Can one increase the rate of charge to the battery?

[BTB 500]

The O/p does mainly short journeys so a fair percentage of the alternator output will be taken in replenishing the starter draw.

The charging voltage is only around 14V, which isn't high enough to put more than 40-50A or so through a battery even when it's fully discharged. So a 150A alternator really isn't going to be a restriction.

 

[Pitts Pilot]

Yoy don't say how old the car is but typical lifespan of a battery is 5-6 years. If your car is newish, an alternative to replacing your battery which wouldn't be so costly is to have a trickle charger installed. CTEK are meant to be among the best: www.ctekchargers.co.uk


This would also prevent getting caught out with a flat battery on a cold winter morning.

The car is 2007, and as mentioned in the post, I changed the battery for a new MB one when the new audio system was installed less than a year ago.

Robert

 

[Pitts Pilot]

Fit a capacitor to the audio system.

I thought that was an excellent idea, and a common solution for power hungery ICE.

However, I came across this article that said the capacitor will actually make the situation worse!

Car Audio CAPACITORS: Why They DON'T Work

I'm no expert, so I can't comment

 

[Pitts Pilot]

Try downloading this zip file and then have a look at the electrical section/battery.

MBUSA Technical Training

Because your new amplifier setup may be making peak current demands on the convenience battery this may be enough to drop voltage sufficiently to trigger the Vehicle power supply control module (BNSG) to start switching off "non priority" consumer electronics such as the roof to protect the power supply of safety-relevant electrical consumers (e.g. electrohydraulic brake, easy-shift manual transmission etc ) and stabilizing the vehicle electrical system voltage. While the voltage drop maybe transient its enough to trigger this. Your car will have a 150 amp water cooled alternator so I doubt if charging is the problem Its more likely to be peak current demand hence Olly's [Black C55] suggestion that a capacitor IN THE POWER SUPPLY might make help smooth out these peak demands. At the heart of this is the fact that car electronics really need to move to 24volt or even 48volt systems to cope with today's higher electrical loads.

That is an interesting theory. I don't have the music turned up particularly loud - not a high current drain- but I did read that I should consider upgrading to a heavy duty deep cycle battery , like the front engine battery that is designed to supply high currents for short periods of time.

Additionally, deep cycle batteries are more able to handle peaks of current drain than the existing convenience battery.


Anyone a battery expert? Is the the upgrade and change to a Deep Cycle battery a good idea?


Thanks

Robert

 

[Pitts Pilot]

Yoy don't say how old the car is but typical lifespan of a battery is 5-6 years. If your car is newish, an alternative to replacing your battery which wouldn't be so costly is to have a trickle charger installed. CTEK are meant to be among the best: www.ctekchargers.co.uk


This would also prevent getting caught out with a flat battery on a cold winter morning.

Thank you

I already use an Optimate 4 that both trickle charges the rear battery, but also reconditions it. However its use is only occasional.

Robert

 

[Pitts Pilot]

Sorry again getting me units mixed up again. 180amps

Do alternators get 'old and tired'? Mine is the original from 2007.

I guess I'm asking whether having it overhauled, new brushes/contacts, etc, would keep it at peak output?

Alternatively, would I just be wasting my time and money?

I should add that I have no reason to suppose that it is faulty. It charges the engine battery just fine.

Thanks,
Robert

 

[Pitts Pilot]

It may be that you're supposed to have the engine running when you operate the roof anyway - what does the handbook say?

There is nothing in the handbook that says you must have the engine running.

And are you sure the roof operates from the convenience battery?

Yes, definately!

If the car is used for short runs then a maintenance charger (as mentioned) would be a good idea. Car batteries are designed to be fully recharged straight away, and lifespan is shortened if they are left standing partially discharged.

My SL is kept on a maintenance charger and the battery is now 9 years old.

Thanks
Robert

 

[grober]

Do alternators get 'old and tired'? Mine is the original from 2007.

I guess I'm asking whether having it overhauled, new brushes/contacts, etc, would keep it at peak output?

Alternatively, would I just be wasting my time and money?

I should add that I have no reason to suppose that it is faulty. It charges the engine battery just fine.

Thanks,
Robert

Might be worth getting the alternator checked for output by an experienced vehicle electrical technician. Other possibilities the "new" battery is faulty [ it does happen but rarely] or the car has developed a large parasitic drain somewhere meaning the battery gets very little charge while sitting. The article on capacitors is OK but neglects the voltage drop issue taking always in terms of current demand

 

[Pitts Pilot]

ps I assume the 700 watts is not an RMS figure but rather a music power one??

Thanks for the videos

I would have to check with Rob at Comand on Line, but I agree the 700w is probably not a RMS figure.

