Victron solar regulator, custom settings for Trojan T105s.

[GILow]

Hi all,

I’ve bought a pair of Victron 100/30 Smartsolar regulators to charge my new battery bank based on Trojan T105s.

I’ve been looking at the preconfigured charging profiles on the Victrons and none of them precisely match the voltages recommended by Trojan.

That’s ok, because the Victrons allow you to set your own charging profile using their VictronConnect app over Bluetooth.

Hers the thing though... the Victron manual, on page 7 states: “Fully programmable charge algorithm (see the software page on our website) “

That SOUNDS like they have some predefined software profiles for different batteries to me?

That might be silly optimism on my behalf, because I can’t find anything that looks right, now I wonder if anyone here can shed any light on the idea?

Also, has anyone come up with a particularly good charging profile for the T105s they’d like to share?

Matt

[conachair]

Originally Posted by GILow

Also, has anyone come up with a particularly good charging profile for the T105s they’d like to share?

Matt

bulk = 14.9v
float = 14.9v


Even then with extensive logging of volts & amps it's hit and miss if they actually really get back to 100% by the time the sun gets low.... based on current going in finally leveling off.

[GILow]

That bulk is reasonably close, but I’d be real worried about that float voltage. That’s surely going to cook them?

I’ve got a reasonably large amount of solar compared to my usage, so I should be getting to float by early afternoon I believe. That would leave a lot of cooking time.

[noelex 77]

Trojan recommend 14.7 v for absorption and 13.5 v for float (@ 25°C). The drop down to float should be when the battery return amps drop to 1%-3%.

Personally, providing you can keep the water up, I would be a little more aggressive than these recommended settings. For example 14.8 v and 13.7 v, (don’t forget temperature adjustment). I would aim for arround 1% battery return amps and this will determine the ideal absorption time.

Equalisation is recommended at 16.2 v, but don’t set this to be automatic, as the voltage is high enough to damage some electronics.

There are detailed instructions here:
https://www.trojanbattery.com/tech-s...y-maintenance/

[GILow]

Originally Posted by noelex 77

Trojan recommend 14.7 v for absorption and 13.5 v for float (@ 25°C). The drop down to float should be when the battery return amps drop to 1%-3%.

Personally, providing you can keep the water up, I would be a little more aggressive than these recommended settings. For example 14.8 v and 13.7 v, (don’t forget temperature adjustment). I would aim for arround 1% battery return amps and this will determine the ideal absorption time.

Equalisation is recommended at 16.2 v, but don’t set this to be automatic, as the voltage is high enough to damage some electronics.

There are detailed instructions here:
https://www.trojanbattery.com/tech-s...y-maintenance/

Thank you for those numbers.

Do you see the advantage from the slightly higher voltage settings to be faster charging or improved battery life? (Or both?)

The manual you linked is interesting. Not least because Trojan seems to give slightly different voltage numbers depending on which document you are reading, and of more concern, VERY different equalisation instructions.

In one document they say equalise every 30 days, in another they say only once a year unless specific gravity readings are varying by greater than .0030.

Your recommended 1% battery return rate is based on the 20C capacity?

[Frankly]

One thing, if I remember correctly, the standard absorption voltage is set slightly lower because in a solar setup you are typically going through some absorption level charging every day. Victron had decided that might be a little harsh on the batteries so they backed off the absoption voltage a few tenths.


I have been running my 75/15 into a 600 AH Sams Club best GC2s bank for over a year and all appears fine. Real proof will be in 4 or 5 years.


Frankly

[GILow]

Originally Posted by Frankly

One thing, if I remember correctly, the standard absorption voltage is set slightly lower because in a solar setup you are typically going through some absorption level charging every day. Victron had decided that might be a little harsh on the batteries so they backed off the absoption voltage a few tenths.

That rings a bell, I think I might have read that in one of the documents. Thank you for reminding me and drawing the connection.

Good luck with the new battery bank, I’ve heard a few positive remarks about the Sam’s GC batteries.

Not an option for me here in Oz, however.

[conachair]

Originally Posted by GILow

That bulk is reasonably close, but I’d be real worried about that float voltage. That’s surely going to cook them?

I’ve got a reasonably large amount of solar compared to my usage, so I should be getting to float by early afternoon I believe. That would leave a lot of cooking time.

I would have shouted exactly the same from the rooftops for many years, until lots of logging into a database showed what was going on, with shadows, the fridge cycling on and off, panels pointing the wrong way even with 300W solar & 225Ah just going down to maybe worst 75% the batts just weren't getting to full charge very often if ever when dropping down to float after a good few hours, even with no float @ 14.9v often the current going in will more often be low, maybe 1.5%, but still dropping down when the sun goes away. And they seem to be holding up very well, though need to figure out how to do a real temp controlled load test to know for sure. I reckon the trojans can handle a bit of voltage on and off for a hour here and there better than constantly never getting to really 100%. They don't gas that much.
No one can argue either way cos no one has any real data on the subject, at a guess multitudes of cruising boat batteries get killed every year from constant under charging but very few if any die from a highish longer bulk, decent flooded deep cycle anyway.
L-16 recommended charging voltages - OutBack Power Technologies User Forum

[noelex 77]

Originally Posted by GILow

Thank you for those numbers.

