Batteries for Dummies

[riverliver]

Hi All

My hobby is frying batteries with a small amount of boating attached. My new years resolution is to give up my hobby. I have hopefully been wonderfully educated by the threads on this forum and I finally worked out it is pretty simple really. Firstly you can only take out (50%) of what you put in the batteries and secondly you cant know that without monitoring them.

I have a starter battery and house both exide 110 - both about 12 months old and (touch wood) in good shape. I have a bow thruster (Vetus 150 - 35) battery Exide Dual leisure 80 Ah (RIP). Plus 1-both- 2- off selector.

I don't have any monitors of any type for them. No solar or genny.

Problems come from overnight away days. Typically moor up about 4 and move off 8/9 am next morning.
We have a fridge rating 70 W and nominal voltage 2/4 Amp. Lights are negligible and all LED now.
Last year I had the jabasco toilet converted to electric and that gets a fair amount of use when moored. Online literature says amp draw of 24 Amps. No other kit to speak of. So allowing something for lights I think I might be drawing say 80 Ah overnight which I now get is too much for a single house battery. Solutions seem to be either switch off the Fridge when moored up (which sort of defeats its purpose) or increase the house bank with another 110 Ah battery. A thread from January last year shows the correct wire up and looks like something even I could do.
So Q1 please: Am I on the right track?

My second point above means I need to be able to monitor the batteries. Looking through all the threads I have seen a few recommendations and I would love to be able to monitor via my phone but all bar one solution requires (for me) serious work putting in a shunt and re arranging cables. The exception seems to be a smartguage and looking at the utube sales pitch it seems my kind of thing. Simply wiring it up as is to the house battery with a voltage reader for the starter battery seems almost too easy. So Q2 any pros and cons I haven't thought about before I buy one?

My bow thruster problem is simpler in one sense. I used it to moor up and then switch it off. I am asking for trouble. Lesson hopefully learned. But Q3: Is the battery the right size for the thruster? I have simply replaced like for like when renewing (please don't ask how often) what was there when I got the boat but my reading here suggest a dual leisure might not be right type.

Final Q4 (its been a long winter). I think I need a monitor for the bow thruster battery but haven't seen any commentary that suggests one that can cover all three - house starter and BT? So I am inclined to pay the cost of a second smartguage for that one - bit pricey but I reason its the price of a battery more or less so worth it in the long run.

Any comments or advice gratefully received.


Cheers and Happy new year

 

[vyv_cox]

We run a fridge 24/7 for months in Greece, plus we have 125 watts of solar panel. We also had an electric toilet. When we had 2 x 130 Ah domestic batteries the voltage would often be down to 11.9 or 12.0 first thing in the morning. I increased the battery bank to 3 X 130 Ah with the result that morning voltage leapt to 12.4 or so. At anchor for several days the solar input will keep at this level in mid- summer.

I now have 3 X 100 Ah Winner Solar batteries (plus a Red Flash 1100 starter) and these perform about the same.

I suggest there is no way that one battery can cope with your discharge regime and two will struggle, giving short life due to the level of discharge.

Also, keep an eye on acid level. I top up my wet cells most months with half a litre or so of deionised water

 

[slawosz]

I don't have any monitors of any type for them. No solar or genny.

I would consider some kind of generator, wind, or if you have space, also solar. It is possible to monitor voltage to have an idea of battery capacity. But the ability to charge, when you have relatively large needs is crucial (and rather simple).

 

[Aquanaught]

I have similar requirements to you - fridge/lights when away from shore power for up to 10 days in UK and a seperate dedicated bow thruster. I need 2 x 140 Ah house batteries to keep the fridge on and run led lights and occasional tv /stereo as well as instruments whist sailing . Batteries need to be charged daytime by using a folding 100W solar panel. Generally I find this set up works OK in UK summer with also some engine running every few days as we transit to next port. I fitted a NASA Marine BM1 bluetooth battery monitor which works well and fairly simple - the shunt is included in the kit but you may need a longer lead made up depending on where you intend to fit the shunt. The bow thruster / windlass battery is charged via a B2B from the house bank which includes a digital charge display.

