Question About solar charging

[abslayer]

I have a concern about adding 160w solar power to my TC charging system.
What happens when plugged into shore power and both systems the TC charging and solar charging are both charging battery's at same time or for that matter also when going down the road and truck is also charging TC.
What stops battery's from being cooked.
Is there something I need to know about this Guys ??

[Redsky]

Be sure you have enough battery capacity to justify 160 Watts of solar. I have two 110 AH 12v batteries and my 200 Watts charges them back on average in 3 hours. The two batteries seldom are discharged more than 22% regardless of the season.

[DiploStrat]

trail-explorer wrote:

DiploStrat wrote:
-- Similarly, half, but not all, of the comments and suggestions that you find on websites are simply wrong...

DiploStrat wrote:
....for use outside of the U.S. where most current is 240v.

referring to 240v VOLTAGE as CURRENT is wrong, just sayin'.

Voltage and Current are two different things, just like an apple is not an orange.

Trust me, I know the difference between voltage and amperage quite well. The common expression is that the "the current in the U.S. is 110 and the current in the UK is 240."

To your point, the current to most houses in the U.S. is provided at 120v.

[svjim]

There is a lot to learn about solar power as others have stated. Here is one of the best tutorials on solar that I have found

Here is another one

[trail-explorer]

DiploStrat wrote:
-- Similarly, half, but not all, of the comments and suggestions that you find on websites are simply wrong...

DiploStrat wrote:
....for use outside of the U.S. where most current is 240v.

referring to 240v VOLTAGE as CURRENT is wrong, just sayin'.

Voltage and Current are two different things, just like an apple is not an orange.

[trail-explorer]

abslayer wrote:
I have a concern about adding 160w solar power to my TC charging system.
What happens when plugged into shore power and both systems the TC charging and solar charging are both charging battery's at same time or for that matter also when going down the road and truck is also charging TC.
??

Nothing happens, other than the fact that the batteries simply charge up faster because there's more than one source charging them.

THey won't "cook."

A battery will only accept the amount of current it requires to become fully recharged.

[sabconsulting]

RoyB wrote:
sabconsulting - Steve I have been looking into the BLUE SEA SI-ACR smart relay available here in the states for charging an added battery bank in the back of my truck bed that can be used for additional radio comms in the truck or combined to the my off-road POPUP trailer to add additional batteries as needed.

When only used in the truck I can use this BLUE SEA SI-ACR 120AMP smart relay that will sense the batteries and direct the Truck Alternator charging flow where needed. Looks like this does about the same as your identified CTEK smart relay and should work equally well using SOLAR as one of the 12VDC inputs..

BLUE SEA SI-ACR RELAY

This unit is available from AMAZON for less than $100

Roy Ken

It looks like a good product, though it is fundamentally a smart relay.

The difference with the CTEK DC-to-DC dual charger (and similar but heavier duty products from Stirling Power and other suppliers) is that rather than simply connecting the batteries together it is an MPPT and therefore uses switch-mode electronics to trade off volts against amps. It adjusts its output voltage and current to the optimum for the point in the stage of the charging cycle it has reached (it has 5 different stages - desulphation, bulk, absorption, float & pulse). The really clever part is that when the solar panel produces higher voltage than is usable for charging, the electronics take that current at the higher voltage and transform it into the ideal (lower) charging voltage at a higher current maximizing the power extractable from the solar panels.

I believe it also does the inverse - e.g. where the wiring from the alternator to the camper can carry sufficient current, but the resistance of the wiring causes a voltage drop to a voltage at which the camper battery won't absorb that much current. Again the MPPT can make up for that, trading some of the previously unusable current for higher voltage to get a combination of current and voltage that will put the maximum charge into the camper battery. Very clever stuff really.

Steve.

[okan-star]

abslayer wrote:
Thx for responds have PM some of you.
Things that I am concerned with is camper on board charge systems have a bad habit of boiling battery's dry.

And if solar has battery at full charge and then I plug into shore power, converter will also be attempting to charge my camper battery
What will happen??:?
My TC is a 2012 Adventure 980 RDS
I am installing 160w solar system camper has 2 group 24 battery's
Will upgrade when they die.

If your camper has a converter not "smart" enough to only provide
power to a storage level, and maintaining it by going to float level as required and not cook the battery as a trickle charge or old magnaflex or other old converter would thats a seperate issue that you should deal with by changing converters or if its a progresive dynamics converter add a charge wizard if one is not built into it

A solar charge controler will not bypass power to the battery once it sences its reached its preset max level

[abslayer]

Thx for responds have PM some of you.
Things that I am concerned with is camper on board charge systems have a bad habit of boiling battery's dry.

And if solar has battery at full charge and then I plug into shore power, converter will also be attempting to charge my camper battery
What will happen??:?
My TC is a 2012 Adventure 980 RDS
I am installing 160w solar system camper has 2 group 24 battery's
Will upgrade when they die.

