Journey Electrical upgrades JJOB

mikerezny

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Thanks Mike...yes I have a J35B in my van, That's what I don't yet know...haven't had the opportunity yet to investigate what the 12v switch actually does. I do know that when i switch it off the monitor panel goes off along with every other 12v light and output, as last time I switched it off even the fridge shut off while on gas.

I wired these batteries in so I know there are no phantom connections anywhere. As I noted above I may just put a proper battery isolator switch between the negative terminal and the shunt....that way I know there will be zero leakage when isolated.

The low voltage disconnect according to the specs for the J35B is 10.8v, + - 2 volts...it does read that there is still a small voltage drain after disconnect of 8 milliamps...obviously to keep the BMS alive.

It is embarrassing actually as I am always all over this stuff...my real problem is I haven't spent enough time in this van off grid to know it, if I add it up I think it is a total of 5 days off grid in all...seriously ...that will change as I am not really a caravan park person.

With my previous camper trailer I ran both a large 12v fridge and a separate 12v freezer, lights, water pump, phone charge etc I knew where every amp went never running low in power...all off solar input...weeks off grid with that and knew it inside out. Same battery set up - 2 x 140 amp AGM's. I used to record morning and evening battery levels along with spot check solar input through the day. I carried a generator but never had to crank it up.

The van should be using virtually nothing as when off grid the fridge and water heater are on gas, it is only a few lights at night, water pump and phones using some power. In reality the puny 160w panel on the roof should just about put all that back in! I'll get on top of it this trip away...take some notes.

I do wish I could keep the van at home as it would make sorting these sorts of things a cinch, but not possible as I live in a Townhouse with shared driveways etc so have to pay to keep the van elsewhere. Any maintenance in storage is difficult or impractical too due to it being squeezed in between other vans, boats etc.

I am going to set this tug up and wire the van after this trip away so that I can charge the van batteries while on the run if I wish as well...
Hi,
I am sure you will get on top of it!
The only difference between your old set up and the new van is that previously, it was probably completely set up by you over a period of time, piece by piece knowing why each new piece as being added, how it was installed, and how it all worked.
Now, it is a little more complicated because it is an entirely new system with a lot of unfamiliar bits and pieces. It is obviously a major impediment not being able to walk outside whenever you want to investigate something and have a bit of a fiddle.
One thing you can do at home is to ensure you have hard copies of the manuals for every electrical device that is in the van and spend some time reading them. If you have any questions, there is unlikely to not be a person or two on this forum who can supply and answer of two to help out.
Is it possible to spend a day and pull the van out from undercover and spend a bit of time becoming familiar with how it all fits together?

We ordered our Penguin and in the months we had to wait until delivery, I was downloading and reading every manual and going out to the dealer and crawling all over ones they had on the yard looking all over it to see how everything worked.
Then when we got it home, I spent endless more hours again becoming more familiar with everything, adding bits and pieces to get it working exactly how I wanted it.

Fortunately, I discovered this forum and in those days I got a lot of assistance in helping me up the steep learning curve.

cheers
Mike
 

Boots in Action

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Thanks Mike...yes I have a J35B in my van, That's what I don't yet know...haven't had the opportunity yet to investigate what the 12v switch actually does. I do know that when i switch it off the monitor panel goes off along with every other 12v light and output, as last time I switched it off even the fridge shut off while on gas.

I wired these batteries in so I know there are no phantom connections anywhere. As I noted above I may just put a proper battery isolator switch between the negative terminal and the shunt....that way I know there will be zero leakage when isolated.

The low voltage disconnect according to the specs for the J35B is 10.8v, + - 2 volts...it does read that there is still a small voltage drain after disconnect of 8 milliamps...obviously to keep the BMS alive.

It is embarrassing actually as I am always all over this stuff...my real problem is I haven't spent enough time in this van off grid to know it, if I add it up I think it is a total of 5 days off grid in all...seriously ...that will change as I am not really a caravan park person.

