Leece Neville alternator and Trojan T105 batteries

[swift1894]

Looking at the drawing it appears they they bring out the phase (AC) connections on the back of the unit:

http://www.prestolite.com/productinfo/alternators/8LHA2159V/8LHA2159V_dim_r.jpg

 

If so you could probably just connect a 3 phase bridge rectifier to the phase connections, then take the + output to starter batt positive, and get split battery charging without needing relays or VSRs etc.

 

A 100A 3 phase rectifier can be had quite cheaply from asia via Ebay:

http://www.ebay.co.uk/sch/?_nkw=3 phase rectifier

 

Maybe a relay would be easier though.

 

I guess the Trojans will like a higher voltage in winter and a slightly lower one in summer, so some sort of switchable diode arrangement might come in handy, 'schottky' diodes have a smaller drop for a lower voltage boost.

 

cheers, Pete.

~smpt~

That's a useful diagram, thanks.

Think I'll stick with the Sterling route.....all this talk of 3 phase bridge rectifiers is way beyond my comprehension

I've already got the relay

DURITE 0-727-33 12V 140A SPLIT CHARGE INTELLIGENT RELAY

[smileypete]

That's a useful diagram, thanks.

Think I'll stick with the Sterling route.....all this talk of 3 phase bridge rectifiers is way beyond my comprehension

I've already got the relay

DURITE 0-727-33 12V 140A SPLIT CHARGE INTELLIGENT RELAY

 

Sounds good, best ignore my technical dribblings then.

 

With the relay, helps to ensure the cables to the relay terminals are well supported.

[swift1894]

 

With the relay, helps to ensure the cables to the relay terminals are well supported.

Noted. Ta! Edited March 22, 2016 by swift1894

[swift1894]

Btw

What's the difference between my alternator giving 150 amps at 14 volts and my battery charger giving 80 amps at 14.6 volts?

[BMC problems]

932W

[swift1894]

932W

Yes but how does it affect the charging as far as the batteries are concerned?

[by'eck]

Btw

What's the difference between my alternator giving 150 amps at 14 volts and my battery charger giving 80 amps at 14.6 volts?

 

Simple answer - the batteries state of charge. When the alternator was supplying 150 amps (max 160 I believe), the batteries had previously been discharged enough to allow the alternator to work near flat-out recharging them since it probably was not being regulated yet. Later in the charge cycle the alternator would be putting considerably less current in and charge voltage would have risen a little to the regulated limit even if it was only a fraction over 14 volts.

 

Comparing the charger figures, since the charge voltage is already 14.6v, this suggests the batteries are at a later stage of the charge process although still accepting a good charge current. Not sure what the max charge current is though.

 

To sum up, not a fair comparison, although ultimately the charger would better fully charge the batteries given the higher charge voltage available. This is of course why you are fitting the external alt. reg.

[nicknorman]

The currents you quote are the maximum possible output from the device. However the battery will only take the current it wants, and this depends amongst other things on the voltage. So there is no point in having huge current capability if the voltage is too low.

 

Trojans like a high finishing voltage of at least 14.8v to ward of sulphation and stratification, so charging with the alternator will get the early stages of charging from a low SoC done well, but it will start to falter at the latter stages of charge. There just won't be enough voltage to finish the charging properly, regardless of the current capability.

[swift1894]

Simple answer - the batteries state of charge. When the alternator was supplying 150 amps (max 160 I believe), the batteries had previously been discharged enough to allow the alternator to work near flat-out recharging them since it probably was not being regulated yet. Later in the charge cycle the alternator would be putting considerably less current in and charge voltage would have risen a little to the regulated limit even if it was only a fraction over 14 volts.

 

Comparing the charger figures, since the charge voltage is already 14.6v, this suggests the batteries are at a later stage of the charge process although still accepting a good charge current. Not sure what the max charge current is though.

 

To sum up, not a fair comparison, although ultimately the charger would better fully charge the batteries given the higher charge voltage available. This is of course why you are fitting the external alt. reg.

Thanks the Sterling is on my shopping list.

The currents you quote are the maximum possible output from the device. However the battery will only take the current it wants, and this depends amongst other things on the voltage. So there is no point in having huge current capability if the voltage is too low.

Trojans like a high finishing voltage of at least 14.8v to ward of sulphation and stratification, so charging with the alternator will get the early stages of charging from a low SoC done well, but it will start to falter at the latter stages of charge. There just won't be enough voltage to finish the charging properly, regardless of the current capability.

Thanks for the extra info. I'll never understand the black art of battery charging so I'll just get the Sterling and let it do the hard work.

[swift1894]

Btw what's the ideal location for the Sterling twixt alternator and batteries, assuming cables are only nominal lengths.

[mattlad]

 

One failed after direct lightning strike to masthead - in fairness though it took £12,000 of other electronics with it

 

 

Blimey! Hope you were insured.⚡️⚡️

Doesn't a lightning strike count as an Act of God?

[by'eck]

 

 

Doesn't a lightning strike count as an Act of God?

 

More like an act of nature surely - suffice to say my insurance company paid up

[swift1894]

More like an act of nature surely - suffice to say my insurance company paid up

Did you jump when the Lightning struck?????

Edited March 30, 2016 by swift1894

[by'eck]

Did you jump when the Lightning struck????

 

Not on this occasion (yes lightning can strike twice ) although my partner did

 

Btw what's the ideal location for the Sterling twixt alternator and batteries, assuming cables are only nominal lengths.

 

Well you only need one cable (the red sense one) connected to the battery positive, most of the others connect to the alternator so it makes sense to locate the Sterling reg. close to latter. Its likely some of the reg's cables will need extending though. I use bullet connectors on all connections so the reg. can easily be removed.

Edited March 30, 2016 by by'eck

[swift1894]

Not on this occasion (yes lightning can strike twice ) although my partner did

 

 

 

 

 

 

Well you only need one cable (the red sense one) connected to the battery positive, most of the others connect to the alternator so it makes sense to locate the Sterling reg. close to latter. Its likely some of the reg's cables will need extending though. I use bullet connectors on all connections so the reg. can easily be removed.

 

I'll look for a suitable place now that I know that. Good idea re the bullet connectors.

[swift1894]

Confusing info on the Sterling site

 

"This product is recommended for alternators lower than 150A rating, for larger refer to the Pro reg D (PDAR)Unit actual rating (the actual device rating): Positive field control 8A maximum field current, Negative field control 13A maximum field."

 

But then.........

 

"Real world rating (rule of thumb): 12V alternator with standard regulator fitted, up to approx 350A alternator, more if negative field control. 12V alternator with no standard regulator, stand alone, about 150A more if a negative field"

 

Leece Neville inform me that my alternator is 160A negative "GROUND" ( I presume that's the same as "field", which is what I asked).

 

So my alt is more than 150A but way below 350A.

Do I need to get the Pro reg D (PDAR)?