Battery Pack Drain Rate: a case of the DR970X BOX-2CH PLUS and B130A battery pack

[SC@AU]

I think the reason is that with the expansion pack attached, most of the batteries take 90+ minutes to charge, and not many people regularly drive for long enough to make them worth having, thus sales of expansion packs are going to be quite low.

Yes, good point. It does seem to be a dilemma, large capacity vs practical charging times...and one which I'm currently weighing up myself.

Vehicle alternators are quite capable of providing the load, however they are not designed to provide that much power continuously, so you can get issues with overheating and prematurely worn bushes. It is a serious warning for smaller vehicles, but like batteries, the more you use them, the faster the alternator will wear out, if you use them a lot then don't expect a normal lifespan. A new set of alternator bushes is generally a lot cheaper than a new battery, although these days, cars don't tend to be designed for them to be easily replaced, and a complete new alternator is a significant cost.

Hmmm, interesting.....Having somewhat stumbled across all this and being new to a full dash cam setup, it is something I'm also a bit wary of....

When we say 'small car', what are we talking these days..?! eg BMW 1 Series and below..? Smaller, larger..? I drive a '22 MINI JCW Clubman, which in my 'English' eyes I consider a medium sized 5-door (well, 6 strictly speaking!) car and reasonably powerful at 300+bhp – surely this shouldn't have an issue accommodating a 8-16amp additional battery load..?!? But then, I'm in a country where everybody nips to the shops or ferries the kids in a silly 4WD Ram or F150 which must have enough onboard juice to power through a nuclear winter – that's now the 'norm' it seems....🙄

I thought/read, that a large point of these external dedicated dash-cam batteries, along with capacity gains, was to save the potential wear and tear on the vehicle's main battery....But here we are considering load and wear on the alternator....

Which brings me to another point – I haven't yet searched around the forum re any similar queries, but just what is the score and any potential concerns re using a external battery setup with Stop & Start systems that are fairly prevalent on modern cars now..? My car has it on by default and I do tend to leave it on for 'daily' type drives....Is this extra load a long term concern – sitting at the lights or heavy traffic, engine off, but battery continuing to pull charge from the car's battery...??

SC

 

[Nigel]

I drive a '22 MINI JCW Clubman, which in my 'English' eyes I consider a medium sized 5-door (well, 6 strictly speaking!) car and fairly powerful at 300+bhp – surely this shouldn't have an issue accommodating a 8-16amp additional battery load..?!?

I have a medium size 5-door MG, and if I park next to a MINI, I have to look up at it, I count a MINI as a BIG car, a proper mini is a small car!

It is really about engine size, not car size, if you have a modern 3 cylinder 1.0L eco turbo engine then the alternator is probably packed into a small space without much ventilation and can get quite hot, bigger cars with bigger engines tend to have better ventilation for the alternators, suitable for carrying heavier loads and towing heavy trailers/caravans, the smaller car with small engine isn't designed to ever carry more than 4 people or to tow anything significant.

Your MINI is a British car, or at least anything that didn't meet our standards got sent back to Germany for improvement! It is designed for the alternator to provide power for winter nights with the headlamps, front and rear foglamps, rain wipers, windscreen demisters, heated seats, all on at the same time, and also be able to recharge the car battery and tow a decent size trailer.

16 amps x 14 volts = 224 watts, which is a significant amount of power.

But here we are considering load and wear on the alternator....

It is something to be aware of, not something to worry about. Like I said, new alternator bushes are not too expensive, and IIRC, normal life is around 18 years, so if you half that, it is not a big deal, although I do expect some cars to have a lot more of an issue than others. When I last replaced my alternator bushes, they cost me about £23, and came attached to a new regulator, not available separately. Bushes on their own can be only a few $. A lot of people unnecessarily get sold a new alternator though, and for a BMW, they can cost $1000 fitted!

