High Volts or High Amps?

[Dave Taylor]

If you can try to fit as large an engine pulley as possible as this will enable an alt pulley to be reasonably large to increase belt wrap, a small alt pulley isn't an ideal setup as regards belt slip.

Good point! Thanks

 

If you're going to be that precise on ratios, best to get your facts straighter!

If you're measuring the outside diameters of the pulleys, the proper figure to use is the Pitch Diameter which is rather less. I'd have to look it up to be sure, but there's a fudge factor which from memory is about 10mm less than the OD for each pulley. Using that figure, as an example, your ratio would be 165/70 or 2.4:1.

 

Tim

 

OK, Tim, I asked for that, quoting all those decimal places! 10 mm seems about right, taking into account the rim and the depth of the grooves. I make it 160/65 or 2.46, there or thereabouts!

 

Even re-calculating using Tim's advice your drive ratio seems a tad low.

 

Almost impossible to know what current a particular alternator would put out at various rpm without the manufacturer's spec sheet.

 

FWIW I have a little over 5:1 drive ratio and with clamp on meter measured 156 amps from a Leece Neville 160 amp alternator at just 650 rpm engine speed.

 

 

Looks like there's a PDF on the Iskra website that gives the output over different RPM, though a shunt or DC clamp ammeter would be handy.

 

cheers, Pete.

~smpt~

 

 

I use 57mm twin A belt pulleys on Leece Neville 24v 95A and 110A alternators and have no problem with slippage and engine pulley is 200mm. So just under 8k alt rpm at max engine rpm. Alt limit is 8k rpm, but car/auto derived alts can go to 15k+ rpm.

 

 

My 100A Iskra alternator on a Beta 38 gives max output at about 1200rpm which would indicate that Beta have probably got the pulley ratios correct.

 

Richard

 

All useful stuff - thanks! Last one a bit reassuring, and I'll see if I can find the PDF Pete refers to and check it out.

[Dave Taylor]

Thanks to Pete, I have found the relevant PDFs on the Iskra site.

 

They don't list a 175 amp alternator, but 120, 130, 140, 150, 160, 170 and 200 amp versions.

 

From the pulley ratios calculated earlier, at 1200 rpm engine speed, alternator speed will be 2.46 x 1200, i.e. 2952 rpm . At 1400 rpm, alt speed will be 3444 rpm.

 

The Iskra performance curve for the 170 amp alt shows about 150 amps at 3000 rpm and 155 amps at 3444 rpm. So Beta calling these '150/175 amp alternators' seems about right.

 

From this, I reckon that we shall be OK for amps output, with perhaps some extra if we go for a paralleling option with the 45 amp 'starter battery' alternator.

 

Just leaves the voltage question, as focussed on by Eeyore, looking at the fact that these are tall forklift truck cells and may benefit from some gassing for the stirring effect, plus to ensure full charge to keep sulphation at bay as much as possible.

 

I can't get the alternator voltage above 14.4 volts yet, so reckon it is probably regulated there. Gibbo's modifications look attractive, certainly cheaper than buying an external alternator regulation system. I haven't looked inside the alternator yet to see how easy I might find it to do the mods. Fortunately, I have a spare alternator which I can look at at leisure, without needing to remove it from the engine. Obviously I don't know for sure what voltage that one might be regulated at!

 

Any more suggestions gratefully received.

[Dave Taylor]

I have been doing some more reading and thinking about the need (or not) to take the charge voltage up above 14.4 volts for these tall forklift cells.

 

Seems that perhaps the main reason to exceed 14.4 volts would be to introduce a certain amount of gassing to reduce the 'stratification of electrolyte' - i.e. the bubbles will stir it all up a bit - as Eeyore said:

Fork truck batteries are usualy quite tall, and for that and other reasons have a higher charging voltage. The gassing is in efect used to "stir" the electrolyte and maintain a uniform specific gravity across the surface of the plates. The exact charge voltage for your batteries will of course be in the manufacturers spec, which is very likely to be 14.8 volts or higher. A lower voltage is likely to shorten their remaining life. Gibbo and others will be able to provide a more indepth technical explaination if you need it. My own experience of taller batteries is on preserved 1950s diesel railcars (DMUs) which charge at 31.5 volts on a 24volt system, which is 15.75 volts across each 12 volt bank! (Stones 150 amp dynamo with Liliputt dual carbon pile regulators for those of you into regulator porn )

 

According to the info I have gleaned for these forklift cells, gassing starts at between 14.1 and 14.28 volts, so the actual charging process is complete (or nearly so) when this voltage is reached, plus at least some gassing (enough for my needs?).

