Battleborn - charge settings

I am using the settings provided by Battleborn. At the moment I have more than enough sun, so the batteries are topped off every day. As far as I understand it would be best not to charge them over 80% (unless needed or maybe once every couple of weeks). What setting can I use best?

Victron 30amp set to 14.6 Volts absorb and 13.5 Volts constant.

Is it normal for two 160 watt panels (series) two get Pmax of more than 350 W?

Thanks for any advice

rando and craig are more the battery/lithium experts, but I am using lower settings than those... 14.2v absorb, 13.2v float.  I understand that tops the batteries at around 90% and the low float value means that they don't actually float at all, which is what you want.

The voltage drop of a lithium battery is so flat, I'm not sure you could reliably find a "80%" value to set it at.

I've never heard that you shouldn't charge over 80%; that's pretty important. Where did you find that information?

A panel's Pmax rating is based on a lab 'standard' for what may be considered normal operating conditions, which is essentially a non real-world condition. Under the right orientation, tilt, irradiance and temperature conditions a panel's real-world Pmax could exceed it's listed rating. So, is it normal for two 160W solar panels to top 350 Watts? Possibly, if you are sitting in the optimal solar sweet spot. But you wouldn't see those conditions on a regular basis year round unless you were, say, at the Equator and never saw a cloud in the sky and parked in a totally unobstructed site with the panel's cells lined up perfectly for maximum output. And that's why Pmax and other ratings are provided with typical, optimal-average operating conditions in mind, as opposed to atypical, theoretical best case lab scenarios.

Also, in the case of Battle Born LiFePOs, the company techs suggest that your battery should receive an adequate charge on a regular basis. It doesn't need to be seeing 14.4-14.6 V every day, but they do suggest reaching that level at least once a week or so, unless the battery is in long-term storage. And of course you wouldn't stay at 14.6 V in absorption for long if your batteries were topped up all the time. You might find that you would only stay at that level for one minute if you already had a high SOC (90-100%), before the voltage began to taper off down to 13.6 V or 13.2 in its resting state, I have a floating set point of 13.5, but after the battery leaves absorption and enters float it will tend to hover at around 14.2, more or less, until the end of the charging cycle, when the sun goes down. I'm using a Victron 100/30 mppt controller and those are real numbers in my setup. Solar charging conditions are pretty fluid, with lots of fluctuations in voltage, which is actually pretty healthy for a battery. I'd rather be charging my battery using solar vs. plugged into an AC charger and constantly hovering in float mode.  I've got two 160 W panels and use the BB recommendations for bulk, absorbtion and float set points. Those set points are not destroying my battery performance. They actually work pretty well. This may be an overly simplistic way to think about it, but it's like eat when you can (or top it off when you can in the case of solar) - you never know when it might be your last meal for a while.

Rich

Edited by ri-f, 18 February 2021 - 05:09 PM.

Thanks for the info so far! Actually I am at the equator, so almost floating with full batteries most of the time. No missunderstanding Li batteries can and are to be charged full to 100%. I just read somewhere its best for their health to be in a charging state of 60 to 80 %. I have no idea if this is of any real worl relevance.

The 60-80% value I have read before is about long term storage... no need to be FULL, just 60% or so and they will be good for months.

But storage at full is not a problem, either. 

BB recommends, for long-term storage of their batteries, charge to 100% and then disconnect the wires. I never do that though. I just let the Victron control the solar charge. I leave the camper outdoors year round and never plug in.  During our overcast, dim winter, it stays topped off unless we're out camping and running normal loads, then we have to rely on the sun to make an appearance and short of that, run the B2B for a while when under way and then its topped up once again. Seems like these batteries are resilient and not too particular about charging routines.

Rich

Edited by ri-f, 18 February 2021 - 04:02 PM.

For me, this is the most difficult thing about LifePO4 batteries.  You have so many variables you can set (assuming you have a BMS and a Victron DC-toDC charger).  

I'm still adjusting my values and not sure if they are totally correct or not but they seem to be working.  You also have the question of which takes precedence ; the BMS or charger (ie. which values should be allowed to control the battery before turning off charging?).

You also have the question of which takes precedence ; the BMS or charger (ie. which values should be allowed to control the battery before turning off charging?).

The BB BMS will have precedence and turn off charging if it detects a danger to the battery, for example, an internal battery temp of less than 24 degrees F. Other than that, why would you want to set the parameters to turn off charging, assuming you are using a reliable smart charger that is compatible with a LiFePO4 battery? Just curious.

Rich