#143530  by Skiwi
 Fri Aug 10, 2018 3:27 pm
Thanks again Neddy,

It looks like my DC-DC charger is pre-set, so without opening it up and tinkering with the innards I'm limited to the 14.7V limit specified on the underside. I can live with the .2v difference ;)

Cheers
Skiwi
 #143973  by Skiwi
 Sun Aug 26, 2018 5:19 pm
Ok, an update...
I’m 90% done, I’ve run all the wiring and installed my monitoring, just waiting on my 7 stage mains charger to arrive from China. https://www.aliexpress.com/item/Top-Qua ... 64766.html

One thing caught me by surprise, I added this monitor https://www.aliexpress.com/item/DC-6-5- ... autifyAB=0

It works fine, however it doesn’t show charge going into the batteries, only the draw going out. When the charge is greater than the draw it reads zero, I was expecting it to read a negative number indicating a “neagative” draw.
I’m pretty sure I have my wiring right with the negative of all draw and charge on same side of the shunt.
Anyone got one that they can comment on?
 #143976  by scubadoo
 Sun Aug 26, 2018 6:10 pm
The meter in your link is not intended to be used as a battery SOC monitor but as an energy useage meter. i.e how much energy has been consumed over time by a device - one-way. Sure it can also instantaneously display the voltage input and current ouput.
For true battery SOC monitoring a suitable product is required.
There are NZ options or if you choose to go the aliexpress or ebay way Neddy has a selection here:
viewtopic.php?f=55&t=17215
 #143977  by Neddy
 Sun Aug 26, 2018 6:12 pm
I think you will find that the problem lies with the meter which appears to lack the ability to measure current flowing both ways. The absence of any AmpHour measuring capacity and the very low price are further pointers to its unsuitability for the task you want it to do.

Neville.
 #143985  by Skiwi
 Sun Aug 26, 2018 8:56 pm
Thanks for those replies.
I have solar input and battery SOC info off my MT-50 display but I think I’m going to grab another meter and have a play around setting the chargers up on a seperate circuit with it’s own shunt and meter, that should give me all the info I want.

Or I could just go old school and throw a 200 amp meter inline ;)



Cheers
Skiwi
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 #144001  by Skiwi
 Mon Aug 27, 2018 12:22 pm
Hmm? Thinking out loud...

Could I wire another of these in reverse on the existing shunt to give me the amps in?

If not then this https://cart.payments.ebay.com/sc/rfc may fit the bill

Cheers
Skiwi
 #144003  by Neddy
 Mon Aug 27, 2018 2:09 pm
"I have Battery SOC info off my MT-50 display".
Nah - not really. From the MT-50 manual :-
"The Battery SOC% is an estimation based on the charging voltage". (For "estimation" read "rough guess"). What you need is a proper shunt-based Battery Monitor that logs all current flowing into and out of your House battery. Prices start at way less than you paid for your MT-50 display unit.

"I’m going to grab another meter and have a play around setting the chargers up on a seperate circuit with it’s own shunt and meter, that should give me all the info I want."
All meters involved would need to be capable of measuring AmpHours, not just current. But don't you want this information in an easily understood, readily available form? Think about what you would have to do to get any sort of SOC% estimation. Starting from a known battery SOC Ah, you would have to add "charge" Ah from all sources, then subtract all "discharge" Ah, then divide by the battery AH capacity, with the result expressed as a percentage.

"Or I could just go old school and throw a 200 amp meter inline".
That still won't tell you what you most need to know - the battery SOC%.

"Could I wire another of these in reverse on the existing shunt to give me the amps in?"
Yes, you could, but knowing the amps in at any given time will not give the AmpHour figure that you are lacking. You would be throwing good money after bad, ending up with bits and pieces of gear cobbled together and still not having a readout of your battery SOC%.

"My end goal is to have a seamless power management (translation = my wife and family can use the motor-home in my absence without needing a hour long dissertation in the intricacies of power consumption and battery maintenance)"

That makes good sense - so why don't you want to fit a proper Battery Monitor that would give a simple "Battery %" figure that anyone could understand?

Neville.
 #144996  by Skiwi
 Mon Oct 01, 2018 8:09 am
Neddy wrote:
Mon Aug 27, 2018 2:09 pm
That makes good sense - so why don't you want to fit a proper Battery Monitor that would give a simple "Battery %" figure that anyone could understand?
Neville.
I will add one, but I was also wanting to know the instantaneous battery draw of individual items as many vary wildly from what's stated on the box. I like doing the rough sums in my head to see if their draw is "acceptable" in my mind weighed against whatever benefit they are currently bringing to our comfort.

PS: We did our first trip away this weekend with all the new wiring and upgraded gadgets - worked great :)
Used the grill/microwave for lunch and between the solar and bus charging the batteries were back to 100% within the hour :TU

Cheers
Skiwi
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