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12V, 24V, 240V How to power, what to power. Lights, solar, what's around to make it more comfy.



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Old 14-10-2014, 05:04 PM
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Piranha Piranha is offline
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which monitor?

Hi All, I have just had a dual battery system installed in my 4wd, i'm now looking for a reliable monitor to show accurate state of charge readings for the battery running the fridge. I'm not keen on the generic ones that come with the fridges because their not accurate. Has anyone used the enerdrive pro units? and what are they like? worth the cash?

cheers
Wes
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Old 16-10-2014, 06:02 AM
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I looked at a few different types of monitors when I rewired my patrol. In the end I decided a dual voltmetre with an inbuilt ammetre for $100 worked best. I'm a bit skeptical on the validity of the info they give you. Very little info is available on the algorithms they use, do the just use a soc chart vs voltalge thats available on the internet? The soc (state of charge or the % reading the display gives)is normally calculated via voltage readings or current readings over time. To get an accurate reading batt temperature, battery age and constant discharge are required for calculating soc, which it wont know. I Think the $400 they ask could be better spent on other accessories, but if money isnt an issue I'd purchase one. I think knowing the soc curve for your type of battery and the corresponding voltages for the state of charge are just as effective at a cheaper price.
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Old 16-10-2014, 04:20 PM
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Thanks for the info Scubascott, sounds like you know your stuff mate I have found a different brand that has the same capabilities for $200 so i might go with that! thanks again
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Old 17-10-2014, 01:16 AM
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No worries, all the accessories you add to ya 4WD can get expensive quickly, so I spend a fair while working out the value vs $ cost of all the things I buy.
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Old 19-10-2014, 04:05 AM
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After a bit of reading I found out the new units let you add battery life and capacity to determine SOC when you set them up from new, then temp,output, and over time history ect are added in got one ordered so we'll see how they go
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Old 31-10-2014, 02:33 AM
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For anyone looking for a good battery monitor the Victron units seem pretty good for a touch over $200, they give accurate voltage, amps in and out, current draw, time remaining, and a state of charge shown in % which is very handy, and their easy to use

I went for a 120ah agm for the fridge and it says it will run it for 375 hours at 2 deg with the outside air temps between 25-30deg before needing charging which sounds promising
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Old 11-12-2014, 07:10 AM
lukereneeseth lukereneeseth is offline
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if that is what your over priced investment says then I'd just put it in the bin if you cant get a refund!

Even in the dead of winter in Tasmania could you ever get 375hrs of running time for a 35L fridge @ 2deg.

120ah battery is good for 80ah of usage max.

Every time you open the fridge you will add 10 minutes to the cycle. If you add 1L of water that is not the same temp as the fridge inside, you will add 20min to a cycle, etc. etc.

Some facts: Assuming you can use 120amp of a 120amp deep cycle battery just isn't so. Optimally you wouldn't want to draw anymore than 80amp (60-70 being more appropriate to get a good 6 years out of it)

Assuming info of power consumption on the side of your fridge box is something to work off just isn't so. A 35 - 50L fridge will average 15 - 30amp per 24hr

If your fridge was @ 2deg with everything inside already 1-5deg and the battery was at full charge (not the 80-90% which is the max from a dual battery system). You open the fridge up only 3 times a day. Your fridge would cut out after 72-120hrs.

To be honest, you should never have a need for anything more than a $20 multimeter.

This kind of gear (Victron) is designed for the camper market. Where power consumption is large and sporadic.

Even a $10 digital LED monitor does everything you need to know, which at the end of the day is just to make sure the battery doesn't reach damaging lows.

Last edited by lukereneeseth; 11-12-2014 at 07:15 AM.
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Old 03-01-2015, 02:44 AM
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if that is what your over priced investment says then I'd just put it in the bin if you cant get a refund!

Even in the dead of winter in Tasmania could you ever get 375hrs of running time for a 35L fridge @ 2deg.

120ah battery is good for 80ah of usage max.