With my previous camper trailer I ran both a large 12v fridge and a separate 12v freezer, lights, water pump, phone charge etc I knew where every amp went never running low in power...all off solar input...weeks off grid with that and knew it inside out. Same battery set up - 2 x 140 amp AGM's. I used to record morning and evening battery levels along with spot check solar input through the day. I carried a generator but never had to crank it up.

The van should be using virtually nothing as when off grid the fridge and water heater are on gas, it is only a few lights at night, water pump and phones using some power. In reality the puny 160w panel on the roof should just about put all that back in! I'll get on top of it this trip away...take some notes.

I do wish I could keep the van at home as it would make sorting these sorts of things a cinch, but not possible as I live in a Townhouse with shared driveways etc so have to pay to keep the van elsewhere. Any maintenance in storage is difficult or impractical too due to it being squeezed in between other vans, boats etc.

I am going to set this tug up and wire the van after this trip away so that I can charge the van batteries while on the run if I wish as well...
Some more info for you @Hitting the road . When my solar "farm" (1 X 180w and 2 X 200w portable solar panels in series) is charging battery after a bit of use, the displays on my MPPT controller show all sorts of valuable info. Also, I have a separate volt meter across the battery terminals even though this info is displayed on MPPT controller. Just because your battery voltage shows 13.2 volts on charge ??? does NOT mean that battery is anywhere near fully charged when charging! When charging from my panels, battery voltage eventually rises to 14.6 volts (max charge setting) even with a 2 to 3 amp load on at times and MPPT display shows "boost" or "MPPT" charging. After a while, controller shows "FLOAT" at 13.7/8 volts which is close to the FLOAT setting for battery I have on controller. So you should expect to see up to the charging voltage as set on BMpro or on your MPPT controller also when charging. Later, it should also drop to Float voltage as set, subject to battery temp if you have a sensor on battery, otherwise the controller uses 25C as default . In cold weather, battery temp in my van as per MPPT controller can be as low as 10C and on hot days as high as 26C. Unlike @mikerezny's frugal power use, my daily use in summer can be as high as 40ah and in winter around 25ah. This info from my MPPT controller is available every morning for checking before I reset readings to zero. What sort of MPPT controller do you have, as if any good, will provide you with a lot of info without going to extra costs???

And there is truth in the information that "continuous float charging" is not in the best interests of battery health, even with the latest "smart" chargers. Continuous float charging of a fully charged battery tends to corrode the positive plates. It is stated that it is best to discharge battery (AGM types anyway) to around 80% capacity or thereabouts and then recharge fully, than it is to discharge lower to say 60% capacity and then recharge. Discharge a little and recharge immediately and frequently?? If possible.
Battery voltage in my van usually stays around 13.0 volts after charging and stays there for many days unless there is some load placed on electrics. To test battery capacity to hold a charge after letting battery settle down for an hour or so after charging, turn on a couple of lights (low loads) and see if battery voltage holds. If voltage drops away at all, that is an indication of insufficient charge or a failing battery.

Some battery charts for your AGMs may be helpful to you.
 

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Hitting the road

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Many thanks Mike for your valuable comments...I will have a read of the manuals that came with the van giving an insight in to amperage of each item. I haven't really carried out any audit of power usage through the day / night at all with this van

Things I am aware of but not looked in to, the gas water heater will use power when igniting, probably a fair bit, the fridge will also have a small drain happening as it maintains it's power even though on gas. The fans in and at the back of the fridge will use power if operating. Water pump, lights, radio if on or TV if on of course, and phone charging all use power from the batteries. Lats time all of these were in play at some point.
I'll definitely spend serious time next week getting to know the power setup and usage a whole bit better, I am leaving too much to chance me thinks. The power failure was a wake up call.

Thanks Graham too for your input...much appreciated. I'll set up a separate voltage reader across the terminals as you have independent of the solar regulator, makes good sense. I'll be making a trip to jaycar later today to pick up what I need to install next week.

