Solar Top Off Estimates

[DoctahDeane]

On this topic sort of - battery recharging - I have a 125A VMAX battery, new. Charged it when I got it. As I've finished this build and electrical, it was down to 12.40 remaining, so I plugged it in. Went put to 12.75 quickly - like an hour, then crept up to 13.1 or so, when I unplugged it. Then ut dropped back a bit to 12.9. I think as I understand it, it'll creep back up a bit now. What number = full charge? I *think* this battery charger ought to shut off automatically at full charge?

Yes, the battery charger will shut off by itself when the battery is charged. You can leave the charger plugged in all the time without worry about overcharging the battery.The voltage will go as high as 14.4-14.7V, depending on the charger but that's okay. I would get a battery meter like this: Battery Monitor if you want to make sure you don't run the battery too low while camping. Judging battery state of charge with a voltmeter is a wet finger in the wind method at best. Just don't put the meter where you sleep, the display back light flashes when the battery charger is charging.

Here's a chart showing the rough battery state of charge versus voltage:



This is enough to keep you from running the battery too low while camping, but it really doesn't tell you much more than that.

Bruce

Exactly what I needed, thanks Bruce. Just wanted simple guidelines - don't go below say 12.3 and leave the charger on overnight at home. Thanks again.

So now, on to solar panel. Wondering if you (or anyone) has a creative idea to make life a bit easier. Please see photos. I have an under trailer box for all electrical and battery. Works fine. It's a bit of a PITA to push back the mattress, open the hatch to do stuff. For battery, I have a plug on the outside of the box so that works well. For solar, I'd like to be able to stick a portable panel outside on the ground and run to the box - ideally without having to open the hatch each time. I see some suitcase panels even have the controller built right in. That would work fine for my purposes. For existing setup (photos) I added two vent holes just to be safe and then on the rear facing exterior, I put boating bilge pump covers over them. So maybe some sort of Start Wars airlock? I know it would not be cool to have cables dangling outside and obviously, want to avoid getting moisture inside. Any suggestions appreciated.

[tony.latham]

...a creative idea to make life a bit easier...

Well... assuming the trailer is wired so that the tow vehicle can charge the battery while towing, you could plug your solar panels into the trailer's pigtail (with a trailer fitting). And that's assuming the panels have a controller.



Tony

[DoctahDeane]

...a creative idea to make life a bit easier...

Well... assuming the trailer is wired so that the tow vehicle can charge the battery while towing, you could plug your solar panels into the trailer's pigtail (with a trailer fitting). And that's assuming the panels have a controller.



Tony

Yeah that's a good suggestion. When I last looked, could not find a panel that would fit on roof next to fan. This trailer is a little narrower than most. That's why I was thinking portable/suitcase version.

[tony.latham]

That's why I was thinking portable/suitcase version.

That's what I meant. A suitcase solar system you'd plug into your camper's pigtail.

Now... if it were me, I'd think about an external connector on the cabin that you'd plug your portable panels into.

With our old teardrop, I had one of these on the front of the tongue box:



https://www.amazon.com/Perko-1190DP0CHR-Marine-Watertight-Connection/dp/B00144B67C/ref=asc_df_B00144B67C/?tag=hyprod-20&linkCode=df0&hvadid=241946017885&hvpos=&hvnetw=g&hvrand=7237606993130404169&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9029516&hvtargid=pla-571845013358&psc=1

That was connected to the $40 controller in the box. It worked great.

Tony

[DoctahDeane]

That's why I was thinking portable/suitcase version.

That's what I meant. A suitcase solar system you'd plug into your camper's pigtail.

Now... if it were me, I'd think about an external connector on the cabin that you'd plug your portable panels into.

With our old teardrop, I had one of these on the front of the tongue box:



https://www.amazon.com/Perko-1190DP0CHR-Marine-Watertight-Connection/dp/B00144B67C/ref=asc_df_B00144B67C/?tag=hyprod-20&linkCode=df0&hvadid=241946017885&hvpos=&hvnetw=g&hvrand=7237606993130404169&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9029516&hvtargid=pla-571845013358&psc=1

That was connected to the $40 controller in the box. It worked great.

Tony

Thanks, Tony. That's exactly what I was asking - looking for an external port like that. I assume the external connector ports are some sort of standard that solar panels use. This will be cool, because I can pout the solar controller in the galley and then a simple run to the battery. Very cool, thanks for clarifying this. Big help.

[tony.latham]

That's why I was thinking portable/suitcase version.

That's what I meant. A suitcase solar system you'd plug into your camper's pigtail.

