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Only one battery charging from outboard

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ct95949
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Aruba
300 Posts

Initially Posted - 08/30/2015 : 11:28:29

I've been trying to figure out why only one battery is getting charged when the motor is running and the battery switch is on 'Both'. Now, before we get into the whole battery switch can of worms let me say that my old boat had separate on/off switches for the house batteries and a separate outboard battery. I liked that set up better than what my new boat came with which is two batteries and an 1/2/both/off switch. I have been reading about combiners and isolators will eventually get rid of the switch I have now.

I thought I had fried my rectifier yesterday by turning the switch to 'off' with the motor running (switch has no AFD protection) but after cleaning my terminals good and running the batteries down I was measuring 14.3 volts on the battery that has the motor cable. The other battery measured 12.5 which is what they both were before starting the motor. I just can't figure out why I wouldn't get some increase in voltage on the second battery or cable when the switch on 'both' should be joining them. The cables are hooked to the correct posts on the switch. Here are some pics. Thanks, Craig.

'90 SR/WK #6017. PO of '79 SR/SK.

Davy J
Master Marine Consultant

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Response Posted - 08/30/2015 : 12:04:22

quote:
I was measuring 14.3 volts on the battery that has the motor cable.

What is this???? You have a cable that goes directly from the battery to the outboard?

Davy J

2005 Gemini 105Mc
PO 1987 C25 #5509 SR/SK
Tampa Bay

ct95949
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Aruba
300 Posts

Response Posted - 08/30/2015 : 14:02:38

Yes, on a 100 amp fuse at the battery. That is why I didn't damage the charging system when I moved the switch to 'off' with the motor running. Do I have to have the motor cable switched when it has a fuse? Car battery cables go directly to the starter without going through a switch.

'90 SR/WK #6017. PO of '79 SR/SK.

Edited by - ct95949 on 08/30/2015 14:10:11

Davy J
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Response Posted - 08/30/2015 : 14:16:08

I think you need to move that cable from the battery and connect it to the common side of the battery switch.

See this Blue Sea PDF:

http://assets.bluesea.com/files/resources/instructions/9001e_web_version.pdf

Davy J

2005 Gemini 105Mc
PO 1987 C25 #5509 SR/SK
Tampa Bay

ct95949
Captain

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Aruba
300 Posts

Response Posted - 08/30/2015 : 14:46:12

The old Guest switch I have has three studs so short only one lug will fit with the nut flush with the end of the stud.
This is what I think I'll get, I like the four studs and separating the batteries:
https://www.bluesea.com/products/7650/Add-A-Battery_Kit_-_120A
Do you know any reason though, why I wouldn't get some of that charging voltage through the switch to the second battery?
Thanks, Craig.

'90 SR/WK #6017. PO of '79 SR/SK.

Davy J
Master Marine Consultant

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1511 Posts

Response Posted - 08/30/2015 : 15:39:01

quote:
Do you know any reason though, why I wouldn't get some of that charging voltage through the switch to the second battery?

I'm no pro, but my guess is that the battery connected to the outboard cable is acting like a sponge and taking up the charge.

I ended up connecting my batteries in parallel and liked that arrangement. You double the amp hours of the battery bank and if you should run them both down accidentally, you can usually pull start the outboard to get going.

This site has a ton of info:

http://www.solar-electric.com/deep-cycle-battery-information-faq.html/

Davy J

2005 Gemini 105Mc
PO 1987 C25 #5509 SR/SK
Tampa Bay

rdthoms
Deckhand

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USA
15 Posts

Response Posted - 08/31/2015 : 15:14:51

Blue Sea has a smaller version of that battery kit. That is what I intend to use when I do this upgrade. I think it is sufficient for our small boats/power setups. Let me know if you think otherwise.
Blue Sea Systems m-Series Mini Add-A-Battery System
http://www.defender.com/product3.jsp?path=-1|328|2290051|2290060&id=2263607

Richard
Huntsville, AL
1984 Catalina 25 SR/FK #4309

Dave5041
Former Mainsheet Editor

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3758 Posts

Response Posted - 08/31/2015 : 18:52:43

Both my motor output and battery charger connect to the +common post on my 4 position switch and charge with no problem. If one battery has a much lower charge I charge it in the 1 or 2 position but use the both position most of the time for charging. As voltage in one battery rises, the decrease in potential with the charging source makes more current available to the other battery. Current flow is a simple, inverse relationship of resistance and voltage. Severe corrosion on the switch contact could drop voltage significantly and impact charging. A new switch will likely solve the problem.

