Battery Condition Monitor

[NB Alnwick]

We have had more than a few problems with batteries and charging in the last six months and are in the process of installing a new battery bank.

 

Our 24v electrical system is fairly basic with only a crude analogue ammeter to show when the engine alternator is charging and a 'Durite' analogue voltmeter to give some indication of the state of the batteries. The batteries are arranged in two banks the first having two 12v 110 A/Hour batteries connected in series for starting the engine only and the second bank having two pairs of similar batteries - each connected in series and then in parallel to provide 24v from the four 12v 110 A/Hour batteries for the inverter and cabin electrics. Both battery banks can be isolated separately and when charging, the engine batteries always get charged first and as soon as these reach 24.6 volts (usually after half an hour or so if they have been used or almost immediately if they haven't), a relay switches all the charge to the cabin batteries thereafter.

 

When everything is working, we generally reckon on needing at least six hours of cruising (engine charging - our vintage engine rarely exceeds 450 rpm) or at least as long with our Honda petrol generator running and charging through a Sterling International 15 Amp mains charger, in order to provide enough 240v power to watch TV etc. (Sterling 1800W modified sine wave inverter) and get us through the night without having the batteries drop too much below 24v. Lately we have needed to use the generator a lot more and it seems sensible to have a more reliable way of monitoring the state of the batteries. There is an 'Adverc' alternator voltage regulator/controller fitted.

 

What is the best product out there? Ideally, I would like something that I can install and understand myself without making too many changes to the existing wiring and system.

[GUMPY]

What is the best product out there? Ideally, I would like something that I can install and understand myself without making too many changes to the existing wiring and system.

 

No contest at all

The best is:

http://www.smartgauge.co.uk

 

Simple to fit 4 wires and fuses, no change to the existing wiring, and tells you exactly what how charged your batteries are.

 

Having said that what is the pulley ratio on your engine/alternator set up it should be about 10:1 at least for those revs, so for a 2.5" alternator pulley you need a 24" engine pulley.

If its less than this then changing it will bring the single biggest improvement to your charging system.

 

Oh and 24v systems should not be allowed to go below about 24.3v off load.............................

 

Julian

[blackrose]

No contest at all

The best is:

http://www.smartgauge.co.uk

 

Simple to fit 4 wires and fuses, no change to the existing wiring, and tells you exactly what how charged your batteries are.

 

If you just want to see remaining amp/hours as a % and also volts then I agree, but although the Smartguage is the most accurate for amp/hours remaining it doesn't show current in or out. So if you want that function you'd need a different meter - such as one with a shunt.

[tosher]

.

 

What is the best product out there? Ideally, I would like something that I can install and understand myself without making too many changes to the existing wiring and system.

 

I fitted a "Smartgauge" a couple of weeks ago and all seems to be working well with sensible readings being displayed. I bought it direct from Gibbo who was very helpful with the questions I had regarding it's suitability for my system and advice on fitting. I feel much happier now I have an accurate measurement of the status of my services batteries and can modify my charging regime to suit. tosher

[colin stone]

Concur Smartgauge. And Smartbank to link engine and domestic battery. However, I also wanted to monitor amps and got a Victron BMV 602, although the BMV 600 is a simpler and cheaper version.

[Justme]

I use the smartguage & a Sterling ProPower gauge which can monitor amps on FOUR items & amp/h on one of those 4 plus 4 independant voltages.

 

Justme

[Nickhlx]

I use the smartguage & a Sterling ProPower gauge which can monitor amps on FOUR items & amp/h on one of those 4 plus 4 independant voltages.

 

Justme

 

 

Impressive line-up you have there, Justme !

 

Nick

[chris w]

I use the smartguage & a Sterling ProPower gauge which can monitor amps on FOUR items & amp/h on one of those 4 plus 4 independant voltages.

 

Justme

I also have the Sterling ProPower gauge, and it's really good for currents (via 4 shunts) and 4 separate volts readings. However, the AH meter needs to be used with discretion because it can measure the AH used (A x H) but takes no account of the Peukert factor (which will be significant if using an inverter with a heavy load) nor does it take into account the fact that, on recharge, one needs to put back in almost 50% more than one took out. So, when the AH meter gets back to zero on recharge, the batteries are actually only 70% recharged.

 

Chris

[Theo]

Smartguage Advanced for monitoring and Smartbank for split charge operation.

 

Nick

 

I also have the Sterling ProPower gauge, and it's really good for currents (via 4 shunts) and 4 separate volts readings. However, the AH meter needs to be used with discretion because it can measure the AH used (A x H) but takes no account of the Peukert factor (which will be significant if using an inverter with a heavy load) nor does it take into account the fact that, on recharge, one needs to put back in almost 50% more than one took out. So, when the AH meter gets back to zero on recharge, the batteries are actually only 70% recharged.

 

Chris

[Justme]

IHowever, the AH meter needs to be used with discretion because it can measure the AH used (A x H) but takes no account of the Peukert factor (which will be significant if using an inverter with a heavy load) nor does it take into account the fact that, on recharge, one needs to put back in almost 50% more than one took out. So, when the AH meter gets back to zero on recharge, the batteries are actually only 70% recharged.

