Best value, reliable (smart) charging system?

[stuhaynes]

Alternator: 24 volts rated at 60 amps

Domestic batteries: 4 x 110AH wired in series and parallel to give 220AH @24 volts
Starter batteries: 2 x 110AH wired in series to give 24 volts

Most of the time we are on marina power, charging the batteries and supplying 'domestic' needs from 10amps @ 230 volts.

We're about to spend more time away and looking at the the best way of utilising the alternator power. I know that from previous questions I've asked, our battery bank isn't big, though I thought it must be last year when we bought it!

I can hook up the two 110AH starter batteries into my domestic bank (they're only a year old and had virtually no use, which will increase capacity, but how to wire them for best results? Also, if I do this, what would be the best AH batteries to replace the existing starter ones?

Last year (before replacing all 6 batteries) I had 1 knackered battery and one that I took off my car (to give me 24 volts for the starter motor), at the time I had no choice! It worked a treat. Spun the old engine like a good un! If I add the 2 starter batteries to my domestic bank I have very little room for 2 more starter batteries so I'm looking for suggestions as to the smallest sensible batteries I can replace them with.

Engine is heavy industrial, 60 years old, 30HP diesel and about 2250CC.

The smart charger option is to give us the max performance while cruising to avoid excessive genny use whilst stood. I still have to spend loads on the boat, even without altering the charging method. I'm looking for something reliable that will look after the batteries and not cook the bank account.

Your considered opinions very welcome...

 

[sailorman]

Alternator: 24 volts rated at 60 amps

Domestic batteries: 4 x 110AH wired in series and parallel to give 220AH @24 volts
Starter batteries: 2 x 110AH wired in series to give 24 volts

Most of the time we are on marina power, charging the batteries and supplying 'domestic' needs from 10amps @ 230 volts.

We're about to spend more time away and looking at the the best way of utilising the alternator power. I know that from previous questions I've asked, our battery bank isn't big, though I thought it must be last year when we bought it!

I can hook up the two 110AH starter batteries into my domestic bank (they're only a year old and had virtually no use, which will increase capacity, but how to wire them for best results? Also, if I do this, what would be the best AH batteries to replace the existing starter ones?

Last year (before replacing all 6 batteries) I had 1 knackered battery and one that I took off my car (to give me 24 volts for the starter motor), at the time I had no choice! It worked a treat. Spun the old engine like a good un! If I add the 2 starter batteries to my domestic bank I have very little room for 2 more starter batteries so I'm looking for suggestions as to the smallest sensible batteries I can replace them with.

Engine is heavy industrial, 60 years old, 30HP diesel and about 2250CC.

The smart charger option is to give us the max performance while cruising to avoid excessive genny use whilst stood. I still have to spend loads on the boat, even without altering the charging method. I'm looking for something reliable that will look after the batteries and not cook the bank account.

Your considered opinions very welcome...

the most reliable is the alternator`s own regulator

 

[saltylegs]

And good isolators so you can charge the bank you want or both.

 

[prv]

I was planning to get a "smart" regulator, but in the meantime I rewired the boat including the "heavy" parts around the battery. Following the rationale here, I did my best to ensure a smooth low-loss path from alternator to domestic battery - a pair of 16mm2 cables from alternator lugs to battery posts, broken only by a bolt-on fuse in the positive side. The engine battery gets to share that charge by a Smartbank relay between the two batteries, and of course there are the normal starter motor connections as well.

The domestic battery now charges at 14.5 volts whenever the engine is running; I've not experienced any shortage of power and it doesn't take much engine running to keep things topped up. It's not at all clear to me that a "smart" charger would do significantly better.

Pete

 

[Mistroma]

Good advice so far. I had a very simple system that worked well for 23 years. Alternator regulator for control and simple manual switch between engine & domestic. I never failed to switch to charging domestic after engine topped up (though only because my wife always prompted me when I forgot).

My current system would make NASA jealous and works automatically. But that came at quite a cost (because it was attached to a new boat).