Now... if it were me, I'd think about an external connector on the cabin that you'd plug your portable panels into.

With our old teardrop, I had one of these on the front of the tongue box:



https://www.amazon.com/Perko-1190DP0CHR-Marine-Watertight-Connection/dp/B00144B67C/ref=asc_df_B00144B67C/?tag=hyprod-20&linkCode=df0&hvadid=241946017885&hvpos=&hvnetw=g&hvrand=7237606993130404169&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9029516&hvtargid=pla-571845013358&psc=1

That was connected to the $40 controller in the box. It worked great.

Tony

Thanks, Tony. That's exactly what I was asking - looking for an external port like that. I assume the external connector ports are some sort of standard that solar panels use. This will be cool, because I can pout the solar controller in the galley and then a simple run to the battery. Very cool, thanks for clarifying this. Big help.

It’s not specifically for solar. You’ll need to put the male fitting on your solar cable. No big deal.

T


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[DoctahDeane]

Thanks again, will do.

[DoctahDeane]

In March or April, I got a 100Ah VMAX rechargeable battery and (about 90% sure of this) used the Noco Genius 3500 charger I got to charge it up to "green" as the manual suggested, then installed it in it's tray. Been using it since, as I get everything working and as I said the other day, battery was down to 12.40, so plugged it in to recharge. I think I left it plugged in for about 8 hours and it got up to 13.00 or so, and maybe dropped to 12.95 when it stabilized. Then I read the manual more carefully and it suggested that it would take quite a bit longer to recharge fully. It is definitely doing that. The blinking lights show progress but it is still not indicating that it's 75% charged as that last light is supposed to be orange and steady. The meter is up to 13.71, plugged in right now. There's nothing wrong except for my expectations that it'd recharge maybe overnight but this has been plugged in now for more like 36 hours. I'm gonna let it run it's course and like I said, nothing seems off. But for those of you with a battery in my size range, when you go away for a few days and come home, how long do you expect it to take to fully recharge? And I guess related to this question, maybe going forward, I should not let it drop below - I don't know...12.50? Everything I've read/heard says don't go below 12.00 and so I thought 12.3 - 12.4 would be very safe. But hey, if it takes a day or two upon return to get back to full power, that's not a problem, especially once I get a solar panel.

It does make me appreciate what electric cars are able to do - like Tesla - when you can quick charge in an hour or so and full charge overnight.

[tony.latham]

Don't let it drop below 12.0 volts. And that reading should be done at least 45 minutes after any usage.

But keep in mind, the battery will last a lot longer if you only use –-for example-- 15% before recharging. That 50% will eat into the duty cycle lifespan.

T

[DoctahDeane]

Don't let it drop below 12.0 volts. And that reading should be done at least 45 minutes after any usage.

But keep in mind, the battery will last a lot longer if you only use –-for example-- 15% before recharging. That 50% will eat into the duty cycle lifespan.

T

OK thanks, Tony. Yes, my working number (from you, another time) was "no less than 12.0 volts." I'll stay above that for sure. I guess i needed to pay more attention to this Noco Genius light panel. Even last night, as it got to green and I unplugged it, I was drifting off to sleep and thought, "wait a minute, I think it was blinking green," not solid. That was true and indicates that it's more than 75% but less than 100% - so wait until solid green. Wow, this will end up having it plugged in for a total of around 48 hours. That seems slow. But like I said, big picture, no biggie as I'm not going anywhere yet. Also, maybe most people are continually topping off from tow vehicle while driving, or solar while stationary? Guess I'd have to do a survey. Anyway, now researching the solar connections you pointed me to. I do like the idea of tapping in to the pigtail but I think I'll end up going in through the body with the port you pointed me to. That seems to offer some more flexibility or at least a more direct line to the battery. Thanks as always. I'm on to the fit and finish stuff and that feels good - not sure what I'm going to end up doing with our dog, for example. This trailer is narrower than most. With the other trailer that I hope to finish the build on, someday, I can have a dedicated dog bed, but this one is going to be more of a challenge and here in the Northeast, you really have to worry a bit about ticks and Lyme disease. Anyway, I had coffee, can you tell?

[tony.latham]

Also, maybe most people are continually topping off from tow vehicle while driving, or solar while stationary?

That's certainly the way I did it with Flash, our old teardrop that still has it's original FLA battery from 2013.

But things changed with this new build. In fact, I hesitated during a sip of coffee to sharing.

I installed a VMAX Group 24. And as we both know, VMAX batts aren't cheap. AGMs are supposed to be charged at something around 14.5V or so and automobile charging systems don't quite put that out. (And I have no idea how "smart" they are. After all, they don't even know they are dealing with two batteries at two different states of charge. And in this case two different types of batteries.)

