19v custom camper battery... will a MPPT charge it?

[rruff]

Will a MPPT charge controller work ok with a 19v battery? They say 12v or 24v and that they auto-sense. They also have custom profiles... but does anyone know if any will work with an odd voltage within that range?

Why? Because the biggest load on my system will be a laptop computer (max 300W; it's gaming computer with a video card), which specs 19v input. It's not only the highest max draw in my system, but probably the highest average as well. I'd hoped it would run on 12v (the battery is 3 cell, 11.4v nominal) but it does not. The laptop doesn't actually use 19v internally; rather it takes 19v and converts it to whatever the different components need. I suspect it would run on 24v just fine, since step-down converters usually do ok with a wide range of inputs, but that's kinda risky since I'm not certain.

So... if I built a 19v battery for the camper, the plan would be to use a 19v-12v DC-DC buck converter (these are cheap and very efficient) for 12v loads, which will mostly be lights. Maybe a refrigerator, but I doubt it. Possibly an electric blanket.

 

[john61ct]

No.

Get a 12V car adapter, ideally from the PC mfg.

But there are "universal" ones, all that needs matching is voltage, polarity and plug size

 

[rruff]

No.
Get a 12V car adapter, ideally from the PC mfg.
But there are "universal" ones, all that needs matching is voltage, polarity and plug size

Why do you say no? They don't make any car adapters that put out that kind of power. But it's easy to find a 12v-19v boost converter that will do the job.

I'd just rather not have an extra contraption in the line if I can avoid it, for efficiency and safety reasons. I 100% trust the battery... but I'm not sure what would happen if the converter had a problem. I've run many laptops directly from 12v house batteries, but their internal batteries were lower voltage.

Sounds like a perfect excersise of needless complexity to thrill any Legitimate ExPo Guy.
Ultimately, will be far better off building conventional voltage solar system and use a custom voltage converter to create 19VDC at whatever current that appliance requires.

Ha! ? It really isn't "more complex" though. It is however unconventional.

I'd rather have the simpler and more efficient step-down converter running smaller non-critical loads, and use direct house-battery voltage for the laptop. I'm going to need a converter for one of them, regardless. It's just a question of whether the MPPT can charge a battery that is 19v.

 

[john61ct]

You need to stick to 12V or 24V nominal for your main House bank.

Get a good quality PSW inverter and run off AC if you don't want to mess with DCDC conversion.

Nominal wattage say 500-600W to give some headroom.

But there are great quality converters made by solid traditional Western firms, not expensive on eBay.

Do not use cheap Chinese for any of it.

Another option is an RC Hobby charger, they take DC as input, check out RCGroups for recos you want one where it can work in PSU mode, and with the cell balancing function disabled.

 

[rruff]

But there are great quality converters made by solid traditional Western firms, not expensive on eBay.
Do not use cheap Chinese for any of it.

Could you link to what you are thinking of on ebay? They all appear to be the same Chinese converters: https://www.ebay.com/sch/i.html?_from=R40&_nkw=12V+to+19V++Boost+Step+Up+Converter&_sacat=0&_sop=16

 

[jonyjoe101]

With an mppt controller if it is programmable, you can adjust the bulk setting to whatever voltage you need, but some bulk settings go only so low. But I suspect the laptop probably needs stable 19 volts if it goes too high or low it might stop charging the laptop.
There is a 30a boost converter (paid 25 dollars for it) that I used previously that might work. I never had problems with it but never used it at more then 10 amps. Its a china product but seems well made with a large heatsink, but anything from china if its rated at 30 amps, probably good idea to not use it at more then 15 amps. Definitely install a large fan on it.
Recently I been buying alot of dewalt 20v batteries, I bought some of the larger 10 ah batteries in the 100 dollar range, they sell the adapters (12 dollars) so you can use these as a powerpack for things other then powertools. I only buy the genuine dewalt batteries. quick chargers in the 25 dollar range. 20 volts is close to what the laptop might work with. And the dewalt batteries even the small ah ones are high discharge so they can easily handle a laptop.

 

[john61ct]

Yes seems not so many now, I bet the supply chain, shortages.

Mean Well is good, but a quick search looks like 12/24/48V outputs only.

The fully adjustable lab-style gets too pricey at high amps output.

