Battery charging systems

[Manxcat54]

I am at the beginning of my old narrowboat refurb, and one of the first things I wish to tackle are the old electrics (still not worked out what goes where) especially the battery charging system, I must admit I have googled charging systems, but nothing is clear. I built my own campervan a few years ago, and I fitted a C-TEK split charger, it wasn't the cheapest I could have used ! over the last 3 years it has worked perfectly, I have 2 Leisure batteries, and 2 starter batteries, and the C-TEK keeps them in perfect health, it also has an input for solar. Ok so why should I not use this on my narrowboat? I see all these fancy expensive Victron systems, which is all good and well, but I was at a well known boatyard recently and brought the subject up, the Engineer said "keep it all simple" now I am fairly new to narrowboats, well the technical side of them, so please tell me what you all think, I have noticed there are some Electronics experts on the forum, so without dazzling me with the technicality's please explain what I should go for, I am planning 3 leisure batteries and a starter battery, and probably solar. Thank you all. Malc.

[MtB]

22 minutes ago, Manxcat54 said:

I am at the beginning of my old narrowboat refurb, and one of the first things I wish to tackle are the old electrics (still not worked out what goes where) especially the battery charging system, I must admit I have googled charging systems, but nothing is clear. I built my own campervan a few years ago, and I fitted a C-TEK split charger, it wasn't the cheapest I could have used ! over the last 3 years it has worked perfectly, I have 2 Leisure batteries, and 2 starter batteries, and the C-TEK keeps them in perfect health, it also has an input for solar. Ok so why should I not use this on my narrowboat? I see all these fancy expensive Victron systems, which is all good and well, but I was at a well known boatyard recently and brought the subject up, the Engineer said "keep it all simple" now I am fairly new to narrowboats, well the technical side of them, so please tell me what you all think, I have noticed there are some Electronics experts on the forum, so without dazzling me with the technicality's please explain what I should go for, I am planning 3 leisure batteries and a starter battery, and probably solar. Thank you all. Malc.

 

Start by reading and understanding the "Battery Charging Primer" here:

 

 

 

 

[Tony Brooks]

From what I can gather from the internet, that is a 20 amp battery to Battery charger with only a 20 amp output. Assuming you have the alternator charging the start battery and then the B to B charging the domestic battery, I would say 20 amps is a bit low for many boaters.

 

If you are NOT going to use lithium batteries and stick with lead acids for both banks, then a simple Voltage Sensitive Relay (VSR) plus solar control leer will do the job for probably far less cost and be simpler to understand. If you then wire the alternator to the domestic bank -the bank that normally has the most demand on it - you can use as much of the alternator output as the batteries need. Its operation is also easy to understand.

 

Until you understand things, be very wary of charts and marketing blurb that talks about and shows more than three stages of charging or clams that an  extra device massively reduces charge time or more filly charges the batteries. They work to a degree, but with a properly wired system and a modern 14.4Volt plus alternator will be good enough, especially with a decent amount of solar charging.

 

I agree with that engineer. Apart from your camper van experience, there is an excellent chance that anew boater will destroy their domestic batteries within weeks or months but consistently over discharging them and never fully charging them - especially in winter when solar has all but zero effect.

[Tony Brooks]

Just now, MtB said:

 

Start by reading and understanding the "Battery Charging Primer" here:

 

 

Yes, absolutely. Also, if you are wiring your boat you may find the electrical notes on my website helpful (tb-training.co.uk).

[Manxcat54]

20 minutes ago, MtB said:

 

Start by reading and understanding the "Battery Charging Primer" here:

 

Thank you for this, just another point worth mentioning, my boat has 2 alternators, so how do they work? does one do the leisure and one the starter battery, and if so how the hell do I wire those up.

 

 

 

[BEngo]

With two alternators the smaller one for start and the larger ons for domestic is normal

  The only common electrical bit is that both negatives should be connected to the hull.  A Google of 9 diode alternator wiring may help.

 Broadly:

Connect the positive wire ( from B+, usually)  to the battery positive via a good master switch. (NOT one with a red plastic key).   Connect the negative wire ( from the case or B-) to the battery negative.

Connect an ignition switched wire,  via a warnjng  lamp of about 2.2 W, from the engine side of the master switch to the D terminal on the alternator.

Repeat for the other alternator.

 

Connect both battery negatives to the hull.  Connect the domestics to one battery master and the starter to the other, on the side not connected to the battery.

 

Insert fuses to protect your cable.

