Adding an extra alternator

[Laura]

Hi we are thinking about adding a second alternator for charging.

Is this a good idea and are there any pros and cons we should consider?

What sort of cost should it be?

Any suggestions welcome.

Thanks.

[w1ntersun]

I cannot think of any reason why you need an extra alternator as the standard one is more that up to the job. The main time you need extra charging is when the engine is NOT running

 

So its more batteries, extra gen or solar panels

 

Richard

[crinklystarfish]

Hi Laura, as above, I don't get the reasoning either. I have heard of 240v ac 'alternators' being fitted to internal combustion engines but they were silly money and would offer little advantage on a motorhome given inverter / generator technology.

What do you perceive as the advantage(s) of this project?

[Brian Kirby]

Agreed!  It would help if you could say what you are hoping to achieve, that you cannot achieve at present.

[Laura]

Thanks for the replies.

We thought about this becasue narrowboats use twin alternators for more charging power.

Our main thought is quicker charging as there will be more power output of course its an uneducated thought as we dont have a clue.

If a solar panel is better advised then perhaps that will be the way to go with an additional battery.

We want to ensure there is enough power without running a generator for the laptop which my partner uses for hours on end for work and a 12v tv so about 120w plus pump when we ran a tap,lights use.

The laptop will be used during the day then a few hours of tv a night perhaps.

Thanks.

[crinklystarfish]

You’ll be fine with the standard alternator, but for a really comprehensive answer it would be useful to know if you have a compressor or absorption type fridge and if you have diesel or gas powered heating. Also useful to know would be how much you intend to drive every day, or how many days you plan to stay stationary with no driving. Do you intend to camp in winter? Further, 120w for a TV seems quite a lot, what sort of telly is it? 

If you can supply these details then I’m sure you’ll get some good advice regarding battery requirements and the best way to keep them up to the job.

[w1ntersun]

The first thing is to mount as many batteries that you can reasonably carry.. As a starter 2 X 115 amps. This should run a tv for approx 20 hrs without recharge. Laptop I am not sure about.

 

Then fit a charging system if that time period is too short either gen or solar or if you can afford it elfoy( not sure of the spelling ) system.

 

I run 2 X 115 amp batteries and 130 watt solar and never run out of power inc running my wifes hair dryer.

 

Richard

[colin]

As above, solar panels are a good way of getting batteries charged, we have been using them for over 10years. A word of warning, I was in Maplins the other day there was a cheap solar set up, it was at least twice as large as our panel for half the output, so don't be afraid of asking about any panel before buying.

Other alternatives are a heavier duty alternator, or stirling battery to battery chargers, but these will of cause rely on you running engine.

[Brian Kirby]

crinklystarfish - 2010-07-02 5:56 PM

You’ll be fine with the standard alternator, but for a really comprehensive answer it would be useful to know if you have a compressor or absorption type fridge and if you have diesel or gas powered heating. Also useful to know would be how much you intend to drive every day, or how many days you plan to stay stationary with no driving. Do you intend to camp in winter? Further, 120w for a TV seems quite a lot, what sort of telly is it? 

If you can supply these details then I’m sure you’ll get some good advice regarding battery requirements and the best way to keep them up to the job.

I would add to that, it would also be useful to know where you are thinking of going, how many you are, and what van you have.

[Laura]

Hi and thanks for the replies.

The tv we plan to buy for the van is the same as my Dads which is a cheap one from Tesco with built in DVD that says the power is 60w.

We assume this is while running at full power with the dvd running.

The laptop takes around 60w to run too hence the 120w requirement.

 

We are going to be living in the van full time in the UK for about 6 months while we are selling our house. For one reason and another we are very unhappy where we live and just wish to sell up and move on. My partner also relaxes a lot more in the motorhome.

I assume we will be moving around the area not stopping in one place for more than two nights at a time.

We run our fridge on gas not electric.

Our cooker is gas too.

We do plan to have a gaslow setup soon too to save on gas costs.

Our leisure battery needs replacing and is the smaller one not the long one.

However my partner has said about getting two I think they are 85amp.

Not sure what charger setup we have.

Someone mentioned their wife using a hairdryer,is this a 12v one or are you using an inverter?

Thank you.

[Laura]

w1ntersun - 2010-07-02 5:56 PM

 

The first thing is to mount as many batteries that you can reasonably carry.. As a starter 2 X 115 amps. This should run a tv for approx 20 hrs without recharge. Laptop I am not sure about.

 

Then fit a charging system if that time period is too short either gen or solar or if you can afford it elfoy( not sure of the spelling ) system.

 

I run 2 X 115 amp batteries and 130 watt solar and never run out of power inc running my wifes hair dryer.

 

Richard what solar panel are you using and how much did it cost please?

And are you using an inverter to run the hairdryer?

Thanks.

Richard

[crinklystarfish]

Hi Laura,

For the use you describe the solution is cheap and easy. You will more than likely be alright with just an upgrade to your leisure batteries. 2 x 100Ah (or slightly bigger if you can fit them in) will serve you without the need to mess about with solar panels (few users actually need solar panels - but have them anyway); or any other source of external supply like wind or EFOY generators etc.

If you change all your light bulbs for readily available LED replacements you will also help your cause massively when it comes to longer winter evenings. Further, if you can manage, a modern flatscreen TV / DVD of just over 10 inch will draw significantly less on your battery reserves. Ours is 10.3 inch and is more than adequate - in fact any bigger and it would be rather vulgar and dominate the lounge.