Every time you open the fridge you will add 10 minutes to the cycle. If you add 1L of water that is not the same temp as the fridge inside, you will add 20min to a cycle, etc. etc.

Some facts: Assuming you can use 120amp of a 120amp deep cycle battery just isn't so. Optimally you wouldn't want to draw anymore than 80amp (60-70 being more appropriate to get a good 6 years out of it)

Assuming info of power consumption on the side of your fridge box is something to work off just isn't so. A 35 - 50L fridge will average 15 - 30amp per 24hr

If your fridge was @ 2deg with everything inside already 1-5deg and the battery was at full charge (not the 80-90% which is the max from a dual battery system). You open the fridge up only 3 times a day. Your fridge would cut out after 72-120hrs.

To be honest, you should never have a need for anything more than a $20 multimeter.

This kind of gear (Victron) is designed for the camper market. Where power consumption is large and sporadic.

Even a $10 digital LED monitor does everything you need to know, which at the end of the day is just to make sure the battery doesn't reach damaging lows.
Ease up champ, the monitor performed and calculated very accurately as stated.
A $10 monitor does bugger all and does not give an accurate state of charge especially while drawing current, a multimetre or 10 dollar unit does not take into account battery size, air temp, running history among other things.

The victron protects your battery by diconnecting when the voltage reaches a certain level. a manual monitor or voltmetre won't do that when your out fishing will it

I would rather know exactly what the system is doing by glancing at a screen while walking past instead of having to get gear out to test then guess the state of charge but by all means continue with your guess work
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Old 03-01-2015, 04:53 AM
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Ease up champ, the monitor performed and calculated very accurately as stated.
A $10 monitor does bugger all and does not give an accurate state of charge especially while drawing current, a multimetre or 10 dollar unit does not take into account battery size, air temp, running history among other things.

The victron protects your battery by diconnecting when the voltage reaches a certain level. a manual monitor or voltmetre won't do that when your out fishing will it

I would rather know exactly what the system is doing by glancing at a screen while walking past instead of having to get gear out to test then guess the state of charge but by all means continue with your guess work
I have to say that the Victron isnt giving an accurate indication either, and Luke is right. I dont know if it hasnt been setup correctly (cant recognize battery capacity, battery type etc) but even running the battery completly flat you will never get 375 hours from your fridge, that is over 2 weeks. The auto elec/ portable solar industry would become almost extinct if a fridge ran for 2 weeks off one battery charged purely from the vehicle. The paper maths just dont agree with the electronic display.

To prolong the batteries life it is best practice to only discharge the battery to 50% soc (around12.3V for an AGM battery) which means you have 60aH to use. My CFX-40 draws an average of 1.38A/h (I measured it via 0 degree internal, 30 degree external temp with current draw measured every 3 mins for an hour and averaged). Your 35L maybe 1 amp for easy calculations. So according to the monitor 120a/h divided by 375 hours gives and average current draw of .32 amps per hour. Now it may draw this much when the compressor isnt running but as you said the monitor should look at the history of power draws to give a figure, and adjust your expected time remaining accordingly. Giving 375 hours is completly inaccurate. This is calculated using the batteries full capacity too. If you use the 50% soc rule that the monitor should work with this drops your monitors calculated current draw to .16 amps and hour. Its just not logical.

The battery disconnect feature shouldn't be required unless you are using it to monitor your cranking battery, and if your using an AGM im assuming its not your cranking battery. Its a feature that counters bad system design, and if your out fishing in an isolated area you dont want your fridge being disconnected and come back to off food. Knowing your power requirements and then designing supplies and loads to suit is required. If your battery is getting low then methods need to be used to bridge the gap between current draw and battery capacity such as solar, generator, running engine etc. If my Patrol is sitting for a day in the bush while im off fishing I'll hook up the solar panel to prolong the battery charge. A simple jaycar voltage switching relay to deenergize a supply contactor could be used at a preset voltage if you wanted to protect your battery though.

