Dual Batteries - One died.........

Redphone107

Cadet
Joined
Jun 17, 2015
Messages
25
Hello boaters. I have a quick question. I have a 2017 Hurricane CC19 with two Deka Marine Master (24M7) cranking batteries with a Perko switch to separate them. I went to tender the batteries since we are in dead of winter, and found the 2nd battery will not take a charge. My Schumacher digital charger will get it to about 73% charge and then shut down. The battery had a 12 month warranty and is now out of that date range (07/17-07/18). FYI: Most electronics on the boat go to the switch first as to not drain the batteries, but the bilge pump is direct-wired to the 2nd battery for automatic pumping even when the switch is off. Also, I have an amplifier for speakers wired with + to the perko and - to the 2nd battery. My questions:

1) Could the bilge still be drawing enough power being direct-wired to drain the battery?

2) Could the amp still be drawing current or something even wired through the Perko?

3) If I replace that one battery, could I replace it with a deep-cycle battery? This is primarily the battery that we use when parking on the lake and listening to music and running the lights. That is, do both the batteries have to be identical seeing that when we are driving the boat, I switch to "All " on the Perko to charge both. Is there an issue with having two different batteries that are connected by the switch? Also, when I replaced batteries in my diesel truck, I had to replace both at the same time. Do I need to replace both batteries since one when dead?

Thank you for all the advice. I just don't want to ruin a new battery by replacing with the wrong one.
 

harringtondav

Commander
Joined
May 26, 2018
Messages
2,438
It's unusual for a one yr old battery to go bad just from completely discharging unless it froze or lost enough fluid to expose the plates. Make sure the fluid is topped off and completely discharge it again. I use a 12V auto running light socket with alligator clips. Then try to recharge again. This may wake it up if it's not damaged, or defective from day one.

Deep cycle batteries are preferred for auxiliary power. They're designed to be drawn to flat line and recharged to full. Charging a cranking battery and your house (deep cycle) battery in tandem is common, no problem.
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,583
1) Could the bilge still be drawing enough power being direct-wired to drain the battery?

No, only way is if it was running

2) Could the amp still be drawing current or something even wired through the Perko?

Yes, if the amp was ON even if radio was OFF

3) If I replace that one battery, could I replace it with a deep-cycle battery?

Yes

do both the batteries have to be identical seeing that when we are driving the boat, I switch to "All " on the Perko to charge both. Is there an issue with having two different batteries that are connected by the switch?

No, both do not need to be identical
No, issue with bats attached to same switch so long as one bat does not have a problem and switch stays connected. The switch connection places bats in parallel, and they can be changed that way, but it can also damage one of them if one goes bad.

Also, when I replaced batteries in my diesel truck, I had to replace both at the same time. Do I need to replace both batteries since one when dead?

Different animal, but the diesel needs to bats when weather gets cold to start. The truck always is charging and discharging both full time. in warm weather the truck only needs one bat to start. So if one bat gets weak, its best to replace both

Suggest the best way to wire your bats is with a Automatic Charge Relay (ACR). the ACR will change both when the motor is running, and will disconnect when motor stops, with no need to move perko to both. If your using a lot of power out of the house bat (stereo and amp) and the motor does not run long enough to fully recharge, then it will have some issues over time, a deep cycle would be best, and maybe even a on board charger

Click image for larger version  Name:	Two Bat one switch and ACR.jpg Views:	11 Size:	41.5 KB ID:	10697284
 

Redphone107

Cadet
Joined
Jun 17, 2015
Messages
25
Harrington - Thank you. I will try to discharge the battery fully and start over. I had not thought about that. And it is good to know that I can charge both batteries at once on the lake even though they are different types.

AllDodge - I will look into an ACR like you have shown. I will have to check the amp to see if it is remaining on after the switch is turned off. I think it has a remote wire that goes to the radio to shut it off when the radio goes off. I will see. Again, I think I will replace the 2nd battery with a deep-cycle this time since we use it for running the stereo and lights while at float. Thank you both for the advice. I really appreciate it!!
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
15,417
I've had dead batteries coming out of weatherization twice in 25 years. Both where the result of bilge pump failures.

The first was the result of water freezing in the bilge actuating the float switch. Burned the motor up killing the battery.

The second failure was an oddity. A short in the bilge pump winding leaked (shorted) to ground which was then feed back into the lighting circuit. No bilge pump, but you could switch the lights off and on with the switch for the bilge pump. The hazard of multiple ground planes on a boat.

I have two Grp. 27 deep cycle batteries with an ACR on my boat. Date codes...4/10 and 5/11

The primary (start) battery supports motor functions and primary navigation (Chart Recorder and VHF) The "house" supports non-essentials (sonar, backup electronics) and peripherals.
 

JASinIL2006

Vice Admiral
Joined
Feb 10, 2012
Messages
5,525
Harrington - Thank you. I will try to discharge the battery fully and start over. I had not thought about that. And it is good to know that I can charge both batteries at once on the lake even though they are different types.

AllDodge - I will look into an ACR like you have shown. I will have to check the amp to see if it is remaining on after the switch is turned off. I think it has a remote wire that goes to the radio to shut it off when the radio goes off. I will see. Again, I think I will replace the 2nd battery with a deep-cycle this time since we use it for running the stereo and lights while at float. Thank you both for the advice. I really appreciate it!!

Get the Blue Sea Add-A-Battery kit. Comes with an ACR and a modified Perko-type switch. It makes adding an ACR an easy process. (The included instructions are pretty awful, but there are lots of folks here who can advise if you can't figure out connections.)
 

Old Ironmaker

Captain
Joined
Dec 28, 2015
Messages
3,050
I've had a Deca go bad after 2 seasons. I took it back to the Marine dealer I bought the boat from and many things for the boat and they just gave me a new battery, that is excellent customer service, no wonder they have been in business for 75 years. I don't know your relationship with the seller but I would return it. If you don't ask you will never know.
 
Top