 

Some manufacturers offer a cell type with built-in air bubble percolation, which obviously stirs the electrolyte all the time, not just at full charge and gassing voltage. According to the blurb, this is beneficial and assists full charge and prolonged life.

 

Could I achieve the same by rigging up a simple 12 volt aquarium air pump and inserting aeration tubes in each cell, to run whenever the batteries are being charged? Or would it probably be sufficient to use something like that to stir up each cell each time I check and top up electrolyte level? (Once or twice a month is my normal routine)

 

As far as charge voltages are concerned, 16.2 volts are recommended (2.7 volts per cell) for an equalisation charge and apparently this " voltage is reached when the charge current has dropped to approximately 3% of the cell capacity." That is obviously when using a charger designed for forklift cells.

 

This is certainly a 'higher charging voltage' as Eeyore refers to, but may not be needed all the time? Some mains battery chargers offer this sort of voltage, but should I really be trying to push the on board charge voltages this high?

 

Just for comparison, the (late) Sterling A to B charger blurb shows highest charge voltages of about 14.8 volts, and we usually achieved 'float charge' status with that after a few hours cruising.

 

Does the extra voltage (14.8 or more as compared to 14.4 volts) make a substantial difference? I have been told it probably does, but don't want to spend unnecessary cash if it doesn't!

[nb Innisfree]

Mystery edit

Edited September 22, 2012 by nb Innisfree

[blodger]

I have been doing some more reading and thinking about the need (or not) to take the charge voltage up above 14.4 volts for these tall forklift cells.

 

Seems that perhaps the main reason to exceed 14.4 volts would be to introduce a certain amount of gassing to reduce the 'stratification of electrolyte' - i.e. the bubbles will stir it all up a bit - as Eeyore said:

 

 

According to the info I have gleaned for these forklift cells, gassing starts at between 14.1 and 14.28 volts, so the actual charging process is complete (or nearly so) when this voltage is reached, plus at least some gassing (enough for my needs?).

 

Some manufacturers offer a cell type with built-in air bubble percolation, which obviously stirs the electrolyte all the time, not just at full charge and gassing voltage. According to the blurb, this is beneficial and assists full charge and prolonged life.

 

Could I achieve the same by rigging up a simple 12 volt aquarium air pump and inserting aeration tubes in each cell, to run whenever the batteries are being charged? Or would it probably be sufficient to use something like that to stir up each cell each time I check and top up electrolyte level? (Once or twice a month is my normal routine)

 

As far as charge voltages are concerned, 16.2 volts are recommended (2.7 volts per cell) for an equalisation charge and apparently this " voltage is reached when the charge current has dropped to approximately 3% of the cell capacity." That is obviously when using a charger designed for forklift cells.

 

This is certainly a 'higher charging voltage' as Eeyore refers to, but may not be needed all the time? Some mains battery chargers offer this sort of voltage, but should I really be trying to push the on board charge voltages this high?

 

Just for comparison, the (late) Sterling A to B charger blurb shows highest charge voltages of about 14.8 volts, and we usually achieved 'float charge' status with that after a few hours cruising.

 

Does the extra voltage (14.8 or more as compared to 14.4 volts) make a substantial difference? I have been told it probably does, but don't want to spend unnecessary cash if it doesn't!

Many ordinary open lead acid batts end up with a short life due to failure to periodically equalise amd restore some lost capacity. The Heart EMS I used to have, an 1800w inverter/50 amp charger, used to equalise at 16 to 16.5v. I have no experience of forklift cells but presume similar is necessary for a long life. Since the demise of the EMS one way I have found of achieving equalising cheaply is using the old unregulated C40 dynamo driven by an old lawnmower engine. During the summer I can charge at 14.8v by cutting out the regulator on some of the solar panels. I would not mess with your alternator but my A127 70 ampers I can use a Sterling Alt controller or switch in diodes to achieve 14.8v charging. There are many ways of skinning cats

Edited September 22, 2012 by blodger

[smileypete]

Does the extra voltage (14.8 or more as compared to 14.4 volts) make a substantial difference? I have been told it probably does, but don't want to spend unnecessary cash if it doesn't!

