Advice on my battery charging arrangements

[cpedw]

We currently have a 12V system with 3 100Ah domestic batteries and an engine start battery, all wet lead acid.

Charging is from a 60A engine alternator (Volvo standard) directly to the start battery and through a relay that is energised by the alternator output so I think not exactly a VSR. The alternator sense is connected to the Domestic bank. I don't remember ever seeing more than 14.0V on the domestic bank when the engine is running.

There's also 20W of solar connected by a 2 output PWM controller. I'm looking to find space for more panels but I'm not finding that easy.

There's a Sterling Pro Charge mains charger but we are rarely able to connect to mains during the summer.

Sailing is about 2 months through the summer. Some days long motoring, others mainly sailing but several periods of 2-3 days anchored in one place.

This year, with brand new domestic batteries well charged at the start of the year, we never actually ran out of charge but it was close on a couple of occasions. I'd like to improve on this, especially as I expect the battery performance will decline with age and there's sure to be more drain as the gadgets proliferate.

Two specific questions are:
Would there be a significant benefit from fitting an alternator regulator such as https://www.sp-shop.co.uk/Sterling-...-Advanced-12v-Alternator-Regulator-AR12W.html and what's the difference between that and Sterling's Alternator to battery charger, https://www.sp-shop.co.uk/Sterling-Power-Alternator-to-Battery-Charger-12V-80A.html apart from the price!

Other observations are welcomed.

Derek

 

[matthewriches]

You’ve got newish batteries so add a VSR or lossless splitter (aka diode pack) to go on the alternator That will keep the 2 separate. Parallel switch if you deem necessary, this will enable you to start engine if battery fails for example. Charger wired in as normal, charging 2 banks separately. Maybe some solar to keep the domestic topped up.

What engine do you have? Ordinerially I’d stay clear of the Sterling stuff as it isn’t what it used to be but as you have the charger, use it.

Get the system up and running before fitting a regulator or any other wild gizmos. Simple is best.

 

[duncan99210]

The AR12 is a piggy back alternator regulator which boost the alternator’s performance. It requires opening the alternator, removing the bushes and soldering a wire to one of them. If you’re happy to do that (or pay someone to do it) then it will help the alternator provide the power you need.
The Alternator to Battery gadget is much simpler to fit in as much as you simply wire it into the output from the alternator. You then run a cable from it to the starter battery and a second one to the domestic bank. It fools the built in regulator into producing an improved output, charging the engine battery first and then providing a staged charge to the domestic bank. I’ve got one fitted and it does what it says on the tin. It also means you don’t need to fit a VSR or diode splitter. You can also fit a temperature sensor to the alternator and a battery voltage sensor to the domestic bank (temp sensor included in kit) but the box will work without either of these.

 

[vyv_cox]

Your setup is not a million miles from mine, with the difference that we have 125 watts of solar, in Greece. This is enough to run a fridge 24/7 plus relatively light other electrical consumption. We are completely self sufficient for power until about September, when sunlight hours have fallen away too much. We have a Sterling alternator regulator but can cope without running the engine for at least a week.

Your only answer is more panels, maybe on an arch, or perhaps a wind generator.

 

[lw395]

1) if you never actually run out of power, do you actually have a problem?
If you have to run your engine a few hours a year extra, just to charge batteries, that's not ideal, but what is its real cost and engine life impact?
Or do you wish to have more power available, e.g. use a fridge more?
2) Having said that I would consider a bigger alternator regulated at a higher voltage.
I would suggest measuring currents and voltages and looking at the spec of your existing alt, in case you can improve its performance by changing pulleys and turning it faster, and to get the best out of a more modern one.
An advanced alternator regulator is a good option, but you'd need to understand how much extra current your existing alt might give at low rpm.
It sounds to me that your total engine hours are likely to be low enough that overcharging anything is unlikely to shorten the life of any batteries?

If you spend time at anchor wanting the fridge on sunny days, a few portable solar panels might be worth considering?

 

[Tranona]

Before you get too worked up about charging, perhaps look at consumption first. 2 or 3 days at anchor and you can consume a lot of power and your alternator may not be able to put all that back. Better to monitor your typical consumption and charge with a battery monitor first so you understand where your problem lies.