 

[Mistroma]

Solar won't be great if you are sailing in winter but it must be around 8-10 x bang per buck. Solar is a no-brainer for normal summer sailing. I used to average about 10Ah/day in summer from a Rutland 913. Pretty much the same from West coast of Scotland to Atlantic Spain. I'd get 140Ah/day on 1-2 days each year when very windy and lots of days with 0Ah/day. Don't be fooled when you see one spinning in light wind, it is probably not putting anything into the battery. MPPT controllers should boost the wind-gen output in light wind but you will still be better off attaching it to solar panels.

I have had a Smartguage since 2012 and am pretty happy with it. I do check my T105s every 5-6 weeks to keep electrolyte level up and look at temp. corrected SG. Smartguage is usually pretty good but tends to get it wrong when charging and says 100% too early. However, that corrects pretty quickly on discharge as it drops a few percent to show the correct reading. Not a big deal as long as the batteries are still charging well beyond 100% reading. More of a problem if you were on mains power and turned it off because it said 100%.

I don't see any point in fitting Smartgauge to a bowthruster battery. It only monitors one battery anyway and just shows voltage on the 2nd battery (usually engine). Bowthruster and engine start batteries are usually at or close to 100% and then sit with no discharge. The voltage will settle and give a decent indication of battery state in that situation. It isn't State of Charge, more an indication that your battery is taking and holding charge. Just make certain you are charging the bowthruster battery after use by running the engine for a bit or connecting to shorepower. Engine battery is usually kept charged by normal use.

 

[sailorman]

Hi All

My hobby is frying batteries with a small amount of boating attached. My new years resolution is to give up my hobby. I have hopefully been wonderfully educated by the threads on this forum and I finally worked out it is pretty simple really. Firstly you can only take out (50%) of what you put in the batteries and secondly you cant know that without monitoring them.

I have a starter battery and house both exide 110 - both about 12 months old and (touch wood) in good shape. I have a bow thruster (Vetus 150 - 35) battery Exide Dual leisure 80 Ah (RIP). Plus 1-both- 2- off selector.

I don't have any monitors of any type for them. No solar or genny.

Problems come from overnight away days. Typically moor up about 4 and move off 8/9 am next morning.
We have a fridge rating 70 W and nominal voltage 2/4 Amp. Lights are negligible and all LED now.
Last year I had the jabasco toilet converted to electric and that gets a fair amount of use when moored. Online literature says amp draw of 24 Amps. No other kit to speak of. So allowing something for lights I think I might be drawing say 80 Ah overnight which I now get is too much for a single house battery. Solutions seem to be either switch off the Fridge when moored up (which sort of defeats its purpose) or increase the house bank with another 110 Ah battery. A thread from January last year shows the correct wire up and looks like something even I could do.
So Q1 please: Am I on the right track?

My second point above means I need to be able to monitor the batteries. Looking through all the threads I have seen a few recommendations and I would love to be able to monitor via my phone but all bar one solution requires (for me) serious work putting in a shunt and re arranging cables. The exception seems to be a smartguage and looking at the utube sales pitch it seems my kind of thing. Simply wiring it up as is to the house battery with a voltage reader for the starter battery seems almost too easy. So Q2 any pros and cons I haven't thought about before I buy one?

My bow thruster problem is simpler in one sense. I used it to moor up and then switch it off. I am asking for trouble. Lesson hopefully learned. But Q3: Is the battery the right size for the thruster? I have simply replaced like for like when renewing (please don't ask how often) what was there when I got the boat but my reading here suggest a dual leisure might not be right type.

