Increasing voltage output from alternator on 1GM10

boggybrn

boggybrn

Well-Known Member
Joined
5 Nov 2005
Messages
128
Location
Hampshire
www.messingaboutinboats.co.uk
I'm finding that running a tiller pilot & laptop when sailing, my occasional engine use is not enough to charge my domestic battery.

When I checked on Monday the battery was at 12.2v - so I decided to run the engine for a bit to charge it. After about 20 minutes I thought that I would measure the current going into the battery, and found that it was less than 0.7A. At that rate charging will take for ever!

One problem I have is that the batteries (engine & domestic) are fed through a splitter diode. By shorting out the diode for the domestic battery the charge current jumped to 1.7A and the voltage on the battery terminal was around 14.1V. This is a major improvement, but still not great.

Shorting the diode doesn't seem like a long term solution as this leaves the possibility of the engine battery taking charge from the domestic battery. The obvious way to sort this is to replace the splitter diodes with a voltage sensitive relay.

However being a closet Yorkshireman I wonder if a 50p diode in the sensing wire to the alternator regulator would provide suitable compensation.

and so to my question...

There is no external connection from alternator (a Hitachi LR35) to the regulator sensing wire. Before I start pulling the alternator apart has anyone done this before? Is it possible to get at the regulator sensing wire?

As a supplementary question - any thoughts on boosting the output further by using two diodes in series, with a switch to short one out when the batttery is chaged?
 
If you are only charging at 0.7A and the batteries are flat they are probably knackered.

If you replace with a VSR, you may find that an alternator controller/diode fix is unnessary.

I'd a) get the batteries tested and replace if necessary b) swap the diode for a VSR.

The Hitachi is probably the most difficult alternator to access the field terminal. It involves splitting the alternator. However, on the regulator the Field terminal is marked F so you would solder to it.

Hope this helps

james
 
If you look at the graph in the Yanmar manual, the Hitachi Alt has a pretty max low current output at low revs. You could consider replacing it with a more modern alternator.
You can compensate for the drop of the splitter diode by effectively putting an extra diode in the path between the rectifier and the regulator in the alternator. I think the Sterling or similar website has details on this for many different alternators. I have done this on a Bosch alternator.
I removed my Hitachi and fitted a Bosch from a Ford Mondeo, cost £25 from a breakers yard. Had to saw a few mm off the mounting lug on the engine to align the belt.
Measure the volts as well as the current, at the same time, it will tell you if the battery is knackered and not drawing a charge or if the Alt. is not providing the charge.

I have done the 'extra diode to boost' trick. It did not work quite as expected, I found it necessary to put a resistor to ground to pull a little more current through the diode. I think I used a 100ohm 5W, but it could have been lower like 33ohm perhaps. I think this may be necessary due to the filtering present in the regulator, which is switching not linear I believe.
The diodes need to be fairly high current, i used a bridge rectifier as it had an isolated heatsink/case which helps.
A sterling or similar is the way to go, but there are more fun ways of spending money.
Careless use of the boost circuit can give the drive belt a very hard time! On a 1gm (mine was 3gm) it might even make the engine hard to start! Best switch it in after a few minutes running.
Cheers.
 
If you have a diode splitter - you must battery sense the charge - so that alternator ups it's voltage to compensate for the ~ 0.7V drop across the splitter. If you don't battery sense and leave the alternator machine sensed as most are - then voltage is not high enough to PUSH charge into batterys resulting in low ampage .. low charge level batterys. I know - because I had this situation some years back.

There are ways to overcome this - a) get rid of the Diode Splitter and fit a VSR system that has no losses on split, b) do away with splitters altogether and manually switch charge via old fashioned battery switch, c) fit a diode in the alternator regulator itself to 'fool the sense' into upping voltage.
 
Beware those offering....

