Charging LiFePo4 Batteries With Just Solar

[JBP-PA]

That's not exactly correct. It will combine batteries any time the voltage is over 13.6v for 30 sec or 13.0v for 90 seconds. It doesn't matter what the source of the power is, charger, alternator, or solar. It will not open the circuit until the voltage reaches 16.0v. While LA batteries are somewhat tolerant of over voltage, LFP batteries are not. Over voltage will damage the battery and may cause the BMS to shut down.

They are programable. Well, some are, which is really the point of using a DC-DC charger instead of an ACR. Victron says "Controlled charging will also protect the alternator in lithium systems where direct charging can overload the alternator due to the low impedance of the lithium battery. "

 

[dlochner]

They are programable. Well, some are, which is really the point of using a DC-DC charger instead of an ACR. Victron says "Controlled charging will also protect the alternator in lithium systems where direct charging can overload the alternator due to the low impedance of the lithium battery. "

DC-DC chargers are programmable, however an ACR is completely different, it is relay that opens and closes based on the battery voltages. Which is one of the problems using them to combine an LFP battery with an AGM. The batteries have different charging profiles which will lead to one battery being chronically over charged or under charged depending on how the charger/alternator/solar controller is programmed.

 

[JBP-PA]

Yep. I get it. An ACR was fine if your house and starting battery were both lead acid. DC-DC chargers are designed specifically to address the problems when the two battery systems are different. That is what I tried to say, apparently not clearly enough.

 

[JBP-PA]

Mostly what I was saying is it's not a bad solution to charge your starting battery off your engine and use DC-DC charger to charge your LFP house bank for people who frequently run their engine. I agree with @dLj that It's not ideal for long range cruisers who rely mostly on other sources, but for some it's quite OK and quite common.

 

[JBP-PA]

DC-DC chargers are programmable, however an ACR is completely different, it is relay that opens and closes based on the battery voltages. Which is one of the problems using them to combine an LFP battery with an AGM. The batteries have different charging profiles which will lead to one battery being chronically over charged or under charged depending on how the charger/alternator/solar controller is programmed.

I rewrote my offensive post. It's it better?

 

[colemj]

Perhaps my wording was not as clear as it could have been, but I meant exactly what you said; X hours at 100% panel rating, no credit for other hours. Except the industry standard is 5 hours, not 3 hours. 3 hours is a good fit in the UK and in winter in snowy latitudes (assuming you clear the snow, obviously), but 5 hours works in temperate areas in the warmer seasons, including clouds and rainy days. Winter cruising, running the heat and lights half the night, and with low sun angles and short days, are tough, but how many cruise in the depths of winter? I have on my PDQ, and 3 hours is about right then.

Got it. However, while I find 3hrs to be a bit conservative, I find 5hrs to be too liberal. The problem is heat throttling output. It was 95F and sunny here today, and our panels are too hot to touch. This is typical, and we get 3.5x rated output as an average. Pushed 4x a couple of days, but 5x is never going to happen.

Having spent many years with solar in Connecticut, I could see how 5x might be expected there in summer. Outside of these narrow geographic and seasonal bands however, I don't see 5x as an expected standard.

Mark

 

[colemj]

I do prefer the Wakespeed controller. When I looked at them compared to Balmar there was no contest - the Wakespeed was notably better. I understand there is a new Wakespeed 500 pro or something like that. But in any case, looking at what's currently available is a good idea as things change.

For sure the Balmar is the least feature-rich of the current offerings, but I just cannot figure out what additional functions I need from my regulators. I can control and program the Balmar from my phone, so that previous issue with the little magnet is gone. Otherwise, I don't need it connected to my N2K bus, nor do I need to control output based on engine rpm, nor any of the other features other regulators have over the Balmar.

I tend to operate in a different direction from what everyone else is doing now. We have extensive electrical and electronic systems, but they are all self-regulating, separated, and addressed individually. There is no single component that can take down the others, nor is there any single component that can control the others. All switches and relays are mechanical, and there is failover and redundancy in many of the systems.

Mark

 

[colemj]

We have ACR's that have completely programmable connect/disconnect voltages.

Any AGM or sealed FLA used for starting will have a charge profile so close to that for LFP that being a tenth of a volt or so off won't make a lick of difference in their lifespan.