 

You may find the alternators dont have  D terminal. If so  Google on 6 diode alternator wiring should help

N

 

 

Edited February 17 by BEngo
Add 6 diode alternator

[Manxcat54]

MtB

 

Thanks I already have an understanding of the charging systems and the stages of charge, a lot came from my motorcycle knowledge and using optimate chargers etc. What I would dearly like to know is, what would be the best way to keep my batteries in shape without getting too complex, I see all Vitron equipment and I just feel it is overkill, someone told me to look at the Mastervolt Alpha Pro, which seems straightforward enough, I am all for the simple life, and a believer in the fact that too much technology can mean more to go wrong, so has anyone used any systems that have proven to work well. Thanks for your input (no Pun)

[nicknorman]

46 minutes ago, Manxcat54 said:

MtB

 

Thanks I already have an understanding of the charging systems and the stages of charge, a lot came from my motorcycle knowledge and using optimate chargers etc. What I would dearly like to know is, what would be the best way to keep my batteries in shape without getting too complex, I see all Vitron equipment and I just feel it is overkill, someone told me to look at the Mastervolt Alpha Pro, which seems straightforward enough, I am all for the simple life, and a believer in the fact that too much technology can mean more to go wrong, so has anyone used any systems that have proven to work well. Thanks for your input (no Pun)

If you just have lead acid batteries and one alternator then there is not much complexity that can be created! Just use a VSR as previously mentioned, to connect the engine and battery banks together when charging is taking place. Using a VSR is slightly better than a split charge relay because the latter is associated with charging from the alternator only whereas a VSR keeps everything charged from a battery charger or solar.

 

So looking at other sources of charging: Solar is very popular these days, and for good reason. Prices are down and efficiency is up. But it depends on your type of usage, which I don't think you've mentioned. Certainly if you are a live aboard it would be crazy to not have as much solar as you can reasonably fit on the roof (whilst still allowing access to lock ladders etc). On the other hand if you tend to cruise for long days every day, it is not worth it.

 

But then again, for 3 months of the winter solar does virtually nothing so you need another means of charging and this of course could be your boat engine with the VSR already mentioned. But another way is to use a generator (a quiet one please!) and battery charger. And the battery charger does also allow you to charge from shore power if you are in a marina or some moorings where there are electric bollards.

 

If you are going to be running the engine a lot just to charge the batteries, it might make sense to use some sort of external alternator controller, since the built-in regulators suffer from current tailing off long before the regulated voltage is reached, and this slows charging. Adverc used to be the popular one, not sure if that is still sold. Or a Sterling one. The Alpha Pro is a good regulator but very expensive and I'm not sure it is worth it for lead acid batteries. Plus you need to do a certain amount of surgery on the alternator to access the field circuit directly.

[Tony Brooks]

34 minutes ago, Manxcat54 said:

MtB

 

Thanks I already have an understanding of the charging systems and the stages of charge, a lot came from my motorcycle knowledge and using optimate chargers etc. What I would dearly like to know is, what would be the best way to keep my batteries in shape without getting too complex, I see all Vitron equipment and I just feel it is overkill, someone told me to look at the Mastervolt Alpha Pro, which seems straightforward enough, I am all for the simple life, and a believer in the fact that too much technology can mean more to go wrong, so has anyone used any systems that have proven to work well. Thanks for your input (no Pun)

 

If you already understand charging systems, then you will know that lead acid batteries take many, many hours to get fully charged from whatever source because the batteries themselves control the charging current at any specific voltage. All such fancy alternator add-ons can do is boost the voltage, so the battery accepts a bit more current. The problem is that the amount you can boost the voltage is very limited before it is enough to damage the batteries. This is why, despite all the fancy talk about stages and the fancy graphs, any improvement on  a properly specked system is not as great as the bumph tries to make out.

 

It is true that such systems convert machine sensed alternators to battery sensed, and that does make a larger improvement on poorly designed or faulty wiring and passive split charge diode systems.

 

Over discharging and under recharging WILL wreck LA batteries by using up their cyclic life. Not regularly fully charging LA batteries will allow them to sulphate and lose capacity. It is not unknown for a new boater to wreck their domestic batteries within weeks.

 

In my view, you would do better to put your money towards both as much solar as will fit on the boat and, more importantly, a shunted battery monitoring system that allows you to read charging amps and battery voltage - but for your own good ignore the % charged and other similar readouts, because if you have not fully digested the manual, set it up properly, and regularly resynchronise it the % readout will encourage you to undercharge and possibly over discharge the batteries. The learn how to use charging voltage and tail current to know when the batteries are as near fully charged, and rested voltage to assess the state of charge (when it is time to recharge). By using the Amp Hours used readout plus the assessed state of charge from rested voltage, you can work out the capacity of the batteries at that time. The Victron BVM-700 is such a system, but there are other makes.

 

In winter (no or very little solar charge) you would be well advised to fully recharge at least once a week and expect it to take in  excess of 10 hours, but the tail current will tell you when to stop charging.

[Manxcat54]

I haven't mentioned which batteries I am using ?

[nicknorman]

Yes I fogot to mention battery monitoring, which is silly because it is something I am always recommending! Personally these days I would go for the BMV712 because the bluetooth link to the phone is so useful.

 

I disagree somewhat with Tony on the advantages of alternator add-ons. I used to share his view until I installed a precisely controlled alternator controller (this was as a precursor to fitting Lithium batteries, but I still had the lead acids for a while). I found that the modern digital regulation did make much more difference than I expected. Tony is correct to say that a battery will only take so much current, but in practice the regulation of a conventional built in alternator regulator is very poor in that there is long period where the maximum current it can supply reduces, long before the charging voltage reaches the regulated value of 14.4v or whatever. It really does make a big difference during the mid-charging phase, although it is of course true that the lengthy tapering off of charge current to reach 100% state of charge once the voltage has reached 14.4v, still has to be endured.

