59 replies to this topic

[buckland]

With the ACR in there, it's logic is "Is there charging voltage available?"  If YES, then connect the two systems.  Your solar panel and MPPT are putting out 14.84V.  That will flow into the batteries for sure, and if the LiFePo4 battery is fully charged, then the current will flow into the truck battery.

 

This is one of the reasons I like the manual switch on my ML-ACR 7622.  To disconnect if I want to.  

 

Also, you could lower the "charged" and "float" voltages in you MPPT settings, that would reduce this effect, but not eliminate it.

 

Also, I think you don't have a Victron BMV, do you?  With that you could at least confirm the LiFePo4 house battery's SOC and see any current flow.

Vic on this thought, If I left the key in the on position in the truck, everything like lights, radio, fan all off, just the ignition on, would the solar on a good sunny day send enough juice through the ACR too keep the battery from running down?  

The reason I ask.... sounds nuts I know but one needs to make adjustments at time.

We live in a rural spot where there is no internet... but there is a Cell tower that we get 2 bars. I got a $20/month hotspot wifi in my truck through Onstar (even though I don't have an account)... that gives me over 20 gig data. I wired a Battery Tender 4 amp with a plug through the grill. If I park close to the house I can connect to the wifi spot with my laptop in the den... and then screen share to TV!  (The tender is like the police use to keep the electronic gear on in their cars when parked). 

So I was wondering if the solar output through the ACR would be sufficient to keep it charged if the truck was on during the day. Or for that matter while camping (in sun). 

Edited by buckland, 21 June 2020 - 06:02 PM.

[ntsqd]

To answer that you'd need to know what the total draw is from the truck being just turned on and compare it to the average power supplied by the solar system.

 

Suggestion: If the hot spot will work in the ACC position I'd use that instead of IGN-on. The ACC position doesn't power up a bunch of stuff that you don't need running when you're using the truck this way.

[Vic Harder]

Vic on this thought, If I left the key in the on position in the truck, everything like lights, radio, fan all off, just the ignition on, would the solar on a good sunny day send enough juice through the ACR too keep the battery from running down?  

The reason I ask.... sounds nuts I know but one needs to make adjustments at time.

We live in a rural spot where there is no internet... but there is a Cell tower that we get 2 bars. I got a $20/month hotspot wifi in my truck through Onstar (even though I don't have an account)... that gives me over 20 gig data. I wired a Battery Tender 4 amp with a plug through the grill. If I park close to the house I can connect to the wifi spot with my laptop in the den... and then screen share to TV!  (The tender is like the police use to keep the electronic gear on in their cars when parked). 

So I was wondering if the solar output through the ACR would be sufficient to keep it charged if the truck was on during the day. Or for that matter while camping (in sun). 

What Thom said is true, you need to know the total draw of all the accessories that are on when you are using your hotspot.  (pretty clever!).  

 

As rando said above, the "watts" in to your battery will give you a pretty good idea of how much power is available during daylight hours.  So, let's say your truck uses 50W when powered.  50W/12.3v = 4A or so.  And let's assume you leave it on all day.  That's 24h*4A = 96AH.  And let's say you get 8 hrs of usable light... during those hours you would need to put out at least 96/8=12A.  12A * 12.8V = 154W of solar (assuming 100% efficiency).  

 

So, a 250W solar array should be easily able to keep up with your draw.  BUT... 

 

You need to have enough battery capacity to store the power coming in so that it can be used at night.  Your truck battery is not LiFePo4... so you need about 2x your draw to keep the truck battery from draining below 50%... So your truck battery would need to be 200Ah.  That's a big truck battery!

 

Or to look at this another way, let's say your PV panel kept up with the draw all day, but then the sun goes down, and you draw 12hrs at 4A = 48AH.  And you want to start the truck in the morning?  Hmmmm.

Edited by Vic Harder, 22 June 2020 - 02:27 AM.

[buckland]

Ya I was hopeful but realistic. The set up currently until we get access to internet has worked. With the quarantine and stay at home my wife has had to do a bunch of zoom meetings and that would have been impossible with just our iPhone. It works BUT... in the winter it is a PITA. After 20 years of promises our town decided to do its own internet infrastructure ...it has taken 3 years of work (only 1000 people in town) ... they were smart enough to spend a bit more and have strung Fiber Optic cable instead of DSL. It is now on all the poles in town and I dug a 500 foot trench across our field to get to the closest pole and installed a conduit for the line to be pulled through to the house...... and now we wait (again) .... with the lockdown no one is allowed to enter houses to install....! Should hopefully happen in the next month.....maybe ....and if so it will be strange.... like getting indoor plumbing or electricity for the first time. We are way behind in what people watch streaming.....20 years behind!

[Vic Harder]

Can you leave the LiFePo4 camper battery in the system?  It would easily keep up with your demand and allow the truck to start when needed.

[buckland]

Well Vic I thought the ACR kept both batteries, camper and Truck connected while the solar panel is making electricity. Filling the camper battery then sending excess to truck battery?
So I would think that at most my fridge is on (isotherm) which uses very little , so thought that there would be plenty solar extra to maintain the truck with the key on (WiFi does not work on accessory).
Just ruminating.

[Vic Harder]

Yes, the ACR keeps the batteries connected if there is a charging voltage detected.  At night, that isn't the case so they would disconnect and only the truck battery would be trying to keep the wifi hotspot running.

 

If you could provide a trickle charge to batteries at night, then that should keep them connected though.

[pvstoy]

Your wifi is powered with key on. Could you temporary find the hook up and hot wire it to the battery for using it. Then wire it back to key on when done? That way you would,d not have to have the key on. It probably draws much amps and need the alternator to keep it happy.

Edited by pvstoy, 24 June 2020 - 11:28 PM.

[buckland]

Thanks guys living in the boonies I only use the internet as a chore in that it isn’t there all the time. So I choose a time to get things set up to do the chore of being online. When a friend still sends me a 20 Meg photo of some silly thing .... what most folks don’t even think about... it sends me over the edge. I click the usage like a person on a boat monitors fresh water.
This too will pass one day. My curiosity in asking was academic... as I have thrown that idea overboard. I will wait for the future arrival of tech folks have had in Timbuktu for 20 years. I’m not boo hoo-ing ... I have fresh water. Folks in Flint ... now that is worse.

[ntsqd]

Space-X's fleet of mini-satellites? OR Viasat's existing competitor?