I'd suggest monitoring how well the existing system works as a first step. You can buy a cheap clamp meter to check Amps going into battery. Check if the alt. is giving 10% of quoted battery capacity for a hour or two. If it is, then you probably don't need a bigger alternator. I forgot to say that you need to add any load (fans, fridge etc.) to the 10% figure so that battery is getting 10%.

Monitor the voltage to make certain the regulator is getting to a reasonable voltage when batteries are 80% charged (poss. 28.2-28.8V).

If all OK so far then system might be good enough and extra expense will give a small return.

Moving engine batteries to domestic side sounds fairly sensible and you can buy cheap start batteries. CCA is the main thing to look at here, not capacity. Do you know CCA of existing ones?

Battery capacity sounds adequate unless you are using a lot of kit (microwaves etc.) or have very inefficient fridge. You said 220Ah and that sounds low, but it is at 24V so comparable to 440Ah on a 12V system. So both systems store same amount of energy.

e.g. I'd use 6A when fridge motor running but you'd only use 3A for similar kit (i.e. Both come to 72W).

 

[Mistroma]

Just noticed reply Pete made when I was writing mine.

He is saying the same thing as I was about alternator output. i.e. If Voltage is already high enough then a smart egulator may not make much of an improvement.

I also have a Smargauge/Smartbank Advanced system and it works well. Existing battery/alternator wiring was upgraded from 16mm2 to 50mm2 when that was installed.

However, I do miss being able to turn a manual switch to stop charging the engine bank. The automatic system keeps engine and domestic charging even when engine side has no need to be connected. So some advantage with a simple switch, but it doesn't suit everyone as system doesn't just look after itself.

 

[Ariadne]

Balmar do a good system and it's programmable but not cheap.

My alternator has been stuffed for 4 months now and we've been at anchor all the time or sailing using invertors and a fridge no problem. So, a decent bank of solar panels is the way forward then, they'll pay for themselves with a year!

 

[mitiempo]

I agree you have received good advice. As long as your alternator is set at a good voltage - 28.8 or close to it - there is no low cost improvement that will mage much difference. The batteries will only accept so much anyway - they are flooded I assume. As prv posted an expensive 3 stage alt regulator will not charge faster as long as your current alternator has an output at the correct voltage.

Ariadne suggested solar panels and that would be a bonus. After about 80-85% state of charge the batteries will accept less and less current - no matter what normal battery type and no matter how large the alternator. To recover this with an alternator will take many hours. Solar does it quietly, without engine time and the fuel/maintenance costs tied to it, and after the panels are purchased and installed at no cost at all. As well if anchored in sunny weather they will help with the bulk charging as well. That is what I would spend my money on.

 

[KellysEye]

>the most reliable is the alternator`s own regulator

The batteries will last longer if a smart regulator is used because of it's variable input as the battery charges. We have them on both 12 and 240 volts charging circuits. They can also be set to handle a mix of batteries such as ours, one lead acid deep cycle and three gel cranking which require difgferent charging regimes.

 

[Trundlebug]

A Sterling Alternator to Battery Charger is good value, easy to fit, and mine has proved reliable in the last 3-4 years since I fitted it. It's a smart / fast charger, charges both domestic and starter battery banks automatically (no clunky manual changing over) and you'll get the best out of all of your batteries.

It's probably not as efficient as voltage sensing relays but it's been fine and is a lot cheaper than some equivalents.

Be aware that on top of the cost of whichever smart charger you fit will be additional cable cost, as it will undoubtedly need uprating to cope with the higher charge currents.

 

[mitiempo]

Remember that flooded batteries are not going to accept more than 20-25% if their capacity, whether the alternator is 60 amps or 600 amps. Many spend money on alternators whose capacity cannot be used fully.

 

[pvb]

However, I do miss being able to turn a manual switch to stop charging the engine bank. The automatic system keeps engine and domestic charging even when engine side has no need to be connected. So some advantage with a simple switch, but it doesn't suit everyone as system doesn't just look after itself.

If the engine battery is charged, it won't continue to take any significant current, even if it's left connected permanently.

 

[Mistroma]

Yes, I appreciate that the engine battery won't take much current. However, it is usually 100% charged and when domestic bank is getting near to full charge the engine battery is still charging with a higher Voltage than it needs. Even if the current is small it would be better not to put 14.8 Volts across it.

