Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 03-10-2017, 06:03   #1
Registered User
 
Stillwater1's Avatar

Join Date: Apr 2014
Location: Florida West Coast
Boat: Watkins W27
Posts: 26
Send a message via Skype™ to Stillwater1
Alternator Overcharging Batteries?

Last week I installed new house and start batteries on my (new to me) 1979 Watkins 27. The wiring is still in need of some serious sorting out, as it is a tangle and nothing is labeled, but I was moving from a marina slip to a mooring and needed to also install some solar, which I also did, 2 days ago.

Yesterday was the day to move her. I had checked my electrical systems after finishing the installs and so I knew everything was working as it was supposed to, including that the alternator was in fact charging the starter battery. Who knows why but at the end of a long day I did not check to see if it was charging the house batteries as well.

We ended up needing to motor for about 2 hours of the 5 hour trip, and it occurred to me to check charging status again. I had installed the Balmar SmartGuage which provides SOC and Voltage reading on the house bank, and voltage on the starter battery. The MPPT charge controller connects the solar panel to only the house bank, and it also gives me SOC and voltage for the house bank.

The house bank is at 100% SOC and is receiving a float charge of 13.2 volts when we leave the dock and stays there for 3 hours under sail. The start battery is at 12.55 volts. Then we start the diesel and the Balmar and the charge controller both show the house bank and the start battery at 14.0 volts, I assume this is indicating they both are being charged by the alternator, but then it occurs to me:

Am I overcharging my house bank (2 DuraCell 215Ah 6volt GC2's) which will shorten their lifespan?

Advice please.

Bob
__________________

__________________
Stillwater1 is offline   Reply With Quote
Old 03-10-2017, 12:22   #2
rom
Registered User

Join Date: Mar 2016
Boat: Lagoon 440
Posts: 464
Re: Alternator Overcharging Batteries?

Quote:
Originally Posted by Stillwater1 View Post
The MPPT charge controller connects the solar panel to only the house bank, and it also gives me SOC and voltage for the house bank.
Sorry I am not qualified to answer your question, I am just curious about that MPPT that gives you a SOC ... The only time it would theoretically be able to do that is when reaching absorption and that would not even be accurate. Which brand is it ?
__________________

__________________
rom is offline   Reply With Quote
Old 03-10-2017, 12:54   #3
Registered User
 
Stillwater1's Avatar

Join Date: Apr 2014
Location: Florida West Coast
Boat: Watkins W27
Posts: 26
Send a message via Skype™ to Stillwater1
Re: Alternator Overcharging Batteries?

Renogy is the brand and the model is Rover 20 amp

https://smile.amazon.com/dp/B01MRWTA...ing=UTF8&psc=1
__________________
Stillwater1 is offline   Reply With Quote
Old 03-10-2017, 13:10   #4
rom
Registered User

Join Date: Mar 2016
Boat: Lagoon 440
Posts: 464
Re: Alternator Overcharging Batteries?

Quote:
Originally Posted by Stillwater1 View Post
Renogy is the brand and the model is Rover 20 amp

https://smile.amazon.com/dp/B01MRWTA...ing=UTF8&psc=1
OK got it, page 14 of the manual:"NOTE:The Battery Capacity (SOC%) is an estimation based on the charging voltage." I can only think of scenarios where this would lead to plain wrong results, I would not trust that.

Anyway, your question reminds of another thread where someone recently said that his batteries could handle 14.2V float, as per manufacturer recommendations. You might first check what your battery manufacturer says.
__________________
rom is offline   Reply With Quote
Old 03-10-2017, 14:17   #5
Registered User

Join Date: Jul 2016
Location: East Coast USA
Boat: Catalina 400
Posts: 208
Re: Alternator Overcharging Batteries?

Those Duracell GC2's are East Penn batteries and their absorption voltage is 14.4 to 14.7. If your charging system is set to 14.0 they will be chronically undercharged. Your going to have to get under the hood of your charging system to make sure they all dance together.
__________________
kenbo is offline   Reply With Quote
Old 03-10-2017, 14:50   #6
Registered User

Join Date: Mar 2013
Location: East of the river CT
Boat: Oday Mariner 19 , Four Winns Marquis 16 OB, Kingfisher III
Posts: 550
Send a message via Skype™ to Colin A
Re: Alternator Overcharging Batteries?

I guess the key question is how is the alternator setup for regulation. Most stock alternators just put out a set voltage then cut back when the alternator heats up.

