Monitoring battery capacity

Norskeman wrote:
http://www.skycraftsurplus.com/meterdcdigital85-30v.aspx

Digital 3-1/2 Digit LED Panel Meter, 8.5-30VDC. Sure Electronics ME-SP038 $24.99

Does this need to be wired direct to the battery for accurate measuments?

Also how much power does this take from the battery if its on all the time?

http://www.skycraftsurplus.com/meterdcdigital85-30v.aspx

Digital 3-1/2 Digit LED Panel Meter, 8.5-30VDC. Sure Electronics ME-SP038 $24.99

Only reads up to 30V...Is this enough for a 120w / 12V solar panel....?

http://www.skycraftsurplus.com/meterdcdigital85-30v.aspx

Digital 3-1/2 Digit LED Panel Meter, 8.5-30VDC. Sure Electronics ME-SP038 $24.99

DEBUD - Another note that just come to my attention last week is my setup was done in 2009 and I used SURE ELECTRONICS LED meters being the ME-SP038 for the DC VOLTMETERS meters and the ME-SP230 for the 70A DC CURRENT ammeter. These were very inexpensive meters unit in 2009.

Someone was researching ebay to get these same meters from ebay/china and found the ME-SP230 70A Dc current meter now costing some $820 verses the $40 it cost me back 2009. The cost of the ME-SP038 DC VOLTMETERs remain inexpensive.

I have no idea of the outcome of this or what might be a good replacement for the ME-SP230. No way would I pay $820 for a HALL EFFECT DC AMMETER.



Roy Ken

debud - actually not knowing when dry camping leaves you in the dark around 10PM in my experiences usually haha...

One thing I would really like to have my BATTERY MONITOR PANEL which is just meters to do is give me an audible alarm that goes off when the batteries get down to their approximate 50% charge state.

The good smart alarms will have this feature... At least the TRIMETRIC RV-TM2025 one does... The one drawback I might have with the TRIMETRIC is monitoring multiple battery banks at the same time.

I was going to add an VOLTMINDER to my monitoring setup to give me the settable audible alarms and the company went off line for a few months to redesign a new meter. It is now in prototype status and will be in production soon they tell me.


I think the new one will look something like this


Roy Ken

Thanks all. Lots to think about. Not knowing when dry camping leaves you open to lots of guesswork.

^^^^ Chart above is for a battery with a modest load. Open circuit resting voltage is higher.

OP, get a voltmeter. Biggest thing to know is when to start recharging. 12.20 or less is time for recharge. To 90% charge is fairly fast and the last 10% can take 6 to 10+ hours. So you are not really looking for 100% while in use or charging on a generator.

Next you need to review your charging system to see if you need to run the generator 2 hours or 20 hours to get close to 90%.

Once you get the hang of it and discover what voltages those lights mean they actually become quite useful.

But what will the battery read when there is a load in it, like the fridge or a light on, the above state of charge is for no load correct?

The Trimeteric is an excellent product but there are others. Link 10, Xantrex, Magnum, and Outback all make battery gauges. If you have a Blue Sky solar charge controller they also make a battery gauge that will integrate with it. The Xantrex, Magnum, and Outback gauges all integrate with their inverters.
A battery gauge uses a shunt to measure actual amps in and out of your battery. It is far more accurate than relying on voltage readings.

I do it by just monitoring the 12VDC power coming from the battery bank. My game plan is have enough battery capacity to operate all of the 120VAC Items we want to have from an Inverter and all of the 12VDC items we want to have direct connected to the battery bank. This is all planed to run my battery bank down to around its 50% charge state by 8AM the next morning when we are allowed to run our 2KW Generator to recharge the battery bank back up to its 90% charge state in a short three hour generator run time.

I monitor my battery DC voltage with my home made battery monitor panel but any DC VOLTS monitoring capability will work just fine. When my battery drops to around 12.0VDC which is around 50% charge state then I know its time to start re-charging my battery bank of quit using my batteries.

This chart is helpful showing the DC VOLTAGE verses the STATE OF CHARGE. It is not absolute but close enough for me to use. have been very successful the past five years camping off the power grid with my same 255AH capacity battery bank...



It does take some planning to be successful camping off the power grid

Roy ken