ATV Charging... am I overthinking this... or?

[Rednecktek]

So I've got a small solar system in my pump house and 2 ATV's that are going to live up there in the near future. What I think I want is some sort of charging system tht will take power from my 12v system and do all the fancy absorption/equalization/etc functions that keep the FLA batteries in the ATV's happy while they're sitting in the shed for months on end untouched.

What I've got installed so far:
1x 120Ah AGM battery
1x 120Ah FLA battery (I know, but I had them already)
20a Weize MPPT SCC with 20a available on LOAD ports
2x 100w panels in series, west facing (I'll work on remounting it when the inspectors aren't looking)
28w of 12v LED lighting
USB/Cigar block (to feed the phone and speaker, gotta have TUNES!)

What I think I'd like is a basic 2-5a battery tender that would feed from 12v and do all the maintenance functions, but they don't seem to exist soooooo....

I can think of 3 ways to keep the ATV's topped up, all of them have their Pro's and Con's and I'm on a serious budget so take that into account please.

Option 1: Load Terminals -> DC Fuse Block -> pigtail -> ATV
Pro: Uses what I have on hand already, cuts charging to the ATV's if winter really, REALLY sucks and the panels can't keep up via Low Voltage Cutoff.
Con: Just provides a constant voltage source of power, no other functions.

Option 2: Load Terminals -> DC-DC Converter -> pigtail -> ATV
Pro: Should provide all the maintenance functions needed, sources from existing 12v system.
Con: Most expensive option as each DC-DC converter is going to be about $100 and I don't know if I can do both pigtails from the same converter OR if I'm going to need a DC-DC converter for each ATV. Options I'm looking at are Renogy 20a DC-DC, the Atem Power 20a DC-DC, or the Kanruis 20a DC-DC units. 20a should be WAY more than I need for the little batteries but I don't see them any smaller really.

Option 3: Load Terminals -> DC Fuse Block -> Magic 12v source battery tender -> pigtail -> ATV
Pro: Would provide all the maintenance functions I'm looking for, should be cheaper than the DC-DC converters?
Con: No luck finding battery tenders that don't require mains power.

So y'all, any ideas for an Option 4 or a 12v based tender or am I overthinking this whole project? I really don't want to have to replace ATV batteries every time I head up there. That gets expensive fast!

 

[bluespur]

A small cheap inverter running a mains voltage battery maintenance charger ? Most of the maintenance chargers seem to be mains voltage input.

 

[Rednecktek]

A small cheap inverter running a mains voltage battery maintenance charger ? Most of the maintenance chargers seem to be mains voltage input.

I don't have mains power up there and I really want to avoid getting an inverter involved just to drop it back to 12v.

 

[Checkthisout]

Easy.

1) Use a trailer breakaway battery charger. It's nothing more than a diode. Juice will flow into your atv batteries from your solar setup but not back out.
Hopkins 20007 Break Away Battery Charger https://a.co/d/gsCKutD

2) Use this 12V DC to DC charger if you want all the functions Tekonsha 2024-07-S Heavy Duty Quick/Maintenance Multi Stage Charger https://a.co/d/ccAroXv

3) Take the batteries out and take them home for winter.

Your atv batteries are agm. They don't need equalization.

 

[Rednecktek]

Easy.

1) Use a trailer breakaway battery charger. It's nothing more than a diode. Juice will flow into your atv batteries from your solar setup but not back out.
Hopkins 20007 Break Away Battery Charger https://a.co/d/gsCKutD

Sounds like it has a hard time getting 2a and I'd like to be able to get more charge if possible, but it's an option. I don't see anything in the description about doing all the maintenance I want though.

2) Use this 12V DC to DC charger if you want all the functions Tekonsha 2024-07-S Heavy Duty Quick/Maintenance Multi Stage Charger https://a.co/d/ccAroXv

Sticker on the box says 800ma, not near enough.

3) Take the batteries out and take them home for winter.

Kinda defeats the point of having them there, especially as I don't really have a home when I'm not there, I'm a sailor and my home rocks with the waves.

Plus, I'm usually only able to get there in winter.

Your atv batteries are agm. They don't need equalization.

Nope, I poured the acid in myself, they're FLA.

 

[Checkthisout]

Sounds like it has a hard time getting 2a and I'd like to be able to get more charge if possible, but it's an option. I don't see anything in the description about doing all the maintenance I want though.

Sticker on the box says 800ma, not near enough.