Dave B. aboard Pearl
1982 TR/SK/Trad. #3399
Lake Erie/Florida Panhandle

Voyager
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5369 Posts

Response Posted - 09/04/2015 : 03:51:35

Frankly I'm a little unclear about the setup but I think what is happening is this:
(1) battery 1 shown in the first photo has two positive connections. The engine charging and starter circuit which is a direct unswitched connection (except the fuse) thru some #6AWG and a house panel feed that is connected to through the 1-2-both-off switch using some maybe #12AWG. This battery and circuit (I would say) is "running" your boat. If you switch the switch to off does the house disconnect and your lights and radio go off?

Now you've got battery 2 somehow connected to the switch, but I don't think it has any path to the alternator except maybe thru a lot of #12 cable, so the voltage drop would be large. When "both" is selected there should be a dead short between both batteries and their voltages should be exactly equal after a very short time.
Methinks something is amiss... Are all negative leads connected to a single buss bar or connection point? All with the same corresponding wire gauge as the positive side? Any corrosion on that side of the circuit? It's equally important.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

Voyager
Master Marine Consultant

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5369 Posts

Response Posted - 09/04/2015 : 05:22:40

Here's a check for you.

Battery test
Put your voltmeter on the house side. With the engine off and the switch off you should read 0 VDC. If it reads anything else, that's incorrect. If not zero, then one of the two batteries is connected to the house.
Now measure the voltage on battery 1. Say it's reading12.79 VDC. Now put your voltmeter back on the house side. Flip the switch to 1. If all the lights and radios and depth meters etc are switched off, the house should measure just about 12.75-12.79 VDC. If it's reading zero or say 12.4VDC, then battery 1 is not connected to the right switch terminal. Turn the battery switch to off again.
Now measure the voltage of battery 2. Assume it's reading 12.4VDC (which means it's partially discharged). Switch the battery switch to 2. Measure the house voltage. It should measure around 12.4 or less volts. If it measures 0, something's wrong. Or if it measures 12.7VDC or more, then 2&1 are interchanged.
Now flip the switch to both. Measure battery 1, battery 2 and the house. They should all be of equal voltage to within 0.1 VDC. If not, they're not connected together correctly. Battery 1 should be on terminal 1, battery 2 on terminal 2 and both should short them together.

Charging test
Now put the switch on off and start the engine. Measure battery 1, battery 2 and you may find that one of the batteries will be charging somewhere around 13-14VDC. Actually with the switch on off neither should be charging. The other battery will likely remain at its old voltage between 12.4 and 12.8.
Now stop the motor and put the switch on 1. Start the motor. Check to see what's happened to the battery voltages. Is either battery charging? If the voltage readings are the same as in the first charging test then the engine is only connected to the battery that's charging. The other on is not charging.
Turn off the engine again. Flip the switch to 2. Start the engine. Now, measure the battery voltages. Has anything changed? If the other battery is now charging that's good. If not well it's not connecting through the switch nor is it directly connected.
Lastly flip the switch to both. Both batteries should be charging in the 13-14VDC range. If not then the other battery is not charging at all.
I think what might be happening though is the 2nd battery is charging through the house circuit on a skinny #12 or #14 wire. That would limit the voltage and current it would receive and that battery would be starved for power.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

Edited by - Voyager on 09/04/2015 05:38:31

OLarryR
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Response Posted - 09/04/2015 : 08:40:43

I cannot see from your photos if you have the negatives from each battery connected to each other - I mean they must be but thought I would ask anyway.

Larry
'89 Robin's Nest#5820, Potomac River/Quantico, Va
http://catalina25.homestead.com/olarryr.html

ct95949
Captain

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Aruba
300 Posts

Response Posted - 09/04/2015 : 10:08:46

Yes the negatives are connected, then go to a neg. buss bar. Both pos. cables go the correct posts on the switch then to the fuse panel. A separate pos. cable from batt. #1 goes directly to the outboard. All the terminals have been cleaned and tightened but I haven't taken the switch apart to check the contacts as Dave mentioned earlier. The path from the alternator to batt. #2 should be at the batt. #1 post, to the switch on 'both', then to batt. #2, no small wires involved. Changing to the BlueSeas dual circuit switch and charging relay will provide a switch for the motor and balance the charging. I'm thinking I have a bad switch.
One thing I learned from all this is don't turn the battery switch off with the motor running. The only thing that prevented some expensive damage to my charging system is that the motor cable wasn't run through the switch. I'm sure most of you already knew that but I didn't, the rectifier on my Suzuki is $164 and in a bad place to remove.