An other way to get higher voltage is change the starting alt to 14.8V and parallel with the big alt, this'll give a higher charge voltage at the flick of a switch. Only thing is the start batt might not like 14.8V, so maybe keep an eye on it, change it for a calcium batt, put a big diode in there to drop some charge voltage.

 

I think 14.8V isn't so good with open cells for unattended shoreline charging, or even 'unattended' charging while cruising, but might be OK if you can keep a watchful eye on things.

 

If your alt has a part# on it, maybe try and find the part# from one of the earlier alts, and get a breakdown off the Iskra site to find the # of the 14.4V and 14.8V regulators, then shop around to see if a cheap one for experimenting. Looks like there's tractor regs available with a thermistor connection, one of these might give better charging year round.

 

cheers, Pete.

~smpt~

[Gibbo]

I won't repeat what others have said. I'll just fill in the gaps...

 

I have been doing some more reading and thinking about the need (or not) to take the charge voltage up above 14.4 volts for these tall forklift cells.

 

Seems that perhaps the main reason to exceed 14.4 volts would be to introduce a certain amount of gassing to reduce the 'stratification of electrolyte' - i.e. the bubbles will stir it all up a bit - as Eeyore said:

 

Yes, it also does a mild form of equalisation to help prevent sulfation.

 

According to the info I have gleaned for these forklift cells, gassing starts at between 14.1 and 14.28 volts, so the actual charging process is complete (or nearly so) when this voltage is reached, plus at least some gassing (enough for my needs?).

 

Not quite. When the gassing voltage is reached, they could be flat as a pancake (in the case of a large charger) or completely full (in the case of the small charger). What is important is the charge current when you reach the gassing voltage. If the charge current is still high (which it will be with a large charger) you need to remain at the gassing voltage until the charge current drops to a low level.

 

You're sort of getting way past normal battery useage and if you want to go further in learning I think you're going to have to do some serious reading. The field is a lot more complex than it first appears. I think it was Smileyepete who, at one time, produced a link to an old on line book on lead acid batteries. Though it might have been someone else. I can't really remember.

Edited September 22, 2012 by Gibbo

[Dave Taylor]

Many ordinary open lead acid batts end up with a short life due to failure to periodically equalise amd restore some lost capacity. The Heart EMS I used to have, an 1800w inverter/50 amp charger, used to equalise at 16 to 16.5v. I have no experience of forklift cells but presume similar is necessary for a long life. Since the demise of the EMS one way I have found of achieving equalising cheaply is using the old unregulated C40 dynamo driven by an old lawnmower engine. During the summer I can charge at 14.8v by cutting out the regulator on some of the solar panels. I would not mess with your alternator but my A127 70 ampers I can use a Sterling Alt controller or switch in diodes to achieve 14.8v charging. There are many ways of skinning cats

 

Not having access to an unregulated dynamo at the moment, I will need to follow another route!

 

You suggest the Sterling Alt Controller . . . I thought that this, like most (all?) of these devices, required some changes to the internal wiring of the alternator? They all seem to issue mild warnings about possibly voiding warrantys by opening up an alternator to change regulator wiring. Nothing I have is under warranty at the moment, so I am not worried from that angle, but I would obviously prefer NOT to kill my alternator by doing something silly.

 

You also say "switch in diodes" as if it is an easy thing to do. Again, I thought from Gibbo's suggested mods (which I have quoted before) that any mods using diodes involved changes to regulator wiring. If there is an easy (and preferably not too expensive) way to 'switch in diodes' to raise the charge voltage, then please let me know! Gibbo's site describes the process but also says that he will not get into correspondence about it - understandably!

 

As Gibbo has also commented, I am getting in deep here, but all I really want is to be able to charge my forklift cells as effectively and economically as I can!