 

Chris

 

Cheers for that. The manual seems to imply that charging losses are taken into account. Not to worried as I use mine to keep track of wind amps produced (and most are used as produced so less losses) & use the smartgauge for battery SOC level. Once it gets to max reading I will just turn it off to reset it.

 

Justme

[NB Alnwick]

No contest at all

The best is:

http://www.smartgauge.co.uk

 

Simple to fit 4 wires and fuses, no change to the existing wiring, and tells you exactly what how charged your batteries are.

 

Thanks to everyone for all the suggestions - is 'smartgauge' suitable for 24v systems?

There is an abundance of technical info on the website but I couldn't locat this information which is important to me . . .

 

Having said that what is the pulley ratio on your engine/alternator set up it should be about 10:1 at least for those revs, so for a 2.5" alternator pulley you need a 24" engine pulley.

If its less than this then changing it will bring the single biggest improvement to your charging system.

 

Oh and 24v systems should not be allowed to go below about 24.3v off load.............................

 

Julian

 

The engine pulley is about 18" in diameter and the alternator pulley is about 2.25". The alternator kicks in at around 270 rpm on the engine flywheel and charges at around 20 Amps - increasing the engine speed significantly above 300 rpm does not seem to make much difference - so we are happy to settle for that for the time being.

 

If we ever invest in a more powerful alternator we will fit a bigger pulley.

 

The comment about the battery voltage is interesting - our Elecsol batteries have rarely showed more than 24 volts unless they have just been charged. Even when new they quickly settled back to showing an average of about 12.1 volts per battery (with no load to discharge them) after their initial charge.

On the other hand our cheap and conventional five year old engine start batteries regularly show between 12.4 and 12.7 volts per battery even before charging and after turning over our twelve litre engine which must take a considerable amount of juice . . .

[chris w]

Cheers for that. The manual seems to imply that charging losses are taken into account.

Where does it state this - I can't see it in the manual?

 

Once it gets to max reading I will just turn it off to reset it.

You don't need to do this - once the reading gets back to zero AH - that's it. It's reset anyway (even if the answer is not correct because charging losses are not accounted for)

 

 

Chris

[Gibbo]

Thanks to everyone for all the suggestions - is 'smartgauge' suitable for 24v systems?

There is an abundance of technical info on the website but I couldn't locat this information which is important to me . . .

 

Yes it works on 12 or 24 volts. Oddly it didn't actually say so in an obvious place on the website. I've just corrected this.

 

The comment about the battery voltage is interesting - our Elecsol batteries have rarely showed more than 24 volts unless they have just been charged. Even when new they quickly settled back to showing an average of about 12.1 volts per battery (with no load to discharge them) after their initial charge.

 

Those batteries are not being anythng like fully recharged. 24 volts on two Elecsols (assuming no loads connected) is about 45% state of charge.

 

You need to have a serious look at your charging system. If you're charging at the 20 amps you say then I would expect a full charge (from completely flat - ie about 22 volts) to take somewhere in the region of 16 (or possibly even longer) hours.

 

The setup justme has is, I believe, the ultimate but it depends what one wants to know.

 

If you want to know the state of charge but are not interested in what power is going in, coming out etc then (obviously) I say a SmartGauge is best.

 

If you want to know what is going in and coming out but are not interested in the state of charge then an amp hours counter is best.

 

If you want to know both then you really have little choice other than to install both. Amp hours counters claim to show the state of charge, but they don't. They really don't work at all for that purpose. Irrespective of what the suppliers say. Sterling seem to be the only ones who don't claim that they are any use for state of charge indication. All the other suppliers say they are good for that purpose. Having been on the design team for at least 3 commercially available ones I know for a fact they are useless for state of charge indication.

 

Gibbo

Edited December 31, 2008 by Gibbo

[Ernie]

Hi Graham,

 

Nice chatting with you yesterday morning.

 

I normally don’t respond to electrical type questions – but as it’s you – I will put my thick skin and hard hat on hear and now……..

 

I have a BEP Marine DC600 and am quite happy with it.

 

It measures current which is a must for me. If I could only have one function, it would be charge and discharge current measurement.

 

It also indicates percentage capacity and although not entirely accurate (it drifts off if the batteries don’t get a full charge occasionally), I find it good enough.

 

Bottom line – it meets my needs and I am quite happy with it. Would I recommend you buy one – no, purely because I have no experience with the other offerings available so there may be better options for you.

 

From what you say about your batteries (24V on a 24V bank), they are never getting anywhere near fully charged and this may well be the reason for the premature failures that you described yesterday morning. Your charger and alternator are a bit on the small side for the size of your bank (4 x 110s at 24V). When you get yourself sorted with a battery monitor, you will be very surprised just how long it takes to get them up to 90% charge, never mind about 100% !! Get ready to get your cheque book out.

 

As a liveaboard, when my current battery bank gives up the ghost, I am going to make the investment in buying a set of true deep cycle batteries (milk float type).

