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Old 08-12-2013, 03:43   #61
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Re: Alternator does not Fully Charge the Batteries

Thank you everybody for the very interesting, frequent and relevant contributions to this topic - this became much more interesting than I ever thought!

Keep them coming, but here are my mid term conclusions:

1) Unacceptable voltage drop in childish wiring, oxidized connections + split charge diode
2) Despite the correctly connected remote sensing wire, regulator cannot completely compensate the drop due to regulator saturation, resulting in constant underloading.
3) Situation has been going on for three seasons and sulphatized 3-season old leisure batteries to a useless condition
4) I would not have understood what's going on without the battery monitor. Boat's own voltmeter is far too inaccurate.

Plan for fixing the system:
a) significant upgrade in wiring, cleaning of contacts
b) getting rid of split charge diode w.g. with the suggestions given here (or with gadgets in item e)
c) new batteries
d) constant monitoring of the situation
e) if needed, smart solutions like Volvo's 115 amp alternator with intelligent regulator, solutions proposed here, or Sterling's alternator to battery charger.
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Old 08-12-2013, 10:47   #62
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Re: Alternator does not Fully Charge the Batteries

Quote:
Originally Posted by tuomas View Post
Thank you everybody for the very interesting, frequent and relevant contributions to this topic - this became much more interesting than I ever thought!

Keep them coming, but here are my mid term conclusions:

1) Unacceptable voltage drop in childish wiring, oxidized connections + split charge diode
2) Despite the correctly connected remote sensing wire, regulator cannot completely compensate the drop due to regulator saturation, resulting in constant underloading.
3) Situation has been going on for three seasons and sulphatized 3-season old leisure batteries to a useless condition
4) I would not have understood what's going on without the battery monitor. Boat's own voltmeter is far too inaccurate.

Plan for fixing the system:
a) significant upgrade in wiring, cleaning of contacts
b) getting rid of split charge diode w.g. with the suggestions given here (or with gadgets in item e)
c) new batteries
d) constant monitoring of the situation
e) if needed, smart solutions like Volvo's 115 amp alternator with intelligent regulator, solutions proposed here, or Sterling's alternator to battery charger.
Does your Volvo alt have the B+ voltage sense wire internal or external? If external:

Run alt positive direct to house bank (properly fused)
Run v-sense wire to house bank pos (properly fused)
Add an Echo Charger or voltage sensitive relay to charge start bank

Done.....



You really can't sense the alt B+ and get the target voltage you want, at the batteries, unless you go really big with the wires. You will EVENTUALLY get to target voltage but it will be very late in the charge cycle and limit the current your batteries are taking the entire way up there, thus slowing the charge cycle fairly dramatically...
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Old 12-12-2013, 22:14   #63
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how to charge 2 types of batteries

I have learned alot here but haven't found anything addressing my arrangement. I have a large sealed lead acid starter battery for each of dual Yanmars but have large AGM house batteries. On my prior boat, all the house (gel cell) charging was by solar. But no solar on the new boat. A couple posts here suggest the AGM can accept the std Yanmar charging voltage but would I be better to convert one alternator to external regulation for charging the house AGM and then the other left along to charge both starting batteries? Can the std Hitachi alternator be converted to external regulation? Alternate idea, could I run the alternator thru a solar controller for the AGM batteries? I plan to add solar anyway but with 2 engines (2GM20)/ alternators, seems I should take advantage of the existing alternators.
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Old 12-12-2013, 23:18   #64
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Re: Alternator does not Fully Charge the Batteries

AGM and flooded lead acid batteries are very close in charging voltages so it shouldn't be a problem as is. There are advantages to external regulation though, 3 stage charging, alt and battery temp sensors, and programmability.
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Old 13-12-2013, 07:30   #65
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Re: Alternator does not Fully Charge the Batteries

AGM and flooded LA batteries have almost identical charging profiles. As mitiempo said, no problem there.

Your start batteries require VERY LITTLE CHARGING. Typically, starting a small-medium size diesel takes less than 1AH! This is replaced in just a few minutes of charging. Automotive alternators aren't built for continuous output at full capacity.

The thing I'd watch out for is the "large AGM house bank" putting a severe strain on the alternators....possibly to the point of severe overheating and destruction of the diodes.

AGMs can take an enormous amount of charging current. And, if they're pretty deeply discharged they'll take this current for a long time while recharging. Unless there's some way to limit the output from the alternator(s) -- like temp sensors on the alternator or de-rating their output using a smart external regulator -- you run the risk of severe overheating.

Bottom line: all onboard charging sources -- alternator(s), solar, battery charger, generator, etc. should be wired in such way as to charge the house batteries. Then, a battery combiner or voltage-follower device should be used to funnel a bit of the charging amperage to the start batteries to keep them topped up.

Bill
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Old 13-12-2013, 09:07   #66
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Re: charge 2 types of batteries

Bill,
On my prior boat, we seldom took the house battery bank down more than 20% and only once past 50% during a prolonged cloudy/rainy spell. The 360 watts of solar usually had the bank back up to 100% in the early afternoon. (nothing from the outboard alternator) I do not have any solar yet on the new boat but plan to add at least 400 watts this time.

I guess "large" is a relative term. There was one new 4D battery when I bought it and will add a second in the spring. I had under 400 AH on the prior boat and that seems fine for us cruising. The new (to us) 40ft cat will likely use a bit more electricity (has a large windlass installed). Not sure how large the std Yanmar alternator is ( just purchased the new cat and I have not had it in the water yet)

I have an unused Blue Seas ACR7600. Are you suggesting to charge the starting battery as the secondary off the ACR7600? The boat came with an older Heart inverter/charger which I am still learning about. There is a lot of wiring on this boat and I am still trying to make sense of it.

