BMV 712 consumed amp hours

[cruxarche]

Camping with a 100 watt solar setup:
Smart solar 75/15 and a BMV 712
200 amp hour GC batteries.

when I plugged in the solar this morning consumed amp hours was 14.7 on the 712

Panel was putting out about 5.2 amps. Fridge was running (Engel draws 2.7ish amps) and teenage daughter charging phone.

over the next few minutes The 712 shows consumed amp hours slowly reducing( 14.7,14.6...)

When I checked back about 30 minutes later consumed amp hours shows 0.0. An hour later no change.

smart solar andBMV both showing panel still generating about 83 watts.

Any ideas what happened? Why the reading zeroed out?

thanks.

 

[cruxarche]

 

[cruxarche]

 

[dreadlocks]

Turn off the auto calibration when your using solar.. By default the BMV will reset to full charge if it sees it absorbing at very low intake.. but in your case, its because your using such a small charger it thinks nearly full and resets to 100% charged.

Manually Calibrate it to 100% full when its on shore power before you roll out.. then let it do its thing while your out w/out auto calibrating.

 

[cruxarche]

Awesome. Will do. Thank you.

 

[cruxarche]

Just to confirm, I switched the “battery starts synch” off as below. Is that the setting you are referring to? Thanks

 

[dreadlocks]

nope, that's the setting for what its gonna read if your BMV loses power out in the field.. looks like they changed settings since I set mine up, whats your charged voltage, capacity and tail current set too?

 

[cruxarche]

13.2. 4%

 

[cruxarche]

Settings.

 

[dreadlocks]

ok so its that 13.2 thats wrong first of all.. that should be more like 14.4-14.6v depending on what you have setup in your solar charger.. 4% of 200AH is 8A, so its gonna think its charged when its at your charged voltage, and under 8A (tail current) for 3m (charged detection time).. this will triger auto calibrate to 100% SOC.

Lets set tail current to like 1%, and charged detection time to like 30mins.. then it wont think its full til its been at your charge voltage, is getting less than 2A of charge for 30mins.. thats a good indication your at the end of the absorb stage for your bank.

To disable auto calibration all together set charge voltage higher than your solar charger is configured to output.. then its on you to manually calibrate.

 

[cruxarche]

Thank you so much. I clearly need to spend more time in the manual.

 

[cruxarche]

One More quick question. I am getting about 82 watts from the “panel” so far this morning. I can’t reasonably expect more than that from my two little 50W panels can I?

 

[dreadlocks]

yeah thats pretty typical, you wont see 100% max output out in the field but very rarely.. close to the summer solstice, at low latitudes, at 70F you might see it creep up to full output or close too it..

100W of solar per 100AH of battery is kinda the minimum I suggest.. the sweet spot is 200W of solar per 100Ah of battery, so with your big bank you could definitely use more solar panels if you got the ability.

 

[cruxarche]

Thanks. And yes, this is little 100 Portable pack is just to keep the fridge up for a few days at a time, and allow me to always have 100 watts regardless of my choice of vehicle. I know you are not a big fan of flexible panels. . I have another 100 watt panel that will soon live on trailer roof. Making this setup a 200 watt deal.

 

[dreadlocks]

at least you put a rigid backing on em, the'll last much longer because of that.. Flexible is a poor description, they are moldable.. flexible implies you can flex em w/out damage, rigid implies they will break if you flex em.. "Flexibles" realistically need some sort of rigid structure under em, however you can shape it to that structure (like a curved roof) once, thus they should be called Moldable Panels IMO.