Adding charger to my solar

[NctryBen]

So I’m in Minnesota for another month. I am building a little truck camper and put a couple battle born batteries with a Renogy 30 amp mppt controller. I purchased a 130 watt portable solar panel suitcase deal to power for now. Wouldn’t you know that not only is the sun not clearing trees so hot anymore, it’s cloudy and raining a lot these days. What options do I have for charging my batteries otherwise? Can I hook up a regular battery charger directly to batteries? Do I need a smart charger? I was running my fridge but can’t get batteries charged between clouds enough without some help. I’ve got my load hooked to the controller also so I can monitor everything. Before all this weather I had no trouble staying near 100%.
I’m sleeping in the camper as I do some tweaking and trimming it out. So I’d like to have the fridge running again, but not at the expense of my batteries. 
I plan on visiting Santan solar when I get down that way... I want to get three hundred watts mounted.

 

[Camper]

I'd get a real lithium charger that will protect your big investment. The day I bought my lithium batteries I ordered a new charger to go along with them. I won't take a chance with my new lithiums.

Beware of used solar panels.... I'd see in person how many watts it will put out before paying.

 

[jonyjoe303]

on battleborns any cc/cv charger that puts out 14.4 volts will work (the lifepo4 can go as high as 14.6 volts). I wouldn't spend hundreds on a special charger you might only use a few times. The battleborns can be charged directly from the alternator which puts out more amps then any AC charger.
Myself I was going to buy a 20a lifepo4 AC charger from ebay (60 dollars) last year due to cloudy weather but then I would have needed a generator to run it. Eventually I got a larger panel. This AC lifepo4 charger charges to 14.6 volts which is what I want but some people prefer 14.4 volts for lifepo4 some even less.
Your idea of getting a larger panel is very good. I have a 365 watt panel and it easily keeps my 500 ah of lithium batteries fully charge even in winter.
In winter I get up to 15 amps of charge power, in summer I get about 22 amps, and max out at 27 amps. The prices in the suntan website are very good, even if the panels are used. I'm cheap I would definitely buy one of the larger panels, as big as would fit on your camper. I wouldn't settle for 300 watts if you got the room, those battleborns need alot of amps. Your renogy 30a can handle at least 365 watts maybe a little more.
If I were you I would get a coulombmeter to monitor the lifepo4 batteries, thats the best way to know there SOC. I use the tk15 (about 30 dollars) That hooks right near the battery terminals and measures the actual voltage directly (without voltage drop) it also counts the amps in/out so you know how much amps your putting into the battery. That way while your charging you know the voltage in real time.
Also check for voltage drop on your solar system, I dont trust the readings from the mppt controller, if you got voltage drop, your controller might not be sending max amps to your battery. If your controller is reading 14 volts, the battery terminals also need to be reading 14 volts, if its less then you have voltage drop which will affect how much amps the controller will charge at.


tk 15

 

[Camper]

That's a nice meter.... I bought this one from Amazon and it's working good for me.

https://www.amazon.com/dp/B07FGFFHC6?ref=ppx_yo2_dt_b_product_details&th=1

Where did you buy that 365-watt panel?

 

[NctryBen]

Thanks for reply’s. Second part of question was can hooking up a charger to batteries muff up my controller? I did toss a smart charger on them one time. But just to keep them from bottoming out. Trying to keep things simple and make use of shore power when I can. I don’t see anything showing what I’m trying to do... or asking about.
I guess I’m not seeing the charger you suggested Camper...

 

[tx2sturgis]

You can hook up a regular off-the-shelf (5A to about 30A) lead acid 'smart' charger but it probably won't charge the lithiums to 100%...but this wont hurt them....they just wont be 100% charged. If you hook up this charger for a few hours, set it for FLA 'flooded lead acid'...but if you intend to leave it on the lithiums for an extended time (multiple days or weeks) set it for GEL or SEALED, if you have those options.

This will get you thru the shake-down tests. 

Or you could disable the fridge for now, letting the portable panel you have try to maintain the lithiums...knowing that when you get out to the southwest, you will be adding another panel (or two) and be able to run the fridge.

 

[MikeRuth]

You guys might think I'm crazy and cheap, a little of both but this charger from HF does the job perfectly for me. What is really cool is it will not go into a desulfation mode on it's own. in My use in the evening when the sun is gone I plug in, tap the amps button three times to set it at 15 amps and then hit the start button, bam will not take it over 14.4 and for me that is close enough to full.

I have a fridge running and some other minor draw stuff, when it drops down it kicks in automatically with out intervention.

https://www.harborfreight.com/2815-...er-56796.html?_br_psugg_q=battery+charger+car

Mike R

 

[ldsreliance]

As tx2sturgis said, a lot of smart chargers that work for a variety of chemistries and have a lithium mode will not fully charge some LiFePO4 batteries. I know for sure that NOCO Genius chargers, for example, are among those. They will get you to the 85-95% charged range and stop.

Also, and this is critical in the long term, but if you don't use a good CC-CV charger that has the right settings and use a "close enough" charger that is cheaper or you already owned over the long term, it won't hold a voltage for a long enough time at the end of the charge for the BMS to properly balance all of the cells. This won't make a difference for spot duty or temporary use. But over time that BMS won't be able to keep all of the cells in balance and you will have a dead or greatly degraded battery after a much shorter cycle life than advertised.

 

[frater secessus]

if you don't use a good CC-CV charger that has the right settings and use a "close enough" charger that is cheaper or you already owned over the long term,

There is no reason inexpensive or older chargers with appropriate settings (or configurable setpoints) cannot charge Li properly. It does require understanding how LFP cells charge and age and how chargers work. I'd much rather have a simple, configurable controller than one with an uneditable "Lithium" preset.

it won't hold a voltage for a long enough time at the end of the charge for the BMS to properly balance all of the cells

It's a catch-22. Pushing higher Li voltages for longer durations is a primary cause of cell imbalance, due to "runners" hitting the knee and shooting up in voltage. Don't believe me on this: I encourage onlookers to test-charge to 100% SoC at both 14.4v and 13.8v and see what the cell voltage delta is in each case. Watch the runners to see if the balancing current can keep them in line.

They will get you to the 85-95% charged range and stop.

That is close to optimal for Li longevity, all other things being equal.

 

[frater secessus]

It just most likely will not use a CC-CV charging profile because that isn't how lead acid chargers have operated for decades.

What? Bulk = CC. Float and Absorption = CV.

charging to 85-95% for most cycles probably will increase longevity, although that has not been proven with LFP that I know of.

Holding 100% SoC can cause lithium metal plating and permanent capacity loss. Complicating matters, Li doesn't have enough self-discharge to come down off 100% on its own after charging. Plenty of academic research out there on the topic.

The problem is I don't have any customers that are happy making the investment in lithium and then only getting 85% of its capacity

IMO we should not make general charging recommendations here based on the expectations of customers who do not understand (or care to understand) how things work.

f you don't want your BMS to be able to finish doing its job of cell balancing because the charger cut off the juice too early.

Overcharging lithium to trigger cell balancing is like approaching every red light at 100mph because otherwise the ABS won't activate when you slam on the brakes. Well, right, that's now it's designed. if we drive moderately the brakes won't be locking up and ABS has no need to engage. Likewise, if we charge at moderate voltages the cells likely won't become imbalanced enough to trigger balancing (15mV delta or whatever the BMS setpoint is).