Charging battery bank via solar and alternator simultaneously?

dwh

Tail-End Charlie
If FWC is still using the 30amp iota, it advertises 14.2v absorption and 13.6 float, no programmability. Hmm.

Depends on if it has the IQ/4 brain module. Without it, an Iota is a 2-stage - bulk, then float, no absorb. With the IQ/4, it will bulk to 14.8v (fine for the Odyssey), then drop to 14.2v for an absorb (it'll work, but it's a bit low for an Odyssey) for 8 hours then float at 13.6v. One nice thing about the IQ/4 is that every 7 days of float, it will trigger and run through all three stages again (they call that "equalization", but it's not the true equalization like what would be done to a flooded battery).
 

dwh

Tail-End Charlie
Just food for thought, but a simpler and less worrisome design would be to have a relay in between the solar system and the alternator. The relay coil would be energized by 12v ignition ON voltage. So then the battery bank would normally default to solar charging, but when ignition and engine is on, charging comes from alternator. This is what I am doing on my vehicle.

That is neither simpler nor less worrisome. :) It's also not needed. That's an either/or setup - alternator or solar. Without it, if the battery is low, then both solar and alternator can supply current.

Also, say with an Odyssey that wants 14.7v, and a programmable solar charge controller that is set to 14.7v. If the voltage regulator on the truck isn't set that high, then the alternator+solar can push the battery up to whatever point the voltage regulator shuts down the alternator, but the solar will keep pushing until the battery reaches 14.7v. If you cut out the solar while the truck is running, that won't happen unless the engine is shut down.
 

brianjwilson

Some sort of lost...
Just food for thought, but a simpler and less worrisome design would be to have a relay in between the solar system and the alternator. The relay coil would be energized by 12v ignition ON voltage. So then the battery bank would normally default to solar charging, but when ignition and engine is on, charging comes from alternator. This is what I am doing on my vehicle.

Thanks for the idea. It did occur to me initially to be able to turn off the solar charge if it would be problematic. But with the solar controller at 14.7v, I'm assuming (once again) that the alternator won't regularly get that voltage to the batteries or all the way back to the solar controller. Time will tell. I feel like none of my other rigs showed more than 14.1/14.2v charging, but I could be wrong! I'll have to see what it's doing on the tacoma when I'm back home.


I think I'll roll with this plan and see what the results look like. Since FWC pushed my delivery date back another six weeks I won't have anything to do with it until the end of July. :( I guess it keeps me from spending money on batteries for now, seeing as I don't have a way to keep them properly charged on the truck yet!
 

dwh

Tail-End Charlie
or all the way back to the solar controller.

That sounds like you are thinking in terms of voltage drop. Don't.

Voltage drop is deceptive. It's important when running loads from a battery, but pretty much irrelevant when charging a battery.

You have to keep in mind that voltage drop is a function of load. So if you calculate a voltage drop of X with a load of say, 20 amps, that's one thing, but as the battery gets full, the amps flowing drops to almost nothing - and the voltage drop goes away. In other words, by the time the battery gets full, there is no voltage drop.

It works the other way when running loads - as the battery voltage goes down, the amp load increases, and so does the voltage drop.
 

unseenone

Explorer
The way it actually works with my setup, when you start the vehicle, the solar system goes into "float" almost immediately. So the two systems coexist happily. I guess you just need the right systems, My main concern is that the vehicle charging system might have been fooled into thinking the batteries were charged, and no charge them, and end up with nothing being charged. Everything behaves properly.. some pics of my setup here.
 

bjayf

New member
If you add a charger, can you have all three hooked up at the same time?

I have the same setup as brianjwilson and I'm about to install a NOCO G26000 to keep the batteries charged in winter. There's no sunlight here so the solar panels aren't doing what they used to in the summer. Can I just hook up the charger and leave in connected even if I start the vehicle? It seems like the solar controller will be fine, but will the alternator and charger be fighting each other or will the regulators in both figure it out? It would be running that way for too long but I want to make sure I'm not going to damage something if I turn the van on before I unplug the NOCO.

I would assume a 2015 truck will have a computer controlled voltage regulator which will adjust voltage based on several variables. If it's temperature compensated as well, it might go to 15v or more in the cold. So I think that "14v" assumption is probably not valid.

Certainly a good shore power charger would keep them in top shape - as long as it was programmable or was made to do an Odyssey charge profile. No way would I want to leave that job to a regular ol' RV converter, which are notoriously crappy and dumb.
 

dwh

Tail-End Charlie
I have the same setup as brianjwilson and I'm about to install a NOCO G26000 to keep the batteries charged in winter. There's no sunlight here so the solar panels aren't doing what they used to in the summer. Can I just hook up the charger and leave in connected even if I start the vehicle? It seems like the solar controller will be fine, but will the alternator and charger be fighting each other or will the regulators in both figure it out? It would be running that way for too long but I want to make sure I'm not going to damage something if I turn the van on before I unplug the NOCO.

Answered on other thread.
 

dwh

Tail-End Charlie
Thanks a lot for your help. Didn't know you were in on that other conversation.

I'm a "new posts" user (or "what's new" in the mobile version of the site). Every new post in every thread shows up in the new posts list.

I just happened to see the one in the other thread before I saw this one.
 

Bbasso

Expedition Leader
My system works just like dwh described in this thread.
It's awesome and despite its complexity it's so simple.
 

brianjwilson

Some sort of lost...
For what it's worth since the thread was revived. I had no issues with this setup. The only downfall I think was having the starter battery and house batteries in different "climates" and no temp sensors.

On my current sprinter build I went with a ctek d250s with smart pass, and 300 watts of solar. Yet to be installed. I thought it might be nice to have one unit controlling everything on a daily basis.
House battery is a lifeline 8d. Additionally I have a magnum 2000w inverter/charger with remote control.
 

DLTooley

Observer
Your wiring and controller configuration makes a difference. Voltage drop between the charger and each individual battery is a factor. I **think** the biggest issue is making sure your solar cuts off when charging the **starter** battery. My setup requires a separate solar controller at the starter, I used my old $10 charger for this as I don't often do extended drives.

Done properly I think solar will help extend the life of the starter battery, providing that tail charging that the alternator does not.
 

DLTooley

Observer
Oh, just did my educational research on an ACR - consider my contribution a 'cheapo' alternative to accomplish same.
 
Have a similar concern hoping someone can add info.

I have a charge controller connected to my battery and panels on that. All is great shuts power off from the panels when charged and connects power from the panels when needed. To this i want to add an Alt. feed to supplement the solar when it either isn't putting out or cant put out. Im not worried about the battery or anything "behind" the controller but in regard to the panels themselves.

Will it be safe for the solar panels so see this feed from the Alt. or will a power supply on the panels some how "blow" them out (basically running the Alt and Solar in parallel into the controller)? Im assuming that it should be fine since if panels are wired together and some get sun but other dont, some would "see" voltage from the others and they are fine, but anyone know for sure?

Diagram of how I want to hook this up is attached.

TIA for any help
 

Attachments

  • Untitled.jpg
    Untitled.jpg
    14 KB · Views: 64

Forum statistics

Threads
185,527
Messages
2,875,544
Members
224,922
Latest member
Randy Towles
Top