Suggestion for Inexpensive Lifepo4 Charge Controller

[saxon11]

I started with my small off-grid 100W panel, which had AGM battery, and this cheap charger. I'm powering wifi and a security camera. System worked great.

I have since upgraded to a lithium battery, and figure I'd need a lifepo4 charger, so this says it works with lithium, but skeptical small controller that says works with lithium batteries. The slightly larger version looks like more suited to lithium, but loses the USB ports (which i love!). Darn it!

Does anyone else have a suggestion on a controller that could work well without spending a lot? I like the idea of a MPPT controller. They have a cheap MPTT controller on Amazon but reviews say they are not even MPPT! Hard thing to solve for budget controller for a good lithium battery and setup like mine.

 

[12VoltInstalls]

Don’t buy that junk
This is pretty hard to beat. You can user configure it to your needs or use their default. You will need to purchase a battery temp monitor and either an mt50 or the usb cable to conveniently configure it.

I bought one for my boat (200W of solar), although I’m uncertain if I’m going to return and just use a P30L PWM.
There’s limited advantage with mppt on sub-200W systems and nearly none for 100W single 12V panels.

The ‘slightly larger version’ you mentioned is renogy (which I avoid like covid) and states it’s pwm.

 

[fratermus]

I have since upgraded to a lithium battery, and figure I'd need a lifepo4 charger.... a controller that could work well without spending a lo

Might spend nothing at all, using the existing single-stage PWM you already own. I'd start with 13.6v and see how well it charges. If the batt only gets to 80% go up to 13.7v and watch. If it stays pegged at 100% drop to 13.5v and watch, etc. The caveat: since the controller cannot back off the charging voltage we should undercharge a bit rather than overcharge -- lithium does not like being held at 100% capacity for long periods.

Both of the linked Renogy PWM have lithium profiles; you can find details in the manuals for each. I have no concerns with Renogy gear. OTOH buying even a better PWM doesn't gain you much since lithium doesn't use staged charging in the normal lead-acid sense.

Since the battery has a 9A charging limit I don't think I'd be looking to increase charging power. If you do want MPPT the 10A epever 12VoltInstalls mentioned is probably the cheapest option. Maybe $60 in a bundle including MT50 display for easy config. The temp monitor won't be needed as Li doesn't use temp coefficients to adjust charging voltage. Maybe charge to 14.0v and float at 13.4v or something.

 

[12VoltInstalls]

The temp monitor won't be needed

Does that not stop charging at X voltage based on that?! I don’t use lithium but I just assumed… it would be so easy.

 

[fratermus]

Does that not stop charging at X voltage based on that?! I don’t use lithium but I just assumed… it would be so easy.

AFAIK only one of the models in the Ep line (the oddball Triron, maybe?) has the ability to stop charging based on low temperature. Perhaps it uses different firmware.

The rest of the Tracer line seems to use the same firmware and has temp probe connections so I agree it should be a no-brainer to add the feature. In the meantime my Li sits on a lizard warming mat.

 

[bobkart]

I've had good results with the very-affordable MPPT LFP charge controllers at Powerwerx:

MPPT 150W Solar Charge Controller

MPPT 300W Solar Charge Controller

The one issue I've encountered is, when running 325Wp modules through the 300-watt model (in full sun), the output connectors got hot enough to melt/bulge somewhat. I spliced on Anderson SB-50 connectors in place of the PP-45s and they work fine now.

 

[Browneye]

+One on mini 10A Tracer AN mppt. I put my 160W folders in series and it works perfectly.
The RS485 com cable and a tablet or laptop offers easy charge parameter settings with their very slick and free software.

 

[fratermus]

AFAIK only one of the models in the Ep line (the oddball Triron, maybe?) has the ability to stop charging based on low temperature. Perhaps it uses different firmware.

I've since come across a couple videos that suggest the EpEver PC software can enable low-temp cutoff on some non-Triron models . Here's an example using what appears to be a small AN model. He goes into the software setup.

I don't have the software loaded here ATM (linux and my WINE config is messed up) but the Li dialog in the software in the vid seemed to mention the AN, TriRon, Xtra-N, and some others I couldn't make out.

I have not tested any of this. If I can get it running on linux I'll take a peek and report back.

 

[Browneye]

AFAIK if you have the remote temp sensor connected to your controller then you can set for low/high temp cutoff.
I rely on my Overkill BMS, so I haven't paid attention to it. I know the temp sense feature can be turned on or off.

Now I forget, maybe that's only for temperature compensation, which isn't used for lifepo. I'll look again...

 

[12VoltInstalls]

since come across a couple videos that suggest the EpEver PC software can enable low-temp cutoff on some non-Triron models

Except the video linked does not indicate if that cuts off charging which is actually the real concern.

 

[Browneye]

Here's a couple of screen captures from the EPEver PC setup software, and from the TracerAN installation manual.

There is a toggle for 'over temp drop power' to enable or disable. And for 'lithium battery protection'. I'm not positive for either, but I think the lithium battery protection is applicable when there's a temp probe attached to the batteries and connected to the controller. At least that's what I gather from the excerpt from the installation manual.

Temp compensation is another setting - something used for lead acid batteries, not applicable here.



From the manual...65C is 149F:



And the temperature settings profile. I am not sure if you can set both on the lithium profile.

 

[fratermus]

Except the video linked does not indicate if that cuts off charging which is actually the real concern.

Good catch. Charging cutoff is demonstrated in the previous video using a non-TriRon controller I do not recognize.

I tried getting the software installed under WINE but it's been crashy-crashy so far. Might try to install in a virtual.

 

[Browneye]

Yeah, float shuts off current, will ramp up for loads.

 

[fratermus]

I tried getting the software installed under WINE but it's been crashy-crashy so far. Might try to install in a virtual.

Update: the Epever Pair app has separate cutoff temps for LFP charge/discharge on supported controllers:

I don't remember what the values were before I started dorking with them. I can't guarantee the settings actually do anything, and hope to never find out (my batt is on a warming mat).

Note: the EQ duration is at the minimum (10mins) so set it the same as Vabs to make it a non-issue.