...."advice" which is thinly cloaked sales pitch on these forums. a diode charge splitter will take around one volt from you. you cannot expect much of a result from 20 mins of engine running with a standard alternator regulator. it is an automobile device intended to replace what is being taken by the car's lights, heater blower, wipers etc. plus an additional 5% to replace "natural losses" it is NOT intended to re-plenish a service battery on a yacht after a night at anchor with the lights and the fridge running. i cannot understand why boat builders don't make their clients aware of this FUNDAMENTAL FACT. what you need is either to run your engine for many hours a day OR, and this is the reality, install a device which turns your alternator into a "Battery Re-charging" Device - more commonly known as a generator! all that a vsr (voltage sensitive relay - it prevents the house battery from receiving any charge until the starter battery reaches 13.7 volts) will give you, as opposed to your diodes is the loss of the one volt loss, if you see what i mean! for your seemingly intent to actually "SAIL" quite a bit and NOT be a motor-boater i would suggest that you need something which decides on how to charge your battery by reference to the battery's actual charge state (commonly known as -"battery sensing") this requires either a crude rheostat governing what voltage goes to the alternator field - works but oh so much the path to disaster since you have other things on your mind when in command of a yacht that you WILL forget to turn it down at the crucial moment! no a proper, well researched "advanced" controller is the ONLY way to go. this takes you to the age-old arguement between the "Advercsists" and the "Sterlinglists. The Adverc simply works on battery sensing (as opposed to the standard set up of "machine sensing") which is a step in the right direction. The Sterling, offers a sophisticated "critical path" solution which endeavours to ensure that the MAXIMUM charge safely attainable from your existing alternator over several (3 or 4 depending on choice of product) stages in the charging sequence. you "pays your money and takes your choice" here in the med. we only have one choice in re-plenishing over 500Ah of batteries.
Chas, once more on Kentrina's access to the forum
 
Fitted a Sterling regulator to our 3HM with a Hitachi 35amp alternator last week. Splitting the alternator apart wasn't too bad - I just undid the bolts, turned them round and used them gently against the lugs with spacers to prise the two halves of the alternator apart. The task is to pull the back bearing (on the shaft) out of its holder on the backplate - it's just a push fit.

Once inside, I tested resistances using advice from the Adverc site to find the sensing brush (it turned out to be the rear one as suggested on that site for Htiachi alternators) and soldered a wire on. Took the wire out through the backplate and put the two halves back together, using the bolts again to push the back bearing into place again smoothly.

After that adventure it was simple to wire the Stirling up as instructed. I was getting 14.7v on the house battery through the diodes afterwards (it was a dismal 13.something before). Early days, but I'm expecting that our charging will improve radically now. THe 3HM was working harder and the alternator is much warmer, but I can hold my hand on it still after 30mins so nothing to worry about it seems.

Hope that helps? PM me if you wish.
 
Thanks for the help so far...

I've just had a look at the Stirling web site. It looks like the DAR12 regulator is the thing to go for. This isn't much more expensive than a VSR (£110 vs £70), and even with the splitter diodes this should be able to charge the batteries at a good rate.

It looks like you solder wires onto the two brushes taking current to the field coil. Presumably the Stirling just sits in parallel with the regulator and allows additional current to flow.

My main worry with the Sterling is the amount of power that it might take from my 9HP engine. However it looks like you can safely disconnect it from the field coil. So maybe I could fit a switch to disable it when I am trying to get back into Portsmouth against a bit of tide!

I'm a bit tempted to just use a couple of resistors and switches to manually achieve the same thing as the Stirling. However I'm sure that Ken_Irby is right and it would only be a matter of time before I forgot to turn off the higher charging - and fried the batteries. Either way round step 1 is to open up the alternetor and solder some wires on.
 
So your choice is to tear the alternator apart or try to manage without this surgery. If you tear it apart and reassemble successfully then you can buy a smart regulator or brew up some other sort of charge increaser.
Have a look on Google for SLA battery charger you will find some projects for building a 3 stage battery charger which could be modified to alternator controller. (if you are confident enough to do so)

If you decide not to disect the alternator then you must go relay or switch in lieu of diodes. You might like to replace the diodes with low voltage drop Schotky type which will give some improvement.
A VSR of simple design can work quite well consisting of a relay driven by an Op amp voltage comparator. PM me with email address if you want.
Or a relay driven by engine power switch or oil pressure switch can do a similar job. There are all sorts of possibilities. good luck olewill
 
Another vote for the Sterling. I have a 10hp Bukh and installed a Sterling regulator 2 years ago and achieved much more effective charging. You can install with a switch to revert to lower charging rate if you are worried about taking too much power off your engine. I did this but have not needed to use it although it's fun to test the difference.
Morgan
 
Be careful loading the alternator to much
GM starters are not the best for cold starting. On a cold day with alternator on full load you might be complaining? Thats why they only offer the LR35 alt. Be careful of charge management systems heard to many issues they run the alt at max output causing the alternator to overheat reducing efficiency. recommend BEP VSR go to http://www.bepmarine.com/
 
I am now going to upset a few people !

I don't see need for Adverc or Stirling on average boat. But I do see need to make sure alternator is doing the job it was designed for.

