Balmar high output small frame alternator

[John_Clarke]

I am thinking about fitting a 100 amp 6 series Balmar alternator to my Volvo MD2020 to reduce charging times at anchor; it seems to have very good output at low revs. To control this I am considering a Balmar Maxcharge regulator. Does anyone have experience of fitting or using these or any other comments?

 

[Heckler]

i wouldnt bother, the std alternator 65amps? with a sterling advanced regulator will do all that you want, i went down this route and it is superb. i moor on piles so no shore power, with the regulator i used to run 1 hour to make up for a day and night battery use, fridge, telly, kids! i then put a compass solara solar panel 56 watt on and now get to the boat with the batteries 2 times 85 amp fully charged and they last 2 days now before top up needed.
stu

 

[davidbains]

A 100amp alternator is massive, you'd probably need twin belts. Most of the
time it would be unnecessary. Fit an Adverc controller and/or buy a solar
panel so the battery will be fully charged when you arrive onboard.

 

[pvb]

Battery capacity?

Don't buy a 100A alternator thinking that it'll pump 100A into your batteries - it won't necessarily do that unless you have a very big battery bank (say 600-700Ah). The Balmar alternators are good (as you'd expect in view of their price) and as you say they have good output at lower revs, but so do many much cheaper alternators. You might ask Adverc for details of the Prestolite/Leece Neville alternators they sell - these also have good output at low revs.

The other problem with putting a high output alternator on in place of the standard alternator is that the belt drive is rarely up to it. I have a 90A alternator on my 2003, and it's really as much as a single belt will drive happily.

I'd suggest you tackle your charging problem in 2 stages. First add a smart regulator (Adverc, Sterling, etc) and a battery monitor (Link 10) and see what sort of charge your standard 60A alternator is giving. If it's not approaching 60A, try adding battery capacity. Only if that's not enough would it make sense to add a bigger alternator.

 

[John_Clarke]

I am concerned about the belt and would not want to have to fit twin ones.

I agree with you and skipper_stu that solar (or wind generator) would be good to charge batteries fully during the week. What I would like it better charging when cruising for a few weeks in Scotland. Solar is not so good there and anchorages can be quite sheltered.

 

[John_Clarke]

Re: Battery capacity?

I only want to generate about 50 A at about 1200 rpm which should be OK with a 330 Ahr bank. The 60 A Valeo alternator unfortunately doesn't give this sort of output at these revs.

I asked Adverc but they don't have an alternator that can give that output at low revs. The Balmar cost £240 which doesn't seem too bad for the performance.

I am also concerned about over-heating my 60 A alternator.

Do you have a 1/2" belt on your 90 A alternator?

I would have to change the pulley on the engine if I am to use a 1/2" belt. I was hoping that a 330 Ahr bank would limit the maximum output to about 75 A which the 3/8" belt might cope with?

I have a 6 year old Adverc regulator but you are right that my current 200 Ahr bank will limit the maximum charge. The batteries are 6 years old and will need to be replaced soon which will give me the oportunity to increase capacity to 220 Ahr AGM or 330 Ahr calcium maintenance free.

I am monitoring charging rates with a clamp ammeter and SOC with an accurate digital voltmeter (I rest the batteries for an hour before testing). This is a fiddle but has worked well but a battery monitor must be nice to have.

Thank you for your advice. It makes me have to think twice as hard about what I am proposing to do!

 

[andy_wilson]

A different reservation.

My somewhat older 2002 struggles to achieve revs for 30 secs - 1 min. when starting from cold with low batteries. I have a 50 Amp Valeo alternator and no charge controller. As the load rises with revs., it needs a good warm up before it will climb over 1000 rpm, and I would not expect it to turn the prop at the same time.

I have the cylinder head off for a very minor problem just now, and everything is within tollerance. It has always been a first time starter, the engine pulls full revs. and gives the right sort of speed for my boat - so there is nothing wrong with the engine.

