Self Exiting ALTERNATOR

[nickfryer]

Hi all I need to replace my alternator & was looking for one with a larger output, as you do,

 

I have been offered a One wire self exiting alternator, rated at 150A with V belt 60mm pulley.

 

 

 

Any thoughts by you tecs out there as to pro's and conS.

 

Evidently no warning light & the engine needs to be revved slightly to start the charging.

 

Cost is a fair bit cheaper than a standard unit.??

 

 

 

Cheers

[nickfryer]

Oops typo crept in above.

 

Should read. self exciting alternator.

[Chalky]

I don't think a v belt can handle the sort of power you're going to be putting through it - well not for long. Automotive practice is to use a poly v belt - they're flat and about 1" wide.

Many modern high powered alternators are controlled via CAN (1 or 2 wire) or LIN (1 wire) and some are water cooled. You really don't want one of these.

 

If you've got details of the alternator (electric machine) that would help get you a more detailed reply.

[Ark Right]

Hi all I need to replace my alternator & was looking for one with a larger output, as you do,

 

I have been offered a One wire self exiting alternator, rated at 150A with V belt 60mm pulley.

 

 

 

Any thoughts by you tecs out there as to pro's and conS.

 

Evidently no warning light & the engine needs to be revved slightly to start the charging.

 

Cost is a fair bit cheaper than a standard unit.??

 

 

 

Cheers

 

Hi Nick , I think some more info will be required, i.e. Engine make and size ? Does the existing alternator run a tacho ?

 

My initial thought is a 150 amp alternator seems a bit on the large size for a single v belt pulley ( if indeed that is my correct interpretation of your post). A poly vee belt and pulley system would be more suitable, the downside of course is you are into changing pulleys on the engine, which may negate any cost saving .

 

I will stand to be corrected in due course no doubt.

 

Cheers

A

[Nickhlx]

I don't think a v belt can handle the sort of power you're going to be putting through it - well not for long. Automotive practice is to use a poly v belt - they're flat and about 1" wide.

Many modern high powered alternators are controlled via CAN (1 or 2 wire) or LIN (1 wire) and some are water cooled. You really don't want one of these.

 

If you've got details of the alternator (electric machine) that would help get you a more detailed reply.

 

On our Beta 43 we have the Iskra 175 Amp device, which replaced the 150 Amp on previous models - to date this has been fine... Not sure how they would cost to replace though...

 

Nick

[ditchcrawler]

On our Beta 43 we have the Iskra 175 Amp device, which replaced the 150 Amp on previous models - to date this has been fine... Not sure how they would cost to replace though...

 

Nick

Well here is a 150A http://compare.ebay.co.uk/like/220917374903?clk_rvr_id=304849314155

[nickfryer]

Hi Nick , I think some more info will be required, i.e. Engine make and size ? Does the existing alternator run a tacho ?

 

My initial thought is a 150 amp alternator seems a bit on the large size for a single v belt pulley ( if indeed that is my correct interpretation of your post). A poly vee belt and pulley system would be more suitable, the downside of course is you are into changing pulleys on the engine, which may negate any cost saving .

 

I will stand to be corrected in due course no doubt.

 

Cheers

A

Engine is a. Bukh DV24. I do not want to change the pulley on the engine.

 

There is no Tachometer fitted

 

Was wondering if the V belt would take it, and if there any other problems in fitting this TYPE of alternator.

 

I believe they are an American unit, supplied to a uk marine alternator supplier.

 

Thanks

[pandajulienne]

On our Beta 43 we have the Iskra 175 Amp device, which replaced the 150 Amp on previous models - to date this has been fine... Not sure how they would cost to replace though...

 

Nick

Nick

We have just replaced ours and it was £281-43p Plus Vat, These are made under licence for Beta and Vetus by Iskra so you can only get from Beta or an agent. But if you buy a 150 amp one you can get them from Iskra on line shop for around £181.00 plus vat

Regards

Paul

Edited January 6, 2012 by pandajulienne

[nickfryer]

Well here is a 150A http://compare.ebay.co.uk/like/220917374903?clk_rvr_id=304849314155

 

Yes looked at that and others but that particular one would not fit mine.