 

Since starting this topic, I have heard back from Sterling that my recently deceased A to B charger died from excessive heat at the output terminal of the unit, melting through the board. The jury is out as to whether the cause of that heat was within the unit or in the crimp/terminal connection. (The cable/crimp look OK to my untrained eye.) One of my concerns with this unit IS that all the current from two dynamos (up to 220 amps in my case) is (potentially) passing through this box which is trying to do some clever electronics at the same time. Hence my interest in enhancing voltage and possibly also paralleling alternators, but preferably not all in the same little box!

[Dave Taylor]

An other way to get higher voltage is change the starting alt to 14.8V and parallel with the big alt, this'll give a higher charge voltage at the flick of a switch. Only thing is the start batt might not like 14.8V, so maybe keep an eye on it, change it for a calcium batt, put a big diode in there to drop some charge voltage.

 

I think 14.8V isn't so good with open cells for unattended shoreline charging, or even 'unattended' charging while cruising, but might be OK if you can keep a watchful eye on things.

 

If your alt has a part# on it, maybe try and find the part# from one of the earlier alts, and get a breakdown off the Iskra site to find the # of the 14.4V and 14.8V regulators, then shop around to see if a cheap one for experimenting. Looks like there's tractor regs available with a thermistor connection, one of these might give better charging year round.

 

cheers, Pete.

~smpt~

 

Thanks, Pete. Some possibilities here if I can get the voltage up to 14.8 volts.

 

In terms of the 'unattended' angle, I have been considering the value of getting a SmartGauge, which would help me to monitor voltages as we cruise. As I understand it, if combined with SmartBank, it would also enable me to 'un-parallel' the two systems when the voltage rises above a level which I could choose, so I could use that to protect the started battery, or change to a calcium one, I suppose. However, to give effective higher voltage to my domestic bank, I would need to raise the voltage on the larger alternator, not the smaller one. Probably more expensive, but I can't see another way round it.

 

The Iskra site gives some information, but not that much, no regulator part nos. that I can see! Parts are not easily available, as I understand it. One alternator repairer told me they were totally unobtainable, another repairer did obtain them, but only after waiting many weeks for them to be sent from Slovenia!

 

Perhaps I should approach this repairer and see if he would be prepared to undertake the mods with diodes that Gibbo suggests?

[blodger]

Well I did say that I would not mess with your alt, because of its cost and my not knowing too much about it. Also, the sterling alt controller and possibly diode introduction will not get you much above 14.8v when you need 16 or more. An unregulated dynamo with charged batteries would. Pretty cheap at about 20 quid plus similar for an engine and maybe a tenner for wiring, crocodiles, diode, etc. Just a suggestion as I and others have found it works.

[Dave Taylor]

I won't repeat what others have said. I'll just fill in the gaps...

 

 

 

Yes, it also does a mild form of equalisation to help prevent sulfation. Good, that is all the better!

 

 

 

Not quite. When the gassing voltage is reached, they could be flat as a pancake (in the case of a large charger) or completely full (in the case of the small charger). What is important is the charge current when you reach the gassing voltage. If the charge current is still high (which it will be with a large charger) you need to remain at the gassing voltage until the charge current drops to a low level.

 

Point taken! I had quoted out of context, which was, of course, that the cells were being charged with a purpose-built forklift cell charger, AND that the charge current would have dropped to a low level. Sorry!

 

You're sort of getting way past normal battery useage and if you want to go further in learning I think you're going to have to do some serious reading. The field is a lot more complex than it first appears. I think it was Smileyepete who, at one time, produced a link to an old on line book on lead acid batteries. Though it might have been someone else. I can't really remember.

 

Thanks very much, Gibbo. My response to your comments in bold red above.

 

I realise that I am getting in deep, and it is certainly very interesting, but really all I want to do is get these cells charging as effectively and economically as possible, and avoid damage and sulphation as much as I can. The Sterling A to B unit seems to have done this quite well for the last 2 years, but I have developed some reservations about it, as I have outlined to blodger this evening, especially reinforced by its reported cause of death!

 

I appreciate that you don't want to respond to questions about your alternator mods with diodes, but I hope that, if they seem too much for me to tackle, I may find an alternator repairer who could do them for me.