In reality I doubt it does much harm but I still miss not being able to switch out a bank manually when I know that's the best option. I accept it is a small price to pay for a completely automated system. So just a minor niggle.

 

[capsco]

Not sure if it is what you are looking for but I just happen to have an Adverc
24v system, inc loom, surplus to my requirements, other members will no doubt comment on its suitability.

 

[DaveS]

Remember that flooded batteries are not going to accept more than 20-25% if their capacity, whether the alternator is 60 amps or 600 amps. Many spend money on alternators whose capacity cannot be used fully.

Are you sure you've got that the right way round? Most sources reckon on charging to about 80% of capacity with a normal regulator, with smart chargers coming into their own by increasing the voltage to get the last 20% of capacity charged in a reasonable time.

 

[VicMallows]

Are you sure you've got that the right way round? Most sources reckon on charging to about 80% of capacity with a normal regulator, with smart chargers coming into their own by increasing the voltage to get the last 20% of capacity charged in a reasonable time.

I think he is saying that the charge acceptance of a battery is around 20-25% ... so for example a 100Ah battery will only accept 20A and therefore fitting a much larger alternator is pointless as far as battery charging is concerned. I agree.

 

[stuhaynes]

I think he is saying that the charge acceptance of a battery is around 20-25% ... so for example a 100Ah battery will only accept 20A and therefore fitting a much larger alternator is pointless as far as battery charging is concerned. I agree.

Our current charger is a 'garage' type one. On 12 volts it will produce 200 amps (in boost) for starting (not really relevant on our boat). I ought to mention that it does 12 and 24 volt so although it's fine for our 24 volt system, I worry about voltage levels. On low charge it appears to settle at below 30volts but if left on high charge it can go in excess of 30 volts according to the voltage meter I'm using now.

Course, one of the prob's is the accuracy of the meters I've been using. I had an electronic one that was reading 10% more than the new Durite volt meter in the dashboard and it also disagreed with the voltage meter on the new inverter fitted last year. It really can get confusing, but batteries are expensive too. This is why I'm looking for something that will do the job, will not be too expensive and will not fry the batteries

 

[mitiempo]

Are you sure you've got that the right way round? Most sources reckon on charging to about 80% of capacity with a normal regulator, with smart chargers coming into their own by increasing the voltage to get the last 20% of capacity charged in a reasonable time.

An internal regulator is fixed voltage - normally about 14.4. A smart reg (Balmar, Xantrex, etc) has the same 14.4 for bulk/absorption and as the battery's resistance increases after about 80% of charge it drops to a float charge, generally about 13.4 volts. These voltages are of course adjustable for different battery types.

If the voltage increased you would be adding water very often, and shortening battery life as well.

If the external regulator is set at the same bulk/absorption voltage as the voltage of the internal regulator it will not charge faster, something the manufacturers of external regs do not tell you. There are advantages - adjustable ramp up, ability to dial back alt output for longer life, temp sensors, and of course the float stage that is kinder to batteries if you are under power for long periods.

Below is a chart showing voltages of the different programs for the Xantrex XAR - the Balmar is similar.

 

[charles_reed]

The benefit of an external smart regulator is that it compensates for the inadequacies of most marine wiring systems.
Improve the wiring by shortening runs and increasing cable cross-sections and that advantage disappears.
I've had an Adverc controller for 18 years, recently it failed and the charging was dependent on the alternator internal controller. Apart from system volts never going above 12.5 there was no appreciable deterioration in power available.
With the (small) size of your battery bank and providing you improve the wiring to your batteries I can see little benefit to you in fitting an external smart controller.
In my case, with a 3-way splitting diode and a 12m run to and from the domestic battery the smart controller has definite benefits.

 

[sahibs123]

We hate to disappoint the thousands of users who think the Ample Power Smart Alternator Regulator, V2, is the best way to charge batteries, however, there is now a better way ...the V3. Combining the best features of the V2, with the best features of the Next Step Regulator, and adding a few new wrinkles to the art of battery charging, the V3 is the culmination of years of engineering.