Charging Issues - solar bulk charge =12.65v, alternator=14v

[thomm225]

Originally Posted by sailinglegend

When a charger drops back to Float the battery is never fully charged, maybe only 90-95%.

Of course it doesn't.

It's just a way of speaking which some hobbyists seem to have trouble with

I was at the boat this am expecting something near full charge up to Float, but my batteries were only at 12.7 or so

Before I left voltage was up to between 13.28 to 13.67 volts (depending on how I aimed my panels) so I'm thinking it will be charged up to float in an hour or so.

I get there at 2:30 pm and it's still in absorption phase with the voltage at 14.25 so I know there's a connection problem or a bad battery

I move all connections at the batteries and while waiting hook up a 20 watt panel that I had just soldered wires on

I didn't have enough wire to install my PWM Controller with this panel so I just hooked it directly to the batteries

Within a couple minute the Float light came on and I had around 13.58 volts on the batteries according to my uncalibrated $20.00 meter so it was definitely a connection problem

After a while and before I left I disconnected the 20 watt panel from the batteries, but it does fit quite nicely on the cabin top

[john61ct]

Originally Posted by sailinglegend

When a charger drops back to Float the battery is never fully charged, maybe only 90-95%.

That is the usual case, but a problem up to the owner to solve, not something to tolerate if you care about bank longevity.

> Only a a very few chargers have a shunt to see "endamps"

Yes, so it is up to the owner to adjust the Absorb Hold Time until she sees the charger only drops to Float after endAmps is reached, at least a few times per week.

> It is desirable that the charger doesn't stay at this high absorption voltage this long,

Absolutely false, in fact many solar setups are optimized by never dropping to Float at all while cycling. Reset when in storage of course.


> better to drop to float at around 2% of Ah capacity.

The endAmps spec used should match what is given by the batt vendor, just like the voltage setpoint it varies.

[thomm225]

I checked my system this am and it read 13.8 volts and still in Bulk stage.

It hadn't charged all the way up to Float yet which is 13.8 volts

As far as your batteries being charged to near 100 %, my PWM controller would hold the max voltage at 13.8 which was my float setting. When this would first occur the voltage on the panel side would also be 13.8 volts but after a time the voltage on the panel side would near VOC or around 20 volts or more which tells me the battery was continuing to charge until close to max when it could take no more.

I haven't tested this yet on my MPPT.

[sailinglegend]

Originally Posted by john61ct

....> .....so it is up to the owner to adjust the Absorb Hold Time until she sees the charger only drops to Float after endAmps is reached, at least a few times per week...

This is dangerous because if a battery is already fully charged and you motor for several hours then any "smart" alternator you have programmed is going to stay at absorption for several hours and dry out the batteries.

Originally Posted by john61ct

.....> It is desirable that the charger doesn't stay at this high absorption voltage this long,

Absolutely false, in fact many solar setups are optimized by never dropping to Float at all while cycling. Reset when in storage of course.

I'm sorry but batteries should not be held at absorption voltage when they are fully charged. The batteries limit the current they will take but the absorption voltage will cause increased gassing and dry out the batteries.

Many solar controllers allow you to never drop to float because they know that for the majority of solar setups there are just not enough hours in the day to get the batteries fully charged - even if you run an engine or generator first thing to bring the charge up to about 80%.

Originally Posted by john61ct

.....> better to drop to float at around 2% of Ah capacity.

The endAmps spec used should match what is given by the batt vendor, just like the voltage setpoint it varies.

Most vendors don't give this info. I don't know anyone who uses endAmps to set the absorption time, so most chargers will drop to float at around 2% of Ah capacity because chargers are all designed to charge batteries not overcharge them. This is their built in safety feature, so why interfere with it?

I only use endAmps to check in the morning after a night on shorepower that the batteries are fully charged. My "smart" Victron charger will only stay at absorption voltage for a few minutes if they are full, so no damage can be done by checking, but I wouldn't then want the charger to stay at absorption for several hours that might happen with your programming.

[john61ct]

Originally Posted by thomm225

I checked my system this am and it read 13.8 volts and still in Bulk stage.

It hadn't charged all the way up to Float yet which is 13.8 volts

In Bulk it is not trying to get "up to Float", but up to Absorb voltage. Which is still many hours from 100%.

What is your Absorb setpoint.

Float is irrelevant to your setup currently, since it should only **drop** to that setpoint after reaching 100% Full.

No charging happens after that point.

You need to get more energy into your bank or it will die an early death. And stop using so much, until you see you are regularly getting to Full, at least 2-3 times a week.

Completely ignore the voltage on the panel side, unless you think something is broken.

Measure volts and more importantly amps, on the battery posts to verify your SC is doing what the bank needs.