Maine sail has a good article on it
Automotive Alternators vs. Deep Cycle Batteries Photo Gallery by Compass Marine How To at pbase.com
__________________
mysite: Colinism.com
Work for
Bass Products
Colin A is offline   Reply With Quote
Old 03-10-2017, 17:21   #7
֍֎֍֎֍֎֍֎֍֎

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 13,636
Re: Alternator Overcharging Batteries?

Alternators don't care about voltage. Regulators do that. And whether they are integral or external, the regulator has a battery voltage sense lead which it uses to read the battery voltage. (It can use the charge output lead if the electronics are sophisticated enough, but that's rarely done.)

Note that says "battery voltage sense" singular. One battery. Once you have two batteries or banks, and the ability to switch or charge them separately, someone has to either hoodwink the regulator and give it some mythical kludge, or switch the sense lead to each battery bank as they are switched. And, there's no way to accommodate two different brands or types of batteries, or integrate other charging sources, and still have it all done accurately. So...If you really want to "do it right"...there's no simple answer.

You'd have to detail all the equipment and then try to work out a solution that integrates it all, or at least, minimizes the insults to the battery.
__________________
hellosailor is online now   Reply With Quote
Old 03-10-2017, 20:13   #8
Registered User

Join Date: Jan 2017
Posts: 3,753
Re: Alternator Overcharging Batteries?

If you **need** your Alt to contribute a lot of charging power **and** your House bank is expensive and fussy, either

spend heaps converting to something like an MC-614 external regulator, maybe go for large-frame alt that can sustain rated output, or

use a quality batt2batt DC-DC charger like Sterling or ProMariner
__________________
john61ct is offline   Reply With Quote
Old 05-10-2017, 16:09   #9
Registered User
 
Stu Jackson's Avatar

Join Date: Jan 2011
Location: Cowichan Bay, BC (Maple Bay Marina)
Posts: 6,584
Re: Alternator Overcharging Batteries?

Quote:
Originally Posted by Colin A View Post

1. I guess the key question is how is the alternator setup for regulation.

2. Most stock alternators just put out a set voltage then cut back when the alternator heats up.

3. Maine sail has a good article on it
Automotive Alternators vs. Deep Cycle Batteries Photo Gallery by Compass Marine How To at pbase.com
1. Yes, good question.

2. Colin, as far as I know, ONLY Hitachi alternators are built that way with internal regulation. These come with Yanmar engines. Universals used Motorolas, which did not have built-in temp sensing on their internal regulators. "Most stock alternators" do NOT do that. Just to clarify for newbies.

3. Yes, he has a wealth of info on his website, including his long discussion about Hitachi alternators.
__________________
Stu Jackson
Catalina 34 #224 (1986) C34IA Secretary
Cowichan Bay, BC, (Maple Bay Marina) SR/FK, M25, Rocna 10 (22#) (NZ model)
Stu Jackson is offline   Reply With Quote
Old 06-10-2017, 09:23   #10
Registered User

Join Date: Jul 2016
Location: East Coast USA
Boat: Catalina 400
Posts: 208
Re: Alternator Overcharging Batteries?

Quote:
Originally Posted by Stu Jackson View Post
1. Yes, good question.

2. Colin, as far as I know, ONLY Hitachi alternators are built that way with internal regulation. These come with Yanmar engines. Universals used Motorolas, which did not have built-in temp sensing on their internal regulators. "Most stock alternators" do NOT do that. Just to clarify for newbies.

3. Yes, he has a wealth of info on his website, including his long discussion about Hitachi alternators.
Sorry, statement #2 is incorrect. Most internally regulated Delco, Paris Rhone and Valeo alternators as well as Hitachi have temperature compensation. I believe the point that Maine Sail was making in regards to Hitachi alternators is that their temperature compensation factor was higher than most and at high temps could make the Vset too low to adequately charge the battery.
__________________
kenbo is offline   Reply With Quote
Old 06-10-2017, 09:26   #11
Registered User

Join Date: Jan 2017
Posts: 3,753
Re: Alternator Overcharging Batteries?

I read "built that way" as referring to the full "just put out a set voltage then cut back when the alternator heats up" in #2, rather than temp compensation / protection in general
__________________
john61ct is offline   Reply With Quote
Old 06-10-2017, 09:26   #12
Registered User

Join Date: Mar 2013
Location: East of the river CT
Boat: Oday Mariner 19 , Four Winns Marquis 16 OB, Kingfisher III
Posts: 550
Send a message via Skype™ to Colin A
Re: Alternator Overcharging Batteries?