 

The type recommended to me by this supplier is well over £100.00 cheaper than that one.

 

I do not want the cheapest just one that does the job.

 

I had never heard of a. Self Exciting Alternator before?

[Timleech]

Yes looked at that and others but that particular one would not fit mine.

 

The type recommended to me by this supplier is well over £100.00 cheaper than that one.

 

I do not want the cheapest just one that does the job.

 

I had never heard of a. Self Exciting Alternator before?

 

Quite likely it's not actually self-exciting, but needs a battery connected before it will do anything. I know this can be a source of annoyance with some 2-wire alternators (yours will be effectively a 2-wire unit, the frame and mounting form the second 'wire') when used with split charge relays.

 

Tim

[Nickhlx]

Nick

We have just replaced ours and it was £281-43p Plus Vat, These are made under licence for Beta and Vetus by Iskra so you can only get from Beta or an agent. But if you buy a 150 amp one you can get them from Iskra on line shop for around £181.00 plus vat

Regards

Paul

 

Thanks for that Paul...

 

Whilst the 175 amp unit is fine and has been no problem, I think if ours went I would replace with the 150 amp if it saves around £100 - it seems to spend very little time above about even 100 amps and when we go cruising, its generally for several hours a day so I don't think we'll be missing much - probably a bit kinder on the battery bank too - I have seen it peaking at over 200 amps, although only for a very short time and the bank is (was) only 480 aH Trojans when new - they spend much of their time between 80 and 100% SoC and are frequently on a shoreline for topping up...

 

Thanks again,

 

Nick

[nickfryer]

Quite likely it's not actually self-exciting, but needs a battery connected before it will do anything. I know this can be a source of annoyance with some 2-wire alternators (yours will be effectively a 2-wire unit, the frame and mounting form the second 'wire') when used with split charge relays.

 

Tim

I understand it IS self actuating and just has one large connection straight to the battery bank, nothing else.

 

Thanks. Nickfryer

[Tony Brooks]

I understand it IS self actuating and just has one large connection straight to the battery bank, nothing else.

 

Thanks. Nickfryer

 

 

Er - No. Even if it does have only one wire connected to it you will still have the effect of another wire via the metal frame, engine etc. All electrical equipment needs a "go to" and "come from" connection to work.

 

A quick calculation indicates it will try to take about 5hp off the engine when running at full output and I would never try to drive more than a 90 amp alternator off a single V belt.

 

I think the DV24 has a large exposed flywheel at the front so there is every chance that a polyV belt around a matching pulley on the alternator but just wrapped around the flywheel circumference would work. However what sort of electrical loads do you have? A 60 amp alternator on my DV36 seems to keep the 3 x 110Ah domestic bank well enough charged on my DV36. I fear a larger alternator will not shorten the charging time as much as you may think it will. My advice is to stick with something common and readily available because it will fail eventually.

[onionbargee]

I'm doubting you need 150 amps, at C5 charge rate that's 750 AH of battery !

 

2100 watts, 2.8 hp just in theory, 7-8 hp according to manufactures data !

 

you will definatly need mega strong mountings, and a multi vee belt.

[nickfryer]

Er - No. Even if it does have only one wire connected to it you will still have the effect of another wire via the metal frame, engine etc. All electrical equipment needs a "go to" and "come from" connection to work.

 

A quick calculation indicates it will try to take about 5hp off the engine when running at full output and I would never try to drive more than a 90 amp alternator off a single V belt.

 

I think the DV24 has a large exposed flywheel at the front so there is every chance that a polyV belt around a matching pulley on the alternator but just wrapped around the flywheel circumference would work. However what sort of electrical loads do you have? A 60 amp alternator on my DV36 seems to keep the 3 x 110Ah domestic bank well enough charged on my DV36. I fear a larger alternator will not shorten the charging time as much as you may think it will. My advice is to stick with something common and readily available because it will fail eventually.

Thanks for the info Tony, yes of course it needs a return for the circuit to work, I understand that, the return is via the bolted connection of the alternator to the engine.

 

Think I will abandon the self exciting alternator, not enough info available. It was only an option given to me by my supplier.