Kinda defeats the point of having them there, especially as I don't really have a home when I'm not there, I'm a sailor and my home rocks with the waves.

Plus, I'm usually only able to get there in winter.

Nope, I poured the acid in myself, they're FLA.

You also pour the acid in yourself on atv AGM batteries.

Post a link to what make/model of batteries they are.

Option A, you can buy as many of those and parralell them as you see fit if you want more amps. Equalization on a battery tender is 14.4 volts. Option A the atv batteries voltage will track with charge controller voltage.

 

[Checkthisout]

FYI, the renogy DC to DC charger does not do what you think it does.

It does not raise output voltage higher than input voltage, among other things.

It does the exact same thing as option 2 that I posted but is sized for RV house batteries.

 

[Vigo]

If you want 'multi-stage charging' and customizable setpoints etc etc, here is what i would do.

Load ports > 12v to 15v dc-dc converter > $10 pwm SCC > battery.

Basically, a device to step voltage up enough for charging, a cheap adjustable charge controller to turn that into 'adjustable multi stage charging', still cuts off based on your MPPT load port settings.

You can get the converter and the pwm scc for <$30 total on Amazon.

There are a lot of statements about not using anything but solar panels as inputs on pwm SCCs but i've done what i'm saying here and it works fine. The only thing you would need to do is make sure that the 12v side of the 12 to 15v converter pulls less than 20amps. I would just buy a 10amp version.

Also, i think you'd be surprised how little current you need for this job. That 800ma charger would be fine to float one, or maybe even both of those batts.

 

[Substrate]

This is exactly what you are looking for. An Optimate TM-500v3
Then again, I'm Optimate biased if you've ever seen my other posts.

https://www.amazon.com/Tecmate-Optimate-TM-500v3-Battery-maintainer/dp/B08CHCBZN3/ref=sr_1_1

2A dc-dc rockin' charger. Just clamp it onto your existing battery. A true charger from a long established company, and smart enough not to drain the "source" battery dead. No settings to get wrong.

Pricey, but so are all good quality tools.

 

[Checkthisout]

This is exactly what you are looking for. An Optimate TM-500v3
Then again, I'm Optimate biased if you've ever seen my other posts.

https://www.amazon.com/Tecmate-Optimate-TM-500v3-Battery-maintainer/dp/B08CHCBZN3/ref=sr_1_1

2A dc-dc rockin' charger. Just clamp it onto your existing battery. A true charger from a long established company, and smart enough not to drain the "source" battery dead. No settings to get wrong.

Pricey, but so are all good quality tools.

Does that charger increase voltage higher than its source voltage? In other words if it's hooked to a 12.8 battery, will its output be increased so it can go through all the charging steps?

 

[Vigo]

It doesn't specifically say so in the listing, but the markings on the device, and some of the diagrams farther down in the listing, make it clear that it CAN step up voltage.

It might say something specific about that in writing in the actual owner's manual, but i didn't look that far. Sometimes amazon listings have links to the documentation at the bottom of the listing so you don't have to google it.

 

[Checkthisout]

It doesn't specifically say so in the listing, but the markings on the device, and some of the diagrams farther down in the listing, make it clear that it CAN step up voltage.

It might say something specific about that in writing in the actual owner's manual, but i didn't look that far. Sometimes amazon listings have links to the documentation at the bottom of the listing so you don't have to google it.

Where do you think it shows the voltage being stepped up?

Edit: Manual says source must be stable between 11 and 16 volts so yes it looks like it steps up voltage.

 

[Vigo]

Well, im reading between the lines a little bit because there are no 12v batteries (in common use, that i know of) that are actually fully charged at 12.0 volts. The device doesn't say 12.8v on it, but the listing title does, and there is a line on the side of the box (not in english) about 12-13.2v which suggests it can charge batteries with 'resting' voltage in that range, while the device itself says 12-16v input. I don't think it would say 12v input, say 12.8v in the title, and 13.2v on the box, if it couldn't step up voltage. Then there's the pics in the description which, in spite of the direction of the arrows not making sense, seems to suggest stepping up voltage.


So it's really just me using background knowledge to read a bunch of context clues. In general that's not a safe way to deal with ads that might not just be poorly written but actively deceptive. But since i am VERY confident that no brand that has any actual legal accountability in the US market sells a '12v' battery charger that won't output over 12.0v on US Amazon, that combined with the other small clues was enough to make me certain that this can step-up voltage while just skimming the ad. If i wanted to buy it id find the manual and read it (which you did!), but from the sidelines i'm still 99% certain based on those combination of factors.