Quote:
Originally Posted by kenbo View Post
Sorry, statement #2 is incorrect. Most internally regulated Delco, Paris Rhone and Valeo alternators as well as Hitachi have temperature compensation. I believe the point that Maine Sail was making in regards to Hitachi alternators is that their temperature compensation factor was higher than most and at high temps could make the Vset too low to adequately charge the battery.
I was wondering about that I'm no expert but I knew I had run into other alternators that react the same way (or similar cutting power on hot days or long runs) as the Yanmar ones. You also run into the ones that simply regulate at a set voltage with no real failsafe.
__________________
mysite: Colinism.com
Work for
Bass Products
Colin A is offline   Reply With Quote
Old 06-10-2017, 09:28   #13
Registered User

Join Date: Mar 2013
Location: East of the river CT
Boat: Oday Mariner 19 , Four Winns Marquis 16 OB, Kingfisher III
Posts: 550
Send a message via Skype™ to Colin A
Re: Alternator Overcharging Batteries?

Quote:
Originally Posted by hellosailor View Post
Alternators don't care about voltage. Regulators do that. And whether they are integral or external, the regulator has a battery voltage sense lead which it uses to read the battery voltage. (It can use the charge output lead if the electronics are sophisticated enough, but that's rarely done.)

Note that says "battery voltage sense" singular. One battery. Once you have two batteries or banks, and the ability to switch or charge them separately, someone has to either hoodwink the regulator and give it some mythical kludge, or switch the sense lead to each battery bank as they are switched. And, there's no way to accommodate two different brands or types of batteries, or integrate other charging sources, and still have it all done accurately. So...If you really want to "do it right"...there's no simple answer.

You'd have to detail all the equipment and then try to work out a solution that integrates it all, or at least, minimizes the insults to the battery.
You are correct on the voltage regulator but most engines now a days seem to be internally regulated.
__________________
mysite: Colinism.com
Work for
Bass Products
Colin A is offline   Reply With Quote
Old 06-10-2017, 09:37   #14
Registered User
 
Stu Jackson's Avatar

Join Date: Jan 2011
Location: Cowichan Bay, BC (Maple Bay Marina)
Posts: 6,584
Re: Alternator Overcharging Batteries?

Quote:
Originally Posted by kenbo View Post
Sorry, statement #2 is incorrect. Most internally regulated Delco, Paris Rhone and Valeo alternators as well as Hitachi have temperature compensation. I believe the point that Maine Sail was making in regards to Hitachi alternators is that their temperature compensation factor was higher than most and at high temps could make the Vset too low to adequately charge the battery.
Thanks for that input, much appreciated. Very true conclusion.
__________________
Stu Jackson
Catalina 34 #224 (1986) C34IA Secretary
Cowichan Bay, BC, (Maple Bay Marina) SR/FK, M25, Rocna 10 (22#) (NZ model)
Stu Jackson is offline   Reply With Quote
Old 06-10-2017, 09:49   #15
Registered User

Join Date: Mar 2012
Location: On board in Alanya, Turkey
Boat: Hunter Legend 420 Passage
Posts: 633
Re: Alternator Overcharging Batteries?

Quote:
Originally Posted by kenbo View Post
Sorry, statement #2 is incorrect. Most internally regulated Delco, Paris Rhone and Valeo alternators as well as Hitachi have temperature compensation.....
My expensive hot rated Balmar 6 series alternator has temperature compensation so after half an hour is down from 14.4v to below 14 volts.

It's set up on a two-way switch so if the external regulator fails you switch to the internal regulator.
__________________

__________________
sailinglegend is offline   Reply With Quote
Reply

Tags
alternator, charging

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Alternator grounding out or overcharging Strider34c Electrical: Batteries, Generators & Solar 4 28-08-2015 10:38
Generator / Battery Charger overcharging engine batteries mmarin Electrical: Batteries, Generators & Solar 1 03-06-2015 19:44
High Rated Alternator with Alternator to Battery Charger Rumbero Electrical: Batteries, Generators & Solar 113 18-07-2014 05:29
Overcharging Marine Services Australia Clairedelune Monohull Sailboats 17 22-09-2013 14:22
Overcharging batteries David Carver38 Powered Boats 2 28-06-2012 05:50



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 16:09.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.