Solar panel charging profile

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Solar panel charging profile

Postby Dogsbody » 09 May 2020, 14:34

Hi,

Hoping for some help!

I am testing a solar panel and MPPT charge controller as the WAV keeps flattening the battery, but want to check the charge profile for the battery!

Using a Victron 75/15 MPPT controller and a sun power panel, it has factory presets for certain battery types but not sure which one to use.

I can set voltages and times for different stages (bulk, absorption and float).

The battery installed is a Yuasa ybx9019....

Dog
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Re: Solar panel charging profile

Postby Burgerman » 09 May 2020, 17:13

Its an AGM sealed battery. What settings does your charge controller allow? And what is the solar panel output?
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Re: Solar panel charging profile

Postby Dogsbody » 09 May 2020, 17:49

The panel is nominal 100w

The presets in the controller are:

AGM spiral cell
Gel Victron deep discharge (1)
Gel Victron deep discharge (2)
Gel Victron long life (OPzV)
Lithium ion phosphate (LiFePO4)
PzS tubular plate traction (1)
PzS tubular plate traction (2)
PzS tubular plate traction (3)

It has defaulted to the third in the list giving:
Absorption voltage 14.4
Float voltage 13.8
Equalisation voltage 16.2

Which seem ok but not sure!!

Many thanks burgerman,

Dog
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Re: Solar panel charging profile

Postby Burgerman » 09 May 2020, 20:19

Well you dont want equalisation! So best turn that off however you do that.

If you were charging these in cyclic use (you are not) then you would want to charge at 14.4V and keep going until the current falls to a very low level, plus whatever residual load the vehicle has (which we dont know) and not for longer than 8 hours.

Since we dont know that residual drain current we cant do any of the above. It will cook the battery. And as sun goes and comes back it will endlessely run it up to 14.4V over and over. We dont want that. We want ONLY a 13.35V CONTINUAL float level ideally 24/7. Now the sun doesent shine at night. So we need to add a little. But not much.

So set to do ONLY a float charge, continually during daylight, in summer, of 13.45V. In the darker colder months, set to 13.6V max. No higher voltage charge. No equalisation. No anything except the above float voltages. That will keep the battery topped up to 100% without cooking it, drying it out, or any other damage.

No 3 or more stages. Just 1. Be aware that in the coldest darkest 3 months, that solar panel MAY not give enough power to keep it topped off. Check during daytime weekly to see that the voltage is up to the level set.

I do EXACTLY this with my own van, and a 60W panel.
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Re: Solar panel charging profile

Postby Dogsbody » 09 May 2020, 22:03

Ok,

I have followed your advice as much as I can!

I have disabled the absorption by setting it to a fixed duration, and that duration is 0 hours and 0 minutes.

The float voltage is 13.45v.

I can’t seem to do anything about the bulk charge section, so hoping it’ll be ok!

It can restart the bulk charge mode if the voltage drops a set value below the float voltage. I have that set at 1.45v meaning the battery voltage will have to drop below 12v (for 60 seconds) to restart the bulk charging mode. I guess I might be able to disable that by making it 13.45 also, but as you know as the wav tail ramp drops it draws enough current to drop the battery voltage significantly at times.

Many thanks,

Dog

Also apologise for posting lithium ion rather than lithium iron! Unforgivable, so embarrassed as don’t know how to go back to edit the post!
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Re: Solar panel charging profile

Postby Dogsbody » 09 May 2020, 22:04

Ps...

Equalisation need to be turned on... I have read enough on here to know that would be a no no!! Lol

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Re: Solar panel charging profile

Postby Burgerman » 10 May 2020, 03:37

Monitor it for a day with a multimeter... If it reaches 13.4 to 13.45V at the highest, and stays there while the sun shines. And if it drops a little at night or when cloudy, to typically 12.75 to 12.85V then you are good to go.

I have no idea what the actual settings/options will do!

My MPPT solar charge controller is the 6th different cheap one I bought that actually did what I wanted and was adjustable. All the rest tried to me over complex and did a bunch of things we didnt want. If yours is temperature compensated, so it increases volts with colder days automatically then even better. You wont need to change it in winter.

If its parked in sun, and the battery is above 20 to 25C then it is worth reducing the volts to say 13.3 too. If its temp copensated it will do that automatically.
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Re: Solar panel charging profile

Postby Burgerman » 10 May 2020, 03:39

Equalisation need to be turned on...

Off...
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Re: Solar panel charging profile

Postby Dogsbody » 10 May 2020, 11:03

Burgerman wrote:
Equalisation need to be turned on...

Off...


To correct my awful grammar in that line....

The equalisation setting in the controller needs to be actively selected to enable it. So I haven’t and will not, as I have read enough on this forum to know that you might have an aneurysm at the suggestion... lol...

It does do temperature compensation, and is currently float charging away (we’re north of the river from you, so I guess the weather is windy there too)

Hoping the battery will recover from it’s discharges and is able to hold charge. Don’t know what has brought it down but just one day on the panel and it is much more easily started.

Many thanks burgerman!

Ps do you still have that lathe?

Dog
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Re: Solar panel charging profile

Postby Burgerman » 10 May 2020, 12:18

I do.

And a solar panel on the roof of the van!

50 or 60 watts. Depending who you believe. Because its not AIMED at the sun, the best it does is approx 30w. At noon, in summer. At noon in december thats nearer 3 to 4 watts. And only if the sun shines, and only for an hour or two. So solar sucks in winter. Suns too low in sky. Keep your eye on it in the worst darkest 3 months. Nov, Dec, Jan with a volt meter. I add a 13.5v power supply for these 3 months. Depending on drain, and depending on your bigger panels output you may get away with it. Or not!
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