Considering an extra alternator for charging the house bank of Trojan T105s.

[GILow]

Originally Posted by more

You can put 1 million amp alternator,or 1 mw generator in dingy ,but your battery bank only accepts current by charging curve your battery chemistry.
I have Winston life battery bank , 150 AH AGM for bow thruster, connected to starter batery downsized from 180 ah to 75 Ah.
2 inverter pure sine one
havy trafo 4000 W surge 12000 w but consume in standby 50w efficiency sucks except 100% capacity i use this for mini wash,dive compressor and icemaker

Now interested for you
have smart 500-1000 w pure sine vave (smart hm, smart is only fan and No-load power consumption: 0,67A 9W)
i conect this inverter to bow thruster (i have battery selector 102 starter-service battery)

and i connect phone charger, laptop charger, and Victron Blue Smart IP22 30A Charger
only solar good MPPT and Blue Smart IP22 Charger & end other marine smart CC curent charger can charge 100%

battery bank . in winter no sun, simple on phone give command Blue Smart IP22 Charger charge 30A or 15A (200-400 Watt) start engine 900-1000 rpm also 100 amp alternator charge 20-30A boath battery bank. take dog for walking - pooping and drink coffee in bar return in boat battery is almost full

Good for you.

[more]

Originally Posted by GILow

Good for you.

yes, good for me after waste money upgrading the alternator from 50 amp to 100 amp (no aftermarket original Perkins alternator for my engine) Now i have 2 alternators one spare in the garage. i upgrade the alternator but the charging current is always 1-40 amp, usually, 99% of the time is 10-30A both battery bank.

[stormalong]

I have the same engine and same house battery bank. When I ordered the Beta 50 from the factory I had them add the second alternator bracket option to take the 115 amp Balmar alternator that was on my Perkins 4-108. I also had them add a 6 groove belt and a pulley ratio that allows the Balmar alternator to produce full power at idle speed. I left the Beta supplied alternator unaltered, with it's internal regulator and it is connected to the start battery. In 2003 when I put this engine in the stock alternator was 60 amp, not 75.

The Balmar alternator is controlled by an external "smart" regulator. It is connected to the house bank - six t-105's in series parallel.

I also have 390 watts of solar and a battery combiner.

This has worked well and this configuration has been in place since 2003. Originally only four t-105s. I added the two extra batteries in 2009 when I replaced all of the house batteries.

The Balmar alternator seldom produces more than 80 amps. I usually don't let the batteries get below 60%. The current drops off within an hour.

This system has worked very well for me. If running the engine just to charge, when the regulator stops the bulk acceptance mode I usually stop the engine and let the solar top off the batteries.

The one issue with this setup is a lot of belt dust from the six groove belts and they only last a couple of years. I carry lots of spare belts just in case. With the pulley ratio I have it is a big load on the belt.

IMO the second alternator is a big advantage. I don't see the need for anything larger than 100 amps on the second alternator. The battery combiner means that both alternators work together. This also means that when picking up the anchor my windlass is drawing almost nothing from the batteries.

[GILow]

Originally Posted by stormalong

I have the same engine and same house battery bank. When I ordered the Beta 50 from the factory I had them add the second alternator bracket option to take the 115 amp Balmar alternator that was on my Perkins 4-108. I also had them add a 6 groove belt and a pulley ratio that allows the Balmar alternator to produce full power at idle speed. I left the Beta supplied alternator unaltered, with it's internal regulator and it is connected to the start battery. In 2003 when I put this engine in the stock alternator was 60 amp, not 75.

The Balmar alternator is controlled by an external "smart" regulator. It is connected to the house bank - six t-105's in series parallel.

I also have 390 watts of solar and a battery combiner.

This has worked well and this configuration has been in place since 2003. Originally only four t-105s. I added the two extra batteries in 2009 when I replaced all of the house batteries.

The Balmar alternator seldom produces more than 80 amps. I usually don't let the batteries get below 60%. The current drops off within an hour.

This system has worked very well for me. If running the engine just to charge, when the regulator stops the bulk acceptance mode I usually stop the engine and let the solar top off the batteries.

The one issue with this setup is a lot of belt dust from the six groove belts and they only last a couple of years. I carry lots of spare belts just in case. With the pulley ratio I have it is a big load on the belt.