Do you see the advantage from the slightly higher voltage settings to be faster charging or improved battery life? (Or both?)

Both undercharging and overcharging will shorten the life over the optimum settings. The manufacturers recomendations are always the best starting point, but these need to cover a wide range of situations. Undercharging is far more common and does more damage. Knowing this some people go overboard with overcharging which I don’t think is correct, but erring on the overcharging side is better with flooded batteries. This helps keep the average SOC as high as possible and increases the occasions when the battery will reach 100% SOC. Both of these are good for battery life and providing the settings are not overly aggressive the downsides such as positive plate corrosion are kept only slight.

The only caution I would add is try and check the voltages at the battery independently with a meter that is in good calibration and make sure you have accurate temperature compensation. It is not unusual for solar controllers to be a tenth of volt or more out. Especially when selecting settings a little outside the recommended values you want to sure any error is not is not pushing the voltages more outside the nominated voltages.

Originally Posted by GILow

Your recommended 1% battery return rate is based on the 20C capacity?

Yes. Make sure this is measured at the absorption voltage and I think about 1% of C20 capacity is a good point to aim for with these batteries.

Originally Posted by GILow

The manual you linked is interesting. Not least because Trojan seems to give slightly different voltage numbers depending on which document you are reading, and of more concern, VERY different equalisation instructions.

Yes, I have read different recommendations. From memory I have also seen documents where they advise a “finishing charge” for cyclic use, although this is difficult to impliment with normal solar controller algorithms.

[wrwakefield]

Matt,

I have 3 Victron Smart Solar 75/15 controllers. They are all set identically per this T-105 spec sheet from Trojan [Victron image attached]

Absorption: 14.82

Float: 13.6 [up a tick from spec to work with other charge sources; panels never get to float on their own...]

Equalize: 16.2

They all are networked to a Victron battery monitor for temperature compensation and common bank voltage readings. And as of a recent firmware update, all are networked for synchornized charging. [Image 2]

That same firmware update now also displays total network power of all panels when viewing any single panel. [Image 3.]

These settings seem to work well for us the past few years.

In case this is useful.

Cheers! Bill

PS: Screen shots are fresh for this reply; an overcast day on shorepower, so the main charger is active...

[Dsanduril]

There's an interesting disconnect in Trojan's literature that they don't call much attention to, but they do differentiate between "bulk" and "absorption". In Trojan's "ideal" charge cycle (T105) you would charge constant current to the 14.82 "bulk" voltage, then transfer to a constant voltage regime at 14.7 until tail current reaches 1-3% C. One day I may have to experiment with implementing this slight voltage drop from the end of constant current to constant voltage and see what happens. I suspect it reduces gassing somewhat but still allows a short time at the higher voltage to start the breakup of the harder sulfates. Wish some PhD student would do a dissertation.

In the real world, we tend to not end up at float too often because we live on 95%+ solar and get to the right tail current pretty near the end of the day anyway. I don't have the T-105s so won't comment on the exact setting for voltage or current.

I will second Noelex on using a good DVM to calibrate your charge sources, between all the different sources on our boat we have about a 0.25V spread between various charging devices, monitors, and the batteries themselves. Getting settings down to the 0.01V range isn't realistic with the voltage sensors built into most of the available devices.

[sailcrazy]

Following.

[noelex 77]

Originally Posted by Dsanduril

There's an interesting disconnect in Trojan's literature that they don't call much attention to, but they do differentiate between "bulk" and "absorption". In Trojan's "ideal" charge cycle (T105) you would charge constant current to the 14.82 "bulk" voltage, then transfer to a constant voltage regime at 14.7 until tail current reaches 1-3% C. One day I may have to experiment with implementing this slight voltage drop from the end of constant current to constant voltage and see what happens. I suspect it reduces gassing somewhat but still allows a short time at the higher voltage to start the breakup of the harder sulfates. Wish some PhD student would do a dissertation.

A bulk voltage that was slightly higher than the absorption voltage was a common lead acid charging regime a couple of decades ago.

My first solar regulator allowed for this option, but on most modern controllers do not have the ability to select different bulk and absorption voltages.

I suspect in practice the separate voltages made little practical difference although from a theoretical point of view more steps rather than large jumps in the voltage set points has a lot of appeal.

Most battery manufacturers are no longer recommending different bulk and absorption voltages although I think this more because this advice would confuse consumers when it is not possible to enter this as an option on their controller.

[Dsanduril]

Hence my wish for a PhD dissertation

I really would like to know if it makes a difference, or if the simplification is the result of finding out that it doesn't.

[GILow]

Thank you to all so far, a great read and lots to think about.

I hope I’m not kidding myself when I feel the batteries should be getting to float regularly and easily. I will watch more carefully (easier with the Victron regulators than my old system).