 

I can get an 80A alternator and will stick with that.

 

We have no mains charging at our mooring & it is a weekend/holiday boat only & my thoughts were, largest Alternator, quicker charging.

 

Thanks for all the replies.

 

Nickfryer

[pistnbroke]

The internal electronics senses the rotation of the alternator and brings it on line ....been around for a while quite common, Check the voltage regulator setting before you buy

 

Depends what size the V belt is ...may not be a pissy car size

Edited January 7, 2012 by pistnbroke

[Tony Brooks]

Thanks for the info Tony, yes of course it needs a return for the circuit to work, I understand that, the return is via the bolted connection of the alternator to the engine.

 

Think I will abandon the self exciting alternator, not enough info available. It was only an option given to me by my supplier.

 

I can get an 80A alternator and will stick with that.

 

We have no mains charging at our mooring & it is a weekend/holiday boat only & my thoughts were, largest Alternator, quicker charging.

 

Thanks for all the replies.

 

Nickfryer

 

 

Unless the new alternator has a higher regulated voltage than the old one the only part of the charging that will be faster is the first part where it is the alternator that is controlling the current flow. This is the part we usually refer to as "bulk" and in most boats it will be over in less than 30 minutes. Once the regulator starts to work the batteries will in effect be controlling the charge so, given the same regulated voltage, this will not improve.

 

From the above you can gather that it would make sense to try to get an alternator with a regulated volatge of around 14.4 to 14.5 rather than 14.2 volts but do not overdo it unless you want to and are able to top the batteries up frequently.

 

Where a large alternator will help is if you have large inverter and a large load on it when the engine is running. A 150 amp alternator would supply roughly a 1.5kW load with nothing being drawn from the batteries where as an 80 amp one will cover less than 1kW of mains load.

[Nickhlx]

Unless the new alternator has a higher regulated voltage than the old one the only part of the charging that will be faster is the first part where it is the alternator that is controlling the current flow. This is the part we usually refer to as "bulk" and in most boats it will be over in less than 30 minutes. Once the regulator starts to work the batteries will in effect be controlling the charge so, given the same regulated voltage, this will not improve.

 

From the above you can gather that it would make sense to try to get an alternator with a regulated volatge of around 14.4 to 14.5 rather than 14.2 volts but do not overdo it unless you want to and are able to top the batteries up frequently.

 

Where a large alternator will help is if you have large inverter and a large load on it when the engine is running. A 150 amp alternator would supply roughly a 1.5kW load with nothing being drawn from the batteries where as an 80 amp one will cover less than 1kW of mains load.

 

Yes - last part of your post Tony reminds me why I should replace the Iskra 175 with the same unit as we have a washer/dryer on board ( as well as a microwave ) and night storage central heating ( I jest) ) and it does cope with most of the stuff on with minimal drain off the battery bank... I tend to run the engine quite fast to ensure that the alternator is spinning fast for cooling effect, although it will produce high amps ( 150+) at little more than tickover - you can hear the Poly Vee belt straining !

 

Recently I changed the belt and at the same time put on one of the (upgrade) over-run pulleys.. all seems fine but one thing I noticed was that the diameter of it was a bit smaller, so the alternator is even more geared up from the engine now - I'll try to measure the rpm ratio of both the crank and alternator next time I am up there and report what it now is...

 

Nick

[Chalky]

 

We have no mains charging at our mooring & it is a weekend/holiday boat only & my thoughts were, largest Alternator, quicker charging.

 

 

In that case get a solar panel to charge the domestics. Batteries will self discharge over a period of time so a small panel will stop this from happening. What it'll mean is that when you return to the boat the batteries will be in the SOC you left them in or better. If you can start off with a fully charged battery bank you might not need to do the big bulk charge.

[Arthur Brown]

There is a LOT to be said for having a big generator for the bulk charge that life aboard needs recharging to about 90% quite quickly. BUT having that generator doing the next charge phase to 100% will be noisy and expensive so having a suitabley sized and regulated solar system has to be a good idea. It also keeps the batteries charged over the winter against their self discharge. If there is power to spare then you may also have some electric hot water if you are careful!