IMO the second alternator is a big advantage. I don't see the need for anything larger than 100 amps on the second alternator. The battery combiner means that both alternators work together. This also means that when picking up the anchor my windlass is drawing almost nothing from the batteries.

Thank you, some highly relevant data here.

Your battery setup being the same gives me confidence that yes, 100 amps will be heaps. And yes, I was planning to add a second alternator, giving me redundancy as well as the ability to combine the two when needed.

A bit worried about the belt dust issue... I thought the whole point of these ribbed belts is that it stopped that sort of thing. Seems I am going to be disappointed. Thank you for the warning.

[CassidyNZ]

I have about 750w of solar that even on a cloudy day will continue to load 20A into the bank. At 50% SOC on a sunny day I see 40A regularly. FYI I also have 6 6V batteries (not T105’s, US Battery). My daily consumption is about 240Ah over 24 hours.

I have three alternators, one is the original 65A located on the engine. The others are two big-frame alts mounted in front of the engine (facing backwards) and both have switched fields so that I can can choose to run neither, either one or both if necessary. Best redundancy I ever had. Compared to lithium’s it’s like spending Monopoly money.

I was told all the stories about how I’m wasting money, how my batteries are going to be fried, how I’m going to regret this, my engine won’t be able to keep up, my batteries are going to boil all the water off, the litany of doom spreading was amazing.

Truth? My last set of T105’s lasted 10 years. My current set of batteries are now 5 years old and still have full capacity. I top up water once a month or so. I never have to worry about electricity on my boat. My battery monitor says “FULL” every time I step onto the boat no matter what the weather has been like.

I have a wind charger that hasn’t worked for a year or more - don’t need it, one day when I have nothing better to do, I’ll rip it from it’s mountings and chuck it in the sea.

There is nothing wrong with two or even three alternators. It does not spell death to your batteries. It’s a hell of a lot less expensive than lithium’s or even AGM. Your Trojans, with even just a modicum of care will last as well as any other battery chemistry out there.

That’s my opinion. Use it, don’t use it, I don’t care either way.

[Fore and Aft]

Gilow just head north until your butter melts. That should fix your charging issues.
Cheers

[noelex 77]

If you are planning additional alternator capacity don’t forget to include the current required for any loads that will run at the same time.

When the engine is running, it is also the ideal time to operate high power equipment. Ideally, the additional alternator will generate enough power to operate this equipment and charge the batteries at a rapid rate.

It is probably not going to be practical to extract this ideal amount of energy from your set up. If you can fit a large frame alternator, this is the best choice. They are available in large capacities for a relatively low cost and are reliable. They can always be derated with a smart alternator regulator if you feel this is needed for reasons of battery health or engine reliability.

[stormalong]

Originally Posted by GILow

Thank you, some highly relevant data here.

Your battery setup being the same gives me confidence that yes, 100 amps will be heaps. And yes, I was planning to add a second alternator, giving me redundancy as well as the ability to combine the two when needed.

A bit worried about the belt dust issue... I thought the whole point of these ribbed belts is that it stopped that sort of thing. Seems I am going to be disappointed. Thank you for the warning.

I think the belt dust is due to the pulley ratio I chose. It something over 3:1. I don't remember the exact ratio. I asked Beta to give me the best they could without spinning the alternator over 10,000 rpm at full engine rpm.

[MJH]

Originally Posted by GILow

Hi all,

A month or so into the cruising life, and I’m looking ahead to what is likely to be a cold winter with pretty poor solar input.

My power budget is pretty light, I am guessing I’m going to want to find about 150 AH @ 12 volts on those days that the sun doesn’t shine.

I think the simplest option will be to add an after market alternator to my Beta 50. It comes standard with a 75 amp alternator, but I bet it is the sort that will not sustain 75 amps for long.

I’d like to match the second alternator to my needs and my house bank:

The house bank is a set of 6 Trojan T105s, wired to provide 675AH @ 12 volts.

I usually wake up in the morning with the bank at 85 to 90% full. No problem for the 760 watts of solar if the sun is shining.

Reading the Trojan manual, it would appear that this setup would best be charged with at about 90 amps, or 30 amps per parallel string.

Seems a bit low to me.

I wonder, therefore, where to pitch the alternator capacity. If I fit the 175 amp secondary alternator kit supplied by Beta, for example, how much benefit will I really gain? I suspect the battery bank is going to max out a bit over 100 amps acceptance, but maybe the Trojans are happy to accept more!?