Which brings me to another point – I haven't yet searched around the forum re any similar queries, but just what is the score and any potential concerns re using a external battery setup with Stop & Start systems that are fairly prevalent on modern cars now..? My car has it on by default and I do tend to leave it on for 'daily' type drives....Is this extra load a long term concern – sitting at the lights or heavy traffic, engine off, but battery continuing to pull charge from the car's battery...??

I think you will find that the Stop-Start system will disable itself until your battery is full, which will cost you a little extra in fuel. But you do want to make sure that you have a 3 wire charging input, GND, +V and ACC, so that the battery knows that it is not supposed to enter parking mode just because the engine is stopped. Some battery packs only have GND and +V.

 

[GPak]

I’ve briefly read the Cellink manual and also seen a few guides here and there – I think when you connect one expansion unit the battery (and App) is capable of auto calculating the new capacity…However, if you then connect further expansion units, it’s not capable of the auto calculation for some reason, hence you have to manually adjust within the App…(note: the auto set up is dependent upon using the specific In/Out port on the expansion battery, labelled Auto)

Yes, the input charging cable remains connected to the main battery. You can see on the pic I posted, the connection of one or more expansion batteries is done between the expansion unit ports….
It ‘feels’ and looks like daisy chaining, but I don’t know, I guess something could be going on internally….
Also, I think I’m right in this, but when they’re connected the batteries charge in parity (and if there’s a mismatch upon initial connection then the main unit will balance things out before additional charging) – I guess this points to parallel..?

Daisy chain is unidirectional, typically the auxiliary battery is charged by the car's electrical system, and in turn charges the dash cam's main battery, essentially a pass-through connection. In this case main battery cannot charge auxiliary battery.

So the Cellink batteries are definitely parallel connection, and extended battery is charged by main battery.

With the expended battery you get double the capacity but the charge speed stays the same you neither gain or lose here, unless when you drive longer.
"Charge to full" is meaningless: in an hour the 100Wh battery will be 100% charged, and the 200Wh combo will be 50% charged, but both batteries will have the same amount of stored energy and the same parking time.

The 200Wh combo battery definitely makes sense if you're driving longer, but even on short trips it gives you the peace of mind of having extra capacity buffer.

......
Having said that, going back to the pic I posted earlier of the Cellink Expansion Battery manual and their warning, they do seem to advise some caution re different voltage states – I'm still confused by that one though and how you're supposed to fully charge an expansion battery unconnected from a main battery and when you are unable to charge the expansion unit directly..?! 🙄

The warning to have the expended battery at the higher voltage level tells me they want the current to flow to the main battery.
I'm not sure why, but I guess maybe this is how Cellink determines to automatically increase the capacity in the app?

You can discharge the main battery to meet this requirement.

 

[GPak]

I think we are going circles now:

If the current flowing out of the battery pack exceeds its capabilities or safety limits, there should be some form of protection built into the battery pack, you can't assume that nobody is ever going to short circuit the output, so this shouldn't be a safety issue, only an issue of if you will trip the protection or blow a fuse.

.... which in the best case can cause the internal fuse to blow, and in the worst case, damage the battery.

14.6 is the maximum charge voltage, when you stop charging, if the battery is 100% full, the voltage drops to 13.6, and when you put a load on it, the voltage drops further, and the voltage on the charging battery will increase.

.......A more realistic practical voltage range could be 11-14V, which corresponds to an initial difference of 3.0V when the two batteries are connected in parallel.
.......even there the voltage difference can reach 1.0V, which is still too much and can result in currents exceeding the 2-3A limit.

So the recommendation to equalize battery voltages, including LFPs, before paralleling is the best practice in general, and even more so for low-current-rated output circuitry of dash cam batteries, when paralleled as shown on Thinkware diagram.

To make current flow, you need a complete circuit, which on that Thinkware diagram includes a trip to "Vehicle GND" and back, there will be resistance in the circuit, so you are going to need to upgrade to heavy duty cables as well as have 100% empty and 100% full battery packs to possibly have a problem, and even then it should not be a safety problem.