[Justme]

Where does it state this - I can't see it in the manual?

 

 

You don't need to do this - once the reading gets back to zero AH - that's it. It's reset anyway (even if the answer is not correct because charging losses are not accounted for)

 

 

Chris

 

That would be in "standard" show the discharge mode (IE start at 0 & count amps out first). However I have it set up basicaly in reverse. I want to measure how much power the turbine produces. If I did it as standard once it got to 0 it would stop counting. As it would be starting at 0 & no drain would ever go through that shunt it would never count any thing. The wind shunt only has the turbine on the non bat side.

 

Will look up the manual it might be I miss read it.

 

 

Justme

[Lesd]

I use the smartguage for SOC and voltage (start and domestic) and Advercs DCM for curren in/outt. The combination lets us monitor everything we need very simply.

[charles123]

I am considering getting a NASA BM1, very functional, comes with shunt

 

Charles

 

http://www.nasamarine.com/Misc/bm1.html

[Roger Gunkel]

I am considering getting a NASA BM1, very functional, comes with shunt

 

Charles

 

http://www.nasamarine.com/Misc/bm1.html

 

Been very satisfied with mine for the last 12 months

 

Roger

[blackrose]

I am considering getting a NASA BM1, very functional, comes with shunt

 

Charles

 

http://www.nasamarine.com/Misc/bm1.html

 

For the price it's good value (I think I've seen it for about £89), and the big display is good too. You just need to check that the 100 amp shunt is adequate for your system.

 

Used in addition to a Smartguage they will provide all the battery info you need.

Edited January 1, 2009 by blackrose

[ditchcrawler]

I also have the Sterling ProPower gauge, and it's really good for currents (via 4 shunts) and 4 separate volts readings. However, the AH meter needs to be used with discretion because it can measure the AH used (A x H) but takes no account of the Peukert factor (which will be significant if using an inverter with a heavy load) nor does it take into account the fact that, on recharge, one needs to put back in almost 50% more than one took out. So, when the AH meter gets back to zero on recharge, the batteries are actually only 70% recharged.

 

Chris

I have got one of these on my boat and wasted an hour today watching it charge. Without writing down every time the charge current changed and only eyeballing it, the average current inflow for an hour LOOKED greater than the drop in the AH count. but the same may be true on discharge as well for all I know.

[alan_fincher]

Currently we have absolutely nothing, but I'd be interested in adding something if it were not silly money.

 

Whilst I acknowledge that Smart Gauge almost certainly attempts to do what no other monitor currently can, I'm an old fashioned soul who does like the comfort feel of actually seeing "net" amps going into or out of the battery, and to get an idea of how fast.

 

It seems a great shame that one has to buy multiple products in the £100 to £150 price range to achieve everything, but the fact that so many of you are saying you have SmartGauge plus A N Other seems to confirm that's the only way of doing it.

 

As I can't justify a £250 to £300 investment in battery and charging monitoring, my guess is we'll soldier on with none. As I've never had a flat battery in normal use, (famous last words !), and our charging seems to keep up with use, I guess we'll probably manage, but I appreciate things are very different for live-aboards who are not able to move much in the winter months.

 

Alan

[Big John]

For the price it's good value (I think I've seen it for about £89), and the big display is good too. You just need to check that the 100 amp shunt is adequate for your system.

What would be the symptom if it's not? Having installed the NASA BM-1 my Victron's Low battery light has been coming on. Coincidence or problem with my installation, or likely problem with my batteries? The current being shown on discharge is just a few amps.

 

Can you just replace the 100 amp shunt with a bigger one?

Edited January 1, 2009 by Big John

[chris w]

As I've never had a flat battery in normal use, (famous last words !), and our charging seems to keep up with use, I guess we'll probably manage,

Alan

Paraphrasing Hamlet............ "therein lies the rub"

[alan_fincher]

Paraphrasing Hamlet............ "therein lies the rub"

I reckon if you cruise about 700 miles in less than 6 months, spending nearly 50 days on the boat, and your battery voltage never drops below that indicating about a 70% state of charge, then you are probably getting away with it. (The state of charge indicated by voltage is closely matched by hydrometer readings, when I can be bothered to take those).

 

Despite unsophisticated filament lighting, and heavy use of laptops, we really haven't run much else beside pumps and tunnel light, so keeping the batteries well up towards 100% isn't hard. After a 2 day layover in London earlier in the year with no engine running, there was every indication we could easily have gone another 2 or 3 days.

 

Our biggest difference from the model you are probably assuming is that we have no electric fridge. I estimate our power requirements could double if we were ever forced away from a gas fridge.

 

Alan.

[NB Alnwick]

I am considering getting a NASA BM1, very functional, comes with shunt

 

Charles

 

http://www.nasamarine.com/Misc/bm1.html

 

As stated in my original post, 'Alnwick' runs on a 24v setup and, as far as I can see, this equipment is designed for 12v systems. The 24v monitoring systems that I have found so far appear to be extremely expensive which is why I have now made the decision to buy a 'Smartgauge' which is competitively priced and appears to be relatively easy to fit.