Our use is similar to yours and I use 2 x 100Ah Elecsol batteries and only ever use the engine to charge them when out travelling. We can manage 2 to 3 nights in deep mid-winter without running the engine at all. In warmer weather with light nights we don't even think about the power reserves. As an aside, a refillable gas system is a good idea in your circumstances. You might also want to think about extra water carrying capacity at some point.

If you need more specific advice on wiring up the batteries or how to keep them in favourable condition etc, I'm sure many will be able to help.

[Edited for spelling - again!]

[Laura]

Thank you Crinkly thats great news.

However we only have space under the front seats in our van to put leisure batteries.

The one we have now is an 85amp size under the driver seat with space for a second under the passenger seat.

Our van is a Luton shaped autoroller of ten years old by the way.

Its a u shaped lounge at the back with a water tank on the passenger side under the seating and the water heater and charger under the otherside, then along the back its an outside storage locker which we would'nt wish to use for expensive items like batteries.

So as you can see we are limited to an 85amp size battery.

We need to get the batteries anyway so we will have to see how that goes then see if we need to add another charging method.

Thanks.

[Clive]

Agree with the previous posts.

BUT

If you feel the need to fit a second alternator I have some spare new Bosch 90 amp alternators and you would be welcome to one if you wish to pick it up.

 

Chive

 

[Brian Kirby]

The size (in AH) of battery you could fit is as likely to be dictated by the space available as anything else.  You need to have a look at the available space under each seat, and measure what is the largest lump of battery, in terms of length, width and height, you could get into either.  When you know that, you can go shopping.  :-)

Go here http://tinyurl.com/33q55f3 and look down the menu on the left side for "Leisure batteries".  Once there, you will find various makes and types listed.  Usefully, you will find that they give weight, length, width, and height for most, as well as capacity in Ah.

As your batteries are to be located under seats, you will need to select carefully.  The greatest capacity for the lowest outlay will (generally) lie with vented flooded lead acid batteries.  However, these have to have a vent tube from the battery direct to outside air, so that the hydrogen that is generated when the battery is being charged cannot accumulate inside the van.  This is essential as hydrogen is highly flammable and, if ignited, can cause a fire, or even the battery casing to explode, spraying everything around with acid.  You do not want to do this!!

If the existing battery is vented, the new one can be of similar type, but you will need to drill the floor under the passenger's seat to vent the second battery.  If the existing battery is not vented, you must either drill for the vent both sides, or install sealed type batteries.

Before embarking on this, you need to check on your mains charger, to see if it is permanently set to charge only "gel" batteries, or flooded batteries, or is switchable between gel and flooded lead acid.  This is because the charging regime is different for the two types, so may dictate what batteries you can use, unless you are prepared also to change the mains charger.  

Remember that vented flooded batteries need to be topped-up from time to time so, if access to top-up the batteries under the seats will be difficult, sealed, maintenance free batteries will be a more convenient choice.  Such batteries are often identified as VRLA, or valve regulated lead acid.  They are generally more expensive than the vented variety.

If your charger is for gel only, and you don't want also to change that, you'll be restricted to gel, or AGM, batteries.  As you will see from the link, these are considerably more costly than either vented flooded, or sealed maintenance free VRLA, Ah for Ah - being about twice the price.

Check that the Ah rating is being quoted at the 20 hour rate, or as C20.  Otherwise, you will be making false comparisons, and may not actually get what you thought you were buying.  Look at weights: leisure batteries need thicker, so heavier, plates and tend to weigh more, Ah for Ah, than other battery types.  Look first at the good ones, on the linked website Exide or Sonnenschien for gel, and probably Varta for flooded, and note now much the biggest battery you could actually fit from each maker weighs.  Keep this weight in mind when looking for cheaper alternatives, and treat with suspicion any battery that claims equal capacity with lighter weight, or greater capacity with equal weight.

There is no magic to batteries: but they are hugely confusing.  Mostly that is because many of the makers exaggerate their performance for marketing advantage.  Others come closer to out and out lying!  If you want to know more, go and buy the July MMM and look at John Wickersham's article on batteries.

There are two contributors to this forum who know more about batteries than most folk know about their breakfast, so when you've had a hunt around the possibilities come back with your ideas and they will probably be able to suggest some alternatives.

Final word of warning: if buying on line, ring the supplier beforehand, to check that what you want is actually in stock and available.  Most seem to keep their stock ranges on their websites, but do not update these to current stock levels.  The clue is often an apparently low price, which is mysteriously not available when you order, and which will be increased when the stock is replenished!  It's a minefield!  :-D

[crinklystarfish]

One of the reasons I use Elecsols is that they are physically smaller and lighter than most other makes of comparable quality and 20Hr Ah rating. This is supposedly made possible by reliance upon carbon fibre as a substrate. I'd be surprised if 2 x 100s didn't fit in the spaces available.

[Brian Kirby]

I don't have the technical armoury to give chapter and verse, but I have looked at some of the Elecsol data, and it is very strangely arranged. 

Brambles is the man, but I think the shorthand version is the Elecsol's are quite good batteries, but with somewhat overstated claims for their benefits, so that they look better value than they really represent.

If the claims are boiled down, they charge top dollar for a good, but not top dollar, product.  Put another way, on a level playing field, they are either overpriced for what they do, of other batteries can do just as well at lower cost.

But if they float your boat (or power your motorhome), that's fine!

[Laura]

I beleive the existing battery is made by Newmax and is sealed.

I am lucky in one sense though as my brother can get them at trade price from where he works.

Excellent information thank you very much everyone.

[Clive]

Banner batteries have recently been reviewed (amongst others) by that Lad Wickersham in MMM and look to be good VFM.

 

C.