Thanks, Craig.

'90 SR/WK #6017. PO of '79 SR/SK.

Edited by - ct95949 on 09/04/2015 10:18:17

ct95949
Captain

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Aruba
300 Posts

Response Posted - 09/05/2015 : 09:21:31

quote:
Originally posted by rdthoms

Blue Sea has a smaller version of that battery kit. That is what I intend to use when I do this upgrade. I think it is sufficient for our small boats/power setups. Let me know if you think otherwise.
Blue Sea Systems m-Series Mini Add-A-Battery System
http://www.defender.com/product3.jsp?path=-1|328|2290051|2290060&id=2263607

You're right Richard, the 65 amp model https://www.bluesea.com/products/7649/Mini_Add-A-Battery_Kit_-_65A is better suited to our small outboards and $20 cheaper. I just ordered one from Amazon for about $80 and free shipping.
Thanks, Craig.

'90 SR/WK #6017. PO of '79 SR/SK.

Edited by - ct95949 on 09/05/2015 09:22:34

Voyager
Master Marine Consultant

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5369 Posts

Response Posted - 09/06/2015 : 08:27:08

That is quite clever.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

Stu Jackson C34
Admiral

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844 Posts

Response Posted - 09/10/2015 : 09:33:45

quote:
Originally posted by ct95949

The old Guest switch I have has three studs so short only one lug will fit with the nut flush with the end of the stud.
This is what I think I'll get, I like the four studs and separating the batteries:
https://www.bluesea.com/products/7650/Add-A-Battery_Kit_-_120A
Do you know any reason though, why I wouldn't get some of that charging voltage through the switch to the second battery?
Thanks, Craig.

Craig, all this discussion and photos is helpful, but a real wiring diagram would make it a lot easier to help you.

There are four positions on a battery switch (1, 2 B, or OFF), only three studs on the back (C 1 & 2).

The engine should be tied to the C post. When it is off, the switch POSITION determines which battery is used to provide the power to start.

When the engine is ON, the switch position determines which battery gets charged.

The Blue Seas Switch is not really good for sailboats, it is better for small to medium sized motorboats that start and stop their engines often, very often.

Here's why that switch is not so good, and why your old 1,2,B is quite fine:

AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
http://forums.catalina.sailboatowners.com/showthread.php?p=848465&highlight=darn%20agm

Stu
1986 C34 #224 "Aquavite"
Cowichan Bay, BC Maple Bay Marina
(formerly San Francisco)
(formerly C25 #2459 "Capricorn Two")

OLarryR
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3462 Posts

Response Posted - 09/10/2015 : 09:45:15

Stu - Thanks for the link. Based on the various ways to recharge w or w/o equalizing, interesting estimated battery life.

I have AGM batteries I installed a year or so ago. My solar panel provides daily charging and batteries are generally in the fully charged state each time I go sailing. I guess time will tell how long I get out of my 2 batteries. I leave the battery switch in the "Both" mode all the time. I do not equalize charging - Do not have a battery combiner or isolator installed.

Larry
'89 Robin's Nest#5820, Potomac River/Quantico, Va
http://catalina25.homestead.com/olarryr.html

rdthoms
Deckhand

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USA
15 Posts

Response Posted - 09/10/2015 : 09:54:04

Stu - Well now I'm confused again. I thought I had done my homework and read up on this issue with another post from Maine Sail (http://forums.sbo.sailboatowners.com/showthread.php?t=137615) and that was driving me to use the Blue Sea Dual Circuit switch. Is that not what he is recommending in that post?

Here is what I want. Dual identical batteries. 1/2/Both/Off switch which I would not mind turning to #1 on odd days of sailing and #2 on even days of sailing as long as in both cases I've got power to the electric start motor and house circuits, and the motor will give charge to the #1 or #2 battery depending on the selection of the day. As an added bonus I would like to be able to leave a single trickle charger connected to keep both batteries topped off in the slip. I thought the BSDCS would allow all of the above??