[Shadow_Catcher]

We have a Progressive dynamics converter and a Morningstar MPPT controller and they play well together.

[DiploStrat]

I have been doing a lot of research on this very subject. My truck has:

-- 600Ah of batteries
-- 500w of solar panels
-- 250A of alternators
-- No genset

So far, all is working very nicely, but I have discovered that:

-- Most people in the RV world have absolutely no interest in, or understanding of, solar systems.

-- Similarly, half, but not all, of the comments and suggestions that you find on websites are simply wrong, especially when you move to systems of over 200Ah. (sabconsulting being a happy exception.)

I have written a paper on the problems of large electrical systems in a camper and am about to write the second paper, a selection of things that do seem to work. While my truck has 2800w Magnum Inverter/charger, it was specifically designed never to need to be plugged into shore power, especially for use outside of the U.S. where most current is 240v.

Shoot me a PM with your e-mail and I will be happy to share.

All the best.

N.B. The Blue Sea line of ACR's are excellent products, but they do NOT perform the same functions as a CTEK or Sterling Power battery to battery (also known as a DC-DC charger). Depending on a number of including the age of your truck and the size of your batteries, one will be better than another for your case.

[RoyB]

sabconsulting - Steve I have been looking into the BLUE SEA SI-ACR smart relay available here in the states for charging an added battery bank in the back of my truck bed that can be used for additional radio comms in the truck or combined to the my off-road POPUP trailer to add additional batteries as needed.

When only used in the truck I can use this BLUE SEA SI-ACR 120AMP smart relay that will sense the batteries and direct the Truck Alternator charging flow where needed. Looks like this does about the same as your identified CTEK smart relay and should work equally well using SOLAR as one of the 12VDC inputs..


BLUE SEA SI-ACR RELAY

This unit is available from AMAZON for less than $100

Roy Ken

[sabconsulting]

You should not need to worry about overcharging the battery, providing of course you have installed a solar controller and not somehow wired the panels directly into your battery.

So over-charging should not be a problem.

There might be a question about how efficiently the different charging sources interact with each other - i.e. are you getting the optimum charging power from the combination of sources? I have a pretty small single battery in the camper and don't get much sunlight, so I have to worry about this, but most people wouldn't need to be as concerned.

My understanding, and feel free to correct me, is that your truck alternator will push out a regulated voltage sufficient to charge your starting battery. That voltage will drop a bit by the time it gets down the much longer wire to your camper battery, however, it will still charge your camper battery and in doing so that battery will show an elevated voltage. This elevated voltage will probably make your solar controller think the battery is 100% charged, so it may well shut down - this is how it avoids over charging your battery.

If you are plugged into shore power then I guess the converter will also be attempting to charge your camper battery. Depending upon how sophisticated it is it might just act like an alternator, and supply a continuous but safe charging voltage, in which case the solar controller would likely also see the elevated voltage at the battery as indication the battery was full and again shut itself down until that voltage drops. Or the converter might contain clever electronics like the solar controller. In the latter case I'm not sure which power source would win.

My solution, which is probably overkill for most people, was a DC-to-DC intelligent charger from CTEK. This has 2 inputs - one from the alternator and one from the solar. It uses a Max-Power-Point-Tracker (MPPT) algorithm to work out at any given time what is the best voltage to supply to the battery, and it can combine the two voltage sources (solar and alternator) to achieve that. I was concerned about how adding a shore power charger would affect this, but when I looked at CTEK's wiring diagrams they showed a configuration that allowed for adding a CTEK intelligent mains voltage charger in parallel with the output from the DC to DC charger, so that is what I did (I don't have a converter, or not one that I could trust). One thing that is different with this set-up is that I removed the charging relay which isolated the camper battery from the truck battery when the engine was off - the DC to DC charger provides this function and as a bonus it monitors both truck and camper battery and if the camper battery is fully charged will divert solar power to charge the truck battery.

As I said though, you don't need all this - I am just trying to get the most out of my charging system as I can.

Steve.

[RoyB]

The solar panels will have their own CONTROLLER that will sense the batteries and take care of them for you... Once your batteries get past the 90% charge state the solar controller will drop back to float mode keeping from over charging them.

I am also in the planning stages of installing solar panels and will probably have a switching arangement to keep from having both solar panels and shore power charging the batteries at the same time.

I will only be using my solar panels when camping off the power grid so no need to have them engaged when I am on shore power.

just my thoughts.
Roy Ken

[KD4UPL]

There's no problem. The charge controller regulates the solar charging. The TC converter regulates it's charging. The truck alternator, combined with all the long, small wiring in the truck and camper couldn't overcharge your battery anyway.
If you have 3 furnaces in your house, each with a thermostat set to 70 degrees will your house get to 210 degrees?