[Dave Taylor]

Well I did say that I would not mess with your alt, because of its cost and my not knowing too much about it. Also, the sterling alt controller and possibly diode introduction will not get you much above 14.8v when you need 16 or more. An unregulated dynamo with charged batteries would. Pretty cheap at about 20 quid plus similar for an engine and maybe a tenner for wiring, crocodiles, diode, etc. Just a suggestion as I and others have found it works.

 

Right. One to note as a possibility, though probably more practical to use it when we are not actually cruising. Thanks a lot!

[blodger]

The diode mod depends on whether the alternator is amenable in terms of practicality to externally wire in diode(s) to fool it about the voltage it sees/senses from the battery in contrast to its output. On an A127 recognised as the easiest to mod the diodes go between D+ which goes to the charge light and the regulator which is using that voltage to control its output voltage/current. The regulator has a spade on it, so the D+ is internally wired to it. The regulator takes three screws to release, disconnect and make the lead external to the reg. Wire the diodes, I switch them, in line with the disconnected wire and the regulator spade. I have done Boschs; Nobody has gigen me an Iskra to play with

 

Right. One to note as a possibility, though probably more practical to use it when we are not actually cruising. Thanks a lot!

Depends upon the ability to add another drive pulley and mounting. Unlike alternators dynamos do not have to be permanently connected to the batteries when being driven.

Not many boats run around with fork lift batteries and if they do you have to do someat different to look after them and get the advantage they offer fully.

[blodger]

I have gone back over some of the thread to ascertain your ah capacity and whether you have solar and not gleaned either.

 

It just strikes me that you might get what you wnt in terms of charging voltage by sticking 2/300 watts of solar on and running it unregulated for much of the time. Solar from Germany is going for 50p per watt including post just now.

 

I would be interested to know what others think.

Edited September 22, 2012 by blodger

[smileypete]

Thanks, Pete. Some possibilities here if I can get the voltage up to 14.8 volts.

 

In terms of the 'unattended' angle, I have been considering the value of getting a SmartGauge, which would help me to monitor voltages as we cruise.

You could also get a digital panel voltmeter, that gives you a permanent display of voltage all the time. And a panel ammeter with a 500A shunt, then you can find out how many amps the 175A alt is giving, and do a test to see how worthwhile paralleling is.

 

As I understand it, if combined with SmartBank, it would also enable me to 'un-parallel' the two systems when the voltage rises above a level which I could choose, so I could use that to protect the started battery, or change to a calcium one, I suppose. However, to give effective higher voltage to my domestic bank, I would need to raise the voltage on the larger alternator, not the smaller one. Probably more expensive, but I can't see another way round it.

 

All that'll happen is the voltage will charge up to 14.4V on the bigger alt until the current drops say 45A (or whatever the small alt outputs). Then as the smaller alt raises the voltage more the bigger alt will stop outputting current, and the smaller alt keep charging until 14.8V, at which point the current from the smaller alt starts to taper off.

 

The Iskra site gives some information, but not that much, no regulator part nos. that I can see! Parts are not easily available, as I understand it. One alternator repairer told me they were totally unobtainable, another repairer did obtain them, but only after waiting many weeks for them to be sent from Slovenia!

 

Perhaps I should approach this repairer and see if he would be prepared to undertake the mods with diodes that Gibbo suggests?

 

This site sells the 175A Beta alt:

http://www.inetsalesltd.co.uk/shop/article_849/Beta-Marine-alternator-14V-175amp-Iskra-IA1196.html?sessid=vxkMHiX8Ttp4qv7XntPP1HpYnxQ4SosOVSUSTV5btQzEa8AfKX0EYL69KfvEoNJ2&shop_param=cid%3D232%26aid%3D849%26

 

Looking up IA1196 on the Iskra site gives the regulator part no as 16908881. If you PM 'Sir Nibble' on this site he might be able to find a higher voltage equivalent, it looks like a fairly standard Bosch regulator.

 

cheers, Pete.

~smpt~

[blodger]

This site sells the 175A Beta alt:

http://www.inetsales...%26aid%3D849%26

 

Looking up IA1196 on the Iskra site gives the regulator part no as 16908881. If you PM 'Sir Nibble' on this site he might be able to find a higher voltage equivalent, it looks like a fairly standard Bosch regulator.

 

cheers, Pete.

~smpt~

 

So possibly moddable with diodes by leading out an external cicuit loop from where the reg makes its contact with the output to D+, in effect.

