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lapsio
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LtAP mini vs LtAP for regular car?

Fri Sep 20, 2019 1:20 am

I'm considering AP for car and can't decide between LtAP and LtAP mini. I'm a bit worried that "big" LtAP will drain car battery too much to operate 24/7 in regular car. Does anyone have experience with those devices in terms of how much stress do they put on car battery? Especially in winter. Another reason why I'm worried is that sure - car battery is 12v, except when it's launching and it briefly drops below 9v while engine spins up. LtAP accepts 12-20v input so wouldn't it restart due to voltage drop at engine startup?

At the same time I'm mot really satisfied with LtAP mini functionality.
 
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Amm0
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Re: LtAP mini vs LtAP for regular car?

Fri Sep 20, 2019 2:53 am

Well,
LtAP is new, and even though I have a couple, they don't work with the US LTE modems yet.
And, the LtAP mini has some shortcomings (don't use USB to power to, internal GPS seems to be weak, etc.) but it works, today.

Now in theory the choice between the two is the "bigger" LtAP has 2 miniPCIe and/or more CPU power. I had better luck with the wAP LTEs than the LtAP mini, especially if you not going to use external antennas with the LtAP mini.

On the power...
I'd use some up converter to 24V to power any of the Mikrotik stuff, plenty of amps to do that.. 12V "should just work" but don't think you want to add worrying about a voltage drop latter on to list of things some random network issue could be - especially if wiring stuff up anyway. If you wired up some external antennas to that LtAP mini, and get those volts to 24V, that be a good place to start.
 
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lapsio
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Re: LtAP mini vs LtAP for regular car?

Fri Sep 20, 2019 5:53 am

anyway. If you wired up some external antennas to that LtAP mini, and get those volts to 24V, that be a good place to start.
LtAP mini doesn't seem to be affected since it accepts voltage starting from 5v iirc (allows USB power) so voltage drop only worries me in context of "big" LtAP.

I'm primarily considering big one since I may need more than 1 wifi radio besides LTE (I'd like to connect car wifi bsed equipment like dash cam, OBD2 etc to it so they'd be accessible over VPN established over LTE). And they all host own APs so LtAP would need to be station for multiple APs. Idk if single radio can do that

Regarding 24v converts - what's their efficiency? Is it something to worry about? I mean - it wouldn't make much sense to add another device draining like 2-5w when I'm already worried about connecting device draining 7w and deep discharging battery.

Does LtAP have voltage monitor? I could shut it down automatically using script if voltage drops below eg. 11v if it had. Since that would mean battery is discharged noticeably. Also I could send email / SMS or something.
 
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Re: LtAP mini vs LtAP for regular car?

Wed Sep 25, 2019 6:17 am

I'm not the EE expert. AFAIK efficiency is normally pretty high for DC-DC, with the price of the upconverter sometime related to how high the efficiency is... This unit here claims 75%: http://www.tycononline.com/9-36V-In-24V ... _p_22.html
And, even at max 24W it isn't that much for a car battery system, so 50% loss would be 48W – and I can't imagine you'd hit 30W on any of the LtAP. And, that slight inefficiency in an upconverter, essentially, acts like a "buffer" on power irregularities. I'm also not a mechanic, but if a car battery isn't producing 12V consistantly, it a problem with the car (or battery needs to be replaced)... so there that too...

Yup, LtAP mini does have a wider power range, so it does have that going for it. :) But yeah the LtAP says 12V (e.g. and not 11.9V).
 
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Re: LtAP mini vs LtAP for regular car?

Wed Sep 25, 2019 9:13 am

... but if a car battery isn't producing 12V consistantly, it a problem with the car (or battery needs to be replaced)... so there that too...

The problem with typical lead-acid batteries is that they perform worse at low temperatures ... even if they are in excellent conditions. And during those few seconds it takes to crank-up the engine, the battery voltage can drop (well) below 12V.

That is actually a big problem for any serious electronic equipment ... we've been using some professional measurement equipment for measurement of PLMN signal (GSM, UMTS, LTE) and the equipment actually contained own UPS-like hardware (internal battery that could power the whole measurement setup for a few minutes). And yet, equipment vendor stated that vehicle's start-stop system should be disabled while using the measurement equipment exactly due to voltage dips that occur during starting the engine and which might disturb the electronics.

And no, 75% conversion efficiency is not good when it comes to 24/7 operation off a battery. Typical car battery has, say, 60Ah capacity (smaller cars have even smaller battery). With current draw of 1A (that's 12W at 12V), the exemplary battery could sustain such device for 60 hours - two and half days which cover a quiet weekend. If we throw in a 75%-efficient conversion device, we effectively decrease the autonomy time to 3/4 of previously calculated. And I even didn't mention that deep discharging of a typical lead-acid car battery causes damage to that battery and should be avoided.
And the sad fact is that a battery with low remaining charge (say below 20%) can have hard time to start the engine. So a setup which includes 24/7 off-the-battery operation should at least include an under-voltage protecting device ... which disconnects its load when supply voltage drops below certain threshold (can even be 12V, covering lower bound of operating voltage of LtAP) and re-connects when voltage rises above another threshold. Such under-voltage devices come pretty cheap (example device on aliexpress can be found for a few bucks), but might consume some power themselves (the linked device consumes some 50mA at 12V) causing car battery to drain even faster.
 