Final Q4 (its been a long winter). I think I need a monitor for the bow thruster battery but haven't seen any commentary that suggests one that can cover all three - house starter and BT? So I am inclined to pay the cost of a second smartguage for that one - bit pricey but I reason its the price of a battery more or less so worth it in the long run.

Any comments or advice gratefully received.


Cheers and Happy new year suggest you have an adverc, and alternator controller fitted, and just fit and forget?talk to sdverk, you can they are most helpful, if you I bought s sh unit they still helped me?oh I had 3 x 130 Ah batteries from batteymegastore. I hope u
[/QUOTgetE]
Sorted ?

 

[Tranona]

You have sussed the main issue which is lack of energy storage (but have not mentioned how you generate replacement!). As already suggested you need to at least double your house bank. On a similar usage regime on my last boat I had 3*95Ah AGM house bank plus another one of same size for the engine, although that was bigger than really necessary and another for the thruster.

An immediate improvement would be to combine the 2 you have now for the house and install a separate engine start probably a simple car battery of 50-60Ah for an engine under 40hp. Ditch the 1,2,both and fit a split charging system. A battery monitor will help you understand your usage better. You don't say how your bow battery is charged, but it is a bit on the small side. However if it works no need to change. While the current draw is high, it is for a short period so usually quickly recharged like the engine start.

Next you need to consider how you replace your usage. You won't be able to replace your overnight usage with engine alone on a sailing boat so you need to consider alternatives such as solar. However if you have access to shorepower that is key to maximising the usage of your house bank. When you are not using the boat, fully charge your house bank on shorepower which will give you between 1 and 2 days safe capacity with a 220Ah bank. A couple of hours motoring will put back around 15-20anps depending on the state of charge of the batteries after an overnight stop so you could get 3-4 nights before you get significantly below 50%. a marina overnight on shorepower will get them fully charged. This is essentially the regime I adopted on my last boat and the batteries were still in good shape after 6 years.

On the boat I am refitting now I have much lower consumption, probably little over half yours and I have 2*95Ah AGM house bank, an Odyssey 28Ah start charged from the alternator through a BEP Marine switch cluster with VSR and a 105 Ah leisure battery for the bow thruster and windlass charged from the engine start through a B2B charger; a NASA BM1 monitor and a 15amp mains charger for the house bank. I am rarely away from shorepower for more than 2 days so think this will work well.

 

[jac]

One factor in your 50% to clarify. You can not discharge a battery below 50% in any healthy way, but that doesn't mean you have 50% of the nominal capacity available.

If you look at the charge profile of typical lead acid ( including AGM) then you will see that they charge rapidly up to about 80% SOC. Then you get a gradual deterioration in the amount of power they can absorb even with smart chargers. If left with a solar panel for a day or so, or plugged into a battery charger you should get up to 100% but it will take time. if you're then living aboard, sucking the power out with a fridge overnight, lights, charging phones etc then it may not be 100% charged when you set off.

Then factor in that a little bit of use will see the used battery not achieve nominal capacity anyway and the fact that 50% SOC is absolute minimum and that you might want to give yourself a 5% margin of error and you will quickly see that you are better off assuming you will have a maximum of say 30-35% of the nominal capacity available and size accordingly. Based on that 80 Ah load i would suggest a minimum bank of 240Ah. If you're buying 110 AH Batteries then 3 of them would give you some generous slack.

My top priority though if you already have 2 identical batteries would be to fit some solar, do away with the 12Both switch and replace with proper isolators and charger and then get a suitable sized engine start battery. No point in having an oversize engine start battery when your domestic is struggling

 

[PaulRainbow]

Hi All

My hobby is frying batteries with a small amount of boating attached. My new years resolution is to give up my hobby. I have hopefully been wonderfully educated by the threads on this forum and I finally worked out it is pretty simple really. Firstly you can only take out (50%) of what you put in the batteries and secondly you cant know that without monitoring them.

