12V battery charger question for the experts

[618 Syndicate]

The panel has suction cups, easily removed from whatever window you have it stuck in. My goes in a bag and then a door pocket.
Run the wires out of the floor with a grommet, then caulk if needed.

 

[df2x4]

I wonder if you could use something like a solar charge regulator connected directly to the truck's battery instead of a solar panel? Something like this...

https://www.harborfreight.com/7-amp-solar-charge-regulator-96728.html

I'm not entirely sure if this would work, but it says maximum input voltage of 22V so I doubt the alternator would fry it.

EDIT - Just noticed that one says 100W max solar input... Eh...

 

[someotherguy]

Not trying to charge a truck battery.. these are a little bitty 1.3Ah battery used in wireless tow lights.

Richard

 

[someotherguy]

Orion-Tr Smart DC-DC Charger Isolated - Victron Energy

The Orion-Tr Smart DC-DC charger is a professional DC to DC adaptive 3-stage charger with built-in Bluetooth. For use in dual battery systems in...

www.victronenergy.com

Something like this or there’s another company called Redarc that’s popular among overlanders and other people that require dual isolated batteries

That particular item seems like major overkill for my application but it gave me the keywords I was looking for - DC to DC charger. I was doing dumb stuff like searching 12V to 12V and that wasn't helping. Thanks!!

Richard

 

[LTC_]

One of these should do it. You will need a 16-18 vac transformer to power it up.

Ugh, link is posting as media attachment. Search Amazon for Altronix AL624.

Edir:
Nevermind. Just saw that you're charging off of 12 vdc.

 

[thinger2]

I've got a small sealed lead-acid 12V 1.3Ah battery I need to frequently keep charged (wireless tow lights), and I have some problems to solve around that.

1. The charge cord for the battery is "dumb" and just a simple lighter socket plug-in. If you follow the manufacturer's advice of "you can leave it plugged in all the time" you will kill the battery by over-charging it. Seen it happen many times, you'll leave it plugged in because you forget to unplug it.. boom, seriously shortened battery life.

2. I'd like to source an automatic charger that actually does what it claims. It seems the Battery Tender type stuff still just boils people's batteries to death. The charge cord plugs into a small socket on the bottom of the tow light housing. Whatever suitable charger I might find, I'd just hardwire the output to that charge cord end, and hardwire the input side of the charger to a 12V supply in my truck. There's all kinds of 120V->12V stuff that claims to do this (Battery Tender, Noco Genius, etc.) but I need a 12V->12V solution so it can live in my truck.

The batteries:

You must be registered for see images attach

Any ideas? Thanks!

Richard

You might want to look into marine equipment and post the question on sailing forums.
Battery charging is a real major issue on sailboats.
These days solar seems to be the cheap easy option.
Back before cheap solar was available I just used a battery isolator switch and a dedicated volt meter for each battery.
The battery switch has
Off
Bank 1
Bank 2
Both.
Bank 1 is the start battery
Bank 2 is the "house battery"
Both is both charging.
So you can switch too bank 1 charging or bank two or both etc...
You then wire a dedicated volt meter to each battery but not to " both"
The volt meters are on a switch were you can check battery voltage without putting it online to charge and these days you can buy a voltmeter that will light up when that battery has low charge or full charge or overcharge.
You still need to moniter what is going on but the led volt meter will tell you about it.
If you have an obd2 vehicle and you dont want to loose power if you switch it to off you can just wire all of your start systems as bank 1 and not wire the off side at all.
That still keeps bank 2 isolated but monitered.
But you cant switch banks or add banks while it is running unless you have a way to isolate the sudden load and the potential backfeed if your low voltage is from a shorted battery cell.
That is a whole different problem and would require some type of a diode setup that is way beyond me.
I know you can buy them, I just am not qualified to tell you how they do whatever it is that they do.

 

[454cid]

What about a small inverter and then a battery charger/maintainer like a noco genius1?

 

[Orpedcrow]

Just some spitball ideas here, most laptop chargers are 12v and usually less than 3 amp output.

Of course that’s probably what the current dumb charger is, just an ac-dc converter brick that outputs 12v @ 1.5a or something.

First responder vehicle upfitters come to mind as a possible source.

Also thinking about the little power sources for things like under cabinet lights. I’ve seen some with multiple input sources for different world markets and different use cases, but then again that’s just a source and not an actual smart charger.

Maybe a charger for mobile/portable electronics, think flash lights. My stream light came with a cigarette lighter plug.

 

[someotherguy]

Just some spitball ideas here, most laptop chargers are 12v and usually less than 3 amp output.

Of course that’s probably what the current dumb charger is, just an ac-dc converter brick that outputs 12v @ 1.5a or something.

First responder vehicle upfitters come to mind as a possible source.

Also thinking about the little power sources for things like under cabinet lights. I’ve seen some with multiple input sources for different world markets and different use cases, but then again that’s just a source and not an actual smart charger.

Maybe a charger for mobile/portable electronics, think flash lights. My stream light came with a cigarette lighter plug.

Yeah, when I say the dumb charger is a dumb charger, I mean it's the most basic piece of equipment you might imagine. A plug, a fuse, LED indicator, cord, and plug at the other end. Again this is already a 12VDC->12VDC situation; the charge cord plugs into the lighter socket.

What I'm trying to accomplish is a 12VDC->12VDC solution that is "smart" and won't overcharge the battery. Without having to resort to any exotic means, or complex solutions - I do have a small inverter already that would be perfect to run a NocoGenius or other 120VAC->12VDC smart charger like @454cid suggested, that's not a bad solution, just more pieces to the puzzle than I'd prefer. This is a small battery that just needs a simple, but smart, charging solution.

Richard

 

[RichLo]

One would THINK that leaving it plugged in 24-7 would be "OK" as the batteries should just equalize, yeah? The big battery in the truck charges up the little battery in the tow lights. Maybe I'm misunderstanding something about how that works.

If you do hardwire the batteries in parallel, you cannot let them sit 24/7 when the alternator isn't spinning. Even OEM 2-battery trucks need to be battery matched, AKA, buying 2 brand new batteries with the same build date so they don't drain each other. That is unless you add a marine manual disconnect switch like Thinger2 said. That's exactly what I have in my plow truck, 4-position high-amp manual switch... batt1, batt2, both, off. And they are wired with the negative terminal as the switched side.

There are auto-disconnect switches available when the voltage drops below 13v or something (alternator not spinning) but I don't have experience with those so I cant give advice on them.

Maybe if that dumb charger doesn't have a diode, this is why those batteries die sooner if they are plugged in 24/7... If the little ones are more efficient 12.60v and the truck batteries are built like everything else on new cars 12.50v then the little ones are constantly trying to equalize with the big battery until they are drained to 10% or so and seem dead.