[Dave Taylor]

The diode mod depends on whether the alternator is amenable in terms of practicality to externally wire in diode(s) to fool it about the voltage it sees/senses from the battery in contrast to its output. On an A127 recognised as the easiest to mod the diodes go between D+ which goes to the charge light and the regulator which is using that voltage to control its output voltage/current. The regulator has a spade on it, so the D+ is internally wired to it. The regulator takes three screws to release, disconnect and make the lead external to the reg. Wire the diodes, I switch them, in line with the disconnected wire and the regulator spade. I have done Boschs; Nobody has gigen me an Iskra to play with

 

 

Depends upon the ability to add another drive pulley and mounting. Unlike alternators dynamos do not have to be permanently connected to the batteries when being driven.

Not many boats run around with fork lift batteries and if they do you have to do someat different to look after them and get the advantage they offer fully.

 

It's obviously time for me to open up the regulator and see if it is anything like as easy as your A127. If it is moderately easy, I would be happy to tackle it, and making it switchable in some way sounds like a common sense idea.

 

What about the diodes themselves? Will I need to do some experimentation to find the appropriate values? I imagine that different alts will have different parameters and so there is not likely to be a 'one-size-fits-all' solution? Where can I get some starting information on this?

 

I am quite happy to do some more digging on this if it will lead me to a simple solution. In the end, though, I have no aspirations to become an expert - just to get the best out of my batteries. And yes, I have come to realise that true traction batteries such as these forklift cells are more often talked about than actually fitted!

 

Thanks for your contributions to my education on this!

 

This site sells the 175A Beta alt:

http://www.inetsales...%26aid%3D849%26

 

Looking up IA1196 on the Iskra site gives the regulator part no as 16908881. If you PM 'Sir Nibble' on this site he might be able to find a higher voltage equivalent, it looks like a fairly standard Bosch regulator.

 

cheers, Pete.

~smpt~

 

So possibly moddable with diodes by leading out an external cicuit loop from where the reg makes its contact with the output to D+, in effect.

 

Thanks for the link. You have also managed to find more detail on the Iskra site than I did. Where did you find those numbers? On the Iskra UK site or elsewhere?

 

I have gone back over some of the thread to ascertain your ah capacity and whether you have solar and not gleaned either.

 

It just strikes me that you might get what you wnt in terms of charging voltage by sticking 2/300 watts of solar on and running it unregulated for much of the time. Solar from Germany is going for 50p per watt including post just now.

 

I would be interested to know what others think.

 

Ah is about 1300 and yes, we do have solar, but only 60 watts

 

You could also get a digital panel voltmeter, that gives you a permanent display of voltage all the time. And a panel ammeter with a 500A shunt, then you can find out how many amps the 175A alt is giving, and do a test to see how worthwhile paralleling is.

 

 

All that'll happen is the voltage will charge up to 14.4V on the bigger alt until the current drops say 45A (or whatever the small alt outputs). Then as the smaller alt raises the voltage more the bigger alt will stop outputting current, and the smaller alt keep charging until 14.8V, at which point the current from the smaller alt starts to taper off.

 

 

 

This site sells the 175A Beta alt:

http://www.inetsales...%26aid%3D849%26

 

Looking up IA1196 on the Iskra site gives the regulator part no as 16908881. If you PM 'Sir Nibble' on this site he might be able to find a higher voltage equivalent, it looks like a fairly standard Bosch regulator.

 

cheers, Pete.

~smpt~

 

Thanks, Pete!

 

Sorry, I got muddled, and thought that it was blodger who gave me that link - he just quoted you and added a comment! Where did you get those numbers you have quoted? on the Iskra UK site or elsewhere?

 

Can't get the link to work yet!

 

You could also get a digital panel voltmeter, that gives you a permanent display of voltage all the time. And a panel ammeter with a 500A shunt, then you can find out how many amps the 175A alt is giving, and do a test to see how worthwhile paralleling is.

 

 

All that'll happen is the voltage will charge up to 14.4V on the bigger alt until the current drops say 45A (or whatever the small alt outputs). Then as the smaller alt raises the voltage more the bigger alt will stop outputting current, and the smaller alt keep charging until 14.8V, at which point the current from the smaller alt starts to taper off.