I have a starter battery and house both exide 110 - both about 12 months old and (touch wood) in good shape. I have a bow thruster (Vetus 150 - 35) battery Exide Dual leisure 80 Ah (RIP). Plus 1-both- 2- off selector.

I don't have any monitors of any type for them. No solar or genny.

Problems come from overnight away days. Typically moor up about 4 and move off 8/9 am next morning.
We have a fridge rating 70 W and nominal voltage 2/4 Amp. Lights are negligible and all LED now.
Last year I had the jabasco toilet converted to electric and that gets a fair amount of use when moored. Online literature says amp draw of 24 Amps. No other kit to speak of. So allowing something for lights I think I might be drawing say 80 Ah overnight which I now get is too much for a single house battery. Solutions seem to be either switch off the Fridge when moored up (which sort of defeats its purpose) or increase the house bank with another 110 Ah battery. A thread from January last year shows the correct wire up and looks like something even I could do.
So Q1 please: Am I on the right track?

Assuming your 80ah is correct, you need a bare minimum of 160ah to keep the batteries above 50%. Regularly depleting them to 50% will shorten their life compared to keeping them at or above 80%. I would suggest having three batteries of 100ah-110ah.

My second point above means I need to be able to monitor the batteries. Looking through all the threads I have seen a few recommendations and I would love to be able to monitor via my phone but all bar one solution requires (for me) serious work putting in a shunt and re arranging cables. The exception seems to be a smartguage and looking at the utube sales pitch it seems my kind of thing. Simply wiring it up as is to the house battery with a voltage reader for the starter battery seems almost too easy. So Q2 any pros and cons I haven't thought about before I buy one?

Fit a Victron Smartshunt. It's not rocket science to fit, can monitor it from any Bluetooth device or fit a dedicated display.

My bow thruster problem is simpler in one sense. I used it to moor up and then switch it off. I am asking for trouble. Lesson hopefully learned. But Q3: Is the battery the right size for the thruster? I have simply replaced like for like when renewing (please don't ask how often) what was there when I got the boat but my reading here suggest a dual leisure might not be right type.

An AGM would be better.

Final Q4 (its been a long winter). I think I need a monitor for the bow thruster battery but haven't seen any commentary that suggests one that can cover all three - house starter and BT? So I am inclined to pay the cost of a second smartguage for that one - bit pricey but I reason its the price of a battery more or less so worth it in the long run.

You require minimum monitoring for the engine and bow thruster batteries, a simple voltmeter would suffice. The Victron Smartshunt will fully monitor the domestic bank and give you the voltage of another battery (usually the engine battery). You could fit an on-off-on (or even on-on) switch, connect it to the bow thruster and engine batteries and at a flick of the switch check the voltage of either battery, whilst the domestics get full monitoring.

 

[riverliver]

many thanks for the responses.
Clarifying some of my omissions pointed out:
Its a motor boat not a sailer so recharge from the engine - typically next morning at start of days cruising.
The start battery and the house are on opposite sides of the boat ( In a marina with shore power over winter.bankside without shore power rest of the year)
The BT charges from/with one or other battery- will need to check when at the boat next. Weirdly it doesn't charge at all from shore power which does charge the other 2 batteries.
The BT battery is U/S so seems I am in the market for 2 new batteries. One for the BT and one (at least) for house. Reading threads elsewhere should I get 2 new 110 Ah batteries for the house - so they are identical in age - and move the existing house to BT which would also give it a bit more oomph?

One vote for smartguage but no real votes against.
Adverc would definitely be an electrician job and knowing my limitations so would a victron.

