help people like me choose the DashCam that suits their specific needs.

Now, I want to share my project here and maybe help people, who do not want to mess with a car battery and fuse box but are hesitant to spend a lot of money on a dedicated overpriced battery with limited functionality.

To start, here is my bench test.

Bluetti EB3A Power Station on the right, simulates 12V car socket, which I turn ON/OFF to simulate car ignition.

Necespow 161Wh Power Station for parking is on the left.
Note that it...

• GPak
• Replies: 652
• Forum: Hardwiring and Batteries

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[GPak]

I was curious about what makes this charger specific for LiFePO4. Is it because it charges in 3-stages- CC Stage -CV Stage- Full Charger Stage ? I assume Full Charger Stage simply means it stops charging.
interesting it goes CC to CV.

Yes, the CC-CV mode turns AC/DC converter into a charger when connected directly to the battery.
The output voltage of 14.6VDC corresponds to a fully charged LFP battery consisting of four cells connected in series (4S), so called "12V" LFP battery.
The output current of 10A corresponds to a LFP battery with a capacity of at list 10Ah (1C max charge limit for LFP).

However, in the case of the 70mai battery, this AC/DC charger does not connect directly to the LFP battery, but to a built-in charge controller that regulates the voltage and current supplied to the battery.
In this case, the AC/DC charger acts as a converter with a output current set by the 70mai charge controller, and an output voltage of up to 14.6VDC depending on the load.

 

[Hack_man]

its neat that it starts out in constant current and switches to constant voltage

 

[EricSan]

That chart shows the same voltage & current behavior characteristics of a good car battery charger. My C-Tek charger works the very same way.