All cables except the output ones are already heavy duty, as they are designed to carry ±10A charging current.
If the wire resistance is too high, the system is probably unacceptably inefficient.

 

[GPak]

I thought/read, that a large point of these external dedicated dash-cam batteries, along with capacity gains, was to save the potential wear and tear on the vehicle's main battery....But here we are considering load and wear on the alternator....

Your car's alternator is rated at 180A, so I would not worry about additional 16A (10%) load.

Which brings me to another point – I haven't yet searched around the forum re any similar queries, but just what is the score and any potential concerns re using a external battery setup with Stop & Start systems that are fairly prevalent on modern cars now..? My car has it on by default and I do tend to leave it on for 'daily' type drives....Is this extra load a long term concern – sitting at the lights or heavy traffic, engine off, but battery continuing to pull charge from the car's battery...??

Personally, I hate this stop-start system and have permanently disabled it on my wife's 2023 Lexus 350 NX.
It is a very complex and expensive system (not just a switch as many people think).
It saves nothing, increases initial car price and following repairs, it usually requires a special battery and a special starter, some times two starters, etc.
Realistically, it saves nothing if you weigh the all pros and cons, but it justifies the existence of some bureaucrats.
Just my opinion.

 

[Nigel]

It saves nothing, increases initial car price and following repairs, it usually requires a special battery and a special starter, some times two starters, etc.

And the upgraded more expensive alternator at 180A instead of 120A!
But that does mean that it should be more capable of recharging dashcam batteries without overheating, since it is designed to be constantly recharging the car battery, and if it has a dashcam battery to charge, it probably won't need to recharge the car battery, because the stop-start will disable itself.

Realistically, it saves nothing if you weigh the all pros and cons, but it justifies the existence of some bureaucrats.

I'm sure you end up paying extra overall, not saving money, however Stop-start does improve the air quality and people's health in cities, which I think is the justification for having it, not to reduce CO2 output, which it only has a small effect on. Health issues can be very expensive, so maybe overall it does save money for the country, even if not for the individual.

 

[SC@AU]

Daisy chain is unidirectional, typically the auxiliary battery is charged by the car's electrical system, and in turn charges the dash cam's main battery, essentially a pass-through connection. In this case main battery cannot charge auxiliary battery.

So the Cellink batteries are definitely parallel connection, and extended battery is charged by main battery.

With the expended battery you get double the capacity but the charge speed stays the same you neither gain or lose here, unless when you drive longer.
"Charge to full" is meaningless: in an hour the 100Wh battery will be 100% charged, and the 200Wh combo will be 50% charged, but both batteries will have the same amount of stored energy and the same parking time.

The 200Wh combo battery definitely makes sense if you're driving longer, but even on short trips it gives you the peace of mind of having extra capacity buffer.


The warning to have the expended battery at the higher voltage level tells me they want the current to flow to the main battery.
I'm not sure why, but I guess maybe this is how Cellink determines to automatically increase the capacity in the app?

You can discharge the main battery to meet this requirement.

👍 Yep, I agree, would seem to be the case re a parallel setup with this expansion – and probably any others that offer expansion packs...
Totally agree re the red herring that is 'charge to full time' and running around in a car that has a 75% charged Pro12 battery is the '100% charged' of a 7500mA BlackVue, Cellink, etc...Personally speaking, I would probably only be concerned with a full charge of the Pro12 and it's 12500mA for the times I knew I was going to be parked up and wanting parking mode for 24hrs+ etc, in which case I could just ensure a full charge via a wall charger for example (if the car journey wasn't going to be sufficient re charging)...But most other 'daily use' times, I could just reply on the larger capacity 'buffer' as you say.....One of the main reasons I'm currently leaning to towards the iRoad Pro12.

 

[SC@AU]

Great post Nigel, thanks..!

I have a medium size 5-door MG, and if I park next to a MINI, I have to look up at it, I count a MINI as a BIG car, a proper mini is a small car!