I am tempted to look at a basic solar system but commentary suggests that is a benefit but not a replacement for additional battery power.
RE suggestion of simple voltmeter for BT any recommendations of make (remembering my v.limited electrical skills)

cheers and thanks again

PS I have also found the PBO project boat articles a mine of information and well recommend if your are a novice like me - three separate articles on battery and battery maintenance

 

[jac]

I would certainly vote for moving the existing domestic battery to the Bow Thruster and then getting at least 2 identical batteries for the domestic ( ideally 3.) Strictly speaking batteries in the same bank just need to be the same type ( e.g. AGM or Lead Acid) and ideally similar sized but given that this is basically a chemical reaction, you want to minimise the differences between the batteries to ensure that one battery isn't working harder than the others so buying 2 ( or 3) identical batteries at the same time is better than having 3 off different ages and manufactures but it's not a total disaster if you mix if you have to. Don't scrimp on connectors / wires.

Depending on use though i would seriously consider solar. Extra battery capacity is great but if it's not being recharged it will quickly deteriorate if left partially discharged for a long time .

Assuming that the boat is perhaps used Friday to Sunday over the season then even a single small panel ( maybe 50-60W) will provide enough to put maybe 70 - 100Ah into the Battery bank per week and assuming you have a vaguely smart solar controller then leave your batteries sitting fully charged with a nice float charge.

On that basis in priority order i would spend on :
2 New Batteries for Domestic bank
Small Solar Panel and suitable controller
Additional batteries for the domestic bank
Improved monitoring ( e.g. Smart Gauge)

 

[KompetentKrew]

Another vote for Victron Smartshunt not SmartGauge.

A shunt requires minimal rewiring - you just take everything off the battery negative and move it to one side of the shunt; all you need to add is a single cable from the other side of the shunt to the battery negative. In other words, you put the shunt inline with everything that was on the battery negative.

The inconvenient thing about fitting a shunt is that you have to make up a short thick battery cable and you might not have a crimping tool that large, but the local car battery centre can do this for you. In fact they could probably fit the whole thing for you if you ask them nicely.

 

[riverliver]

thanks Jac. What you say makes sense to me, especially for the summer months when off shore power. Will turn my small brain to things solar as my next education step. (Might be back with a new thread)

 

[riverliver]

Thanks KK

Can I ask why the downvote for Smartgauge? I hear what you say about that the work shouldn't be too much for a e.g. victron but for that's still fair bit more than just wiring up a smartgauge which simply wires to the battery terminals? And a quick look on the web doesn't show a significant price difference

cheers

 

[PaulRainbow]

Thanks KK

Can I ask why the downvote for Smartgauge? I hear what you say about that the work shouldn't be too much for a e.g. victron but for that's still fair bit more than just wiring up a smartgauge which simply wires to the battery terminals? And a quick look on the web doesn't show a significant price difference

cheers

Because the Smartshunt is a vastly better product and you can monitor it from any Bluetooth device, or fit a Victron display. It's actually easier to wire up than a Smartgauge.

 

[Tranona]

The Smartgauge is just a fancy voltmeter that converts voltage into state of charge. A proper battery monitor measures the amps going in and out which is much more useful. That is what the shunt is for. You take all the negatives after the shunt so that as you switch anything on it will show the current draw, but also show any charge meaning when the engine is running it will show the net charge and when it is stopped it will show the net draw.

The simple ones like the NASA have a fixed display and the more sophisticated ones like the Victron will also show history and some (like the Smartshunt) use a smartphone for the display. Nothing difficult about fitting them. I have just fitted a NASA BM1 and that comes with the new link to the shunt and very clear instructions. You will need new cables anyway if you are using 2 batteries for the house bank. This is my setup. You can see the shunt top middle if the photo. I made all the cables myself apart from the one to the shunt and the 2 link cable between the 2 batteries which came from Force4



Not fully wired up in this photo but the downside of the shunt goes to a negative common bus bar so anything that is powered by this bank is measured. The batteries are automotive ones used in stop start Jaguars and are 95Ah each. You can get them in larger sizes up to 120Ah or so. I chose those partly because that is the type I had on my last boat and they were the best physical fit in the space. Suggest you consider this type of AGM as they are excellent value for money (£230 the pair) and have a high acceptance rate for charging compared with leisure batteries which will make more use of your alternator. Also likely to last about 50% longer. My start battery is an Odyssey high power start as used in racing cars. Chosen because of space restrictions and extremely long life - a similar type in my Morgan lasted 19 years from new! Not necessary to spend that kind of money if you have space for a standard size car battery.

