Epever Tracer charge controller questions (12-volt battery system)

[sgtcrumb]

Hi All,

I'm looking at the Epever Tracer series, and particularly the 40A BN variant (see https://www.amazon.com/dp/B08CN1QZXF/ref=emc_b_5_t?th=1) to possibly pair with a couple Rolls S6-GC2-HC golf-cart batteries (see battery specs here: https://rollsbattery.com/battery/s6-gc2-hc/). The recommended charge current is 30A for these batteries. I will have two of these 6-volt batteries in series for 12-volts, and 241 AH. Charging voltage range is up to 15V. Loads will consistently range between 20W and 50W. Not much, but they need to be accounted for. Given my rough math, the charge controller should be able to supply up to 35A @ 15V = 525W. Since solar panels almost never produce their STC numbers, I would want 650W or more of PV.

Questions:

1. Is it safe to over-panel the Tracer charge controllers? The 40A tracer charge controllers show a Max of 520W PV input, which will provide a max of 34.7A (520W/15V). This is probably close enough for my needs. Typically, I assume PV panels will provide a max of 80% of STC, so the array STC would need to be ~650W or more.

2. Can the Tracer be programmed to limit the charge current? I know the voltages can be customized. But I need the charge current to be adjustable, probably starting with an initial setting of ~33A and increasing if needed.

3. Do high-voltage strings of panels work well with this controller or should parallel panels be used instead? For example, would this controller work efficiently with three 240W panels in series having a Voc of 37.6V per panel (total of 112 Voc @25c, 135Voc @-25c)? The voltages fall within the controller's listed limits.

Thanks!

 

[sunshine_eggo]

I have some S-605s. Rolls is a great choice.

1. Read the manual carefully. Several models address it in the text. IIRC, they recommend a 50% over-panel max. While rated power is rarely attained, it can happen, particularly around the equinoxes when the panels are tilted to latitude and temperatures are cooler, but yes, a 20-30% over-panel is pretty much what's needed to regularly achieved MPPT max rated output.

2. Not to my knowledge. I know Victron does. Unfortunately, when you limit the controller, it's an absolute limit. If your loads could consume additional power, the MPPT will be restricted to whatever the current limit dictates. If you want to get fancypants, Victron MPPT + GX device + shunt can be configured to restrict charge current to whatever is needed, but allow the MPPT to output additional power for loads if it's available.

3. Generally speaking, parallel for shading; series if no shading; series if the cable run is long. If short cable run, MPPT is generally more efficient closer to battery voltage - about 50% above nominal. MPPT efficiency drops off ~1-2% for every multiple of this over the battery voltage. Often, this efficiency loss is made up for in reduced wiring losses due to higher voltage and lower current. If not dealing with the issues mentioned, a combination is typically most sensible.

 

[mikefitz]

Given the ease of programming and the displayed and stored data that the Victron Smart solar controller offers, together with programmable charge current, I suggest you consider the Victron. The Victron 100/30 cost is similar to the Epever although the 150/35 and 150 /45 will be more expensive.
There are reports of Epever systems having issues,

Epever charge controller dropping out of MPPT mode

I have 2 Epever 40 amp tracers panels are connected in series per controller (2x300w panels) charging a 400amp Lifpo4 battery bank. Its cloudy today sometimes the sun comes out from behind the clouds but it seems when the light dims they will drop back from MPPT mode to PWM mode, once I...

diysolarforum.com

Mike

 

[Crowz]

My 4215bn's charge at 20amps at 12 volts or 40 amps at 24 volts. So the pair I have will do 40 amps at 12 volts when I use both of them.

They don't show to have any protection from over voltage in the docs I have. As for over paneling I have tripled the wattage limit it states but in my opinion that requirement doesn't mean anything since they take what they need wattage wise. I would never over volt them though since that would fry thing for sure. Just make sure to keep the max pv voltage within specs.

 

[littleharbor2]

Here's an older chart but from the same mother company. They are pretty generous with their over paneling allowances.

 

[sgtcrumb]

Thanks for the replies guys. If the Tracer can't limit charge current, then it's definitely a no go for me. Victron was my first choice, so I may be going with them after all.