The MPPT solar regulator I have fitted isn't a fancy name brand unit, it is a Powertech I bought from Jaycar, 12v/24v 30A with Lithium battery capability. It accepts up to 450w and up to 80v solar input. My "solar farm" is made of a supposed 250w panel and a 200w panel...both folding aluminium framed things, though realistically I reckon they are probably about 180w each regardless of what the reseller's claim. Though I can get up to 38v going to the regulator as I run them in series rather than parallel. I use solid high current cabling I made up to connect the system.
I do also have another 200w blanket I could easily hook up as well if I wanted to to add another 18v - 20v to the input on a good day...and of course the van has 160w on the roof. feeding in to the BMS.

It was the first time I put these panels out last trip as have been on powered sites so haven't collected any data as yet,..they are the same panels and same model MPPT regulator that I had in the camper trailer as well as the same battery pack type of 2 x 140A AGM's.

I will be upgrading the total setup eventually, it'll probably mean removing the J35B and replacing it with a newer better BMS that is Lithium capable for the future Lithium upgrade. Will have to do some serious home work on that as it will be expensive.
 

Boots in Action

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Many thanks Mike for your valuable comments...I will have a read of the manuals that came with the van giving an insight in to amperage of each item. I haven't really carried out any audit of power usage through the day / night at all with this van

Things I am aware of but not looked in to, the gas water heater will use power when igniting, probably a fair bit, the fridge will also have a small drain happening as it maintains it's power even though on gas. The fans in and at the back of the fridge will use power if operating. Water pump, lights, radio if on or TV if on of course, and phone charging all use power from the batteries. Lats time all of these were in play at some point.
I'll definitely spend serious time next week getting to know the power setup and usage a whole bit better, I am leaving too much to chance me thinks. The power failure was a wake up call.

Thanks Graham too for your input...much appreciated. I'll set up a separate voltage reader across the terminals as you have independent of the solar regulator, makes good sense. I'll be making a trip to jaycar later today to pick up what I need to install next week.

The MPPT solar regulator I have fitted isn't a fancy name brand unit, it is a Powertech I bought from Jaycar, 12v/24v 30A with Lithium battery capability. It accepts up to 450w and up to 80v solar input. My "solar farm" is made of a supposed 250w panel and a 200w panel...both folding aluminium framed things, though realistically I reckon they are probably about 180w each regardless of what the reseller's claim. Though I can get up to 38v going to the regulator as I run them in series rather than parallel. I use solid high current cabling I made up to connect the system.
I do also have another 200w blanket I could easily hook up as well if I wanted to to add another 18v - 20v to the input on a good day...and of course the van has 160w on the roof. feeding in to the BMS.

It was the first time I put these panels out last trip as have been on powered sites so haven't collected any data as yet,..they are the same panels and same model MPPT regulator that I had in the camper trailer as well as the same battery pack type of 2 x 140A AGM's.

I will be upgrading the total setup eventually, it'll probably mean removing the J35B and replacing it with a newer better BMS that is Lithium capable for the future Lithium upgrade. Will have to do some serious home work on that as it will be expensive.
@Hitting the road , if your MPPT controller has a display and you have all the loads (except heavy demand electrical appliances like inverters) wired through your MPPT controller, you will be able to see what the battery drain on all your individual equipment is - from lighting, water pump to phone and Ipad chargers etc. Also any "parasitic current" leakage as one of our members discovered. Electrical connections are fully set out on a previous post. Something to think about?
 