[Tony Brooks]

8 minutes ago, Manxcat54 said:

I haven't mentioned which batteries I am using ?

 

 

No, you have not, and that makes it impossible to give you a sensible answer. I carefully stated lead acids in my reply because you gave no indication of the battery type that you are planning. If you intend to go lithium, then that opens up a whole lot more complications, unless you are happy to spend thousands on a suitable charging system and batteries. We have seen £5000 mentioned by those in the know. Get a lithium charging system wrong, and you are likely to wreck very expensive batteries. Get the "wrong" type of lithiums and incorrect charging could well set your boat afire.

 

There seems to be much questionable advice on the internet about wiring lithium charging systems. Once some of the suggestions have been in use for 10 years or so, things will be clearer. One thing is for sure, a lithium system is not simple.

Edited February 17 by Tony Brooks

[nicknorman]

7 minutes ago, Manxcat54 said:

I haven't mentioned which batteries I am using ?

Not sure if that is a statement or a question! You did say "3 leisure batteries". I have leisure batteries too. They are lithium! But I presumed you meant conventional lead acid wet leisure batteries.

[Manxcat54]

I will be using Lithium

[nicknorman]

1 minute ago, Manxcat54 said:

I will be using Lithium

Ah well, that is a whole new can of worms!

[Manxcat54]

I think I will tackle it myself, you lot are too smart for me.

[nicknorman]

Just now, Manxcat54 said:

I think I will tackle it myself, you lot are too smart for me.

 

Jolly good. Do let us know how you get on once it is all put together and working.

[Tony Brooks]

1 minute ago, Manxcat54 said:

I will be using Lithium

 

Then ignore everything I said, apart from be careful about what advice to take. If using a "normal" alternator, expect to buy at least one B to B charger and probably other equipment as well.

[IanD]

1 minute ago, Manxcat54 said:

I think I will tackle it myself, you lot are too smart for me.

All the kit to build a good system with LFP is available, but what absolutely *must* be sorted out is alternator charging (if you're going to use this, which most boats do), just connecting one up like (kind of) works with LA is a recipe for an expensive and short lifetime...

[MtB]

4 minutes ago, Manxcat54 said:

I will be using Lithium

 

1 hour ago, Manxcat54 said:

What I would dearly like to know is, what would be the best way to keep my batteries in shape without getting too complex,

 

 

These two snippets are incompatible, I suggest. 

[IanD]

2 minutes ago, Tony Brooks said:

 

Then ignore everything I said, apart from be careful about what advice to take. If using a "normal" alternator, expect to buy at least one B to B charger and probably other equipment as well.

Or an externally controlled alternator... 😉

[Tony Brooks]

1 minute ago, IanD said:

Or an externally controlled alternator... 😉

 

he has not told s how many alternators his engine has, or if he is sticking to LAs for starting. Unless he tells us, then he is still likely to get less than optimum advice.

[IanD]

4 minutes ago, MtB said:

 

These two snippets are incompatible, I suggest. 

 

It's not so much that doing LFP properly -- or at least, not badly -- is especially complex, in many ways they're easier to look after and use than LA. But you do need things which aren't needed with an old-school "dumb" LA setup, a little bit more intelligence is needed -- meaning the kit and who installs it, not the boater using it.

 

What it isn't is super-cheap, because the bits you need cost money on top of the LFP battery cost...

Edited February 17 by IanD

[MtB]

1 minute ago, IanD said:

 

It's not so much that doing LFP properly -- or at least, not badly -- is especially complex, in many ways they're easier to look after and use than LA. But you do need things which aren't needed with an old-school LA setup.

 

What it isn't is super-cheap, because the bits you need cost money on top of the LFP battery cost... 😉

 

 

What would you suggest the OP installs then, keeping it simple, and given his view appears to be that Victron stuff is expensive and over-complicated? 

 

 

I'm particularly interested as the closest I could suggest would be a hybrid system, similar to that in my own boat. 

[IanD]

11 minutes ago, MtB said:

 

What would you suggest the OP installs then, keeping it simple, and given his view appears to be that Victron stuff is expensive and over-complicated?

 

 

It completely depends on how much he wants to spend, what he wants to end up with, and how he wants to use it.

 

As soon as you add an alternator controller (not cheap!) it needs controlling, which ideally means having a BMS which can do this -- and which can preferably also control any MPPT controllers and inverter/charger. If you're going to have all these things anyway (which many boats do nowadays) then it's not much (if any...) extra cost and effort to make them talk to each other, *if* they're designed to do this. Victron gear can do all this and I'm sure other makes can too, but I don't have details of them.

 

Keeping some LA and using a B2B to make a hybrid LFP system looks simpler and cheaper, but also has some pitfalls -- though probably not as many as the "drop-in-LFP+length-of-wire" systems which are even cheaper.

 

If the OP thinks all this is "too complicated", then he should probably stick to a nice simple LA system and put up with its problems -- which of course is what lots of boaters have done over the years, helping fill the coffers of battery suppliers in the meantime as their batteries die early deaths... 😉

Edited February 17 by IanD