 

[pvb]

Adding a "smart" regulator will enable you to get an increased charge voltage into the batteries. The Alternator-to-Battery charger is a good option, as it has isolated outputs so you can get rid of the relay which currently parallels your batteries. It also has an un-boosted output for the engine battery, so that won't get overcharged. And it's easier to fit than the ordinary add-on regulator. If you can find space, adding another one or two domestic batteries would help - larger banks accept charge more readily, and the percentage discharge for a given usage will be lower.

 

[lw395]

Before you get too worked up about charging, perhaps look at consumption first. 2 or 3 days at anchor and you can consume a lot of power and your alternator may not be able to put all that back. Better to monitor your typical consumption and charge with a battery monitor first so you understand where your problem lies.

£150 to measure the problem vs £200 to fix it?
The problem is, measuring your use this year is not always a guide to next year.
Some sort of spreadsheet and a few basic current measurements can get you a long way towards estimating likely consumption.

 

[knuterikt]

£150 to measure the problem vs £200 to fix it?
The problem is, measuring your use this year is not always a guide to next year.
Some sort of spreadsheet and a few basic current measurements can get you a long way towards estimating likely consumption.

The problem with not measuring is that you don’t know what kind of life shortening treatment the batteries are subjected to.
seems you get a Victron BMV-700 for GBP 126

 

[Tranona]

£150 to measure the problem vs £200 to fix it?
The problem is, measuring your use this year is not always a guide to next year.
Some sort of spreadsheet and a few basic current measurements can get you a long way towards estimating likely consumption.

A battery monitor is pretty much normal fit now if you are concerned about getting the best out of your batteries and gives you a good source of real data to add to the dumb spreadsheet.

However the thrust of what I was saying is to look at consumption as reducing usage achieves the same as increasing capacity. or pvb's suggestion of adding another battery to the bank to increase capacity.

 

[cpedw]

Thanks for all the comments so far.

To respond to specific points:
Engine is Volvo MD2030.
I'm expecting the batteries to slowly loose capacity as they age - or quickly if I don't treat them well.
More batteries should be possible though the current battery box is full.
One route to increase solar would be on the sprayhood - simpler than a goalpost. Does anyone have experience if this is a good idea? Extra "loose" solar while at anchor should also be possible.

This summer we ran the fridge 24/7 - it was a lot hotter than we are used to in NW Scotland. But that came with a lot more sunshine on our minimal solar panel than is usual!

Derek

 

[lw395]

The problem with not measuring is that you don’t know what kind of life shortening treatment the batteries are subjected to.

You can get a reasonable idea with a cheap simple volt meter.
You can throw money at it, or look at the cost/benefit of various changes.

ISTM that the OP has 300Ah of house bank, so maybe 150Ah to generate. That's a lot of engine hours, perhaps 5 hours at 30A? Is that a problem? I wouldn't want to do it every week but as an exception a few times a year, maybe its 2 hours of useful motoring and 3 hours of idling?
In my use pattern, it would be easy to see more alternator power as a distinct benefit. Some more solar likewise. I could see the big picture based on estimates of fridge duty cycle and currents for the 'usual suspects'. But I'm a low-engine hours type of boater at heart so I would say that. YMMV.
Sure a well calibrated battery monitor will give your more detail, but more than half the time it's just telling you the same thing as a voltmeter would, or that you know anyway.
OTOH, if your going to keep the boat a long time, the battery monitor might just pay for itself by helping to manage the point at which you buy new batteries. Or if you think its worth its cost as a cool gadget, go for it.

Sure ideally, have the ideal system. But for that money, I'd buy a spinnaker instead, and use the engine less... then I would have a problem

 

[yotter]

Derek,
We are also on the West of Scotland, MD2030 and just over 300AH domestic(open cell lead/acid) and 75AH engine. The large capacity is to reduce the percentage depth of discharge and hopefully preserve battery life. We have replaced the standard VP alternator (retained as a hot spare) with a Presolite 90A. We also use a Sterling AB130 Alternator to Battery charger. At cruising rpm of 2500 we see around 50A going into the domestic bank with little drop in current until the bank approached 100%. As others have pointed out, its probably worth getting a battery monitor if you do not already have one, the Victron BMV is excellent. Beware, the alternator when working hard gets hot and we filled an extra fan to duct outside air at the back of the alternator. We also trialled a photonic universe solar panel (80W) which is on a portable sheet of plywood, this allows us to orientate it to what sun we can find. We have no arch or other convenient place to mount it. The PV panel used the Victron MPPT controller, and on a good day we may have seen 35AH, which is around 25% of daily consumption, or 30 minutes engine at 2500 rpm:-(
Angus

 

[BabaYaga]

At cruising rpm of 2500 we see around 50A going into the domestic bank with little drop in current until the bank approached 100%. As others have pointed out, its probably worth getting a battery monitor

Sorry, but something has to be wrong here. No bank of 300 Ah wet cells will accept anything near 50A current when approaching 100 percent SOC.
Battery monitor out of calibration?

