AC charger for all in one portable build

[lblt]

[font=arial, helvetica, sans-serif]I am interested in building a small capacity setup ala the goal zero yeti 150 or 400. I have read a couple of people's parts lists who are attempting to replicate the yeti a bit cheaper. None of them provide a provision for charging from 120 AC, they just have solar charge controllers. I have tried to search here and elsewhere what charger to use. Some people say "just use a battery tender" or an automotive charger. Some say that an automotive charger will not provide the proper charging profile. I am also wary of using a car or trickle charger because of the bulkyness or potential inability to include it in a self contained portable unit. I would like To put everything in small toolbox or suitcase, perhaps ammo
can so i can unplug from the van and easily carry inside somewhere to charge from a wall outlet whenever i want.[/font]


[font=arial, helvetica, sans-serif]I am looking at using a single 12 to 35ah SLA or AGM. I have modest power needs: a couple led bulbs, a muffin fan, and my phone to charge.[/font]
[font=arial, helvetica, sans-serif]Thanks for the help in advance[/font]

 

[highdesertranger]

I will try to get some pics of my ammo can power pack. I only use it to power some of my prospecting gear but it might give you some ideas. it won't be until Monday or Tuesday I have a busy weekend. highdesertranger

 

[jimindenver]

I use a Megawatt 36a power supply with my AGMs, it allows me to set the voltage to the manufactures specs. With such low power usage you could probably set it to float and it would cover your usage. It's not very big for what it does. Add the very inexpensive RC watt/amp meter sternwake suggest, a fuse and the cords to the battery and it would easily fit in a ammo box. They look huge in the picture, check out the specs. There is a 30 amp for $50.

http://www.12voltpowersupplies.us/

 

[SternWake]

12 to 35 AH agms are not generally the AGMs which can handle high recharge currents. Usually they are the Asian AGMs which limit maximum charging amps to 30% of capacity .

The UB12120 as 12AH agm says 3.5 amps maximum. Hook this battery when depleted to a 36 amp meanwell set to 14.5v and 36 amps will flow. 10 times the recommended initial current. The battery might overheat and vent or go into thermal runaway.

Lowering the voltage to 12's then increasing slowly as battery voltage raised would cause slower charging but more monitoring, and changing the voltage on these power supplies is not hard, but not convenient either.

These 12v power supplies are however quite compact. They are not automatic chargers, On must set the absorption voltage and apply it only long enough to fully charge the battery. Then one either shuts it off,or lowers the voltage to 'float voltages'

This specific Meanwell power supply is rated for 75 watts and the voltage is adjustable from 12.8 to 14.9v and says it can do 5.6 amps.

http://www.amazon.com/Mean-Well-RSP-75-13-5-Power-Supply/dp/B00LS9Q35S

I own a Meanwell RSP-500-15 and while rated for 500 watts it will do 600 watts.

These Specific line of Meanwells with RSP in the title have constant current limiting on Overload. This is important. Some other power supplies when overloaded will shut off until the overload is removed, and do not work well as battery chargers as a depleted battery will exceed the maximum output current.

I would still aim for 24 or more AH capacity with the above specific power supply. It is very compact.

http://www.meanwell.com/webapp/product/search.aspx?prod=RSP-75

Amazon sells many dozens of power supplies that are significantly cheaper, and they will say overload/overvoltage protected, and this might or might not be accurate. The constant current limiting on overload is the desired feature when using a power supply as a battery charger most of these lesser$ power supplies will not have constant current limiting and a depleted battery can overload them causing them to fail, or shut off, making them worthless as a battery charger.

I recently made a larger powerpack with a 125AH lifeline battery as the heart and a PD9245 as the charging source. it included a 400 watt pure sine wave inverter multilpe outputs, and tools for monitoring current into and out of the battery. It weighs 100 Lbs and it will outperform most van dwellers electrical systems.

https://vanlivingforum.com/Thread-My-project-this-week?page=3

I'll see if i can find another Meanwell in the 50 to 75 watt range that employs constant current limiting protection on overload and has the correct voltage range.

 

[SternWake]

This Meanwell also has constant current limiting and is a smidge cheaper and would be good for an Asian AGM battery in the 20 to 35 AH capacity range.

http://www.amazon.com/SP-75-15-Sing...=1440211641&sr=8-1&keywords=meanwell+sp-75-15

With AGM's one should not tickle them to death with too low a charge current.

The wall wart chargers that come with most lead acid battery jumper packs, are slow death by tickling type chargers. These generally have 12 or 18Ah capacity batteries in them and just have a constant 13.6v 1.5 amp maximum output. These can be plugged in and left on forever safely, but they do not properly and quickly recharge the batteries within them. The Meanwells linked will do a far better job, but cannot be left on forever if set to 14.5 volts. They can just be set to 13.6v though, but 14.4v is better for the deeply discharged battery as long as 30% rate is not exceeded on these Asian AGM batteries.

While it is important to not exceed the Manufacturer maximum recommended initial current on recharge, it is beneficial to an AGM battery to approach this rate when the battery is discharged to 50% or more.

With an AGM one needs to know the Amp flowing at absorption voltage as to when the battery is fully charged.

When it decreases to 0.5% of capacity either remove the charger or drop the voltage to recommended float voltages for the battery in question.

Knowing the Amp flow is not as difficult as one might think.
One can use a clamp on DC Ammeter over one of the charge wires going to the battery, or one can get a digital Ammeter.

For a small power supply as this on a small AGM battery, the following product would be a good match showing both voltage and amperage:
http://www.amazon.com/DROK-Ampereme...sim_263_2?ie=UTF8&refRID=126Z9342HMP3ZAQJ42GF

When wired to monitor charging current, this ammeter will not display discharging current unfortunately.

I use one of these to monitor current flowing from the battery:

http://www.amazon.com/gp/product/B0...d_t=201&pf_rd_p=1944687582&pf_rd_i=B00C1BZSYO

It can be wired to count amp flow into battery too, but there is a load and a source side, when charging, the battery is the load, when discharging the battery is the source so the meter must be plumbed correctly to count current.

 

[Optimistic Paranoid]

Random thought.  Rather than build an all-in-one, consider a modular, two piece set-up.  One box contains a battery, an inverter, and a couple or three 12 volt ports, some usb ports, and an input port.  The other box - possibly an ammo can - contains a solar controller, an rv converter like one from Progressive Dynamics, inputs for 120 volt ac and your solar panels, and an output port.  A wire to go between the output port of the one and the import part of the other, and a separate wire could be used to plug into the car when you are driving.

You could carry one box with each hand when moving them.

Just a random thought.

Regards
John

 

[lblt]

I appreciate everyones input and I have a lot more food for thought now on making my decision and directing my research. I am thinking the convenience of a charger that i could feel comfortable setting and forgetting for a while might be better for my situation. I understand this may be a compromise for battery longevity though. Someone has suggested the NOCO Genius to me:http://www.amazon.com/NOCO-GENM1-Waterproof-On-Board-Battery/dp/B00CBTRN26

Their marketing definitely makes it sound like a good and convenient solution. But it may just be that: marketing. Anyone have experience with them?