 

 

 

This site sells the 175A Beta alt:

http://www.inetsales...%26aid%3D849%26

 

Looking up IA1196 on the Iskra site gives the regulator part no as 16908881. If you PM 'Sir Nibble' on this site he might be able to find a higher voltage equivalent, it looks like a fairly standard Bosch regulator.

 

cheers, Pete.

~smpt~

 

Right, link now works, but I think that is a slightly different alternator - case looks a different shape. I'll need to check!

[blodger]

Just a quick reply as am just off to 'work'.

 

Diodes are cheap costing coppers; I use 10 amp ones off Ebay about 10 for a tenner.

 

IIRC Gibbo/SGsite say 3amp would suffice and I do fit one facing the reverse way so that there is continuity each way. Roughly speaking each diode can elevate final charging by 0.6 volts. On the boat with the A127s I just have the ability to switch one in.

 

Lawnmower generator with an alternator I have it with three switchable in independently for equalisation charging.

[Gibbo]

IIRC Gibbo/SGsite say 3amp would suffice...

 

No, I recommend a 10 amp diode.

[smileypete]

Thanks for the link. You have also managed to find more detail on the Iskra site than I did. Where did you find those numbers? On the Iskra UK site or elsewhere?

I got them from this link, putting the part # in the top right box. Looks like that alt is used on a Renault tractor, superceded another alt, and is based on the AAN series alt.:

 

http://www.iskra-ae.com/alba_cat/php/kframe.php?lang=E

 

Edit: One way to get a diode is use a bridge rectifier with blade terminals, cheap enough and easy to connect.

 

cheers, Pete.

~smpt~

Edited September 24, 2012 by smileypete

[Dave Taylor]

Just a quick reply as am just off to 'work'.

 

Diodes are cheap costing coppers; I use 10 amp ones off Ebay about 10 for a tenner.

 

IIRC Gibbo/SGsite say 3amp would suffice and I do fit one facing the reverse way so that there is continuity each way. Roughly speaking each diode can elevate final charging by 0.6 volts. On the boat with the A127s I just have the ability to switch one in.

 

Lawnmower generator with an alternator I have it with three switchable in independently for equalisation charging.

 

I have looked on Maplin for them before, and couldn't find any 10 amp ones, which is what Gibbo recommends. Just done an eBay search and come up with this. Are these OK, or do I need something different? I was looking for something with a heatsink, as Gibbo mentions. Pretty sure I don't need Schottky or Zener diodes. (Gibbo mentions Schottky ones and says that they give roughly half the change in voltage).

 

From earlier posts about the charge voltage requirements of these forklift cells, seems that 0.6 volts on top of my existing 14.4 could be just what I need, with the facility to switch out the diode as needed, either manually or automatically if I get a SmartGauge.

 

No, I recommend a 10 amp diode.

 

Thanks. Don't worry, I knew you had said 10 amp, but thanks for the speedy correction!

 

I got them from this link, putting the part # in the top right box. Looks like that alt is used on a Renault tractor, superceded another alt, and is based on the AAN series alt.:

 

http://www.iskra-ae....rame.php?lang=E

 

Edit: One way to get a diode is use a bridge rectifier with blade terminals, cheap enough and easy to connect.

 

cheers, Pete.

~smpt~

 

Thanks for all your help with this. Yes, blade terminals would make connection that bit easier.

 

Edit: I shall now need to do a thorough check of all our on-board '12 volt' equipment, to make sure that it will take 15 volts. 14.8 is no problem, I think, but 15 might be pushing it, perhaps . . .

Edited September 24, 2012 by Dave Taylor

[blodger]

I have looked on Maplin for them before, and couldn't find any 10 amp ones, which is what Gibbo recommends. Just done an eBay search and come up with this. Are these OK, or do I need something different? I was looking for something with a heatsink, as Gibbo mentions. Pretty sure I don't need Schottky or Zener diodes. (Gibbo mentions Schottky ones and says that they give roughly half the change in voltage).

 

From earlier posts about the charge voltage requirements of these forklift cells, seems that 0.6 volts on top of my existing 14.4 could be just what I need, with the facility to switch out the diode as needed, either manually or automatically if I get a SmartGauge.