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Hitting the road

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Thanks Graham, I'll start a spread sheet later today once I set up camp, Though as I'll be on a powered Park site there won't be much to record as such. But what I can do is monitor what appliances are in use and for what period of time to get an overall picture. Then at the end of the week when we move to the unpowered camp I'll have a base line to start with and can begin monitoring usage.
I can use as you suggest the readout from the MPPT regulator as it does have a reasonably good spread of info available on screen...
Cheers
 
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Drover

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Actually being hooked up to power is not a bad thing if you can shut down the battery charging, then your only using 240v for stuff that you would use LPG for and can leisurly see what each item is drawing .....Originally many moons ago I just hooked my multi meter inline and turned on one thing at a time to see what it drew, then did some maths to work out what was needed for a normal day and honestly not much has changed from as a few years ago when I used the fancy dancy screen on my solar reg to do an audit, if I get up during the night I have a squiz at the screen to see what the batteries are at, they have regularly shown good so don't bother with it very much now..... looking at your storage, your panels I would say cover it well unless you stuff up when you plug them in you should be good as gold having more than most have in store.... No sense going camping if you are just going to watch numbers on a screen.....

Swapping out a BM Pro for another just to use lithiums is an expensive way to go all round especially if using mostly a portable panels set up... I would just get a MPPT reg thats Lithium capable, of course lots of research as lots of ripp offs in that area, disconnect the roof panels from the BMpro and just us ethe MPPT reg with the portables pluggable when needed, lots cheaper and probably more efficient ..... and if your solar is done properly then no real need for a 240v charger but a bench charger is a lot cheaper than a whole system rebuild....

Dabbled in series or parrallel but since I can plug my portable into the main MPPT reg or use the portables own reg parrallel is less hassle and I can add more juice instantly...
My rig sitting there doing nothing in camp draws about 1a thats fridge running, internal fan and external, gas detectors and the breaksafe drawing a charge, that draw is covered by solar on a rainy day, the HWS starting up is bugga all ... parked up with just breaksafe charge and gas monitors its at .4a ............ of course things like the STB's and TV/radio are shut down when not used never left on stand by and phones unplugged, also inverter is only on when in use and shut down when not, many folk leave stuff on stand by which can chew a lot of juice. I don't even like the blue lights on USB ports, its an uneeded draw as well as annoying and all the little bits add up.... like extractor fans, its a van open the bluddy window....
 

Hitting the road

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Still away, but have things working OK. After having the batteries on charge prior to leaving for around 40 hours they were floating at 13.4 volts when picked up. Then for the next 4 days on shore power sat at 13.4 volts.
Off grid since Friday, I put out my panels and they have stayed at 13.5v as they are being charged by the MPPTwhich is set at 13.5v.
No problems at all.. though I will need to set up a charging system for on road...
 

Boots in Action

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Still away, but have things working OK. After having the batteries on charge prior to leaving for around 40 hours they were floating at 13.4 volts when picked up. Then for the next 4 days on shore power sat at 13.4 volts.
Off grid since Friday, I put out my panels and they have stayed at 13.5v as they are being charged by the MPPTwhich is set at 13.5v.
No problems at all.. though I will need to set up a charging system for on road...
Sounds good @Hitting the road. Noted that you have achieved 13.5 volts when you put the panels out. Hopefully that setting is for your FLOAT voltage and not your maximum CHARGE voltage which should be around the 14.7 volt mark. Does your MPPT unit have user settings or are they just default settings?? Check battery voltage when charging, say first thing in morning. You will never get batteries to full charge with a 13.5v charging limit.
 

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Hitting the road

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They do hit as high as 14.6v briefly then fall back to 13.5 and just "float" at that number all day. I had mucked about with the MPPT settings so hopefully now is all good. I'll likely muck around with it some more next time out...but I was also a little more prudent with power usage this time, recording battery levels morning and evening as well as the power draw of all the electrical.
The batteries would be around 13v in the mornings before any sunlight hit the panels, and would charge, then be full and floating back at 13.5v by 8am with sunlight on the panels...
 