 

[riverliver]

thank you so much for the very clear explanation. Time for some new research.

PS see you use my battery supplier!

 

[riverliver]

thanks for the response Paul much appreciated

 

[GHA]

Have to completely disagree with the negative comments about a smartguage, I have a smartguage and a smartshunt & wouldn´t want to be without either though was very sceptical about the smartguage before using both the devices for a good while. Only got one cos it was on discount & the data from marinehowto was so compelling.
Very good in depth review here,
Balmar Smartgauge Battery Monitoring Unit - Marine How To
Masses of very useful info in there about the many pitfalls of battery monitors. Worth reading several times, these forums are a minefield of unresearched opinions & guesswork, scattered with gold dust ?

Simply put, if batteries are buckets of water then a smartguage will tell you how full the bucket is on discharge(not great when charging). Very accurately. That´s it. That battery, then and there, that temperature. It Knows nothing of the size of the bucket, just how full it is. AFAIK there´s nothing else available does anything like that.

Smartshunts et all will tell you how much is going in and out of the bucket, pressure(voltage) and temperature. Very useful. But they don´t know the size of the bucket either, you have to tell it. Which almost certainly will be wrong, brand new batteries are smaller buckets than the label says, takes 50 - 70 odd cycles to break in and get to full capacity apparently. Then they start deteriorating. Cold batteries are smaller buckets than warm batteries. So your discharge percent will hopefully be quite close but a bit wrong. Or very wrong & you won´t know.
Couple examples, during the summer autumn in the morning the smartguage after an overnight discharge will match the smartshunt pretty well, winter smartguage is more like 10% less than the shunt. The cold bucket is smaller. Smartshunt doesn´t know this.
Not so long ago "clean the battery terminals" was on the jobs list, not too bad but needing a scrub. Then I noticed over the course of a few days the smartguage went to like 20% more down in the morning compared with the smartshunt then looking closer it wouldn´t get to 100% during the day. I log all the smartshunt data 24/7 and noticed the temperature going up quite a bit at the start of the charging cycle (mains charger). Smartshunt temperature sensor is on the Pos terminal from memory. Pretty sure what was happening was a bit of resistance at the terminal was using up a bit of the charge current and getting warm, the charger didn´t know this so went to float early, the smartshunt didn´t know this either. The smartguage did spot it, clean terminals & it all went back to how it was.

Personally living aboard I wouldn´t want to be without either the smartguage or smartshunt, but the smartguage has been very educational to just how the batteries are preforming, it´s the only thing that knows the actual state of charge of the battery.
On a budget I´d go for smartguage and and cheaper ammeter/voltmeter off ebay, very useful knowing the current going in/out. And a BIG panel voltmeter off ebay placed where you can see it from many places can be useful, then with a smartguage you´ll start to notice the lower voltage for same state of charge when the batteries are cold ?
Cruising definitely both, gives you a stab at the health of your batteries, in the summer I lowered the capacity a little in the smartshunt to get the 2 devices to track closer when temperatures were closer to the 25DegC which is the temperature the 20H capacity is based on.

So if you want something simple which will accurately tell you the actual sate of charge of your batteries the smartguage fits the bill, just 2 wires. The naysayers don´t understand just how far out even a well set up battery monitor can be, I knew but didn´t really take it on board until seeing the evidence.
Smartshunts are great too though! Just different.

An example of the 24/7 monitoring which this voyage of discovery was based on, in a boatyard where the power gets turned off 10pm - 7am) >

 

[riverliver]

Blimey. Half a bottle of red down is not the time to try and get my head round this. thanks for the input and will re - read over the weekend