Taking original post - it seems obvious to me that battery sensing has failed here and alternator has reverted to machine sensed and that leads to rubbish charging - in fact barely charging at all.
Cure ? Get rid of the splitter diodes - an old and obselete method that really should join Noah in history.

There are a couple of Forum members here that can sort this little problem out very easy with a lot less pain on the wallet, with no need to start dismantling alternators etc.

Halcyon (KDD Power - supplier of bespoke VSR systems - always worth chatting to him ....)

Stemar (Simple method of wiring in a over counter relay to automatically click in to charge second battery when engine starts ... wiring diagram easy enough for even myself to follow !)

Seriously the average alternator will put out 14 - 14.4V, the trick is to reduce losses and get rid of unnecessary gimmicks and gizmos. The shorter more direct route puts amps in.

With Halcyon or Stemar's systems - you can have full alternator voltage going in and both batterys being charged. No fear of cooking batterys as a close friend of mine had on his HR42 when the 'oft-reccomended' booster systen decided to fall apart inside - causing his batterys to literally melt and fill his engine bay with smoke.

I follow the KISS principle ... haven't had any reason to consider anything else yet. My batterys last ages - well past many posts quotes on here.

Now I will be bombed from on high by 'experts' and others who reckon I should be hung from the highest tree for blaspheming against Charge Boost systems !! Bring it on ... I'm ready !! /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif
 
Sorry chaps, all these so called experts and eveyones missed the point.

Its more than likely the batteries are knackered so instead of throwing more money at a problem than is needed do the test first and go from there.

Hope this genuine advice (from someone who's been doing it a while) is of help to Boggy.

Chas/Ken, just for your information - I sell both VSR's and Diodes and Adverc, Balmar and our own (which I designed) alternator regulator system. Yours comments of "thinly disguised sales speak" - if they were aimed at me, I would actually find them offensive when trying to help someone (in my own time during my lunch hour). The VSR option from the business I work for, for example (there are of course other sources) is about £25 in its cheapest form. IF I was simply on some stupid sales crusade I would have recommended an alternator controller and capacity (not voltage) based split charging device which would run in excess of £350. These are simply not needed.

For the record - the difference between VSR's and Diodes:

VSR's initially stay open (off) when the engine is charging the engine start battery (therefore, the engine battery is, to a degree priority charged). Once the engine battery has reached 13.7V from the alternator charge, the relay will close allowing both engine and domestic battery banks to be charged. When the engine is stopped, the voltage returns to normal levels allowing the relay to open again - separating the engine and domestic batteries. Unlike diodes, VSR's have zero voltage drop (so require no battery sensing on alternator or charging device) and won't allow overcharging. Unlike older split charge relays, they will also open when domestics are very flat and recoonect again - preventing them overheating and burning out.

Some VSR's are mono-directional - i. e. they sense off one battery only (usually the engine battery and allowing charge to the domestics). Therefore, if you have other charging sources (e.g. solar panels) which are required to charge the engine battery, I normally recommend using a Dual Sense unit - allowing management of all charge sources on board.

Size the VSR for the largest charging source on board. There is no drawback using a larger than necessary VSR. VSR's other main benefit is that due to their zero voltage loss, alternator charge controllers simply aren't always necessary.

Not many people know this but if you are using a blocking diode in combination with an alternator charge controller, it is quite possible to overcharge and damage your engine battery bank.

Again, I have access to both blocking diodes and VSR's - VSR's are about £20 cheaper than diodes, so no thinly veiled sales speak here, just fact.

The only issue with VSR's is that of relay chatter. If the domestics are very flat, the VSR will chatter on and off as the engine battery voltages increases and then collapses so the VSR opens (and the whole process continues). This will shorten the life of the contacts inside the VSR considerably. The BEP unit is unique in the fact that the VSR has a short time delay built in to protect the unit from chatter (the bit about timing function, is sales speak but hopefully useful sales speak!).

Even a very good friend of mine at Adverc agreed (John Heap - he's passed away sadly now) that, if you have a zero loss system with short cables, good batteries and a good alternator/battery size ratio, an alternator controller simply isn't necessary for most boats - it will shorten charge time marginally but probably not worth the cost or hassle of installing.

Hope this helps!

James
 
[ QUOTE ]
Sorry chaps, all these so called experts and eveyones missed the point.

Its more than likely the batteries are knackered so instead of throwing more money at a problem than is needed do the test first and go from there.

Hope this genuine advice (from someone who's been doing it a while) is of help to Boggy.