Now, if you Google around this forum, you'll find plenty of folks that have had good success with charging AGMs off their tow vehicle. For this new build, I chose to wire the battery to the tow vehicle but included a cutoff switch so that normally the charge would only be from the solar panels ––with the controller set for AGM.

Plan A was to turn that switch on for a travel day while we were changing camps and the battery was low because of clouds, shade, or a combination.



The disconnect switch is that big red thing. (And yes, the wires are hidden these days.)

From what I have seen so far, I doubt I'll ever have to turn it on.

Did I overthink this? Ask me in eight years how that old VMAX is doing.



Tony

[DoctahDeane]

Also, maybe most people are continually topping off from tow vehicle while driving, or solar while stationary?

That's certainly the way I did it with Flash, our old teardrop that still has it's original FLA battery from 2013.

But things changed with this new build. In fact, I hesitated during a sip of coffee to sharing.

I installed a VMAX Group 24. And as we both know, VMAX batts aren't cheap. AGMs are supposed to be charged at something around 14.5V or so and automobile charging systems don't quite put that out. (And I have no idea how "smart" they are. After all, they don't even know they are dealing with two batteries at two different states of charge. And in this case two different types of batteries.)

Now, if you Google around this forum, you'll find plenty of folks that have had good success with charging AGMs off their tow vehicle. For this new build, I chose to wire the battery to the tow vehicle but included a cutoff switch so that normally the charge would only be from the solar panels ––with the controller set for AGM.

Plan A was to turn that switch on for a travel day while we were changing camps and the battery was low because of clouds, shade, or a combination.




The disconnect switch is that big red thing. (And yes, the wires are hidden these days.)

From what I have seen so far, I doubt I'll ever have to turn it on.

Did I overthink this? Ask me in eight years how that old VMAX is doing.



Tony

OK yeah, that's what I figured. Interesting for sure. Once I actually become mobile, it'll be fun to watch this stuff as I guess I'm a low-key data nerd. Of course I've now opened up a can of worms because my tow vehicle has just turned 100K and is showing the effects of New England winters underneath. I like what I've heard about your and others's Tacomas and a 6 Cyl makes all kinds of sense. Getting ahead of myself for now, though. First solar and then depending on the outlook for my CRV, I'll add tow vehicle charging or wait until i get something else. Hate shopping for new/used cars so that might be next year.

[DoctahDeane]

I got a very informative answer from Noco Customer Support re: their battery charger and the long amount of time, mine has been plugged in, without finishing off. Thought I would share here. It's rare to get a quick and detailed reply from a manufacturer!

My question - Hi - I have a VMAX 100Ah deep cycle battery. I bought it in April. Since then, I’ve been using it for lighting in my travel trailer as I completed that build and so the other day, the voltage was down to 12/40 so I plugged in the recharger. It took two days to get o the point where the green light was pulsing. I unplugged it at that time but then read in the manual that the light should be steady green to indicate 100% charged, so I plugged back in and left it on the charger for the past 14-15 hours and the green light is still pulsing. Am I doing something wrong?

Reply - Hello Shaun,

Thank you for contacting NOCO Support. Is the green 100% charge level LED flashing on its own, or were the 25%, 50%, and 75% charge level LEDs still lit?

If the 100% LED is the only led that is lit up and flashing (this is true, in my case), then the charger is in Specific Gravity Optimization mode. The 25%, 50%, and 75% LEDs will shut off when the charge is 98-99% complete. At this point, the charger will drop the current while still slowly raising the voltage to the peak voltage. The voltage will continue to slowly raise to the 14.5V in the 12V Norm charging mode, and the current will be less than 1A and should continue to drop. This process helps to give the batteries a full saturated charge, mix the electrolyte fluid, and repopulate the ions to the plates. For some brands of batteries, this process can last longer, or can happen more frequently, but it should not last more than 60 hours. During this time the charger will pulse the green 100% LED by itself. A good analogy is it's like pouring a beer into a glass. You fill the cup and then have to wait for the foam to go down before you can pour more beer into the glass. Then let the foam settle and you can add a little more, and so on.

[John61CT]

Everyone should get au fait with a DMM and ammeter to see exactly what any given charge source is doing, compared to your battery's charging specs.

Some chargers are just "too smart" sometimes, and you need to be able to tell when they are hurting rather than helping, if (when) they are broken. . .

[tony.latham]

...and repopulate the ions to the plates.

Well... there you go. I hope the ions are back in my plates.

I guess those things really are "smart" chargers.

Tony