Help me choose a fuse and shunt

Every connection on that DC side is a potential hazard because of the amp draw and heat from poor connections, limit your hazards.

Hi,

I actually use a watt meter on the output side.

Here is a 100 amp unit that also does watts:

https://www.amazon.com/DROK-Digital-Multimeter-Voltmeter-Ammeter/dp/B01MRZAFAF/ref=sr_1_6?s=hi&ie=UTF8&qid=1498929714&sr=1-6&keywords=watt+meter

This is the unit I use:

https://www.amazon.com/Efergy-ELITE-TPM-NA-True-Power-Meter/dp/B00GR2XJMQ/ref=sr_1_1?s=hi&ie=UTF8&qid=1498930195&sr=1-1&keywords=efergy+elite+true+power

I have wired it so it measures wattage on shore, inverter, or generator.

DiskDoctr wrote:

pianotuna wrote:
Hi,

I prefer to use Hall effect ammeters--no shunt needed.

Got a link to one at least 200 amps?

DiskDoctr wrote:

BFL13 wrote:
...If you get the Trimetric, you will need its 500a shunt, not the little 100a one. (IMO just bite the bullet and get the Tri instead of fooling around with cheaper kinds that can't do it all)

$200 :(

Eventually may build out Arduino, but looking for something to get started. If we can find a decent hall effect ring in this amperage, I'd be happier to use it. If we go over the amps on it, there shouldn't be any damage to the sensor, right?

The inverter really wants direct cables to the batteries, according to all the installation docs I read. Make sense ?

Same with the converter/charger, then branch to the frame lug and feed to the camper/distribution box.

It may not be "ideal" but should be fine, right?

The inverter installation instructions assume no shunt. You are allowed to have one though. It is easier to do a set up without one for sure.

You don't need any kind of monitor or ammeter to go camping. You must have a voltmeter. So get whatever works. Or keep getting them until you get one that does.

Yes the Tri is more up front, but it lasts. Got mine seven years ago and counting, so 200/7 = 28.57 a year which isn't so bad and will be even better next year!

Okay, going through the key drivers here.

1. Inverter is by far the largest potential user. It has it's own LCD monitor for amps and volts that I should be able to remote inside the cabin area. Covers all 120v appliances, including microwave. Check.

2. Battery charger/converter (PD9270) is the largest potential "reverse user" which can be inferred to some degree by voltage. Inverter also measures this in the same display. Check.

3. Propane furnace fan is a big user. No way to monitor it right now. Need monitor.

4. Most lights are converted to LEDs. I will finish doing so soon. The draw of any/all is negligible. Check.

5. Electric side of DHW is unmonitored. Need lockout/relay/indicator.

6. A/C is unrestricted (electric heat strip also). Need lockout/relay.

7. Remaining battery level and time unknown. Need voltmeter as 'poor man's state of charge monitor'


Perhaps I don't *need* too much right now? If I were going to use just voltage to monitor batteries and remaining state of charge, what chart of voltages should I use? I've seen a number of them, but not very detailed.

Maybe my daughter and I can slowly play with an Arduino based monitor in the future as a project ;)

So if you only had VOLTAGE to work with, what would you use as your guide?

Hi,

My system evolved over time. I started with a 70 amp ammeter and voltage was displayed on my Blue Sky charge controller.

I don't prefer the Trimetric as it requires you to set the battery capacity (capacity is a moving target, dependent on load and state of charge, among other things such as temperature) and it doesn't do a Peukert Calculation.

That said BFL13 makes good use of his trimetric. I would not have the patience to do so.

If you must have an amp hour counter, the Victron units are cheaper and a little more accurate.

If money is no object then look at the Smartgauge unit.

Only a voltmeter is fine. The idiot light thing is in fact a voltmeter, so it too is fine.

You start with full batteries 12.7 and go camping. Next morning, at a time when the furnace is not on and little else is on, see your "morning voltage." Say it is 12.5

Next morning, same thing only now it is 12.3 Your recharge target is 12.2 but you can go lower if required. So you are dropping 0.2 a day.

You predict it will be 12.1 tomorrow, so that means either recharge today while it is 12.3 or wait till next day when it is 12.1.

You have to stick around while doing your recharge, so if you had a planned outing today, you can do the recharge tomorrow.

Idiot lights--start off green but drop to yellow with a load, then go back to green when that is turned off. After a day or two it drops to yellow under load but stays yellow when load turned off. You are now close to 50% and time to recharge.

If you don't, now it is yellow and drops to red under load but goes back to yellow when that is turned off. Recharge today! Yesterday would have been better, but your batts will live if you don't do that very often. Oops the light is red and stays red. Oops.

That is how I do it even with the Tri. The Tri gives the AH count so you can compare that with your voltage and see if they "match." Sometimes you see they don't match and that tells you something is wrong. Oops, you left the converter on when you went to inverter! Turn off the converter!!!!

BFL13 wrote:
Oops, you left the converter on when you went to inverter! Turn off the converter!!!!

I used the ATS-30 and wired it per recommendations so that the converter was wired together with the incoming shore power cord. That way in can only be on when there is external power from pedestal or generator.

In addition, I installed a receptacle at the new converter up front to give the option of unplugging it if necessary (small generator, 15 amp service to run A/C, etc) AND have the option of running an extension cord to just the converter/charger if needed.

We've never tried to run more than one electric heater, though we have used our 1500 watt without issues in the past. We may find ourselves in that "switch-on-off loads" situation in the near future.

We're starting to go to other places this year where we won't know what to expect. Going to only PA State Parks mostly ensures a consistency. Should be fun! :C

Thanks for the battery level info. 12.2 is 50%, recharge point for the four 6v GC-2 batteries?

Your exact resting voltage for the 6s will be in their specs. Trojan says 12.1 for theirs, eg. However you will be camping so they are not really resting. You just take the voltage when nothing much is on and that is close enough. The idea it to do it the same way each morning so you get your daily drop for predicting.

You are going to recharge at some point either over or under exact 50%. No point in getting it exact.

With solar, you need to take your morning voltage before the sun gets the voltage up, making it look higher than it is for the actual SOC.

You are up at 5 anyway, so that's no problem. :) Sure.

First I'd dump the 2ga and go with 00 or 0000 for all the connecting cables battery to battery and beyond.

Shunt: Really does not matter.. Fuse.. The one shown about is what I use

COnnection cable to shunt.. Have ring terminals properly crimped or soldered or both on.. and bolt 'em down.. Just exactly as you do at the inverter.

That MRBF fuse holder in the first post is similar to mine, except mine holds two fuses, one for the charging circuits and the other for the inverter. It's a nice setup, but MRBF fuses are expensive so be extra careful!

For Ah monitoring I use, like others here, one of the cheap ebay Ah meters with its shunt on the battery bank's negative post. It works, sortof, but the amps calibration is tricky, and it often ends up reporting lower Ah than expected when the batts are full (according to sp. gr. and charging regime), so needs resetting often. But it does give more detailed usage info than just battery bank voltage (mine is often stable up to a 20% change in SOC).