Lol...yeah, that be true! I still have our 2002 Gen1 (BMW) CooperS hatch (currently parked up re a clutch issue) and even that looks positively small now compared to our JCW Clubman!...But yeah, when you see a proper MINI out and about it's mind boggling just how small they were...My old man had a couple of original Coopers, I've often got the stories re back in his day tearing around with the back doors open and his mates having their legs dangling out the back..!

Your MINI is a British car, or at least anything that didn't meet our standards got sent back to Germany for improvement! It is designed for the alternator to provide power for winter nights with the headlamps, front and rear foglamps, rain wipers, windscreen demisters, heated seats, all on at the same time, and also be able to recharge the car battery and tow a decent size trailer.

Well, can't say I get the fog lamps or demisters on very often here..!🤣 I guess it's replaced with more Air-Con use though..! Surprisingly, do use the seat heaters a few times through the winter....Strictly speaking, unable to tow anything with our particular JCW as I don't believe it's homogenised, so have some spare capacity there..! But yeah, sounds from a couple of posts that it should be OK and the alternator is probably rated at least 180A, even if I were to go the x2 dash-cam batteries setup in parallel...At this point, I'm currently leaning towards a single iRoad Pro12 and splitting the capacity difference, so to speak...

16 amps x 14 volts = 224 watts, which is a significant amount of power.

But still well within limits though, yeah...?

It is something to be aware of, not something to worry about. Like I said, new alternator bushes are not too expensive, and IIRC, normal life is around 18 years, so if you half that, it is not a big deal, although I do expect some cars to have a lot more of an issue than others. When I last replaced my alternator bushes, they cost me about £23, and came attached to a new regulator, not available separately. Bushes on their own can be only a few $. A lot of people unnecessarily get sold a new alternator though, and for a BMW, they can cost $1000 fitted!

I can well imagine – and it's worse out here in WA as BMW/MINI have a real monopoly, basically two official dealerships and one parts outlet – I swear they think of a figure and add on zeros whenever I used to make parts enquires for our old CooperS – fortunately, I have a good mate back in the UK who's an auto electrician and something of a MINI expert, so it's more often than not it's been way cheaper to get parts sent over incl DHL – madness!

I think you will find that the Stop-Start system will disable itself until your battery is full, which will cost you a little extra in fuel.

Interesting. So I'm presuming from that the car must sense the extra load (if charging the external battery) on the circuit and so disable the Start-Stop function..? Handy if that's the case and it wouldn't concern me too much re fuel use...As I said, I do tend to leave the Stop-Start on if I'm pooling around – it can be toggled on/off per trip from the dash, which I only really do if I'm conscious of a lot of repeated on/off (I really wonder if you potentially chew through alternators with these setups) or if I'm feeling spirited and want to see a silly Mustang in my rear mirror off the lights...!😜

But you do want to make sure that you have a 3 wire charging input, GND, +V and ACC, so that the battery knows that it is not supposed to enter parking mode just because the engine is stopped. Some battery packs only have GND and +V.

And with that, I think I'm really leaning now towards the iRoad Pro12. I know for sure that the popular BV 130 and Cellink options are 2-wire and it's seems the Pro12 is actually one of the few external batteries that is 3-wire...Makes install a bit of an extra phaf IMO and I think I'd prefer to have that VCC+ direct on the battery instead of fuse-tapping anything constant that's going to be available at the fuse box....But I can see the overall benefits. (I guess only potential downside is you become reliant on the external battery's switching circuitry being 100%).....SafeDrive Solutions advised much the same to me re 3-wire in a recent email.

Thanks again....

 

[SC@AU]

Your car's alternator is rated at 180A, so I would not worry about additional 16A (10%) load.


Personally, I hate this stop-start system and have permanently disabled it on my wife's 2023 Lexus 350 NX.
It is a very complex and expensive system (not just a switch as many people think).
It saves nothing, increases initial car price and following repairs, it usually requires a special battery and a special starter, some times two starters, etc.
Realistically, it saves nothing if you weigh the all pros and cons, but it justifies the existence of some bureaucrats.
Just my opinion.