Richard
Huntsville, AL
1984 Catalina 25 SR/FK #4309

awetmore
Master Marine Consultant

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1144 Posts

Response Posted - 09/10/2015 : 10:21:35

I don't see a reason to setup isolated battery banks on a boat with an outboard.

You do it on an inboard boat so that you can start the engine if you accidentally run down the house batteries overnight. On an outboard boat you can start the engine manually, so that isn't a concern.

It greatly simplifies the system to just parallel the batteries all of the time and treat them as a single battery.

Alex W
Seattle, WA
Express 37 "re-Quest"
previously owned 1984 Catalina 25 "Lutra"

rdthoms
Deckhand

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USA
15 Posts

Response Posted - 09/11/2015 : 07:01:08

Parallel batteries would definitely be easier but I've read that can cause problems when one battery goes bad (say low voltage) and starts drawing power from the good battery.

Richard
Huntsville, AL
1984 Catalina 25 SR/FK #4309

Stu Jackson C34
Admiral

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844 Posts

Response Posted - 09/12/2015 : 08:13:03

quote:
Originally posted by rdthoms

Stu - Well now I'm confused again. I thought I had done my homework and read up on this issue with another post from Maine Sail (http://forums.sbo.sailboatowners.com/showthread.php?t=137615) and that was driving me to use the Blue Sea Dual Circuit switch. Is that not what he is recommending in that post?

Here is what I want. Dual identical batteries. 1/2/Both/Off switch which I would not mind turning to #1 on odd days of sailing and #2 on even days of sailing as long as in both cases I've got power to the electric start motor and house circuits, and the motor will give charge to the #1 or #2 battery depending on the selection of the day. As an added bonus I would like to be able to leave a single trickle charger connected to keep both batteries topped off in the slip. I thought the BSDCS would allow all of the above??

That linked thread is about the advantages of the simple 1-2-B switch and includes: "If you kill a bank don't fall into the trap of combining the dead bank with a perfectly good one by using the BOTH feature." Since all the BSDCS does is combine banks, I'm not sure how you came to that conclusion.

Your second para is wrong, the BSDCS will not do that, a 1-2-B will.

Stu
1986 C34 #224 "Aquavite"
Cowichan Bay, BC Maple Bay Marina
(formerly San Francisco)
(formerly C25 #2459 "Capricorn Two")

ct95949
Captain

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Aruba
300 Posts

Response Posted - 09/17/2015 : 07:44:11

You make some good points Stu and thanks for the links. But the studs on my switch only have room for three cables, no room for a motor and fuse panel cable. Your way says that batteries should be isolated, not run parallel, correct? And as Alex points out an outboard can always be started manually. The Blue Seas switch seems like it would actually be better for a small boat that doesn't rely on batteries to start the motor.

I just wanted to switch off all the battery cables when I leave the boat and have both batteries charge equally. I can't do that with the old switch I have now, I'm sure the newer switches have longer studs that accept multiple cables.
Thanks, Craig.

'90 SR/WK #6017. PO of '79 SR/SK.

Edited by - ct95949 on 09/17/2015 07:53:48

Stu Jackson C34
Admiral

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844 Posts

Response Posted - 09/18/2015 : 17:36:45

quote:
Originally posted by ct95949

You make some good points Stu and thanks for the links. But the studs on my switch only have room for three cables, no room for a motor and fuse panel cable. Your way says that batteries should be isolated, not run parallel, correct? And as Alex points out an outboard can always be started manually. The Blue Seas switch seems like it would actually be better for a small boat that doesn't rely on batteries to start the motor.

I just wanted to switch off all the battery cables when I leave the boat and have both batteries charge equally. I can't do that with the old switch I have now, I'm sure the newer switches have longer studs that accept multiple cables.
Thanks, Craig.

Craig, then what you do is buy a Power Post or a bus bar and lead all the wires to it, and then only one wire from the PP or bb to the switch lug. Simple.

Stu
1986 C34 #224 "Aquavite"
Cowichan Bay, BC Maple Bay Marina
(formerly San Francisco)
(formerly C25 #2459 "Capricorn Two")

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