 

[Mistroma]

Sorry, but something has to be wrong here. No bank of 300 Ah wet cells will accept anything near 50A current when approaching 100 percent SOC.
Battery monitor out of calibration?

Yes, doesn't seem to be a sensible figure under normal circumstances. My 450Ah Trojan T105s probably accept around 25A at 14.8V when close to full charge. I'd be at around 85%-90% SOC at most to get approx. 50A going to batteries. Yotter only has 300Ah vs my 450Ah so I'd guess less than 80% for 50A.

I don't know charging regime OPs system is using but doubt it's anything unusual. Few people seem to check temp. corrected Specific Gravity from time to time and confirm that their batteries are actually fully charged and simply read a figure from their monitor.

 

[yotter]

Yes,
I agree, my post may have been misleading, it does drop off before 100%
angus

 

[PaulRainbow]

You’ve got newish batteries so add a VSR or lossless splitter (aka diode pack) to go on the alternator <snip>

A diode pack is not a lossless splitter, far from it. Furthermore, neither a low loss splitter such as the Victron ArgoFET), the diode pack you mention, or a VSR would "go on the alternator". The VSR connects between the battery banks, either at the batteries or the battery terminals of the isolator switches, the low loss splitter or diode pack (who fits diode packs these days ?) connects to the alternator output and then to the batteries.

 

[pvb]

You’ve got newish batteries so add a VSR ......

The OP already has a combining relay.

 

[matthewriches]

Sorry to the OP.


[rantstart]

I used the term also known as, as that’s what they are also known as. Righty or wrongly, in simple terms by a good percentage of the chandelry fraternity. Every customer that mentions wanting a device that keeps batteries isolated from engine start vs leisure load asks for a diode pack. I know some new ones are not diodes, anyone with any electrical experience might know a FET based splitter won’t be based on diodes.

Bugger me for keeping things simple..... Could be worse though, someone could have argued the toss to the Port of London Harbour Authority as to the fact there wasn’t a speed limit in place, when in fact, there was and me doing 22 knots through the speed limit was not appropriate. Oh, wait....

Read my post, it says fit a VSR OR fit a diode pack on the alternator. They were 2 separate options. Either a VSR OR a diode pack.

The fact you connect the diode pack or maybe I’ll start calling it FET based battery isolator; because the layperson going to know what that is, to the B+ ON the alternator, I’d say in simple terms, you’re putting the FET based battery isolator on the alternator, because that’s what I do, each and every single one of them, ordinerially along with the sensing wire to make it work without doubt.

[/rantover]

A diode pack is not a lossless splitter, far from it. Furthermore, neither a low loss splitter such as the Victron ArgoFET), the diode pack you mention, or a VSR would "go on the alternator". The VSR connects between the battery banks, either at the batteries or the battery terminals of the isolator switches, the low loss splitter or diode pack (who fits diode packs these days ?) connects to the alternator output and then to the batteries.

 

[PaulRainbow]

Bugger me for keeping things simple..... Could be worse though, someone could have argued the toss to the Port of London Harbour Authority as to the fact there wasn’t a speed limit in place, when in fact, there was and me doing 22 knots through the speed limit was not appropriate. Oh, wait....

If you want to talk about your extremely poor seamanship, tell it like it was. You were doing 12 knots (not 22 knots, your boat won't do 22 knots) against a strong flood tide, as we left St Kats (shortly after you rammed the lock at high speed). You were so close to a tug that it lost the lines to its tow, resulting in a conversation on the VHF discussing your actions. You then proceeded along the wrong side of the river, on a head on collision course with a Thames Clipper, resulting in the PLA patrol boat pulling you over. We were then followed on radar for all (or as much as possible) of the trip back to Ipswich, followed by a visit from the police on arrival.

No idea why you'd want to raise such a shameful incident on here, as part of a battery thread