Does anyone have real world experience of the same or similar sized Trojan T105 bank with a big alternator to let me know how much they accept, particularly at these higher charge states. Matt

The general rule, as I understand it, is that an alternator should be at least 25% of your battery bank (675Ah x 25% = 168.75A). So just replacing your present alternator with a 175A alternator should do it but you'll need to go with a serpentine belt. Anything you get off the solar will be a plus and save wear and tear on the bigger alternator. That should be cheaper than all the sundry supporting gear that usually goes with a secondary alternator addition...plus it just clutters up the engine compartment with complexity. Selling the present 75A alternator will defray some of the cost.

When I looked into the same question for my boat years ago the total price was unacceptable because so many parts had to be changed...its a bigger deal than most think.

Good Luck.

~ ~ _/) ~ ~ MJH

[CarlF]

Having a 2nd alternator is great for redundancy. Alternators do fail - usually because of diodes. It's very difficult to fix them at sea.

I have a 200amp Balmar alternator on a 2nd mount and never see dust. The belt is going strong after 4 years.

The Balmar regulators have a great feature called the "belt load manager" that let you reduce the belt load. Besides saving belts, this keeps the alternator cooler so it lasts longer and puts out more power. You lose few if any charging amps at the end of the day because the alternator runs cooler. With 100amps cut back a bit with the belt load manager you won't see significant belt dust even with a standard V-belt.

The less time spent running your engine at low rpm while charging -- the better for the engine. The 2nd alternator will help reduce the time and increase the load on the engine which will keep it from running as cool and building up carbon. Getting the batteries up to 80% as quickly as possible and then turning the engine off is the best thing for it.

https://marinehowto.com/programming-...age-regulator/

[sailorboy1]

In the end if the OP doesn't get the extra alternator what is the most likely possible reasonable bad result?

Its that he might have to run the engine an extra. 30 minutes every few days IF needed to supplement his solar.

Doesn't seem worth a lot of time to fix this non issue to me.

[MJH]

Originally Posted by sailorboy1

In the end if the OP doesn't get the extra alternator what is the most likely possible reasonable bad result?

Its that he might have to run the engine an extra. 30 minutes every few days IF needed to supplement his solar.

Doesn't seem worth a lot of time to fix this non issue to me.

The issue is that his electrical system is not in balance with only a 75A alternator to support 650AH house bank, about 11%, on cloudy days. It is true that his big solar will still be providing some power but I have sailed the Pacific and was surprised often by the lack of sunshine...eight straight cloudy days in July across the north. The alternator would be working hard and I suspect the batteries not really getting back up to 100% until the sun returns.

~ ~ _/) ~ ~ MJH

[sailorboy1]

So. That isn't a big deal. Back in the days before solar everyone operated their batteries in the 50-80% soc range.

[stormalong]

Originally Posted by MJH

The general rule, as I understand it, is that an alternator should be at least 25% of your battery bank (675Ah x 25% = 168.75A). So just replacing your present alternator with a 175A alternator should do it but you'll need to go with a serpentine belt. Anything you get off the solar will be a plus and save wear and tear on the bigger alternator. That should be cheaper than all the sundry supporting gear that usually goes with a secondary alternator addition...plus it just clutters up the engine compartment with complexity. Selling the present 75A alternator will defray some of the cost.

When I looked into the same question for my boat years ago the total price was unacceptable because so many parts had to be changed...its a bigger deal than most think.

Good Luck.

~ ~ _/) ~ ~ MJH

These 75 amp alternators are cheap. Not much money to recoup selling a used one. Having a second alternator and adding the output together with a battery combiner is a good solution - it reduces the load and heat from a single alternator system. Beta makes a nice second alternator kit. It is an incredibly heavy bracket. The second alternator is driven by an additional pulley on the crankshaft and does not interfere with the original alternator/fresh water coolant pump at all. I like the redundancy. The tachometer is also driven by the primary alternator and if you start messing with the belt ratio you will need to re-calibrate it.

[JPA Cate]

GILow is located at about 42 deg. South. The sun is on its way north now. The charging days are at low sun angles, and getting shorter fast. I'm thinking stormalong's advice, coming from further north than GILow is south may be really to the point.

Ann