Budget friendly 120v to 12v LiFePO4

[Zenreaver]

So, I need a little bit of guidance again   I decided to spend more initially on a battery. That will leave me without money for solar/controller for a few months until I am able to save up a bit more money. So, I'm just looking for a safe option about 1-2x a week until then.

Here's the battery I'm getting.
https://bigbattery.com/product/12v-lifepo4-power-block/

So, now I find myself looking for a budget portable charger I am able to plug into a house outlet, or one guy has a gas generator when I visit. (don't know generator specifics, but he thinks is a 3000w Honda) This is only a temporary setup, so I want to keep it as cheap as I'm safely able without damaging the battery. 

15amp or higher will work.. any suggestions?

Thank You!

 

[Weight]

I can't recommend a cheap charger. But I can recommend a Sterling or a ProMariner marine type charger.

 

[bandaidqueen]

I don't have much experience with batteries, but I have heard that the lithium batteries can be damaged easily, so be very careful if you're making a big investment! It would really stink to put a huge portion of your budget into a battery and accidentally fry it. I know Bob recommends cheaper batteries, or two 6V golf cart batteries wired in parallel to get the 12Vs. I've been full time over a year and still don't have electrical - just a very small portable jackery (black friday deal last year) that I carry inside and charge at the office at work. I only use it for charging my cell phone and running a USB fan when it's hot. I use battery powered lights and flashlights for lighting and I don't have a fridge yet.

 

[jonyjoe303]

any car battery charger should work since they typically max out at 14.4 volts and should be cc/cv (same as what lifepo4 needs), lifepo4 max voltage is 14.6 volts. Since the battery has a bms it won't overcharge.
I would just monitor the voltage at lifepo4 terminals to make sure it doesnt go above 14.6 volts. Also once the battery reaches full or close to full, unplug from charger. No need to trickle charge lifepo4.

 

[Zenreaver]

bandaidqueenI don't have much experience with batteries, but I have heard that the lithium batteries can be damaged easily, so be very careful if you're making a big investment! It would really stink to put a huge portion of your budget into a battery and accidentally fry it. I know Bob recommends cheaper batteries, or two 6V golf cart batteries wired in parallel to get the 12Vs. I've been full time over a year and still don't have electrical - just a very small portable jackery (black friday deal last year) that I carry inside and charge at the office at work. I only use it for charging my cell phone and running a USB fan when it's hot. I use battery powered lights and flashlights for lighting and I don't have a fridge yet.


I have lived the min. power route, especially when I was living off of a motorcycle. I was averaging 5Ah a day. I "want" not "need" battery/solar. It will simply make many things easier for me, with my compromised health. I have much more room in the van, so I'll carry more electric "luxuries". Eventually, I'll get a fridge, but it's towards the bottom of my list right now.

While I don't want this to turn into a which battery is best thread, this is why I lithium was right for me.

I was planning on cheaper batteries initially. After careful thinking, planning, budget crunching, lithium made the most sense for me. I'm building a mobile system that can be moved into a 2nd vehicle. One lithium is much lighter/easier to move vs 2-3 AGM. Much more compact too.

I paid $810 for 170ah with 10yr warranty. 47lbs. It's also serviceable, being able to replace individual cells rather easily if needed. Roughly the size of one, 100Ah AGM. Built in BMS to protect batteries from most user errors.
vs
2 Vmax 155Ah AGM's. Often considered the highest quality AGM. 155Ah (usable) are about $700 with 1yr warranty 180lbs! (plus a little extra $ and weight for extra cables)
vs
3 UB121000 100Ah Budget friendly, for 150Ah (usable) were about $550 with 1yr warranty and 190lbs. (plus a little extra $ and weight for extra cables.

While my van sure is heavy, most everything inside is from my lightweight motorcycle/backpacking camping stuff. Considering how much I've paid just to save a few ounces/lbs, or for a couple extra pack-able inches, it was a rather easy choice for me. I am willing to sacrifice my solar panels/controller for a few months to get the extra convenience, and longevity of lithium.

 

[Trebor English]

I looked at the page you linked.  They say, among other things, these batteries are perfect for golf carts.  Further down it says you can connect up to 2 in series for 24 volts.  Golf carts need 36 volts.  This page has one inconsistency that glared at me.  Be careful.  Read very carefully. 

About a year ago I recommended a charger for a lithium battery with good results.  What I recommended was a powermax PM4-45.  Amazon doesn't have that one today.  They do have a pm4-55, $132, free shipping.  He has a small Sportsman generator and the goal was to get a converter charger that matched the generator to charge as fast as the Sportsman could handle to reduce generator run time.  The Sportsman is rated at 800 watts continuous so a 700 watt charger would fully utilize that without burning up the engine or generator.  Also, the lithium battery max charge rate recommendation was 50 amps so 45 was a good fit.

The PM3- model chargers are three stage lead acid chargers.  The PM4- chargers have a stage 4.  You flip a switch and it changes to a constant voltage mode.  The voltage is adjustable to the 14.2 you need for the lithium battery.  You need to turn off the generator or turn down the voltage if you are going to have shore power always on. 

You want to get a charger that minimizes generator run time, doesn't charge too fast for the battery, and has a fixed voltage setting that is adjustable. 

The battery BMS is intended to protect the battery.  It is like an over temperature / over pressure relief valve on a water heater or pressure cooker.  It should not normally be disconnecting the battery as a method of setting the charge voltage.  You want the charger to do the right thing normally and the BMS should only come into play when something goes wrong. 

I just called the guy to see how it was all working.  He still has the CPAP machine and the RV and it is working ok.  He typically just pushes the button to start his Onan 3000 watt generator rather than drag out the Sportsman and the extension cord.  Occasionally he uses shore power.  The powermax PM4-45 is working fine.  His van starter battery is a separate issue.  I suggested that he charge the van battery from the coach circuitry with a relay but he still doesn't have that.  I think a new battery price will convince him to look into it.

 

[Psyckosama]

If you're looking for batteries it might be a good idea to go to the DIY solar forum. They tend to have lots of good stuff like group buys of cells from China.

Not trying to shill for them but they tend to specialize in this.