[john61ct]

Originally Posted by sailinglegend

This is dangerous because if a battery is already fully charged

The problem is that 99% of systems are never getting to full.

Meaning most banks are murdered early.

Endamps is the only accurate way of ensuring Full.

With consistent usage patterns, the right Hold Absorb Time will be "close enough" most days, and far better to go too long than constant PSOC abuse.

Holding Absorb for an hour or two "too long" is no problem. With quality FLA even longer, just keep the water topped up.

If your bank is expensive and you are concerned about this then automating stopping based on a shunt reading endAmps is the solution.

> Many solar controllers allow you to never drop to float because they know that for the majority of solar setups there are just not enough hours in the day to get the batteries fully charged - even if you run an engine or generator first thing to bring the charge up to about 80%.

Exactly.

> Most vendors don't give this info.

It would be foolish to buy a bank from a maker that didn't. All the good ones do. They also have qualified tech support readily available to answer your questions. If they don't, avoid them.

> so most chargers will drop to float at around 2% of Ah capacity

If it was any number consistently that would be an amazing coincidence, since they don't measure trailing amps, 99.9% only use Hold Time.

But yes your point is valid, defaults are set so that OOTB they all under charge, premature infloatulation. Better that, than over, right? Say the lawyers.

I'm not saying this is a serious defect. But the owner must make the appropriate adjustments for their setup, and change the settings as usage patterns change - while not cycling at the dock will be very different from offgrid liveaboard, right?

Partying with loud music every night vs singlehanded. . .

> I wouldn't then want the charger to stay at absorption for several hours that might happen with your programming

It is **your** programming - or lack thereof - that will determine your bank's longevity.

Defaults are there to be be changed, there is no one setting that's right for everyone.

With sophisticated adjustable gear, and sufficient energy inputs, seems pretty silly to me to continue to abuse the bank for no good reason.

[thomm225]

Originally Posted by john61ct

In Bulk it is not trying to get "up to Float", but up to Absorb voltage. Which is still many hours from 100%.

What is your Absorb setpoint.

Float is irrelevant to your setup currently, since it should only **drop** to that setpoint after reaching 100% Full.

No charging happens after that point.

You need to get more energy into your bank or it will die an early death. And stop using so much, until you see you are regularly getting to Full, at least 2-3 times a week.

Completely ignore the voltage on the panel side, unless you think something is broken.

Measure volts and more importantly amps, on the battery posts to verify your SC is doing what the bank needs.

Yeah, I know. You need to chill out a little bit. It was a play on words to the rude poster earlier.

My system was probably at float within one hour after I checked this am

It was there at 3 pm anyway. I have way too much power in my panels for my system......like 155 watts when my 50 watt panel arrives. I've done fine with one 65 watt panel and an $18.00 PWM controller for the last 5 years

I just enjoy playing with the solar after so many years in electronics/electrical/computers.

I my add a fridge/cooler soon though

[john61ct]

Again 99% of charge systems go to Float way too early, causing the trusting owner to think the bank is Full, murdering the batts early.

Verify with endAmps with an ammeter

[john61ct]

MaineSail just posted some great info about how common PSOC abuse is and some real-world test results

http://www.cruisersforum.com/forums/....php?p=2706281

[thomm225]

Originally Posted by john61ct

In Bulk it is not trying to get "up to Float", but up to Absorb voltage. Which is still many hours from 100%.

What is your Absorb setpoint.

Float is irrelevant to your setup currently, since it should only **drop** to that setpoint after reaching 100% Full.

No charging happens after that point.

You need to get more energy into your bank or it will die an early death. And stop using so much, until you see you are regularly getting to Full, at least 2-3 times a week.

Completely ignore the voltage on the panel side, unless you think something is broken.

Measure volts and more importantly amps, on the battery posts to verify your SC is doing what the bank needs.

When I say Float, I'm referring to the final stage which is why I say charging up to Float.

My bank is usually recharged in 1/2 a day if all connections are good and there is decent Sunlight.

With my PWM Controller, the voltage on the panel side will tell you how fully charged your batteries are since when it first goes into Float the voltage on both sides is 13.8 V, but after a few hours or the following day, the voltage on the panel side will near your panel's VOC because the battery's internal resistance has increased so much it can't take much current/charge at all

This method doesn't work with the MPPT Controllers though but they will go as high as 14.4 volts during absorption while charging up to Float which on mine at this time is at 13.8 volts.

I'm leaving it at 13.8 volts for now because if I hook up another panel it will connect thru the PWM Controller which is also set for 13.8 volts Float. The PWM has a constant voltage display also which is nice

[john61ct]

The way you continue to phrase things leads me to conclude you still don't grasp how staged charging works.

But I'm not going to repeat it all yet again, re-read my previous attempts, ask clarifying specific Qs if you like

or just carry on, but please don't continue to mislead others.