Thanks,
Robert

 

[Pitts Pilot]

AFAIK the charging is essentially self-regulating - the battery will charge more when the charge is low and less when it's fully-charged. That's a function of the battery

In your case you are pulling more energy out of the battery than you are putting in. There's no way round that apart from longer drives or a battery charger

A capacitor won't help as it doesn't store enough energy to change things. A bigger battery won't help much as you lack charging

I'd fit a charging socket on the car and plug a charger in when it's not in use

The actual load from the additional ICE will be pretty small on average. Your 700 Watt amp will be delivering a couple of Watts most of the time, and consuming a bit more than that.

Nick Froome

Thank for the advice

It is more in keeping with my thoughts on the matter.

I am not convinced that a big capacitor will help, and I agree that the current drain will be a fraction of the 700 watts most of the time.

What is significant is that this problem of the roof not moving when the engine is off did not start until 6 months after the system was installed, along with a new battery.

Presumably the new battery has had a bit of a 'shagging' at times when I have had the amplifier turned way up (Top down with wind noise to overcome).


So I'm thinking about changing to a heavy duty deep cycle battery, because in essence the battery requirements have radically changed. Thoughts?

Thanks
Robert

 

[Dieselman]

Have you tried reprogramming the roof? Maybe it's settings were lost when the battery was changed?

 

[Pitts Pilot]

ps its entirely possible of course the alternator is no longer putting out as advertised!

I suppose I get it checked by Olly, and refurb'ed if it needs it?

Robert

PS. Olly: Is this something you can do (Check the alternator output) if I make an appointment, and then wait around for a hours or so? - Robert

 

[Pitts Pilot]

Have you tried reprogramming the roof? Maybe it's settings were lost when the battery was changed?

OK. This IS going to make me look stupid!

I thought the roof had its programme to go up and down, and was not customisable, so 'losing the settings' makes no sense to this novice

Thanks,
Robert

 

[andy27168]

Hi,
Is the stereo system including the Amp power, coming from the consumer battery? If so can you not just wire the Amp power from the engine start battery? leaving all the control on the consumer one?
Or have I got the wrong end of the stick?

 

[Zulu 10]

I'm slightly surprised that no-one has suggested that the OP should replace the pulley on the alternator with one that is slightly (10-15%) smaller.
That way even at low engine speeds he'll be getting a significant output current from it.
He may also need to go down one size in belt if the tensioner doesn't have the scope to cope.

 

[E270 Owner]

Leisure or deep cycle batteries are just that, no good for anything but an axillary circuit system.

Look to beefing up the alternator and replacing the main vehicle battery with a heavy duty diesel one the biggest you can fit in there

There's plenty of auto-electrical places near you (I worked in a few of them) who could do a little work on the alternator amp output and recommend a battery.








.

 

[V12]

I'm slightly surprised that no-one has suggested that the OP should replace the pulley on the alternator with one that is slightly (10-15%) smaller.
That way even at low engine speeds he'll be getting a significant output current from it.
He may also need to go down one size in belt if the tensioner doesn't have the scope to cope.

The alternator isn't the problem. It can easily provide enough current to recharge healthy batteries very quickly.

Once the car is started, the main battery is using too much current from the alternator.

How many threads have we seen where people have a convenience issue and replace the convenience battery with no resolution until they fit a new main battery and then have no issues?

Search the forum if you won't take my word for it.

New main battery is on the cards.

 

[Pitts Pilot]

Hi,
Is the stereo system including the Amp power, coming from the consumer battery? If so can you not just wire the Amp power from the engine start battery? leaving all the control on the consumer one?
Or have I got the wrong end of the stick?

No, I don't think you have got the wrong end of the stick

I think in principle its a good idea!

However, the draining of the rear consumer battery is not a great inconvenience. Do the same to the engine battery and you can't the car started!

Cheers,
Robert

 

[Pitts Pilot]

The alternator isn't the problem. It can easily provide enough current to recharge healthy batteries very quickly.

Once the car is started, the main battery is using too much current from the alternator.

How many threads have we seen where people have a convenience issue and replace the convenience battery with no resolution until they fit a new main battery and then have no issues?

Search the forum if you won't take my word for it.

New main battery is on the cards.

Interesting idea. But I don't understand how "the main battery is using too much current from the alternator". Do you mean a leakage or part shorted battery? Could you explain in detail please?

I have searched the Forum for related posts as you suggested, but failed to refine my search sufficiently to get a result

Thanks,
Robert

 

[V12]

The main battery is weak so instead of a quick 1 minute to recharge it sufficiently to pre start condition, it's taking up to 10 minutes or so.

The system is effectively an over complicated split charge system with a fancy ecu instead of a basic relay.

I'll see if I can find the document that details how it works.

My understanding is that the aux battery won't receive charge until the control unit is satisfied with the condition of the main battery.