LiFePO Batteries ???

[tpenfield]

Question
A Bat charger reduces the amount of Amps as the need for charge is decreased. The solar charger outputs X amount and is dependent on the sun. What regulates the excess power not needed, and where does it go?

The solar controller does that. It reduces its output as needed . . . basically creating resistance. The problem is that the solar strength varies, as clouds pass by, so it is constantly varying its output. But the solar controller attempts to go through the bulk, absorption, and float stages of charging.

To really get bulk charging, you need a good amount of solar panel to get the amperage at the voltage. My system does not have a lot of power vs. the battery capacity.

This system differs from my prior system in that the MPPT controller 'squeezes' the output as needed to maximize the power output. So, you get situations where the current is held low, which forces the voltage high. My previous solar controller was PWM (pulse width modulation), It attempted to regulate the voltage, but not maximize the power.

 

[tpenfield]

I'm not in love with the EPEver Duoracer . . . charging the LFP bank, the voltage seems to wander up and down, going from 13.5 volts to 14.5 volts and even slightly higher. I'm not sure what it is doing, but I check the voltage at the batteries and sure enough . . . it is wandering.

It seems to do that more in float mode, than in an absorption mode.

The varying voltage caused a fault/warning at the Xantrex. Nothing major, but kind of unusual.

The attractive feature of the EPEver, was the dual output. Time will tell how it works.

 

[cyclops222]

Some chargers do a BULK AMPERES charging if battery is really low. AS voltage comes up to just slightly run down. It switches to constant voltage mode. The goes to a final topping off voltage.
Varying D C supply voltages should not really bother the charger. BUT
if the DCV from the Solar supply if dropping too low ? The charger might go thru a full restart . Some chargers might just stop charging until the Solar panel becomes high enough again.
There are NO NO rules about how Solar Cells and Chargers, have to function together.

 

[tpenfield]

Some chargers do a BULK AMPERES charging if battery is really low. AS voltage comes up to just slightly run down. It switches to constant voltage mode. The goes to a final topping off voltage.
Varying D C supply voltages should not really bother the charger. BUT
if the DCV from the Solar supply if dropping too low ? The charger might go thru a full restart . Some chargers might just stop charging until the Solar panel becomes high enough again.
There are NO NO rules about how Solar Cells and Chargers, have to function together.

This controller (EPEver DuoRacer) is designed for this purpose (solar charging) and it does the 3-stages of charging (Bulk, Absorption, Float). There does not seem to be a way to turn off the float charging, which would be nice, as the LiFePO4 batteries really do not need to float.

Tell me about the "No No" rules of solar cells and chargers. Not sure they apply to a solar charge controller.

 

[cyclops222]

Excellent statement about the FLOAT CHARGING .......NEVER TO BE USED !!!!!!!
A........CONSTANT...... float charge is a way to very slowly destroy the battery.

There is only..............1............100 %................during a recharging of a battery.
Of all the battery chemistries available............. LIFEPO4 has the SLOWEST self discharge in existence. My 20 ? year old Blacker & Decker power tool packs sit on shelves for 5 years with no Trickle charging. They are still at 90 % capacity. Recharge in less than 15 minutes at 4 amps when run down.
Do not float charge LIFEPO4 cells / batteries.
Learn when they are fully charged. Then disconnect the charger. They drop down about 10 or 20 MILLIVOLTS. ALL batteries drop down a little bit slowly after being fully charged.

 

[tpenfield]

What about the "No No" rules of solar cells and chargers ?

 

[alldodge]

My 20 ? year old Blacker & Decker power tool packs sit on shelves for 5 years with no Trickle charging.

Invented in 1996 but your have a B&D tool that was originally came with a Lithium battery?

Dewalt didn't start till 2011

 

[cyclops222]

I am 86. I do not remember dates precisely. Never have. Worse with old age.

 

[tpenfield]

I am 86. I do not remember dates precisely. Never have. Worse with old age.

Wow, you might be the most senior member of the forum.

 

[cyclops222]

I have both feet in the grave.

 

[aspeck]

I have both feet in the grave.

Just do your best to keep your head out of it!

 

[tpenfield]

Quick Update . . .

Things look OK today . . . The sun finally came out, and I have been running stuff on the boat, so the solar controller has work to do. Here is a short video of the status loop of the EVEver controller. First . . . the panel status, . . . . then the LiFePO4, . . . . finally the starter battery.

I also think I figured out what the 'min' and 'max' are telling me.

 

[cyclops222]

I am amazed at how much equipment you had to ad and wire up. I would not add that many items to just use LIFEPO4 batteries. I would just use the simple battery with all the charging system buried inside of it. Simplify any problems greatly. I would just add a FAST BLOWING fuse in the Alternator output charging heavy wire.. To prevent damage to the wires and the Alternator.

 

[tpenfield]

I am amazed at how much equipment you had to ad and wire up. I would not add that many items to just use LIFEPO4 batteries. I would just use the simple battery with all the charging system buried inside of it. Simplify any problems greatly. I would just add a FAST BLOWING fuse in the Alternator output charging heavy wire.. To prevent damage to the wires and the Alternator.

About half of that stuff is independent of the LiFePO4 swap.

What battery are your referring to that has "all the charging system buried inside of it"?

 

[cyclops222]

A boating friend bought 5 100 amp batteries. 2 were defective with bad B M S systems buried under the sealed compartment on top of the battery.

 

[tpenfield]

A boating friend bought 5 100 amp batteries. 2 were defective with bad B M S systems buried under the sealed compartment on top of the battery.

Tough break for your friend. The BMS within (Lithium) batteries are what manages and protects the battery. That is what needs to be buffered by external components like DC-DC chargers, etc.

Direct connecting and forgoing the external components as you suggested would result in a whole host of problems. It does not seem like you are aware of this?

The LiFePO4 batteries in my boat have a BMS inside like most LiFePO4 that do the managing and protection.

 

[cyclops222]

I am aware of the POSSIBLE problems.
But some LIFEPO4 companies STATE that you do not need to design anything for safe operation.
Remove old & put in their battery. Done. My friend now has all 5 connected in the boat uses nothing but a standard fork truck battery charger.

 

[tpenfield]

In other news . . .

In isolating the '1 volt' problem of the electrical system that I have noticed a couple of years ago my attention has been drawn to the starboard side electrical box, which has the appearance of a 100 year old electrical station.
.

.

.
With all of the rain we've been having lately, I noticed that the 'box' is getting water in there (coming down the side) and it has no place to go. (I guess drainage was not part of the boat manufacturer's design ). Anyway, I have drilled a couple of holes in the electrical box to allow drainage, and I'll have to see what I can do to resolve the water getting in there, and clean the place up.

I was going to tackle that is morning . . . but it's raining (again)

 

[cyclops222]

You are committed at this point. Stay with the maintenance.

 

[alldodge]

I am aware of the POSSIBLE problems.

@cyclops222 I'm going to recommend allow this thread to go forward as it was intended from the beginning. Providing input of what may or may not be true is not helping.

Comments are welcome so long as they advise of real world testing/analysis. Ted is working hard to get this right and most that read it appreciate the insight.