Good to know re the additional load, even if I went up to as much as 16A using x2 parallel batteries in fast charge...

I have to admit, I tend to agree with you re Stop-Start. Once I got used to it, I don't mind it too much being on in the majority of daily drive type situations...As I've said, I can toggle it on/off per trip (it defaults to On) which I do occasionally...I could permanently switch it off (not sure about default=Off) via Coding, but just have never got round to it...
But the function, now quite common with most modern cars it seems, does make me wonder whether the wear and tear is passed further down the chain i.e battery, starter motor and alternator, if not more....These days I work in & around areas of computer and network install and I've long understood that when it comes to the majority of electronics they're far happier remaining powered up and the most stressful thing you can do to a box of electronics is pull and restart power – If I can ensure a rack full of network gear remains constantly powered up, they happier I am, as is the kit..! I'm sure there's likely measures and circuitry in place re a car's stop-start system, but I do also highly suspect that future issues likely arise due to the setup – and no doubt not cheap fixes either!
Totally agree, one of those typical red herring situations...and a bureaucratic piece of paper waiving no doubt....Having said that, I do note Nigel's point re fumes and pollution savings, especially in town/city traffic – it's a good point.

I have the same sceptical feelings when it comes to the general subject of EV – for some baffling reason, to me, electric vehicles are held aloft as the modern world saviour of the autobahn, if not the planet!...Yet no one seems to question the km's of extra copper wiring within, the mined lithium and other rare metals and then all the 'magically' generated electricity that's required for charging everyday...! 🙄 Must be me......Anyway, that's a whole other discussion..!

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[Nigel]

But still well within limits though, yeah...?

The only issue is that it will result in the alternator running warmer and with more brush wear, which will reduce the lifespan, same as using a battery always reduces its lifespan. If you keep your cars for 10 years, don't be surprised if you need new bushes at some point. Replacing them should be no more difficult than replacing the battery, although with modern cars they can require a lot of effort to reach them.

Interesting. So I'm presuming from that the car must sense the extra load (if charging the external battery) on the circuit and so disable the Start-Stop function..?

The stop-start is disabled if the car battery is not full, and if you have a 3 wire dashcam battery, every time the engine stops, the dashcam battery will take some power out of the car battery, so after a while, the car battery will not be full and the start-stop will disable. If you don't make many stops then the car battery will fill up again. It is hard to predict exactly how it will work out for you and your car. My father had a Ford with a stop-start, and that liked to keep its battery completely full, otherwise the stop-start didn't stop, but I suspect a Mini might be less fussy.

which I only really do if I'm conscious of a lot of repeated on/off (I really wonder if you potentially chew through alternators with these setups)

No, the cars with stop-start are fitted with uprated alternators, starter-motors and often AGM batteries, so quite likely last longer. Also, starting a warm petrol engine with electronic ignition really doesn't take much battery power, the starter motor only needs to turn it one rotation, there shouldn't be anything to worry about.

or if I'm feeling spirited and want to see a silly Mustang in my rear mirror off the lights...!😜

I haven't seen a Mustang for ages, a bit too silly for around here, I had a Caterham 7 behind me yesterday, some would say that is a silly car... no point trying to race that off the lights though, it has literally half the weight and possibly an identical engine to me!

it's seems the Pro12 is actually one of the few external batteries that is 3-wire...Makes install a bit of an extra phaf IMO and I think I'd prefer to have that VCC+ direct on the battery instead of fuse-tapping anything constant that's going to be available at the fuse box..

Viofo is also 3-wire. The ACC wire doesn't take any power, it is just a signal wire to switch between charging and parking, so you can just run the VCC to the battery and fuse tap the ACC.

and then all the 'magically' generated electricity that's required for charging everyday...!

WA electricity is still a bit dirty, but a fair amount of it is from solar, 42% at the moment, and a fair amount of wind power, sometimes, so if you charge it at the right times, you should be able to run half net zero, it is not magic. Some places have electricity with zero fossil fuel input, Scotland last I looked. Solar and wind have become the cheapest source of power, they are the future.

