Battery charging (again!) - alternator regulators and their friends

[MikeBz]

With 200Ah of AGM house batteries and no shore power, allied to an slight allergy to running the engine any more than is really necessary, I'm looking to maximise the charging that takes place when we do run the engine. To this end it would seem to make sense to fit some kind of smart regulator between the alternator and the house batteries.

Engine is Volvo M2020D with standard alternator (60Ah I think, maybe 70 - manual is on the boat and I'm not).

I'm thinking a Sterling AR12V would do the job well for < £100 (yes I know it needs an alternator mod) but there is 1 thing that I don't understand: If the regulator uses sensing on the house batteries to regulate the voltage for the various charging stages, then surely the starter battery is likely to be severely overcharged in the case where the house batteries need/get a good long charge from the engine whilst the starter battery is already fully charged?

I'm also pretty confused about the real difference between (a) alternator regulators (AR), (b) alternator-to-battery regulators (A2B) and (c) battery-to-battery regulators (B2B). I know that AR involves modding the alternator and the others don't, but other than that the differences are?

And one other thing, would I be advised to spend a bit more and get the version which has an alternator temperature sensor?

 

[Cardo]

You may wish to have a read of this thread -
http://www.ybw.com/forums/showthread.php?383260-Sterling-A2B-charger-versus-Pro-Digital
I asked most of the questions you're asking.

Essentially, a battery will only take as much current as it needs. As long as your house and engine batteries are of similar type, then you shouldn't have an issue, as long as you connect a AR using something like a diode splitter.
The A2B charger essentially has the diode splitter built-in. That's the only real difference I could see for the money.

As for the benefit of a smart alternator regulator (We have the Sterling ProRegD) we have noticed a massive boost in charging whilst motoring. We gain more charge in an hours' worth of motoring than we did over an entire day before.

 

[MikeBz]

Thanks for pointing me at that thread.

My concern is that even if the house & engine batteries were of similar type, if the engine battery is fully charged and the house batteries are substantially discharged then the engine battery will be getting a period of absorption charge voltage when really it should be on float?

I probably shouldn't be too worried since the engine battery is a non-sealed wet cell which I can monitor and top-up as necessary. So I guess I just need to decide whether it's worth paying the extra for a Pro Reg D over a Pro Reg B to get an alternator temperature monitor.

 

[pvb]

My concern is that even if the house & engine batteries were of similar type, if the engine battery is fully charged and the house batteries are substantially discharged then the engine battery will be getting a period of absorption charge voltage when really it should be on float?

One thing you need to realise is that the Sterling alternator regulator can't reduce the alternator's normal voltage, it can only increase it. So, if your alternator is already putting out 14v or so, that's the lowest voltage your batteries will get.

In fact, it's worth measuring the existing alternator output voltage before you go to the expense of buying an external regulator. If it's already 14.0-14.2v, you won't get much of an improvement in charging with an external regulator (on its AGM setting, the Sterling regulator delivers 14.4v max). In this event, if the voltage at your battery posts is being reduced by a diode splitter, adding a remote sensing wire to your alternator would be a cheaper fix.

 

[MikeBz]

One thing you need to realise is that the Sterling alternator regulator can't reduce the alternator's normal voltage, it can only increase it. So, if your alternator is already putting out 14v or so, that's the lowest voltage your batteries will get.

Yes, good point. So the chances are the batteries will get a float voltage higher than recommended. Could this be addressed by putting a diode in between the alternator and the splitter so the voltage it sees from the alternator is reduced by 0.7V? Maybe it's all getting a bit complicated and I would be better off just paying the extra for an A2B.

In fact, it's worth measuring the existing alternator output voltage before you go to the expense of buying an external regulator. If it's already 14.0-14.2v, you won't get much of an improvement in charging with an external regulator (on its AGM setting, the Sterling regulator delivers 14.4v max). In this event, if the voltage at your battery posts is being reduced by a diode splitter, adding a remote sensing wire to your alternator would be a cheaper fix.

The most I've ever seen at the battery is 13.8 or 13.9V, but as you say this is perhaps being reduced by a splitter (which I haven't managed to find yet, but there must be something in there somewhere). I thought the multi-stage charging of the external regulator would be beneficial and will prevent the house batteries from being cooked on a prolonged motoring session?

 

[pvb]

Yes, good point. So the chances are the batteries will get a float voltage higher than recommended. Could this be addressed by putting a diode in between the alternator and the splitter so the voltage it sees from the alternator is reduced by 0.7V? Maybe it's all getting a bit complicated and I would be better off just paying the extra for an A2B.

One key advantage of the A2B device is that it can provide a true float voltage to the house batteries. However, the starter battery output is a diode-protected unboosted feed from the alternator, so it won't have a true float mode (but it's unlikely to overcharge it anyway).

 

[sailinglegend420]

One thing you need to realise is that the Sterling alternator regulator can't reduce the alternator's normal voltage, it can only increase it. So, if your alternator is already putting out 14v or so, that's the lowest voltage your batteries will get.

I think this is wrong, and you say in a later post that it has full float functions.

The A2B charger is very hard on an old alternator as it sucks power out of it by putting it under a very heavy load. With your AGM you need a marine hot rated alternator of at least 100 amps which can also accept an external regulator. Search this forum for more........

In fact, it's worth measuring the existing alternator output voltage before you go to the expense of buying an external regulator. If it's already 14.0-14.2v, you won't get much of an improvement in charging with an external regulator .........

BUT...alternators have built in temperature compensation so their output voltage will go down very quickly under the load of a depleted deep cycle battery, as the alternator heats up, so do check the voltage after say half an hour.

You must get the batteries to their proper charging voltage or they will die prematurely.

 

[GHA]

I think this is wrong, and you say in a later post that it has full float functions.
.