I think the hobby charger world will keep you under $100

Look at ToolkitRC M6, has a power supply mode, might get up past 300W with 24V input

 

[john61ct]

A buck converter will be more efficient, stick to a 24V House bank

 

[rruff]

Look at ToolkitRC M6, has a power supply mode, might get up past 300W with 24V input

They say 10A max output. Also, a high power 12-19v boost converter is easy to find, but not a step down from 24-19v.

I've searched for people using 24v input on laptops that call for 19v, and nearly everyone says "don't do it, your laptop will die!". But the two people who actually tried it said it worked fine. I did run across one guy who had a faulty converter that output 24v rather than the 19v it was supposed to, and he claimed it killed his laptop battery.

All the converters I see for sale have a wide range of allowable input voltages (like a nominal 24v input is 22-40v allowable), and this is apparently true of at least some laptops... probably most. I'm tempted to try 24v directly and monitor the laptop closely to make sure it functions properly. It would be the simplest way to go.

 

[john61ct]

I wouldn't.

The tolerance will vary a lot from one brand / model to the next.

Just get a decent 500W inverter and use the standard input to the PC.

 

[calicamper]

I would even suggest a standard office upc the computer gets plugged into, then just plug the upc into a basic 12v / inverter setup. Why get silly custom building stuff when theres cheap and reliable stuff easily sourced off the shelf. The upc will do its job of voltage control so the expensive and sensitive computer stuff stays happy.

 

[plh]

With an mppt controller if it is programmable, you can adjust the bulk setting to whatever voltage you need, but some bulk settings go only so low. But I suspect the laptop probably needs stable 19 volts if it goes too high or low it might stop charging the laptop.
There is a 30a boost converter (paid 25 dollars for it) that I used previously that might work. I never had problems with it but never used it at more then 10 amps. Its a china product but seems well made with a large heatsink, but anything from china if its rated at 30 amps, probably good idea to not use it at more then 15 amps. Definitely install a large fan on it.
Recently I been buying alot of dewalt 20v batteries, I bought some of the larger 10 ah batteries in the 100 dollar range, they sell the adapters (12 dollars) so you can use these as a powerpack for things other then powertools. I only buy the genuine dewalt batteries. quick chargers in the 25 dollar range. 20 volts is close to what the laptop might work with. And the dewalt batteries even the small ah ones are high discharge so they can easily handle a laptop.
View attachment 704289

Part number?

 

[rruff]

I would even suggest a standard office upc the computer gets plugged into, then just plug the upc into a basic 12v / inverter setup. Why get silly custom building stuff when theres cheap and reliable stuff easily sourced off the shelf. The upc will do its job of voltage control so the expensive and sensitive computer stuff stays happy.

First... I'm not "custom building" anything. Unless you are talking about the house battery; but I'm constructing that from individual cells regardless, so I can easily make it any voltage I like.

Why not an inverter and UPC and and then the laptop PSU?! That's 3 different contraptions sucking down watts and generating heat and subject to failure, vs... none. I've had UPCs and PSUs both fail and fry computers.

I've run 5 different laptops for years directly off a 12v solar system. Laptops work just fine so long as the voltage input is somewhere within the internal converter's range. If that's the case, hooking them up directly to a battery is the safest way to power them, and definitely the most efficient.

 

[calicamper]

First... I'm not "custom building" anything. Unless you are talking about the house battery; but I'm constructing that from individual cells regardless, so I can easily make it any voltage I like.

Why not an inverter and UPC and and then the laptop PSU?! That's 3 different contraptions sucking down watts and generating heat and subject to failure, vs... none. I've had UPCs and PSUs both fail and fry computers.

I've run 5 different laptops for years directly off a 12v solar system. Laptops work just fine so long as the voltage input is somewhere within the internal converter's range. If that's the case, hooking them up directly to a battery is the safest way to power them, and definitely the most efficient.

Then do that. But why setup a strange 19v system then manipulate stuff designed for 12//24v?

 

[rruff]

Then do that. But why setup a strange 19v system then manipulate stuff designed for 12//24v?

I thought I made that plain in the OP. My biggest load (and most expensive device) says it wants 19v, so it makes sense to have a house battery that supplies that directly. Step down converters from 19v to 12v are cheap and efficient. Thought somebody might know if the MPPT controllers play nice with odd battery voltages, as that's the only potential issue.