Measuring Amp-hours

AngusMcDoon

AngusMcDoon

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Can I measure Amp-Hours in to and out from a boat's batteries over a period of time, other than staring at a normal Amp meter all day and keeping a running total?

I have no particular requirement why I need to do this, I just like tinkering. (Motto - If it isn't broken, more toys are required).
 
Yes, the one's I know of are made by Stirling Power one is £99 the other £199. I'm sure there are others available.
 
Yes, Merlin - www.merlinequipment.com do two. I have the junior version; the Link10 and it's great. If you like fiddling you can set it up to indicate battery capacity available as charging power does not equal available power due to losses in the charging process. There are lot of other facilities to play with as well. Bit pricey at £209.

You could probably import one as they're made in the States by Heart Interface Corp who also do inverters.
 
Waeco make the Mobitronic which is another one. I have it fitted to my boat. These things are useful as it can give you a "bank balance" of available amp hours by calculating what goes in and what goes out. Not entirely accurate in my experience, but if you see a huge unexpected deficit you know something is draining power...
 
I have a Link 10 battery monitor new never been installed and still boxed. £150.00 plus postage. <font color="black"> </font>
 
MASTERVOLT do a very good one. A bit more expensive than the others, but we fitted one about 12 months ago and are very pleased with it. It measures the AHrs etc of the domestic batteries and the voltage of the cranking battery. It uses a shunt, of course, just as all the others do which is included in the price. £286 at last years September boat show.
 
Hi,

We've used a Pulstronic Battman II for the last 12 or so years and it's excellent. It uses a standard 50mm square VDO instrument housing, and, via a stainless steel shunt, measures voltage, amps out/in and total amps consumed. This latter is what you need as, as soon as you start your engine, switch on the solar panels etc, you can watch the amps total reducing to zero.

We use an Adverc alternator controller and it's fascinating to watch the various charging stages operating. The Battman is not cheap, but the quality is first rate.

Jerry
 
I feel obliged to make a comment. One thing you don't want on any boat is more electronics. It usually means more worries and dissapointment.
Yes with the aid of modern microcontrollers it is possible to very accurately measure current over time into and out of a battery. but what does that really tell you? The actual amp hour capacity of a battery is a very variable quantity. In aviation in estimating the time a plane could fly on battery alone, we ( government legislator) used a factor of 55% of manufactyurer rated AH capacity of battery. ie thats all you can reasonably rely on from a lead acid battery during it's life. ie until it won't crank the engine. ( even that is a very subjuective guess. It is likely when considering large capacity house batteries that the capacity could fall far lower before you really noticed a problem. (especially for those religiously never discharging below 50%) modern batteries may be better but then in parctice many batteries may be found worse.
So while amp hours in and amp hours out might be interesting it doesn't mean that you ca n get all the current out that you put in or that the battery has anything like the capacity you may have programmed into the device. ( or expect) So there is a contrary opinion just so you don't go off thinking you have to have one. regards olewill
 
Hi Will!

I entirely agree with you!! We do not rely on the 'zero amps' of the Battman to tell us the batteries are 'fully charged', as we are fully aware that a good 10% or so extra is needed to achieve that!! /forums/images/graemlins/smile.gif

But what pretty well all these gadgets do, is give you is a better 'idea' of the state of play and that's extremely useful IMHO. We never discharge our batteries below 10-15% of apparent capacity and as a consequence, they last us for many years. /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

No, the MAIN reason we installed one, was to measure as accurately as possible (short of fitting a temporary ammeter in line to each) the real current consumption of every piece of electrical equipment on board.

Frankly the results were staggering. The manufacturers claims were, almost without exception, for much lower consumption (in some cases hugely so) so that any reliance placed on our total usage based on their figures, would have been useless. /forums/images/graemlins/mad.gif /forums/images/graemlins/mad.gif OK, that doesn't matter perhaps if you're basically weekending your boat, but when long term cruising it's crucial!

The fact that the unit also gives us an accurate 'at a glance' battery voltage was another factor in our decision to install one, and our Battman has now been aboard for 13 years and done 40+ thousand miles, so we are happy with it's long term reliability too!! /forums/images/graemlins/smile.gif

So don't worry,we haven't 'gone off' thinking we have more than we've got!! /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

Cheers Jerry
 
Well put Jerrty. You are quite right I just think aometimes someone should speak and say " These gadgets are not the panacea for no more electrical worries" I still maintain less is best for boat electronics and that every item shou8ld earn its keep in real value to the owner in his style of boating. I am glad your Battman is earning its place with you. olewill
 
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