Battery readings help

[Darthblahh]

II'm confused, maybe someone here can help me. 
I have solar for the van feeding 3 deep cycle batteries, 3 @ 105 amps ea. For a total of 315 amps. Now wanting to never draw them down under 50% that gives me 157.5 amps. 
Voltage meter for the batteries was at 12.8 last night (full).
In the morning it was at 12.5 but also said 48% when going through the options on the MeTer. 
I will draw at absolute most 50 amps over night. That's probably way more than I use but just round up to be on the safe side. 
So, if I draw no more than 50 amps and the MeTer says 12.5 how can I be down 50%?
From what I understand if I draw my batteries down 50% my meter should be at 12.06 or so. 
Hopefully this make sense. 
Thanks for any help.

 

[highdesertranger]

what meter? how was it programed? 50ah is about 1/3 of the 157ah = 66% full. however 50ah is about 1/6 of 315ah which would be about 84% full. math is approximations I didn't get the calculator out. so it all depend on how the meter was programed. highdesertranger

 

[Darthblahh]

what meter?  how was it programed?  50ah is about 1/3 of the 157ah = 66% full.  however 50ah is about 1/6 of 315ah  which would be about 84% full.  math is approximations I didn't get the calculator out.  so it all depend on how the meter was programed.   highdesertranger

I use a Renogy mppt charge controller & bought the MeTer as an xtra add on that gives me all kinds of read outs. I did program the MeTer for the amp hours. I set it at 310. 
Is that what you mean by what the meter is programmed at?

 

[highdesertranger]

yes that is what I meant. something is not right the meter should be reading in the mid 80's. I am going to help install this same system. Renogy does not give a lot of info on the meter. calling Got Smart, maybe he can give us some insight. highdesertranger

 

[Darthblahh]

yes that is what I meant.  something is not right the meter should be reading in the mid 80's.  I am going to help install this same system.  Renogy does not give a lot of info on the meter.  calling Got Smart,  maybe he can give us some insight.  highdesertranger

Just for some added info, all 3 of my agm batteries are less than a year old. 
In the mornings my batteries are back to full by about 10:00am. 
NW Ohio so I'm not in a crazy hot area either.

 

[GotSmart]

I use a Renogy mppt charge controller & bought the MeTer as an xtra add on that gives me all kinds of read outs. I did program the MeTer for the amp hours. I set it at 310. 
Is that what you mean by what the meter is programmed at?

I am not impressed with the electronics sold by Renogy.  These meters are not state of the art.  (Unless you are dealing with the high end commercial large systems) 

They do make a solid panel that is hard to beat. 

Sternwake has a thread on battery charging that could help you.

 

[highdesertranger]

Got Smart tell them to get their act together with their instructions on that meter. highdesertranger

 

[GotSmart]

Got Smart tell them to get their act together with their instructions on that meter.  highdesertranger

Instructions can be had.

http://www.renogy-store.com/Downloads-and-Guides-s/1909.htm

For real help, try this thread.

https://vanlivingforum.com/Thread-9...om-full-How-long-to-full?pid=193288#pid193288

 

[SternWake]

Not being familiar at all with that solar controller, I am hesitant to guess what is going on. 

 I 'think' it can only somewhat accurately display a % remaining when the all the house loads are hooked to the load port on the controller. Any loads hooked to the battery itself( like an inverter with thick cabling should be) cannot be counted by the solar controller, it can only infer a percentage from battery voltage. 


But if the sun was already up when it was reading  12.5v, well to get voltage to raise from 12.2v to 12.5 will happen pretty early on a Sunny morning.  Voltage climbs from 12.x to ~14.4v as the battery charges.  The higher the charging current the faster it rises.  The more sulfated the battery, the faster voltage rises.  When low charge currents cause voltage to rise fast on a healthy battery, the battery was not discharged much at all.  When larger currents cause the voltage to rise only slowly, the batteries are healthy, depleted, and gobbling up everything the charging source can make.  

This is variable depending on  actual capacity and what constitutes a large current, But I will say 10 amps per 100Ah of capacity touches on 'large'




Are these batteries new?
 Flooded group 27's? 
Which make and manufacture?

If removing 50AH from 315Ah of total capacity, assuming a full charge to begin with,  had voltage drop to the 12.2v range, well those batteries are not performing  very well.

In general to have an accurate battery monitor all the loads/charging sources must go through a Shunt, and the battery monitor figures out how much current is flowing through this shunt, and in what direction, and counts amps into and out of the battery and will give an 'AH from full' figure as well as a percentage.  Such battery monitors are in the 200$ range with a few exceptions.

Simply infering % remaining by voltage is not accurate.  Not something renogy will have mastered in their charge controller.

The 'Smart gauge' seems to be able to accurately do this without the shunt inline but it is not cheap.


Regarding the proper monitoring of a battery bank, here are some good links help understand the process:

http://www.pbase.com/mainecruising/battery_monitor

http://www.pbase.com/mainecruising/programming_a_battery_monitor

http://www.pbase.com/mainecruising/smart_gauge

 

[WheelEstate USA]

You can call Renogy tech support...
(909) 287-7100
I bought a charge controller from them and the paperwork was funky. Had to g00gle up a pdf for the correct info.

 

[Darthblahh]

Ok, so it seems to me that the MeTer % is simply not accurate. Through watching the voltage during use of items in my van over time I do believe things are good, just the % is not accurate. Right now I don't think replacing the MeTer for a better one is cost effective just to get the % more accurate. Maybe when I upgrade the system in the future.
I really want to thank everyone for the help. This was my first post ever in the forums and it was amazing to see the speed and generosity of everyone here willing to help.
I knew I came to the right place.
Safe travels to all.