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Boots in Action

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They do hit as high as 14.6v briefly then fall back to 13.5 and just "float" at that number all day. I had mucked about with the MPPT settings so hopefully now is all good. I'll likely muck around with it some more next time out...but I was also a little more prudent with power usage this time, recording battery levels morning and evening as well as the power draw of all the electrical.
The batteries would be around 13v in the mornings before any sunlight hit the panels, and would charge, then be full and floating back at 13.5v by 8am with sunlight on the panels...
Sounds like you now have things under control @Hitting the road .
 
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Drover

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13v in the morning well nothing wrong there, my lot can be down around 12.4 at 0500 dark and thats nothing to be worried about..... so your cruising along quite well really.......... once the sun hits the panels though its not showing a SoC.............. Now you can just enjoy being away and think about things to do with Jeeps....
 
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Hitting the road

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...I did find out that the water heater does draw power even while on gas...0.7A continuous. Obviously it requires power for the initial ignition, but must use a solenoid to keep the gas tap open while running, but will close the gas supply if the heater flame goes out. That's potentially up to 16A of power being wasted if left going all day.
So rather than leave the water heater going all day I now turn it on 15 mins before I need hot water.
The strip lights in the van above the sink and lounge also I found pull 2.5A, so if not needed turn them off....the strip light in the awning and the single lamp on the outside of the van will use 0.5A continuous, a couple of mobile phones on charge will use 1A per hour, but leave them on charge all night potentially that is 12A gone.
The water pump uses 3A while in use, so that too with a couple of showers a day plus washing up etc would take another few amps from the system...

I know why i ran out of power now, after starting with batteries that were not fully charged. Of the 140A I should have had available of the 280A battery pack, I probably had less than 100A to use before the BMS shut down the system at 11v.
 

Drover

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Ah Ha, your eyes are now open...........................
Correct about the HWS the gas solenoid requires juice to stay open and the heat sensor uses 3/100ths of a poofteenth of a amp as well but more important off grid you only turn the HWS on 20 mins before you want it and really only for shower, kettle will do for dishes, the gas you save by only turning it on when needed is quite a bit...... power is renewable daily, gas aint.... as you dig deeper you will see what each little thing uses and why you must turn everything off when not in use, my TV system of TV, 2 x STB's alng with powered speakers all runs from a master panel ( a 4switch light panel) that way I can just turn all off or individual units on, if you switch the stuff off with a remote they are on stand by and still draw juice.....
Once you do an audit, note that you should only use X amount at most a day and it leaves a reserve your set, then you just have to learn to turn stuff off and forget about it.....

Also batteries like solar panels the amount of storage/output is not quite Kosher when you read the fine print you will find that a 100ah battery isn't really, more like 95ah so only 47 usable and then thats a maybe, while they all rabbit on about 50% usable if you work on 40% you are probably close to real world, I work on a 30% that way I have a reserve and like engines and spring not flogging the daylights out of things, longer life ....

Also restrictions like 400w of solar applies to what is coming down the line not what amount of panels is hooked up, you could have 800w of panels and still not hit the the mark
 

Hitting the road

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Yeah, the scales have cleared from my eyes now...lol. I'll take that on board with the 40% usable as that is more realistic for sure...so the 40% of 280A is in reality around 112A...not 140A as I was thinking.
Of course the batteries do degrade over time as well which will see them offer even less as time goes by. If I can't limit my usage to that I am in real trouble. More time needs to be spent off grid to get a clearer picture for sure.
I did fit the shunt to the system when away but not the Bluetooth hook up as I was slack and more keen on chilling out than stuffing around in the van.

Solar is ok I think, being I have according to the "sellers", 1 x 200w and 1 x 250w panel...I rate them both as maybe 180w each, but they do produce around 43v on a good day to be converted to amps as required.
I also boil the kettle for dishes using my little camp stove I cook on outside rather than use gas as you write...I'll be all over it soon...lol
 

mikerezny

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Have you measured the current draw of the fridge when running on gas?

Charging phones etc will draw about 1A each but that will drop off quite a bit once they are charged. I would charge them during the day and take them off charge as soon as they are topped up.
 