Mark

 

[dLj]

For sure the Balmar is the least feature-rich of the current offerings, but I just cannot figure out what additional functions I need from my regulators. I can control and program the Balmar from my phone, so that previous issue with the little magnet is gone. Otherwise, I don't need it connected to my N2K bus, nor do I need to control output based on engine rpm, nor any of the other features other regulators have over the Balmar.

I tend to operate in a different direction from what everyone else is doing now. We have extensive electrical and electronic systems, but they are all self-regulating, separated, and addressed individually. There is no single component that can take down the others, nor is there any single component that can control the others. All switches and relays are mechanical, and there is failover and redundancy in many of the systems.

Mark

It's not additional features I needed, but that the Wakespeed 500 was the regulator that worked best for my particular set-up. It's also quite flexible if I decide to upgrade my alternators.

dj

 

[dlochner]

We have ACR's that have completely programmable connect/disconnect voltages.

Who makes them? The Blue Sea ACRs are not programmable.

 

[colemj]

Who makes them? The Blue Sea ACRs are not programmable.

Ironically, Blue Sea. Their previous models of ACR were fully programmable. I don't know why they switched to the dumb ones. Maybe because people didn't understand how they work and messed with the settings and caused a lot of tech support.

But there are other programmable VSR's by other manufacturers.

Even many of the fixed VSR's are such that the connect is >13.4V and disconnect is 13.2V, so these voltages work well with lithium and lead.

Mark

 

[colemj]

It's not additional features I needed, but that the Wakespeed 500 was the regulator that worked best for my particular set-up. It's also quite flexible if I decide to upgrade my alternators.

Certainly not arguing your choice, and all of the newer regulators are definitely more advanced than the Balmar by a long shot. It's just that I can't figure out what more I would need from a regulator. All I need one to do is charge to a set voltage and turn off. While charging, monitor the alternator temp and adjust output to keep it below my set point. The only features I need are ability to set the charge voltages and temps, and the ability to set the maximum output allowed.

All the recording and graphing, connecting to N2K, controlling or being controlled by other charging and BMS components, etc doesn't matter to me, and many of those couldn't even be implemented on our boat. As for upgrading, we changed from the 60A OEM alternator to a 275A HO alternator and no change in the regulator was needed because it was already setup properly. It was literally plug and play because the regulator doesn't care what the alternator output is, only that the voltage and temp points are met.

Of course, if we change to a 24V or 48V system in the future, we would need new regulators. But that isn't in the plans.

Mark

 

[dLj]

Certainly not arguing your choice, and all of the newer regulators are definitely more advanced than the Balmar by a long shot. It's just that I can't figure out what more I would need from a regulator. All I need one to do is charge to a set voltage and turn off. While charging, monitor the alternator temp and adjust output to keep it below my set point. The only features I need are ability to set the charge voltages and temps, and the ability to set the maximum output allowed.

All the recording and graphing, connecting to N2K, controlling or being controlled by other charging and BMS components, etc doesn't matter to me, and many of those couldn't even be implemented on our boat. As for upgrading, we changed from the 60A OEM alternator to a 275A HO alternator and no change in the regulator was needed because it was already setup properly. It was literally plug and play because the regulator doesn't care what the alternator output is, only that the voltage and temp points are met.

Of course, if we change to a 24V or 48V system in the future, we would need new regulators. But that isn't in the plans.

Mark

Agreed.

I needed a device that could handle 240 incoming amps from two alternators. I wasn't sure if I was going to change to one large output alternator down the road - still in the "maybe" state but the current system works so well that likely won't happen until I loose an alternator. I also really liked being able to program it to have a defined end of cycle where it ramps down slowly when nearing end of charge cycle. When nearing end of cycle the Wakespeed ramps the current down slowly - no abrupt current changes.

dj

 

[colemj]

Agreed.

I needed a device that could handle 240 incoming amps from two alternators. I wasn't sure if I was going to change to one large output alternator down the road - still in the "maybe" state but the current system works so well that likely won't happen until I loose an alternator. I also really liked being able to program it to have a defined end of cycle where it ramps down slowly when nearing end of charge cycle. When nearing end of cycle the Wakespeed ramps the current down slowly - no abrupt current changes.

dj

Not sure I understand why the regulator has to handle 240A? It shouldn't see any current at all except what it draws for power.