Not sure buying an expensive alternator and 3 stage is the best expenditure vs solar, maybe small wind gen to supplement for nights.
thanks again for your input.
Ed
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Old 13-12-2013, 11:07   #67
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Re: charge 2 types of batteries

Quote:
Originally Posted by Sailorman Ed View Post
......

I have an unused Blue Seas ACR7600. Are you suggesting to charge the starting battery as the secondary off the ACR7600? The boat came with an older Heart inverter/charger which I am still learning about. There is a lot of wiring on this boat and I am still trying to make sense of it.

Not sure buying an expensive alternator and 3 stage is the best expenditure vs solar, maybe small wind gen to supplement for nights.
thanks again for your input.
Ed
Ed,

I suppose one strategy might be to use just one alternator for charging the two start batteries, using the ACR7600 to combine them when charging. Then, use the other alternator to charge the house batteries, with or without another combiner to combine the start batteries with the house batteries while charging.

But, I'd wanna think about this, and wouldn't consider any changes before you've thoroughly investigated the existing wiring scheme, and perhaps had the boat in service for awhile to evaluate how the existing setup is working.

Bill
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Old 13-12-2013, 13:21   #68
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Re: Alternator vs Batteries

Quote:
I suppose one strategy might be to use just one alternator for charging the two start batteries, using the ACR7600 to combine them when charging. Then, use the other alternator to charge the house batteries
Bill EXACTLY what I had been thinking before reading this thread. Just using my on the hard time to make some plans. I need to find out which model Heart inverter/charger I have and then how it works. I think it has a AGM setting but probably does not regulate voltage coming from the alternator.
Ed
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Old 15-05-2014, 06:58   #69
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Re: Alternator does not Fully Charge the Batteries

Hi again - just finished installing Sterling AB12130. Otherwise easy installation, but the standard VP MD2040 alternator needs voltage to B+ too to magnetize, due to diodes inside there is normally none. You can magnetize it by touching it with +12V but doubt that my wife would do it every time I ask.. Luckily Sterling has a connector where you can connect a signal voltage from solenoid and when the apparatus notices this it feeds +12 V to B+ for 2 seconds.

Gives a nice kick to batteries even at almost idle - 16 amps instead of 1,6

More info after the maiden voyage in the weekend.
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Old 15-05-2014, 23:11   #70
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Re: Alternator does not Fully Charge the Batteries

Hello Tuomas,

That's similar to my setup. Installed my Sterling AB12130 a year ago and it has worked fine during the first season. Only thing I can complain about is that it didn't start up a couple of times. Had to switch off the engine and start again. That did it. I also have a wire from starter solenoid to Sterling and it should give an initial current to alternator field. It would be interesting to hear if you'll get the same glitch from time to time. This spring I installed a push button between the battery+ and alternator field circuit (fused at 5A). Gives me a convenient alternator start when it doesn't start up automatically.

I have two alternators installed on my Volvo B21A and I kept one of them for start battery charging and another charges house bank via Sterling charger. I could have connected both alternators to Sterling charger as it has a capability to charge two battery banks (house and charge) but decided to keep them separated for a little additional redundancy. Start battery is almost full all the time anyways.
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Old 16-05-2014, 03:04   #71
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Re: Alternator does not Fully Charge the Batteries

Indeed - while installing and testing I noticed that the alternator does not completely magnetize on idle rpm when B+ is touched with 12V. Sterling flashes its leds but goes silent - measured only 2.3 V on B+.

I already had some small concerns that starting warm engine without idle thrust may lead to this - and so it seems to do.

The button is a good idea.

I will let you know more soon.
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Old 16-05-2014, 13:57   #72
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Re: Alternator does not Fully Charge the Batteries

"Indeed - while installing and testing I noticed that the alternator does not completely magnetize on idle rpm"
If these are "one wire" systems, as opposed to "three wire" systems, it would be normal to need to blip the engine to get the alternator started.

Sterling uses the "one-wire" configuration?
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Old 17-05-2014, 00:07   #73
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Re: Alternator does not Fully Charge the Batteries

What do you mean by three-wire vs. one-wire system?
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Old 17-05-2014, 00:38   #74
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Re: how to charge 2 types of batteries

Quote:
Originally Posted by Sailorman Ed View Post
I have learned alot here but haven't found anything addressing my arrangement. I have a large sealed lead acid starter battery for each of dual Yanmars but have large AGM house batteries. On my prior boat, all the house (gel cell) charging was by solar. But no solar on the new boat. A couple posts here suggest the AGM can accept the std Yanmar charging voltage but would I be better to convert one alternator to external regulation for charging the house AGM and then the other left along to charge both starting batteries? Can the std Hitachi alternator be converted to external regulation? Alternate idea, could I run the alternator thru a solar controller for the AGM batteries? I plan to add solar anyway but with 2 engines (2GM20)/ alternators, seems I should take advantage of the existing alternators.

In Mainsails opinion the standard 50 & 80 amp Hitachis are only there to charge up starter batteries after they crank up the motor and rarely give out max amps if at all! I agree too!

I would remove one, keep as spare & fit a larger externally regulated alt to the other motor....say 120 amp. My Electromaax 180 amp goes well but I do have a larger motor to spin it. Important to match alt size to house bank capacity.
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Old 17-05-2014, 10:47   #75
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Re: Alternator does not Fully Charge the Batteries

tuomas-
In a conventional (automobile) charging system with the regulator integral to the alternator, you will find one charging
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