 

[Substrate]

Yes, this is a real charger. Depending on which part of the world you live, you may see it also listed as the the DC-DUO. It is ORANGE to make it easy to identify from the rest of their normal ac-chargers.

The manual can be see here. Click on documents. The manual will be seen right under it:

OptiMate DC-DUO - OptiMate

The DC to DC battery charger is the ideal off-grid charger and maintainer for 12V lead-acid or 12.8V Lithium batteries. Click here to visit!

optimate1.com

 

[Checkthisout]

It doesn't specifically say so in the listing, but the markings on the device, and some of the diagrams farther down in the listing, make it clear that it CAN step up voltage.

It might say something specific about that in writing in the actual owner's manual, but i didn't look that far. Sometimes amazon listings have links to the documentation at the bottom of the listing so you don't have to google it.

We have a butt load of batteries to maintain.

What is your overall opinion of those Tecmate tenders (not just the dc to DC).

 

[Substrate]

Supreme. But anything I have to say would appear like salesmanship, and hotly debated by those who very rightly, have their own - usually lower priced - preference, because "trickle charging" is not really deemed important. Yet done improperly, it is the trickler that kills your batt, rather than extend it's life.

Put it this way - it doesn't use CC/CV. It uses CC but the optimization stage is there for a significant purpose - not just to show another jaggy "stage" on a pamphlet. Float mode brilliantly simple to overcome major problems we nerds used to fight over during the "float voltage wars". (which got so bad when vendors actually participated with us in the public usually ran away, and simply stopped publishing their specs.)

It is in a slightly different category than other chargers, because it truly does *analyze* and react differently than others. Hence the higher price.

 

[Checkthisout]

Supreme. But anything I have to say would appear like salesmanship, and hotly debated by those who very rightly, have their own - usually lower priced - preference, because "trickle charging" is not really deemed important. Yet done improperly, it is the trickler that kills your batt, rather than extend it's life.

Put it this way - it doesn't use CC/CV. It uses CC but the optimization stage is there for a significant purpose - not just to show another jaggy "stage" on a pamphlet. Float mode brilliantly simple to overcome major problems we nerds used to fight over during the "float voltage wars". (which got so bad when vendors actually participated with us in the public usually ran away, and simply stopped publishing their specs.)

It is in a slightly different category than other chargers, because it truly does *analyze* and react differently than others. Hence the higher price.

We have some rather spendy GIL batteries for the airplanes that have been nuked by other chargers.

Would you use this Tecmate brand on a $1200.00 24V battery?

 

[Substrate]

NO - they are NOT aircraft rated. Aircraft batteries such as GILL, Concorde and others have specialized needs - one reason is that to be an aircraft starter, the acidity level in their electrolyte is very high. Each manufacturer has slightly different voltages and algo's.

If you have a GIL, (or Hawker or Concorde) and are looking for a good charger/maintainer, then head straight to Battery MINDER (Not Battery Tender) AIRCRAFT section:

Aircraft Battery Charger | BatteryMINDer

VDC Electronics has a selection of aircraft battery accessories to offer. Visit our website to learn more about our available products.

www.batteryminders.com

Most should come with the "on the battery" temperature compensation probe. If not, get one!

 

[Checkthisout]

NO - they are NOT aircraft rated. Aircraft batteries such as GILL, Concorde and others have specialized needs - one reason is that to be an aircraft starter, the acidity level in their electrolyte is very high. Each manufacturer has slightly different voltages and algo's.

If you have a GIL, (or Hawker or Concorde) and are looking for a good charger/maintainer, then head straight to Battery MINDER (Not Battery Tender) AIRCRAFT section:

Aircraft Battery Charger | BatteryMINDer

VDC Electronics has a selection of aircraft battery accessories to offer. Visit our website to learn more about our available products.

www.batteryminders.com

Most should come with the "on the battery" temperature compensation probe. If not, get one!

That is what we have now. Those big hulking batterminders. Thanks for validating our choice.

 

[Substrate]

At least now you know I'm not an Optimate schill ! I mean, my battery-nerd's honor is at stake here.

Check this out - a guy mounted the orange Optimate to his solar setup. Just clamped to his main battery.

Note: his use of the other manufacturer's "quadlink" would not be recommended for their normal ac chargers, as they perform timed testing from time to time, and this splitter would confuse that test.