The Balmar ramps down current as the charge voltage point is reached. It is usually only a few amps at the end of charging. In fact, all regulators do this because it is a function of battery chemistry, not how the regulator charges.

Mark

 

[dLj]

Not sure I understand why the regulator has to handle 240A? It shouldn't see any current at all except what it draws for power.

The Balmar ramps down current as the charge voltage point is reached. It is usually only a few amps at the end of charging. In fact, all regulators do this because it is a function of battery chemistry, not how the regulator charges.

Mark

I run twin alternators that each can produce 120 amps so 120 x 2 = 240 amps - not sure what I'm missing?

You probably know a lot more about the details of how these things work than I do. I'm simply an end user of these gadgets... It's my understanding, but I could be wrong, the Wakespeed was programed in the following manner - when reaching near end of cycle - the out put of 180 amps (I throttle back my alternators) slowly drops to about 10 amps of output. It plateaus there for a fair bit of time to do two things, allow the alternators to cool down, and finish the charge cycle. Then it slopes down again and shuts the alternators off. Oh yeah, there is also a ramp up cycle. Almost identical to the ramp down cycle, just notably shorter time periods.

It is my understanding that was all done through programming the Wakespeed - but as I didn't do that, I don't know for certain. And it's been a few years since it was done so memory is fuzzy...

dj

 

[Benny17441]

My philosophy is to equip a boat to meet the needs of 80% of my sailing outings and for the other 20% I make adjustments and may temporarily carry additional equipment. Too often I see boaters equip their boat for crossing oceans when all they do is weekend trips. All it does is add cost, maintenance and sources of trouble. In your case I would take a Honda 2000 generator and a 30A battery charger. They work even on cloudy days and at night.

 

[dLj]

My philosophy is to equip a boat to meet the needs of 80% of my sailing outings and for the other 20% I make adjustments and may temporarily carry additional equipment. Too often I see boaters equip their boat for crossing oceans when all they do is weekend trips. All it does is add cost, maintenance and sources of trouble. In your case I would take a Honda 2000 generator and a 30A battery charger. They work even on cloudy days and at night.

I think you missed the OP is planning on long distance cruising.

dj

 

[colemj]

I run twin alternators that each can produce 120 amps so 120 x 2 = 240 amps - not sure what I'm missing?

You probably know a lot more about the details of how these things work than I do. I'm simply an end user of these gadgets... It's my understanding, but I could be wrong, the Wakespeed was programed in the following manner - when reaching near end of cycle - the out put of 180 amps (I throttle back my alternators) slowly drops to about 10 amps of output. It plateaus there for a fair bit of time to do two things, allow the alternators to cool down, and finish the charge cycle. Then it slopes down again and shuts the alternators off. Oh yeah, there is also a ramp up cycle. Almost identical to the ramp down cycle, just notably shorter time periods.

It is my understanding that was all done through programming the Wakespeed - but as I didn't do that, I don't know for certain. And it's been a few years since it was done so memory is fuzzy...

dj

My confusion was how the alternator output mattered to the regulator. The regulator doesn't see or care about the alternator output, and this is the same for all regulators.

Likewise, the ramping down of output toward the end of cycle is common to all regulators, as it is controlled by the battery acceptance rate via internal resistance.

The ramp up isn't shared by all regulators, but has been a function of the Balmar for as long as I've known.

Mark

 

[dlochner]

My confusion was how the alternator output mattered to the regulator. The regulator doesn't see or care about the alternator output, and this is the same for all regulators.

The Balmar alternators use voltage as a proxy for the SOC. Wakespeed and Zeus measure amps, they require a shunt which more directly measures how the charging process is proceeding which allows for more efficient charging. The Balmars are also time limited for stage, I don't believe the Wakespeed or Zeus have time limits at the different charging stages.

 

[dLj]

The Balmar alternators use voltage as a proxy for the SOC. Wakespeed and Zeus measure amps, they require a shunt which more directly measures how the charging process is proceeding which allows for more efficient charging. The Balmars are also time limited for stage, I don't believe the Wakespeed or Zeus have time limits at the different charging stages.

I'm glad you answered that question as I don't know the answer. I can add that the Wakespeed does not have a time limit.

I'm also not sure about the ramp times, but was of the impression it is programed into the Wakespeed. But as I've said, I'm not knowledgeable enough to know how they all work in these details.

dj