Cheap Battery monitor.

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Originally Posted by megatexture

What were you trying to achieve? Car dual battery or a camper setup ?

I'm tempted to get one just to see what its like lol . HMmmm

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Car dual battery. I have just started the install. I would be interested in something like this to be able to monitor the cars batteries.

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Originally Posted by Cuppa

Not really. The way that these monitors are able to be used as a 'Battery fuel gauge' is by first the capacity of the battery being set by the owner. Eg. 100Ah. When the battery is full (determined by voltage) any usage draws Ah's from it. The monitor can then tell how much of the capacity, as a percentage, has been used. Likewise it can add Ah's when being charged. They are smart enough to recognise charging & usage at the same time. It is not uncommon for my monitor to show +ve amps from the solar whilst the fridge is running for example, because there is more coming in than is going out. The problem with switching between two different batteries is that each battery capacity would likely be different, meaning the monitor would need to be reset. Even if they were exactly the same it would still take a little while for the monitor to suss out the other battery's SoC. So not really practical. Besides I can see no point monitoring a start battery in this way. As long as it has sufficient voltage to start the vehicle that is all that is needed, & most dual battery systems have a means of protecting against draining the start battery. For setups with more than one aux batteries, this meter could monitor both if they were connected to each other (would see them as one large battery). If it is desired to not connect them together then a separate monitor for each battery would do the job.

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My question about these is does the charge current from the alternator need to go through this meter (shunt?) to maintain the charged % etc as well as the items drawing power? If so not the best for dual batteries, ideal for portable power pack though.

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Originally Posted by Bloodyaussie

Worth a punt at that price...

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Yes it is... I have ordered one to put in my camper. We'll see what its like when it arrives...

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Originally Posted by MuddyTroll

My question about these is does the charge current from the alternator need to go through this meter (shunt?) to maintain the charged % etc as well as the items drawing power?

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Yes. Shunt is on the negative.

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Originally Posted by mudski

Yes it is... I have ordered one to put in my camper. We'll see what its like when it arrives...

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Will look forward to getting your feedback.

http://www.ebay.com.au/itm/DC-120V25...item27d29d0d45

This one looks the same as the OP posted, but it is cheaper with free postage. However it doesn't have an external shunt included, it does state that it has an internal shunt? Thoughts Cuppa.....

they are all from China

Only 30A, It wouldn't be suitable for heavy power uses, but I would like to see the shunt that comes with the link cuppa posted when you get it mudski:smiley_thumbs_up:

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Originally Posted by sooty_10

http://www.ebay.com.au/itm/DC-120V25A-Volt-Amp-Battery-Capacity-AH-Power-Combo-Meter-Charge-Discharge-Timer-/171037232453?pt=AU_B_I_Electrical_Test_Equipment&h ash=item27d29d0d45

This one looks the same as the OP posted, but it is cheaper with free postage. However it doesn't have an external shunt included, it does state that it has an internal shunt? Thoughts Cuppa.....

they are all from China

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I would concur with Megatexture's reply. 30A doesn't leave a lot of leeway once a few things are switched on ..... but of course it depends what accessories you have (or may add in the future).

MT, there is a pic of the shunt in the ad linked to in the OP.

Same seller also has similar rated to 200A if required, but 100A would suit most camping set ups.

Yeah fair enough on the 30A internal shunt. I just realised that the ones I'm looking at are actually the same seller you posted up Cuppa :) He has them in 50A, 100A, 200A, 300A and 500A. All for about an extra dollar dearer than the last one. Is there any downside to going a larger, say 200A or 300A shunt?

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Originally Posted by sooty_10

Is there any downside to going a larger, say 200A or 300A shunt?

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Not that I am aware of. If you were planning to run a winch off the battery(s) being monitored going for the 500amp one would save having to bypass/reset the monitor as I have to do with my 100A monitor.