The thing just isn't working. I dont disagree with your decision to buy something like this, each to their own and if you find it easier to interpret your 12V system via a display like this then thats totally cool. I just think you have a lot of faith in something that clearly isn't working. The displays are good for advice but just because it gives you a value doesnt mean its correct. If your driving your car and steam pours out of your bonnet but your temp gauge is normal do you just keep driving? It may not be installed correctly or not setup properly but as it stands now the evidence is clear that it isn't reliable and the victron is the one doing the guess work, not the voltmeter that you can walk past and glance at as well.

If you need any help with it or advice I'm happy to help to try get it telling the truth.
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Old 04-01-2015, 04:47 PM
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I have to say that the Victron isnt giving an accurate indication either, and Luke is right. I dont know if it hasnt been setup correctly (cant recognize battery capacity, battery type etc) but even running the battery completly flat you will never get 375 hours from your fridge, that is over 2 weeks. The auto elec/ portable solar industry would become almost extinct if a fridge ran for 2 weeks off one battery charged purely from the vehicle. The paper maths just dont agree with the electronic display.

To prolong the batteries life it is best practice to only discharge the battery to 50% soc (around12.3V for an AGM battery) which means you have 60aH to use. My CFX-40 draws an average of 1.38A/h (I measured it via 0 degree internal, 30 degree external temp with current draw measured every 3 mins for an hour and averaged). Your 35L maybe 1 amp for easy calculations. So according to the monitor 120a/h divided by 375 hours gives and average current draw of .32 amps per hour. Now it may draw this much when the compressor isnt running but as you said the monitor should look at the history of power draws to give a figure, and adjust your expected time remaining accordingly. Giving 375 hours is completly inaccurate. This is calculated using the batteries full capacity too. If you use the 50% soc rule that the monitor should work with this drops your monitors calculated current draw to .16 amps and hour. Its just not logical.

The battery disconnect feature shouldn't be required unless you are using it to monitor your cranking battery, and if your using an AGM im assuming its not your cranking battery. Its a feature that counters bad system design, and if your out fishing in an isolated area you dont want your fridge being disconnected and come back to off food. Knowing your power requirements and then designing supplies and loads to suit is required. If your battery is getting low then methods need to be used to bridge the gap between current draw and battery capacity such as solar, generator, running engine etc. If my Patrol is sitting for a day in the bush while im off fishing I'll hook up the solar panel to prolong the battery charge. A simple jaycar voltage switching relay to deenergize a supply contactor could be used at a preset voltage if you wanted to protect your battery though.

The thing just isn't working. I dont disagree with your decision to buy something like this, each to their own and if you find it easier to interpret your 12V system via a display like this then thats totally cool. I just think you have a lot of faith in something that clearly isn't working. The displays are good for advice but just because it gives you a value doesnt mean its correct. If your driving your car and steam pours out of your bonnet but your temp gauge is normal do you just keep driving? It may not be installed correctly or not setup properly but as it stands now the evidence is clear that it isn't reliable and the victron is the one doing the guess work, not the voltmeter that you can walk past and glance at as well.

If you need any help with it or advice I'm happy to help to try get it telling the truth.
Thanks for that mate,Just to clear things up the unit recalculates itself while in use, it starts off showing how long it can run when fully charged then adjusts accordingly once it starts to get current drawn out, I was not stating that I got 375 hours out of it, that was just it's starting hours calculation before the fridge was running.

It lasted 5 days in 43+ deg day and 28deg min at night running at -1 with no additional input before the battery got to 50% and it automatically disconnected. It re calculated SOC after every time the fridge was opened. It was checked against a voltmetre to make sure everything was accurate.

