3 charging methods, 1 battery bank, Selector switch?

[regis101]

I'm wondering if it is wise to be able to have a means of switching the charging source(s) to the battery(ies) to prevent backfeed?

One source is the vehicle alternator.  Second source would be shore power 3-4 stage charger.  Third source would be solar.

The alternator to aux battery has an isolating solenoid that is ign key activated so that can be perhaps eliminated from the equation.

Is it generally acceptable to have the shore power charger and solar controller pos+ wires simply hard wired to the battery?

Maybe I'm over thinking this?

 

[John61CT]

Yes, no problem.

Except if you ever want a switch between Alt and load dump (e.g. hidden service isolate battery bank), make sure to buy one with AFD feature and have it wired correctly.

 

[tx2sturgis]

I'm wondering if it is wise to be able to have a means of switching the charging source(s) to the battery(ies) to prevent backfeed?


Is it generally acceptable to have the shore power charger and solar controller pos+ wires simply hard wired to the battery?

There is no 'backfeed'...the chargers all have diodes and/or circuits that wont let that happen, as long as the batteries remain hooked up. In fact, most solar controllers warn against having input from the panels and no batteries hooked up. Not a good plan.

Yes, just connect the chargers to the batteries.

You CAN use switches, depending on where, and when, you want power available, for various loads and lights, etc.

 

[regis101]

Thanks guys. When I view google images, hundreds of real time pic's and pic's of hand drawn schematics come up. I do notice lots of pics with a multi position marine type switch. I notice lots of hard wiring also.

I did read in the manual of the new to me Renogy solar kit that the battery(ies) must be hooked to the controller before tying in the solar panels. I was planning on having the solar system mostly portable with the controller attached to the panels and plug into the vehicle mounted battery bank with a bulk head connection but it seems better to have the controller permanently attached to the battery and have the panels plug into it via the bulk head connection.

As for the Samlex 1215 charger, same goes I guess. Hard wire it also to the battery but perhaps have the 120v receptacle switched so I don't make the mistake of having solar and shore power charging at the same time.

Don't laugh. It can and I'm sure it has happened.

 

[John61CT]

that would not be a mistake, no problem at all

 

[John61CT]

Bank switches are good to isolate them completely, simple On-Off

Also 1-2 switches to connect a certain load, like Starter, to one bank or another.

Combine is pretty outmoded, best to hardwire all charge sources to House, then use a combine/isolator/relay to feed Starter.

 

[Trebor English]

All can charge at the same time.  It is unlikely that you will have enough solar, shore power battery charger and alternator that it will damage the battery by charging too fast.  All those sources have a voltage limit.  Only one will be the highest.  When you first start to charge a depleted battery it can and will take a lot of current.  Everyone has the problem where there aren't enough amps to meet the demand.  In very short order the battery voltage goes up and the amps drop.  

Now if you turn off the battery to the alternator it can, if you don't kill the field first, wipe out the alternator diodes.  If you turn off the battery to the solar controller with sun lit panels it can destroy the controller.  Shore power battery chargers generally aren't damaged by disconnecting but your electronics plugged in might be wiped out disconnecting the battery from the charger.  

All on is fine, turning things off can cause damage.  Avoid doing that.

Fuses disconnect things.  Make sure the connections have big enough fuses so a fuse doesn't turn off your charging device.  That will cause the same problem as a switch.  Remember, a big fuse should only be used with a big wire.

 

[regis101]

* All on is fine, turning things off can cause damage.*
New concept and duly noted.

 

[LoupGarou]

Yes!

Having them all connected is ok. Your next question will be how to do it. You'll need both positive and negative connections. A BlueSea DC Power buss is your friend.

 

[tx2sturgis]

Yes, dont make things difficult and try to re-invent the wheel.

BTW the Samlex 1215 is a decent, reliable unit. I run 3 of them.

Just tie the solar controller and the samlex to the batteries. When there is no solar, and the samlex is on 120v, it will do the charging.

When there is solar, and the samlex is on 120v, the solar controller will do most of the charging assuming it has more amps available, or if not, they will both contribute to the charging of the batteries.

If there is no 120v shore power, but there is solar, then of course the solar controller will be feeding the charge to the batteries.

You could use a manual disconnect to the starting battery, or some folks use a continuous duty solenoid.

If you REALLY want to get complicated, there are some microprocessor controlled charge management systems available, but they are NOT cheap.

https://powerwerx.com/emergency-vehicle

 

[regis101]

* When there is solar, and the samlex is on 120v, the solar controller will do most of the charging assuming it has more amps available, or if not, they will both contribute to the charging of the batteries. *

Brian, If I may.  What is your opinion on the Samlex 1&2 dipswitch settings for 2 or 3 stage charging when solar is also connected?

I read in the manual that if the Samlex is charging and the battery is drawing a 12v load, i.e. fridge, radio, lights, fans, then the dip switch(es) can be set to not over voltage.  Makes sense and one of the reason I went with them.

If solar is also charging simultaneously , what is your opinion of dip switch setting?  

After this, I'm pretty much on it.  I should be wiring things up shortly.  Next coupla weeks is shortly for me.

The vehicle starting battery is not part of the equation

Thanks everyone.

 

[tx2sturgis]

Leave them both OFF.

This is for battery with load.

At least on mine, yours could be different, a later model maybe.

Two of mine are so old they dont have switches and are 2 stage.

The later model with switches was used in my old Class A, and I left it on 2 stage all the time.

ProStar in trailer, reading 13.8 on charger only, no solar:



Samlex in trailer, on:



Bottom of Samlex, 2stage, no switches:



Garage, ceiling mounted, for maintaining motorcycle batteries:



3 stage, later model, both switches OFF:

 

[Weight]

Now if you turn off the battery to the alternator it can, if you don't kill the field first, wipe out the alternator diodes.  If you turn off the battery to the solar controller with sun lit panels it can destroy the controller.  Shore power battery chargers generally aren't damaged by disconnecting but your electronics plugged in might be wiped out disconnecting the battery from the charger.  

I can't find any reference that the solar controller will be destroyed. The advice to connect batteries before panels is to avoid shocks, or other unpleasant things, do-to high voltage surges possible with full sun on panels. The same with disconnection. The alternator can blow a diode, if both batteries are disconnected while charging. As long as the set up doesn't disconnect the alternator from the starter battery I don't see a problem disconnecting the house bank.

 

[John61CT]

The alternator can blow a diode, if both batteries are disconnected while charging. As long as the set up doesn't disconnect the alternator from the starter battery I don't see a problem disconnecting the house bank.

Yes, but a switch with AFD is best, long as it's properly wired.

 

[regis101]

It might be so that nothing will happen to the controller, from any vendor. I won't chance it however.
The Renogy manual has large red lettered warning sections about having the battery connected first. I will heed that call. It only takes 1/2 amp to kill a person.

 

[Trebor English]

There was a thread on reddit vandwellers about a person in England with a solar electric system.  Like in the sunnier US the professionals and experts aren't all so competent.  They wired the MPPT controller to the battery using two 7.5 (wrong) amp fuses near the controller (wrong), one in the power lead, one in the sense lead (wrong).  As winter turned to spring the 300 watt as I recall, panel produced more.  It blew the fuse.  The MPPT controller then had panel power and no battery.  That fried the controller.  The goofy display and failure to charge made it clear the controller was dead.  The replacement controller, fused correctly, fixed the failure to charge.