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Hitting the road

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There was zero draw registering with the fridge running on gas...there would have to be something though as the fridge will turn off if the 12v is disconnected, so it must be very small.

Yes, I'll be charging phones through the day when possible in future while there is solar input.
 
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mikerezny

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There was zero draw registering with the fridge running on gas...there would have to be something though as the fridge will turn off if the 12v is disconnected, so it must be very small.

Yes, I'll be charging phones through the day when possible in future while there is solar input.
Hmm, that is interesting about the fridge draw. Just be aware that if you have external fridge fans, they will draw current when they are running.
Once your batteries are on float you will have excess solar capacity. So any power you use comes for free and avoids needlessly using battery capacity when there is no sunlight.
During good sunlight, I charge all our phones and an iPad as well as cycling through all the rechargeable batteries in our lights and torches.

If we are parked up for a week or so, I also put the panel on the car battery to top it up. We rarely use the car once we are set up. Probably overkill. However, we flattened the car battery over a five day stay, mostly due to leaving the glove compartment lid down. Further, everytime we opened a door all the interior lights would come on and stay on for a while. I read the car manual and found a setting to turn off all the interior lights!
 

Boots in Action

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Hmm, that is interesting about the fridge draw. Just be aware that if you have external fridge fans, they will draw current when they are running.
Once your batteries are on float you will have excess solar capacity. So any power you use comes for free and avoids needlessly using battery capacity when there is no sunlight.
During good sunlight, I charge all our phones and an iPad as well as cycling through all the rechargeable batteries in our lights and torches.

If we are parked up for a week or so, I also put the panel on the car battery to top it up. We rarely use the car once we are set up. Probably overkill. However, we flattened the car battery over a five day stay, mostly due to leaving the glove compartment lid down. Further, everytime we opened a door all the interior lights would come on and stay on for a while. I read the car manual and found a setting to turn off all the interior lights!
Agree with you Mike @mikerezny about charging all accessories (and battery) when plenty of sun producing lots of solar charging. I usually do that sort of thing first thing in the morning because I never know what the afternoon brings and before darkness occurs. Usually all lights and phones and Ipad are fully charged by noon and battery in Float charge.
One thing for all the experts that has always been a conundrum for me is what takes precedence - powering accessories or battery charging?? Say a 12 amp load on accessories and a 15 amp charge coming in through the MPPT controller where all loads are wired through the MPPT controller and not taken from battery terminals. Does the 12 amp accessory load get fully powered first leaving the balance of 3 amps available going to charge battery/ies, or is their some sort of uneven split with portion of the loads being supplied by battery?? My MPPT controller is able to maintain Float voltage of 13.7 volts whilst supplying a load of 3 amps or so when sun is out, but what happens when battery is low??? Never checked this out when in the field. Might have a go next time to prove the point!
 

mikerezny

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Agree with you Mike @mikerezny about charging all accessories (and battery) when plenty of sun producing lots of solar charging. I usually do that sort of thing first thing in the morning because I never know what the afternoon brings and before darkness occurs. Usually all lights and phones and Ipad are fully charged by noon and battery in Float charge.
One thing for all the experts that has always been a conundrum for me is what takes precedence - powering accessories or battery charging?? Say a 12 amp load on accessories and a 15 amp charge coming in through the MPPT controller where all loads are wired through the MPPT controller and not taken from battery terminals. Does the 12 amp accessory load get fully powered first leaving the balance of 3 amps available going to charge battery/ies, or is their some sort of uneven split with portion of the loads being supplied by battery?? My MPPT controller is able to maintain Float voltage of 13.7 volts whilst supplying a load of 3 amps or so when sun is out, but what happens when battery is low??? Never checked this out when in the field. Might have a go next time to prove the point!
This is my understanding.
When the solar is kicking in and providing a charge, the controller will be attempting to bring the terminal voltage to the desired level, be it bulk charge at something about 14.6V or float at something like 13.8V. If the terminal voltage is lower than the desired voltage, the controller will be extracting as much power as can be used to get the voltage up. i.e, the system will be limited by the maximum power that can be supplied by the panels.
Now consider this case first and add in the possibility of running accessories at the same time. Lets make a dubious assumption that the accessories will draw the same current regardless of whether the terminal voltage is 12V, 14.6V or anywhere in between. Then is obvious that the current going into the battery will be the difference between the current supplied from the controller minus the current supplying the accessories.
If there is more current available from the controller, it will go into the battery to charge it and bring the voltage up. If not, then the extra current will be taken from the battery and the battery will be discharging and the terminal voltage will be going down.