 

 

 

Thanks. Don't worry, I knew you had said 10 amp, but thanks for the speedy correction!

 

 

 

Thanks for all your help with this. Yes, blade terminals would make connection that bit easier.

Yes those you have linked to will do the job and are akin to those I have used. They do not carry much current, upto 3 amps, but Gibbo could advise better, so I have had none fail from overheating. Yes, the stud-like diodes give only a 0.3v drop/lift but easier to mount on a heatsink. I have found (25A) diodes out of old alternator similar.

[Gibbo]

I have looked on Maplin for them before, and couldn't find any 10 amp ones,

 

Maplin aren't too good for components.

 

Just done an eBay search and come up with this. Are these OK, or do I need something different?

 

They'll handle the rotor current (they won't handle 10 amps, despite their spec) but the problem is they'll get warm which will reduce their voltage drop. As they warm up, your charge voltage will drop. Which may or may not be what you want. You might find it drops so much that you have to put two in series.

 

Better going to a proper supplier...

 

http://uk.farnell.com/jsp/search/browse.jsp?N=2031+203047+110162958+110130975+110162966+110330462+110163055+110163092+110175925+110195763+110182633+110152475+110181727+110130908+110177130+110130899+110162957+110131283+110131034+110130900+110312188+110173061+110141648+110360500+110185247+110190313+110152424+110302068+110141645+110187502+110141741+110196678+110130947+110172954+110163027+110152432+110120476+110197272+110130898+110141643+110130964+110187907+110163034+110141679+110251367+110174383+110141685+110197468+110152498+110163017+110130942+110141731&Ntk=gensearch&Ntt=diode&Ntx=mode+matchallpartial&No=0&getResults=true&appliedparametrics=true&locale=en_UK&divisionLocale=en_UK&catalogId=&skipManufacturer=false&skipParametricAttributeId=&prevNValues=2031+203047+110162958+110130975+110162966+110330462+110163055+110163092+110175925+110195763+110182633+110152475+110181727+110130908+110177130+110130899+110162957+110131283+110131034+110130900+110312188+110173061+110141648+110360500+110185247+110190313+110152424+110302068+110141645+110187502+110141741+110196678+110130947+110172954+110163027+110152432+110120476+110197272+110130898+110141643+110130964+110187907+110163034+110141679+110251367+110174383+110141685+110197468&mm=1002046|110162958|,1002439||,&filtersHidden=false&appliedHidden=false&autoApply=false&originalQueryURL=%2Fjsp%2Fsearch%2Fbrowse.jsp%3FN%3D2031%2B203047%26Ntk%3Dgensearch%26Ntt%3Ddiode%26Ntx%3Dmode%2Bmatchallpartial%26No%3D0%26getResults%3Dtrue%26appliedparametrics%3Dtrue%26locale%3Den_UK%26divisionLocale%3Den_UK%26catalogId%3D%26skipManufacturer%3Dfalse%26skipParametricAttributeId%3D%26prevNValues%3D2031%2B203047

[Dave Taylor]

Maplin aren't too good for components.

 

 

 

They'll handle the rotor current (they won't handle 10 amps, despite their spec) but the problem is they'll get warm which will reduce their voltage drop. As they warm up, your charge voltage will drop. Which may or may not be what you want. You might find it drops so much that you have to put two in series.

 

Better going to a proper supplier...

 

http://uk.farnell.co...3D2031%2B203047

 

Thanks for even putting in the selections for me, that saved me from the enormous wealth of information there! These all look nice and chunky with a heatsink, so presumably no problem with overheating. Guess the common cathode type won't be any good, as I will need one connected each way.

 

I would reckon to have the 2 diodes outside the alternator regulator and receiving some ventilation, most likely on a board with a relay to switch them out as needed. Will the heatsinks be electrically isolated? If not, then guess I will need to isolate the whole thing from chassis earth.

 

Reckon there is now a good chance that I shall be able to do this mod myself! I was beginning to wonder whether I would need to settle for buying a alternator management system.

[Gibbo]

The exposed metal tabs are never (well, extremely rarely) insulated. Look up TO220 mounting kit or insulation kit.

 

Alternatively pick one of the entirely plastic diodes.