How to integrate Solar into an RV electric System

[garyr]

Thanks for allowing me to ask questions.
Ok I have a Sprinter van conversion. The lead acid
battery went dead in half an evening so I decided
to go with Solar...Have not bought the panels yet
have most everything else. See pic if they allow pics.
My question is on the initial wiring. I am not too bright
electrically speaking...well in general so be easy on me.

The van's charging system has an auto switch which directs
the alternators charging to the house batteries once the
vehicle battery is topped off.
Also there is an AC/DC power converter which is auto enabled when
shore power is in use.
The Epever MPPT charge controller Has separate ports to connect
to the battery pos/neg and another to the system load pos/neg
Question: How do I wire the vehicles existing charging systems
incorporating them into the new system?
I may have a related question depending on any advice received here
Thanks Again Gary

 

[12VoltInstalls]

“Last seen July 5”

I didn’t go read your other posts to see- but did you get this off the ground; and figure out how to bypass the wasted load of the on-board converter when not running shore power?

 

[garyr]

Hello,
It all seems to work fine now.
I just use the charge controller to charge the battery now.
Channeled through the bms.
The load then is powered directly off of the battery.
I do not utilize the load side of the charge controller.
Seems to work fine. I have 300 watts of pv on a hinged
rooftop assembly weighing 23 pounds total. Would like another
300 but need smaller size panels.
Does anyone make odd sized panels?
regards gary

 

[Short_Shot]

There are a few goofy panel sizes out there but remember that the total area largely stays the same for a given type of cell or will increase if you use multiple smaller panels.

You also should ensure the new panels are not wired differently such that they result in a different nominal voltage from the other set.

That's a hard question to answer without knowing what you already have in place.

 

[garyr]

A problem just came up. The charge controller just died. Cloudy couple days here and
this morning went out and shunt showed battery level at 11.6v and the charge controller
powered off or dead. The remote meter is blank and the power lights on the coltroler are dark.
300 watts combined Panels are inputting 18-19v into the controller EPEver 40 amp MPPT ...The out to the battery
from the controller shows 0.07 volts.
I am at a loss I think the parameters were undervoltage shutoff 11.6v and the reconnect at 10.5 volts
I am not proficient at electrics so any help here appreciated.

regards

 

[Short_Shot]

Reconnect voltage should be higher than shutoff. Makes no sense to be the other way around.

That would cause it to rapidly shut off then turn back on repeatedly, or on whatever timer it may have. Can't imagine that would do good things to anything attached to it.

You sure reconnect is set so low?

 

[time2roll]

Question: How do I wire the vehicles existing charging systems
incorporating them into the new system?

Mount the controller fairly close to the battery. Connect the controller to the battery direct. Nothing else needs to be moved or changed. Connect the solar panels to the controller. Enjoy the "free" solar energy.

 

[garyr]

Reconnect voltage should be higher than shutoff. Makes no sense to be the other way around.

That would cause it to rapidly shut off then turn back on repeatedly, or on whatever timer it may have. Can't imagine that would do good things to anything attached to it.

You sure reconnect is set so low?

Well I got it working Had to have been The Lord I am not bright enough
When I originally hooked up the BMS it said to run the cc batt negative through the BMS
to the battery.
I touched the battery ground to the charge control batt negative. It sparked and the controller
started working.
apparently when the CC powered off at 10.6 volts it interrupted the negative circuit coursing through
the BMS
That's my story and I am sticking to it.
If I am doing it wrong please advise before I hurt something.
regards gary

 

[12VoltInstalls]

I am at a loss I think the parameters were undervoltage shutoff 11.6v and the reconnect at 10.5 volts

Glad you got it figured out. The bms probably did go to “protect” itself.

The issue I thought I’d mention is either your specs quoted were typed wrong or they aren’t set up correctly in your epever.

Using your numbers it SHOULD be 10.5 shutoff and 11.6 reconnect. However, those numbers are way too low for lead acid batteries if you want to get good life from them/it. I’m pretty sure those parameters are too low for lithium batteries as well. Since you mentioned bms I’m assuming you have (a) lithium battery(s).

If vehicle charging is desired a DC2DC charger can be incorporated.
I like separated house and vehicle starting systems, and don’t like “converter” integrated systems; sounds like you’re setup that way.

 

[garyr]

Thanks for reply
I am thinking the low side parameters are way too low also. Am gonna study that
If I have it figured correctly there are now 3 separate mechanisms to charge the house batteries.
The house and vehicle systems are separate BUT there is an automatic solenoid switch that kicks in when the vehicle
battery reaches full charge, tying the veh alternator to the house system.
Then when you are on shore power there is the 13.6v converter
Then there is the solar
I once thought about running the house strictly off of the house battery and forcing all three "charging"
systems through the charge controller. I mean electricity is electricity and I am thinking that the flow would matter
Am I nuts? Maybe have 3 separate charge controllers?? OR trash the thought???

 

[12VoltInstalls]

Depends on if you have lithium batteries.

 

[garyr]

I am sorry yes they are lithium Iron

 

[12VoltInstalls]

Lithium batteries don’t need or want the higher voltage charging of a vehicle alternator and the ‘converter’ isn’t much better. I’d use a DC2DC charger for the vehicle charging. (I probably would disable the ‘converter’ as far as charging the batteries but I’m probably the fringe: I've never liked converters for anything even before solar was cheap and readily available)

 

[Short_Shot]

Lithium batteries don’t need or want the higher voltage charging of a vehicle alternator.

14.4‐14.6 volts?

Curious that all the lithium chargers run that same voltage then. At the very least during the absorption phase, but some also do during bulk.

Does your alternator run higher than that?

 

[12VoltInstalls]

Alternators can push 15.x volts or more. And depending on the vehicle 150A or more could be available.

I know plenty of people “do fine” on direct hookups to vehicle charging systems and say “it works for me” but my opinion is to not do that. You can if you want to. Lots of people do.
DC2DC chargers are way cheaper than $1200 or $1500 or $3000 of batteries. Ymmv

 

[Short_Shot]

Well. At the very least I agree that a DC to DC charger should be used but if my alt was putting out 15+ volts for any more than a second or two here and there I'd be very concerned about it.

The bigger issue with lithium isn't really the alt voltage as a working alt shouldn't stay that high... ever... but rather the ability of the battery to gobble up every amp it can get.

You kind of touched on it but didn't really point that out.


At any rate I so agree with you that I've had a victron DC to DC charger sitting on my work bench for about a week waiting to be installed.

 

[freans]

Thanks.