As the external regulator piggy banks on top of the existing one, how could it pull the voltage down?

 

[duncan99210]

The Sterling A2B has an alternator temperature sensor to ensure that it does not put an excessive load on the alternator leading to overheating.

 

[Tintin]

Google adverc and give them a call. Very helpful people without Mr Sterlings hype and ego imho.

 

[sailinglegend420]

As the external regulator piggy banks on top of the existing one, how could it pull the voltage down?

You guys need to read up on how the A2B charger works.

From Mr Sterling's own brochure:

In order to maximise the alternator output current, the alternator-to battery charger pulls the alternator output voltage down to about 13V. Then this low voltage is amplified to a higher voltage suitable for effective battery charging, i.e. 14.1V to 14.8V.....When the batteries have been fully charged, the voltage is reduced to float voltage (appr. 13.5V to 13.8V).

The alternator temperature sensor is only a optional extra - not an essential item. The Unit is designed to only run for 15 minutes before resting for 2.5 minutes. So 16% of it's running time it is not charging the house bank, only gently topping up the starter bank - great design Mr Sterling!!!!!!!

IMHO a decent new marine "hot rated" alternator with an external decent regulator with battery and alternator temperature sensors is the best way to go, especially if you have AGMs which will take as much current as you can throw at them in the bulk charging phase.

All this is covered on this Forum in other posts.

 

[GHA]

You guys need to read up on how the A2B charger works..

I know how an a2b works. You're not the only one who can read a data sheet.

The quote specifically stated Sterling alternator regulator, not a2b.

 

[pvb]

I think this is wrong, and you say in a later post that it has full float functions.

Ask Mr Sterling if you don't believe me! And it's the A2B which I said had full float facility, not the AR.

 

[sailinglegend420]

Ask Mr Sterling if you don't believe me! And it's the A2B which I said had full float facility, not the AR.

Sorry I mistook A2B for AR - but my point that you were wrong still is true. The AR can drop to float voltages, but you have to instal it properly and disconnect the internal regulator AND, maybe, modify the regulator to get at the field wires. That is why the A2B was developed. No external regulator can piggy back an internally regulated alternator without switching of the internal regulator. I have a simple switch that powers the internal or the external regulator so I have a backup regulator if needed.

 

[GHA]

No external regulator can piggy back an internally regulated alternator without switching of the internal regulator.

Not so, Sterling units piggy back.

You can't get lower than the internal regulator voltage as float but gain control over absorption voltage and time.

And have the internal as a fall back.

 

[pvb]

Sorry I mistook A2B for AR - but my point that you were wrong still is true. The AR can drop to float voltages, but you have to instal it properly ....

If you install it as instructed by Mr Sterling, it can't drop to float voltages. If you want to install it differently, as you suggest, it can provide float voltage, but you lose the failsafe function.

 

[Cardo]

If you install it as instructed by Mr Sterling, it can't drop to float voltages. If you want to install it differently, as you suggest, it can provide float voltage, but you lose the failsafe function.

Unless the built-in regulator only does float voltage, like ours seems to do.

 

[sailinglegend420]

If you install it as instructed by Mr Sterling, it can't drop to float voltages. If you want to install it differently, as you suggest, it can provide float voltage, but you lose the failsafe function.

This I find very confusing!!! Mr Sterling clearly states in his product literature that his ProRegB Advanced Alternator Regulator is a four stage charger that falls to Float mode when the batteries are charged to prevent overcharging. He also has a very long and complicated explanation of how to remove the alternator to connect to the brushes.

So please provide a link where Mr Sterling says you can ONLY piggy-back his AR and NOT connect to the alternator field wires.

Mr Sterling's marketing skills are not his best asset so it is not surprising that either you or me or both are confused.

 

[pvb]

This I find very confusing!!! Mr Sterling clearly states in his product literature that his ProRegB Advanced Alternator Regulator is a four stage charger that falls to Float mode when the batteries are charged to prevent overcharging. He also has a very long and complicated explanation of how to remove the alternator to connect to the brushes.

So please provide a link where Mr Sterling says you can ONLY piggy-back his AR and NOT connect to the alternator field wires.

Mr Sterling's marketing skills are not his best asset so it is not surprising that either you or me or both are confused.

Well, I'm not confused, as the Sterling literature is clear.

The installation instructions for the AR12VD which are on Sterling's website describe the "Normal installation" method, which they say is "to be used for non-experienced fitters and DIY customers".

These instructions do indeed involve connecting wires to the alternator brushes, but they don't involve disconnecting the alternator's own regulator. Indeed, they say "Remember to replace the old regulator back into the alternator, do not leave it out."

So the Sterling regulator is connected in parallel with the alternator's standard regulator. Because of this, the Sterling can only increase the alternator's output voltage, it can't decrease it.

Despite the claims that it produces a float voltage, the Sterling's float voltage when installed according to the instructions is whatever the alternator's standard regulator produces, maybe 14.0v, maybe more or maybe less. If you look at the installation instructions section on the "LED alarms and indicators", you'll see that it says "Green Float Mode: This indicates that all the high charge cycles are now over and should remain on after all the high charge lights are out. The system is now running at a standard charge rate only (about 14 volts) regulated on the battery."

 

[lw395]

It should be borne in mind that most cars are quite happy with a 14V float from the standard alternator, and that it's not a true float unless the engine is running 24/7.
You can get a good life out of a car battery running it several hours a day at 14V for several years. But if you float it from a charger at that voltage 24/365 it will dry up and die in a year or less.
I made that mistake with a motorbike battery, 13.8V is good for trickle charging or when you're cycling the charger around different battery each week, but for true long term float you want less.

Preferably you want some noise, spikes or modulation rather than clean DC, but that's a new can of worms.
Are we due a de-sulphator thread this year?