 

[SC@AU]

So I don't think that's officially supported, but Thinkware has a diagram in their iVolt Xtra manual that explains how to wire up to batteries in parallel like this.

View attachment 83821
Personally I prefer having two batteries running in parallel rather than a battery plus an expansion since both batteries can charge at full speed. You'll pull 2x the current of course, but for shorter drives, it allows you to recharge your total capacity faster than a single input for both a main battery with an expansion.

I was looking at this diagram again re potential Parallel Connection for batteries – I'm sure this may be a daft question, but I'm confused why there's no GND connection between the two batteries..? Every wiring diagram I look at, plus my own basic understanding, shows both B+ and GND being linked between batteries for a parallel connection...?
Or is there something different going on here...? 😕

 

[Nigel]

why there's no GND connection between the two batteries..?

Presumably there is a connection, since power can only flow in a circuit, so there must be a return path for it to work.

Looking at the diagram, both batteries have a "GND", which is connected to "Vehicle GND" and the dashcam is also connected to a "GND", so I assume that all the GNDs are connected together, via the "Vehicle GND" and are thus the same. In general, this is an unsafe assumption, you should never connect other batteries up in this way without the manufacturer saying that it is OK, because the GND on the dashcam cable may not be the same GND as on the vehicle cable, just as the B+ on the dashcam cable is clearly not the same as the B+ on the vehicle cable, but since the manufacturer is saying you can do this, it should be OK.

The actual answer to your question will be, to avoid a ground (earth) loop, ground loops can cause serious problems and are best avoided.
From a usage point of view it would be better to have GND on both connections, then you can remove either battery and the dashcam will still work, while with this setup, if you remove the battery providing the GND, the dashcam will stop working, even though it has a perfectly good battery! So have they left it out because there actually was a ground loop problem? If so, it would have been nice if they had given a warning.

 

[SC@AU]

Good points Nigel and all makes sense to me....I just don't understand, on that Thinkvue diagram, how that '2nd' battery gets its return flow as such...
If I want to jump-start another car but only connect the B+, it ain't gonna work..!

Re your points concerning ground loops, same B+ cable etc....Yes, but surely in an automobile situation things are inherently a lot simpler re single points of origin, unlike say a domestic power situation, a high-end HiFi setup (and I've chased a few ground loops there!) or a computer network install etc where they may well be potentially multiple sources of power and/or Earth....With a car, everything is going to lead back to the same points of origin (presuming you don't have more than one main battery of course), all GNDs are going to be the vehicle chassis and all the B+ ultimately lead back to the battery's + terminal...or am I over simplifying..?!

 

[Nigel]

If I want to jump-start another car but only connect the B+, it ain't gonna work..!

If you also connect the car chassis then it will work, no need to connect the B-. Likewise, with this, the chassis (cases) of the two dashcam batteries are connected via the car chassis. The car/battery chassis does of course need to be connected to B-, but the reference point for 0 volts is the car chassis, not the Bat-.

With a car, everything is going to lead back to the same points of origin (presuming you don't have more than one main battery of course), all GNDs are going to be the vehicle chassis and all the B+ ultimately lead back to the battery's + terminal...or am I over simplifying..?!

That is correct, however when you have more than one power source, as you have if you have a car battery and two dashcam batteries, then it is no longer certain that a GND output from a battery is connected to its GND input at all times, and you do need to make sure that it is, otherwise you need to treat the output in isolation to the input.

Yes, but surely in an automobile situation things are inherently a lot simpler re single points of origin, unlike say a domestic power situation,

Actually, the house is the simpler situation, because it is probably illegal to have more than one GND. I have two power sources in my house, the grid, and solar-battery-invertor, and regulations require that the two GNDs are connected, mainly because having two earth routes in one building can lead to death! Those regulations generally don't apply to car wiring, although arguably they should.