Float is not part of the charge cycle, but a voltage drop after charging is complete.

In your situation it is irrelevant.

Absorb is the important setpoint for charging, and 14.4V is not a high number, it should be set to whatever your bank mfg specs, many are different.

Your goal is to stay at that voltage for many hours, or your bank gets murdered quickly.

[thomm225]

Originally Posted by john61ct

The way you continue to phrase things leads me to conclude you still don't grasp how staged charging works.

But I'm not going to repeat it all yet again, re-read my previous attempts, ask clarifying specific Qs if you like

or just carry on, but please don't continue to mislead others.

Float is not part of the charge cycle, but a voltage drop after charging is complete.

In your situation it is irrelevant.

Absorb is the important setpoint for charging, and 14.4V is not a high number, it should be set to whatever your bank mfg specs, many are different.

Your goal is to stay at that voltage for many hours, or your bank gets murdered quickly.

Ha! (my "bank" is two $88.00 deep cycle batteries in parallel from auto world, zone, place)

I'm still testing. Boat, batteries, autopilot, paints, anchors, etc.

I know how tech's like to overdo the importance of their opinions. They are so into what they do they cannot let it drop ……. as you can see from our posts.

I'm a tech also......and manager of techs now.

This job though does have it's perks. I can fly when I want. I needed to get away this am and found a Sim not in use so I flew over my planned sail for the weekend. It took maybe 30 minutes but will take me several days on the boat

I totally understand what I'm talking about

How much more simple can it be than the three stages?

I plan to put alligator clips on the 50 watt panel when it arrives so I can use it early in the am and face it directly at the rising sun and attach it directly to the batteries

I moved the 20 watt panel I had on the stern railing to the cabin top just inside the dodger which is rolled up at the moment

I'll try and get pictures on this weekends voyage. I may do the same with my other 20 watt panel. Alligator clips and facing the Sun. My 65 watt panel is a PITA to move and aim due to it's size

Running a 115 volt AC fan all night (and much of the day when it's hot) thru my inverter is very inefficient so it takes quite a bit of juice overnight...….that plus lghts and depth finder really work my batteries

[sailinglegend]

Originally Posted by john61ct

......but please don't continue to mislead others.

Float is not part of the charge cycle, but a voltage drop after charging is complete......

Now you John are confusing others!!!!

It is the third stage of a three stage charging cycle and at 'Float' the charging is still happening.

The voltage drops by about a volt but the batteries still accept current until they are fully charged. The return amps or endAmps maybe too low to measure which is why endAmps at 14.4v is used to show when batteries are fully charged. On my setup the charging current drop from 14.4v to 13.4v is about four times, so the current may drop from 12 amps to 3 amps - it is still charging but takes much longer to get to 100%.

[conachair]

Originally Posted by sailinglegend

On my setup the charging current drop from 14.4v to 13.4v is about four times, so the current may drop from 12 amps to 3 amps - it is still charging but takes much longer to get to 100%.

Could you share your data? How long for the current to level off? What criteria do you use for 100% & how much current does it take to keep the volts at float?

Thanks.

[thomm225]

Originally Posted by conachair

Could you share your data? How long for the current to level off? What criteria do you use for 100% & how much current does it take to keep the volts at float?

Thanks.

It depends on how large your battery bank is.

One example was my first setup. I used the left over starter battery for the diesel that failed plus one new deep cycle 12 volt battery in parallel as a house bank. (not the best idea but the starter battery was practically new)

Solar was one 65 watt panel which charged the batteries thru one of those cheap Chinese Controllers (I paid $12.00 for mine in 2012) that hold the volts to a max of 14.4 volts.

So I had alligator clips on the leads that went to the batteries because I didn't want 14.4 volts on them 24/7/365 when not in use.

So I'd monitor the batteries and after they'd get to 14.4 volts I'd check the panel side. If it was near 14.4 volts I knew the batteries were still charging

When I'd check the panel side hours later or the next afternoon, the voltage on the panel side would then be approaching the VOC (18, 19, 20 volts or so) of the panel so I'd know then they batteries were getting close to fully charged due to the decreased current flow to the battery and the increase in volt. The battery side would still be at 14.4 volts. Then I'd disconnect

I'd monitor my later PWM controllers the same way but didn't have to disconnect because they had float settings which I had set at 13.8 volts during the season.

When the PWM Controller would first get to 13.8 volts on the battery side (the display would show this) the panel side would be the same. Hours later though if you checked the panel side the voltage there would be nearing VOC (on a sunny day) due to the decrease in current the batteries could take because they were nearing full charge...……...and the voltage was climbing similar to if you had an open circuit in TTL or any DC Circuit (there's no current flow in an open circuit so the voltage is at the supplied voltage. This is a good troubleshooting aid as well)