The fact is that with mechanical losses an alternator absorbs a significant % of engine output at low revs when cold.

Some charge controllers have a ramp up feature to avoid this sort of issue on smaller engines.

However, I always have in the back of my mind a situation where after a couple of days in a peaceful anchorage I need to weigh (possibly a dragging) anchor and get out quick. I would hate to be on a lee shore situation with an engine that needs a couple more minutes before it will help out effectively.

 

[pvb]

A few answers...

It seems you're looking for decent charging performance at 1200rpm, which is a fast idle speed. You'd probably have a ratio of 2:1 or maybe 2.5:1 between the crank pulley and the alternator pulley, so at 1200 engine rpm, the alternator will be turning at around 2500-3000rpm. A Balmar 100A alternator would probably be OK for about 75A at that speed.

I have a Prestolite/Leece Neville 90A alternator bought from Adverc in 2000. It's a 110-602 model, and can give 60A at 2500 alternator rpm. You can see the details and output curve in this leaflet. (Adverc still sell Prestolite/Leece Neville alternators, so maybe they didn't check the specs before advising you). I bought it to replace a 130A large-case alternator which was simply too big for my engine and led to serious vibration issues. Although I have a 660Ah domestic battery bank, I never saw much more than 100A charge rate with the 130A alternator, even when the batteries were very low, so I doubt that you'll get much more than a 50A charge into 330Ah, regardless of alternator capacity.

My 90A alternator uses an ordinary 3/8" belt (or metric equivalent). However, I've got it mounted as a second alternator, directly driven by an additional crank pulley. This means that the belt wrap on the alternator is nearly 180 degrees, and this helps to prevent slip. It's important to buy good quality belts. I don't see any reason why you shouldn't use a 3/8" belt for a bigger replacement alternator, on the basis that your battery bank size will restrict the maximum output from the alternator. Changing pulley sizes is difficult, and I think you'd need to modify the water pump too.

As an aside, I'd agree with your proposal to use sealed maintenance-free batteries. The lead-calcium chemistry is quite resistant to overcharge. There's no leakage of acid, and no topping-up. Mine are 8 years old and still seem OK.

Hope this answers your questions. Post (or PM me) any more. One final thought - I guess you've considered and rejected the idea of a wind generator as a possible alternative solution?

 

[John_Clarke]

Re: A different reservation.

I agree with your concerns about the loss of power with a small engine. 80 amps equates to over 3 HP if alternator and belt losses are taken into account (according to Calder). The Balmar regulator has an adjustable ramp up period and also the option to fit a switch that reduces output by 50% when required. I think that it might also be possible to fit a switch in the alternator energiser wire (usually from the ignition switch). This, I think, would switch off the alternator. Merlin Equipment agreed that this would be the case but said it could invalidate the warrantee!

 

[John_Clarke]

Re: A few answers...

Thank you again very much for your detailed reply and advice. Unfortunately my pulley ratio is only 1:1.4 because my engine pulley is only 96 mm and the Balmar pulley 68 mm. The output of the 90 A Prestolite is only about 25 A at this rpm; the Balmar is about 50 A. I explained to Adverc that the engine pulley is constrained by a bump on the front of the engine which limits the pulley size to the one provided – a bit unfortunate.

I currently have calcium sealed maintenance-free batteries so perhaps I have a few more years life in them from what you say; I manage to keep them above 60 % SOC most of the time and regularly take them to full charge. However, I would have to make a larger battery box to add an extra battery and would loose that valuable locker space. I like to experiment and am very tempted to try AGM batteries for myself even though I think that the sealed maintenance-free batteries batteries are probably better value. Perverse I know!

I am keen to get a wind generator but want to get my light winds setup sorted first. We retire in 5 years and that is when we could make use of a larger liveaboard size wind generator so I am planning to hold off with that purchase until then.

However my thoughts are still in a state of flux on these matters and you and the forum are being most helpful yet again in helping the thinking process.