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Re: LtAP mini vs LtAP for regular car?

Fri Apr 28, 2023 10:16 pm

Hello guys...

I'm also going to install MikroTik LtAP Mini LTE Kit in my car. I have already bought LtAP Mini, MikroTik mANT LTE 5o antenna with the relevant SMA cables/pigtails, and a Tycon TP-DCDC-1224G voltage converter. The 12V 70Ah battery in my car is in really good condition. I will take a power (V+ and a ground pins) from the cable pair which goes directly to my car's head unit, in order to cut the power automatically, when I stop the car's engine.

Three questions:

1. Do I really need any undervoltage protection device?
2. What might happen if I frequently disconnect the LtAP Mini from the power source without first shutting it down from the MikroTik App?
3. What might happen to LtAP Mini when I start the car's engine? I mean - could it be damaged during the ignition process? (As I know, the car is producing a non-stable electric impulse during the ignition).

Thanks a lot in advance
 
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lapsio
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Re: LtAP mini vs LtAP for regular car?

Sat Apr 29, 2023 12:45 am

Three questions:

1. Do I really need any undervoltage protection device?
2. What might happen if I frequently disconnect the LtAP Mini from the power source without first shutting it down from the MikroTik App?
3. What might happen to LtAP Mini when I start the car's engine? I mean - could it be damaged during the ignition process? (As I know, the car is producing a non-stable electric impulse during the ignition).

Thanks a lot in advance
Well, I can't tell that with 100% certainty that it's gonna be healthy but I can tell from experience that I'm using my LtAP (big one) for like 3 or 4 years now, I can't remember. It's been used in 2 cars - Opel Astra H in the past and Subaru BRZ now. Both cars are really dead simple since one was quite old, another is barebone sports car without any fancy electronics. I'm powering my LtAP from cigarette lighter socket using chinese adapter to MikroTik compatible power jack - directly 12V. MikroTik is completely fine with 14-15V generated by alternator. It also doesn't seem to mind voltage drops to 8-9V during crank. It's simply hooked up all the time so it turns on with ignition and goes down with engine. I don't use any OVP / UVP. Deadass attached straight to car circuitry. I also don't shutdown it gently.

It just sits here strapped to chassis in trunk using zipties, zero maintenance. It's used basically 5-6 days a week for 3/4 years now. Works just fine even with relatively complex config involving OpenVPN over LTE. It's heavily abused since I'm tracking my car quite frequently and I'm using LtAP to collect readings from my OBD dongle during laps trace recording so it faces relatively strong vibrations, jumps and other kind of rapid movement that race car experiences on track. I also crashed once on barrier and LtAP survived it just fine. Car stays outside so it also survived few harsh eastern Europe snowy winters and few hot summers in direct sunlight.

My only complaint is that SIM card slots are pretty shit and it's quite tricky to put card here properly so that it actually works reliably but once you do that - it just goes forever. Also it takes some time to establish LTE after startup so be prepared for like 2 minutes without internet after ignition.
 
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Re: LtAP mini vs LtAP for regular car?

Thu May 04, 2023 3:18 am

@lapsio

Thanks so much for replying... I really appreciate it.

Well, everything is clear except the antenna part - I have installed my LtAP in the glove compartment and put LTE antenna in the center of the windscreen under the rear-view mirror. The LTE signal was really poor with the internal LTE antenna, which is installed by the manufacturer in LtAP Mini. External antenna did the job, but it takes some space on my dashboard and doesn't look nice :) Some people may wish to steal it, thinking that this is something expensive :D

Is there any solution for boosting the LTE signal? I can't install LtAP Mini on the dashboard, it will definitely be stolen one day...
 
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lapsio
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Re: LtAP mini vs LtAP for regular car?

Thu May 04, 2023 3:30 am

@lapsio

Thanks so much for replying... I really appreciate it.

Well, everything is clear except the antenna part - I have installed my LtAP in the glove compartment and put LTE antenna in the center of the windscreen under the rear-view mirror. The LTE signal was really poor with the internal LTE antenna, which is installed by the manufacturer in LtAP Mini. External antenna did the job, but it takes some space on my dashboard and doesn't look nice :) Some people may wish to steal it, thinking that this is something expensive :D

Is there any solution for boosting the LTE signal? I can't install LtAP Mini on the dashboard, it will definitely be stolen one day...
I'm using magnetic external antennas attached to trunk, outside of car. Cables are routed through rubber seal around trunk. In order to not fuck up car paint I went to detailing shop and they sticked 3 car paint protection foil circles where I have my antennas attached. Works fine.

People are scared shitless when they see those antennas, they think it's some form of bait car with anti-theft gear so it doubles as additional thief detering mechanism xD
 
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Re: LtAP mini vs LtAP for regular car?

Thu May 04, 2023 7:01 pm

LOL :D I would be happy to have something like that... I have found some antennas on eBay. I will start with Laird/Wilson Phantom 4G Multiband Antenna NMO Mount Black TRA6927M3NB. Let's see how it goes

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