Victron Smart MPPT 75/15 solar controller Battery type setting

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Caladh

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I have just fitted the above to my setup of 5 x 90ah SLA house bank to an 80 watt solar panel. Its there a to keep the fridge going whilst occasionally at anchor or mooring. However as I have found there is no specific setting for SLA batteries and the unit defaults to sealed gel. Will this setting damage the batteries? I am unsure of what to input to a “user specified” setting. I also am unable to ascertain any useful information from the battery manufacturer as requested in the manual.
 
Caladh said:
I have just fitted the above to my setup of 5 x 90ah SLA house bank to an 80 watt solar panel. Its there a to keep the fridge going whilst occasionally at anchor or mooring. However as I have found there is no specific setting for SLA batteries and the unit defaults to sealed gel. Will this setting damage the batteries? I am unsure of what to input to a “user specified” setting. I also am unable to ascertain any useful information from the battery manufacturer as requested in the manual.
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I have SLA batteries and find that charging with solar, via a Victon MPPT controller,absorption voltage of 14.6v and float of 13.6v works well for me, i'm onboard a lot. If i was onboard occasionally i might use different settings.
 
Jump into the "advanced mode" option via a smart phone and you can change away to your hearts content. You might make sure the equalisation option is turned off which it should be by default, you don't need 16.5v going into SLA.

Do you have the battery volt/temp widget connected via blue tooth? Useful if the MPPT is in a different location to the batteries as it will feed the correct battery temperature to the MPPT, so if the batteries get hot the MPPT will dial back the voltage and not over charge them. Equally I noticed the MPPT raise the absorption voltage to 15.1v over Christmas as our FLAs are mounted in the bilge and therefore cold.

Pete
 
Don’t have the widget but the controller is sort of next door to the batteries in a well vented cupboard. The batteries are in the large locker next door so temp difference shouldn’t be too much. Tbh during last winter my Rutland wind genny kept both banks of batteries topped up well so I’ll maybe switch the panel off when the time comes. Thanks for the walk thru on the app. I can see it becoming more addictive than looking at the Victron battery monitor!
 
Pete7 said:
Jump into the "advanced mode" option via a smart phone and you can change away to your hearts content. You might make sure the equalisation option is turned off which it should be by default, you don't need 16.5v going into SLA.

Do you have the battery volt/temp widget connected via blue tooth? Useful if the MPPT is in a different location to the batteries as it will feed the correct battery temperature to the MPPT, so if the batteries get hot the MPPT will dial back the voltage and not over charge them. Equally I noticed the MPPT raise the absorption voltage to 15.1v over Christmas as our FLAs are mounted in the bilge and therefore cold.

Pete
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Pete, I have never used the equaliation on my bank (4x110) SLA batteries, but I have always wondered if you should do this occasionally. I have my float set at 13.6V and absorption at 14.4V.
 
So here’s the thing - I put the fridge on yesterday after installing said panel and controller. Batteries were at 100%. This morning The widget graph showed the volt overnight had dropped to 12.7 but looking at 1030hrs were back up to 100% - the sun has been out! Now at 1730hrs still all good but controller is still on bulk charge. As the fridge is using around 3 amps per hour I guess and hope that the solar keeps it all good. BUT in this situation will the batteries ever get to absorption? I’d guess not (set at 14.4v) AND more to the point are the batteries effectively getting over charged.? Should I expect to ignore the normal charging rules because the fridge is effectively using the solar power available ?
 
Further to my last post, 20 minutes later Absorbtion was achieved at suddenly quite a fast rate. Of course Float now won’t be achieved because (unless I am wrong) the set 4 hours absorbtion time won’t elapse because the sun will go down.
 
Getting the optimum charging profile is obviously a good thing but your 80 watt panel may not give enough headroom depending on other loads and whether you have a dull day or three. I'm not sure if it will help your situation (it may depend on how you use your fridge) but in similar circumstances I fitted this voltage sensitive relay to preserve house bank capacity. You can set the point at which you want to turn off the fridge depending on how much capacity you want to preserve. Basically I have more like a cold box with refrigeration assistance which I'm fine with having had no fridge for 15 years on another boat.. So mine switches off in the evening and gets going again when the solar perks up. Since the boat is colder at night it's a fair trade-off. I've recently upgraded the solar so it may no longer be necessary but still a nice to have.

Battery Guard 12V DC: Amazon.co.uk: Electronics
 
I've just fitted the same controller (20a) and a new 240 watt panel. I have to say the documentation is pretty rubbish. Surely they could have written an idiot's guide for this idiot.
 
Baggywrinkle said:
This post from a previous thread might be of interest.

Dumping excess solar energy
Click to expand...

The way you went about planning your setup makes good sense. You ended up with pretty much the same as me, i have 390ah of SLA batteries and 260w of solar, this makes the boat self sufficient during the Summer, unless i get 2 or 3 dull days in a row. (y)
 
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