Strange battery behavior

[boywonder]

Originally Posted by ShuttlePilot

This statement concerns me. I wouldn't change anything in the LinkPro just yet. Which Samlex Solar controller are you using? I think we should confirm item #1 Is your battery bank achieving full charge before moving to far ahead. Be right Back.

-Eric

Sorry! that's not accurate!.........not enough caffeine yesterday perhaps.....

The batteries are roughly at 12.8V when the sun is not shining if the van has been sitting for awhile.....like this morning on the way to work...stuck my head in the side door and looked.

When the sun is directly shining the voltage is is typically in the high 13's, with zero amps when (I'm assuming) the batteries are topped off.

[Flux]

Batteries sound full to me.

[boywonder]

I'm planning on playing with the Linkpro settings (have the cheat sheet in the van), seeing if I have a temp probe for the LinkPro (can't remember!), and a few other things over the next week.

I'm leaving for Kennedy Meadows CA tomorrow am and then Heading to Moab for most of next week. I'll be sleeping in the van for the next 8-9 nights so I'll have time.

I did change the float/absorb voltages on the Samlex (SCC-30) controller sometime last year roughly....

[jony101]

with solar your never going to get a full charge to your batteries. If you use the battery all night and in the morning the battery is quickly charged up and floating right away, it didnt get fully charge the correct way, it is mostly getting a surface charge.

I notice my solar controller was never going into absorb mode, it would bulk then straight to float. What I had to do is crank up the float voltage to 14.3 volts (the highest it would go when bulk was set to 14.4 volts). I ran my system like that for 3 years 24/7, battery liked the higher float voltage. It won't overcharge your battery (mine was a 102 ah agm) , the float amps will just drop as the battery gets full. Even at the higher float voltage the sun will go down before battery is fully charge, but at least you had the higher amps (absorb voltage) most of the day. By increasing the float voltage your forcing the controller to absorb charge your battery, like its suppose too.

Something else I notice is the voltage on the battery reads differently than what the charge controller is reading. The controller reads 14.4 volts but the meter on the battery reads only 13.9 volts, I could never figure if that makes any difference, or if the voltage drop from the wire is accounted for during charging. Maybe someone knows more about this. I only have 10 gauge wire from the controller to the battery, less then 5 feet away. Maybe we have all been undercharging our batteries because of voltage drop?

[Scalf77]

jony101,

Your voltage drop seems high, I am not sure what the current output of your controller is, but 10 ft of 10 gauge (5 positive 5 ground ) @ 20 amps should give you about 0.20 volt drop. I would check and make sure your connections are clean and tight.

Unless, the controller has addition sense wires (usually a twisted pair that goes to the battery for measurement) it would have no way to compensate for the difference.

Not sure what you are using to monitor the voltage at the battery. I would check all voltages with a calibrated meter if possible.

-greg

[boywonder]

I've looked over a few things...still puzzled....

The Samlex Solar controller is set for 14.3V bulk charge and 13.4V float charge. The Samlex has the temp comp probe connected to the battery -ve.

The Linkpro does not have any provisions for a temp comp probe.

The LinkPro Function F1.0 (charger float voltage) is also set to 13.4V, as per the Linkpro setup instructions.

The LinkPro Function F1.1 (Charger's float current) is set to the default setting of 2% of battery capacity, which makes no sense to me since battery capacity is in AH and charger current is in amps (unit problem). This parameter states "when the charging current is below this percentage of battery capacity the battery is considered fully charged"...I left this one alone....

2% of 350 AH is 7AH.....

The LinkPro Function F1.2 (auto-sync time) was set to the default setting of 240 seconds, I reduced this to 60 seconds, but don't have much confidence that this matters much. This is the time that the above parameters F1.0 and F1.1 need to be met to consider the battery fully charged.

[ShuttlePilot]

So, it sounds like your still not ever seeing the LinkPro Auto Synchronize. The one thing that I've never cared for about a LinkPro, next to the fact it's way over complicated IMHO compared to a Trimetric, is that the conditions to Auto Synchronize, and thus declare the battery full, is that the Solar Controller has returned to float voltage after an Absorb voltage. Anyway, I'm about to get on my soap box so I'll stop there.

Boywonder, everything you describe seems on the surface to be fine. My next direction of thought would be to question the behavior of the solar controller. Have you seen the controller get to your absorb voltage of 14.3?
Is it holding the Absorb voltage for the 1 hr Samlex says it should be?
When it's in absorb, is the 14.3volts getting to the battery(voltage drop), is the linkPro detecting the 14.3V at the batteryor is it a tad bit lower?

This is to be confident that the LinkPro has identified Absorb has taken place(full battery).
Then I would look for the conditions that satisfy F1.0, F1.1, and F1.2 and see if it Auto Syncs. I've seen controllers and monitors miss trigger voltages by 0.1 of a volt and cause problems. My caution with all this is to make sure changes aren't made just to satisfy the LinkPro and get the behavior we would like. The priorities of importance should always be, What dose the batteries need, the charge controllers behavior should be serving the batteries and lastly the monitors behavior shall be giving good data. Never the other way around.

Not that you need any more complexity but the temperature sensor connects to the LinkPro through the RJ12 plug expansion port. The Idea of the temp probe is so the LinkPro trigger voltages march up and down with the charge controller. If batteries are stored outside in Taos, NM it's kind of necessary but you mentioned your batteries are inside and so the controller shouldn't be modifying your voltages much.

I hope your enjoying Moab.

-Eric

[Scalf77]

Eric, is spot on. Watch the controller go through it cycle and check the voltages, there is no way that the controller should be as accurate as the Linkpro. The Linkpro reads voltage with two wires that sole purpose is to measure voltage, meaning they don't carry ant current.

Your controller is reading voltage on the same wires that it supplies current, the more current the larger the value of drop. Add to that two entirely different devices, neither that we know is calibrated.

If all things were equal we would expect the controller supplying 14.3 (at the controller) there would be some voltage drop, depending on your wire size and distance to the battery at the battery. Example: Distance from battery to controller 5 ft, (10 ft supply and return) , 8 gauge wire @ 7 amps 0.03 volts or 14.27 volts).

While all this is a pain, it gets you to focus in on the controller and make sure that it goes through a cycle as it is supposed to, and most likely is.

The temp probe would connect to the communication controller if you are using it.

-greg

[boywonder]

Originally Posted by ShuttlePilot

Not that you need any more complexity but the temperature sensor connects to the LinkPro through the RJ12 plug expansion port.

-Eric

...My Moab trip was delayed by a hurricane in FL..on my way now....

The latest literature for the Linkpro has an arrow pointing to the RJ12 port saying "not used".....interesting.

[jony101]

From what I'm understanding is if the solar controller reads 14.4 volts (my controller has a lcd), the battery should also read 14.4 volts?
I put a multimeter on the actual battery and it was reading about 13.98 volts. I have an led meter inline between controller and battery and that reads 14.1 volts.
I have to do more troubleshooting, but I did notice if I crank up the bulk/absorb voltage to 15 volts, I do get 14.4 volts on the inline LED (which is close to what the battery actual voltage is).
I had the same solar system almost 5 years and the inline led always reads 14 volts, I suspect I been undercharging my batteries for years.