Chas/Ken, just for your information - I sell both VSR's and Diodes and Adverc, Balmar and our own (which I designed) alternator regulator system. Yours comments of "thinly disguised sales speak" - if they were aimed at me, I would actually find them offensive when trying to help someone (in my own time during my lunch hour). The VSR option from the business I work for, for example (there are of course other sources) is about £25 in its cheapest form. IF I was simply on some stupid sales crusade I would have recommended an alternator controller and capacity (not voltage) based split charging device which would run in excess of £350. These are simply not needed.

For the record - the difference between VSR's and Diodes:

VSR's initially stay open (off) when the engine is charging the engine start battery (therefore, the engine battery is, to a degree priority charged). Once the engine battery has reached 13.7V from the alternator charge, the relay will close allowing both engine and domestic battery banks to be charged. When the engine is stopped, the voltage returns to normal levels allowing the relay to open again - separating the engine and domestic batteries. Unlike diodes, VSR's have zero voltage drop (so require no battery sensing on alternator or charging device) and won't allow overcharging. Unlike older split charge relays, they will also open when domestics are very flat and recoonect again - preventing them overheating and burning out.

Some VSR's are mono-directional - i. e. they sense off one battery only (usually the engine battery and allowing charge to the domestics). Therefore, if you have other charging sources (e.g. solar panels) which are required to charge the engine battery, I normally recommend using a Dual Sense unit - allowing management of all charge sources on board.

Size the VSR for the largest charging source on board. There is no drawback using a larger than necessary VSR. VSR's other main benefit is that due to their zero voltage loss, alternator charge controllers simply aren't always necessary.

Not many people know this but if you are using a blocking diode in combination with an alternator charge controller, it is quite possible to overcharge and damage your engine battery bank.

Again, I have access to both blocking diodes and VSR's - VSR's are about £20 cheaper than diodes, so no thinly veiled sales speak here, just fact.

The only issue with VSR's is that of relay chatter. If the domestics are very flat, the VSR will chatter on and off as the engine battery voltages increases and then collapses so the VSR opens (and the whole process continues). This will shorten the life of the contacts inside the VSR considerably. The BEP unit is unique in the fact that the VSR has a short time delay built in to protect the unit from chatter (the bit about timing function, is sales speak but hopefully useful sales speak!).

Even a very good friend of mine at Adverc agreed (John Heap - he's passed away sadly now) that, if you have a zero loss system with short cables, good batteries and a good alternator/battery size ratio, an alternator controller simply isn't necessary for most boats - it will shorten charge time marginally but probably not worth the cost or hassle of installing.

Hope this helps!

James

[/ QUOTE ]

Not Everyones missed the point ! Reading your post here quoted - it says same as I have been saying all along. And supports my post saying reduce losses - get it wired better, direct with no additions to induce voltage drops etc.

I have no beef with Boost Chargers / Regulators etc. - many who have high demand / liveaboards etc. need help with charging. But as you agree with my post - a good set-up on average boat has no need for booster.

Thank you for your post supporting my viewpoint ... /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif
 
Agree with simple way, but think boost charging has its place for those trying to minimise engine hours.
An alternator controller that does this intelligently, ramping up at the start has its advantages, particularly in avoiding belt wear.
What do you want/ How much are you prepared to pay for it?
 
However being a closet Yorkshireman I wonder if a 50p diode in the sensing wire to the alternator regulator would provide suitable compensation.
***************************************************
WHy not take the sensing wire to the domestic positive battery post then it will compensate for the splitter.
 
There's lenty of interesting if somewhat conflicting advice in here... It looks like I'll have to make my own mind up! Fortunately I studied electronics, but 20 years of working on software mean that I'm a bit rusty.

Top of my list has to be to get the battery tested, and if necessary to replace it.

Next has to be sorting out the fact that the splitter diodes mean the voltage available for charging is too low for a complete charge. This is where it gets less obvious.

Personally I don't see a problem with the idea of splitter diodes, as long as there is some sort of compensation to ensure that the right voltage is applied to the batteries. Given that I like to sail whenever possible I am leaning towards the Stirling advanced regulator solution as this should get more charge into the battery in the time that the engine is running.

So I have in mind opening up the alternator to attach a wire to the field coil and doing a few tests with a simple resistor / switch to boost the voltage. If this looks promising then I'll go for the Stirling if not then a VSR.
 
You must log in or register to reply here.

Other threads that may be of interest

Skipper Felice
Optimisation of the battery charger infrastructure
Replies
1
Views
141
PaulRainbow
PaulRainbow

Share this page

Top