Second case is when the battery voltage is up to the level desired from the controller. The controller will now be operating in voltage mode and current will only be drawn from the panels to maintain that terminal voltage. If an accessory kicks in, it will reduce the terminal voltage below the desired voltage, and the controller will kick into current mode and attempt to pump enough current into the system to bring the voltage back up to the desired level. If the panels can supply enough current, the terminal voltage will stay the same and the accessory will be supplied from the solar panel. If not, then the system reverts back to the first case until the terminal voltage it back to the desired level.

Clear as mud!

cheers
Mike
 

Boots in Action

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This is my understanding.
When the solar is kicking in and providing a charge, the controller will be attempting to bring the terminal voltage to the desired level, be it bulk charge at something about 14.6V or float at something like 13.8V. If the terminal voltage is lower than the desired voltage, the controller will be extracting as much power as can be used to get the voltage up. i.e, the system will be limited by the maximum power that can be supplied by the panels.
Now consider this case first and add in the possibility of running accessories at the same time. Lets make a dubious assumption that the accessories will draw the same current regardless of whether the terminal voltage is 12V, 14.6V or anywhere in between. Then is obvious that the current going into the battery will be the difference between the current supplied from the controller minus the current supplying the accessories.
If there is more current available from the controller, it will go into the battery to charge it and bring the voltage up. If not, then the extra current will be taken from the battery and the battery will be discharging and the terminal voltage will be going down.

Second case is when the battery voltage is up to the level desired from the controller. The controller will now be operating in voltage mode and current will only be drawn from the panels to maintain that terminal voltage. If an accessory kicks in, it will reduce the terminal voltage below the desired voltage, and the controller will kick into current mode and attempt to pump enough current into the system to bring the voltage back up to the desired level. If the panels can supply enough current, the terminal voltage will stay the same and the accessory will be supplied from the solar panel. If not, then the system reverts back to the first case until the terminal voltage it back to the desired level.

Clear as mud!

cheers
Mike
Thanks Mike @mikerezny , that is logically thought out, and how I had suspected things to go. That means that when my MPPT controller is "Boost" charging, the voltage is the deciding factor. At say 14.3 volts (trying to get to 14.6 volts) , a charging current of 12 amps could be displayed, whilst at the same time there could be a load discharge of 5 amps also displayed. I will have to check to find out if the charge display on controller is the nett figure (12 amps) available to charge battery AFTER suppling the 5 amps for the load. That would mean that the GROSS output from panels at the controller would have to be 17 amps?? I can easily measure this with my Clamp meter on leads from panel next time out.

Surprised a fellow camper late in the afternoon when he said his solar charging for his van battery was finished for the day - he only had a single 160watt panel and a cheap PWM controller. He was amazed when I showed him my MPPT display showing Float at 13.8 volts and still supplying 2.7 amps for loads (small fans running in fridges and charging a small insect zapper light).
But his jaw really dropped when I put my Clamp meter across input line from panels and it showed only 0.68amps coming in. Had to explain to him that as I had my 3 panels in SERIES, that tiny amperage was at 56.2 volts providing me with approx 38 watts, which my MPPT controller converted to approx 2.7 amps at 13.8 volts. Hence the power of having higher voltage and very low line losses. He went away mumbling about MPPT type controllers and how he "must get one!"