It's working perfectly so i'm a happy camper Just need to get a solar panel to finish it off now for longer trips

Last edited by Piranha; 04-01-2015 at 05:01 PM.
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Old 04-01-2015, 07:04 PM
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What agm battery did you get as some models you can run down to 20% charge?
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Old 04-01-2015, 07:58 PM
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What agm battery did you get as some models you can run down to 20% charge?
It's a 120ah marine century, I could run it down that far without too many issues it's just a matter of changing the settings on the monitor/controller
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Old 05-01-2015, 07:18 AM
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What sort of fridge do you have? 5 days running from 60 aH (less that .5A per hour) is hard to believe, how low did your battery voltage get? If that monitor is correct I think ill be swapping my old power hungry 40L engel I use as a 2nd fridge on long trips for whatever fridge your running.
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Old 05-01-2015, 04:02 PM
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What sort of fridge do you have? 5 days running from 60 aH (less that .5A per hour) is hard to believe, how low did your battery voltage get? If that monitor is correct I think ill be swapping my old power hungry 40L engel I use as a 2nd fridge on long trips for whatever fridge your running.
Ice cool 40L , it states in the specs that it uses .4A per hour. I can't remember what the voltage got down to it was a few weeks ago now.
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Old 11-01-2015, 08:46 AM
lukereneeseth lukereneeseth is offline
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Stuklose - sorry to say, but no agm battery can be run down to 20% regardless of what a manufacturer might put on their product. Which has been proven time and time again by independent testing. To get identical models of X battery and run 1 down to 20% and the other down to 60%. Battery 2 will far out live battery 1 and still produce more life by ten fold. There's nothing quantum mechanics about it, that's just the general structure and design of the battery. Same with a phone battery. Run it down and not charging it straight away or putting on charge for 20 min and taking it off, etc will result in half the original life within 18 months.

Piranha - your 5th post is rather contradictory to one of the last.... "It was checked against a voltmetre to make sure everything was accurate."

I know you just want everything to run smooth and be able to just look at a screen for conformation and were its at, etc. But at the end of the day the Victron really doesn't do any more than what most 12v appliances/ equipment do anyway. . . Once they sense the battery is at a certain voltage they cut out. Your fridge should have 2 settings for this; 10.5v and 11.5v. All inverters have them.

I should point out in your response to my post a few things...

" A $10 monitor does bugger all and does not give an accurate state of charge especially while drawing current" . . . This is completely irrelevant when you are just running a 12v fridge off a battery that takes no dual setup or solar additional charging. It is actually impossible to calculate an accurate state of charge while current is being drawn. The victron bases these figures on mathematical equations which are programed into a processor. They are not "accurate", rather a guess based on maths. An when you are only drawing .5 - 1.5amp per hr through the fridge, completely irrelevant anyways. Maybe good to monitor if you had 500รก/h running power tools through a 2000w pure sine inverter.

"The victron protects your battery by diconnecting when the voltage reaches a certain level. a manual monitor or voltmetre won't do that when your out fishing will it" . . . your fridge does this automatically anyway, enough said there.

"I would rather know exactly what the system is doing by glancing at a screen while walking past instead of having to get gear out to test then guess the state of charge but by all means continue with your guess work" . . . . I run 2 x 235a/h batteries via c-tek 250, 35l waeco, 600w permanent backlit pure sine inverter. I don't need to guess. If I ever saw the lights on the inverter go off that means i'd need to go for a drive. But, 5 years so far never had a drama, batteries as good as day one.

Talk to any auto electrician and they will say there's nothing inaccurate about a little $5 backlit monitor simply wired to the + - of the battery.

They are a good bit of gear in the caravanning world but massive over kill just to look at a fridge. They come into their own when you have a lot of power draw, a big battery bank and solar wired in.

But you did say "it says it will run it for 375hrs before needing charge" As that gives real time at the exact moment (id say that figure was the wasted energy to keep current through the cables to the fridge) much the same as a little $5 fixed monitor does; real time Voltage. If you've been in the 12v scene for a while, its easy to rough out Volts ---> hrs of your own setup.

If your looking to run a dual setup up look into the C-Tek 250s. Set it all up yourself in about 2hrs, throw a solar panel on the roof (or folding portable panel) Charge your battery for the alternator while your driving then it automatically switches over to the solar charging when you stop. you will never have to look at the Vectron again.
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