Need to replace both of my batteries on my 22-90 Honda-currently have two starting batteries-rated 800 amps-wondering if I should get a deep cycle (house battery)and a starting battery- do not spend a lot of time on the hook and do not have/run big electronics while underway or at the dock-what's everyone else doing?
Batteries
- Thread starter ken 120
- Start date
My recent selection was two group 31 AGM, but I have probably more demand than the average. This also matches a year old group 31 AGM which I have been using as my freezer battery.
Before I had two DEKA "Marine Master" one an M 24 (starting) and DC 24 (deep cycle) lead acid batteries group 24, which appeared to be over 4 years old when I replaced them, and one was still in excellent condition--the other was marginal (the starting battery).
Before I had two DEKA "Marine Master" one an M 24 (starting) and DC 24 (deep cycle) lead acid batteries group 24, which appeared to be over 4 years old when I replaced them, and one was still in excellent condition--the other was marginal (the starting battery).
Robert H. Wilkinson
New member
Ken, I like to camp out on the hook/locks, etc. where no power is available. But like you I use very little power - I still use a deep cycle however just in case I do run it down. A start battery will be damaged if it is run down too far or too often.
If you are strictly looking to have a start battery with a backup then you would probably be ok with 2 group 24 650amp batteries. You can get them up to 1000amp but they are very heavy. Use some method to keep them separated though, both while in service and while being charged.
Regards, Rob
If you are strictly looking to have a start battery with a backup then you would probably be ok with 2 group 24 650amp batteries. You can get them up to 1000amp but they are very heavy. Use some method to keep them separated though, both while in service and while being charged.
Regards, Rob
Pat Anderson
New member
My thought, whatever you do, isolate your starting battery from your house battery or batteries with a VSR (voltage sensing relay). Your alternator connects to the VSR, which connects to both starting and house batteries. The VSR fully charges your starting battery first, and when it senses the starting battery is fully charged, it automatically switches over to charging the house battery or batteries. You never want to be in a situation where your battery usage has left you unable to start your engine! It is a "smart" battery switch for charging!
As far as batteries go, let your cruising style and budget determine what you get. You definitely want deep cycle batteries for the house. There are two ratings on batteries (forget about "cold cranking amps," that is an automobile thing). What you really want to know is amp hours (AH). If your battery or batteries are rated in reserve capacity (RC), divide by 2.4 to get a rough and apparently conservative converstion to AH. You want to know how much of your battery's AHs your boat's load will use up when the engine is not running. Our house batteries are two NAPA Premium Deep Cycle RV/Marine batteries, with an estimated 133 AHs. When we need new batteries we will probably get AGM batteries with considerably more AHs. We have a freezer and spend a lot of time on the hook. The freezer, lights and a little fan for our Airhead typically uses 20 AHs overnight.
You need to consider your own particular power needs. Say you have a fridge, with a 5 amp rating and a 50% duty cycle. It runs for 10 hours before your recharge. It is going to use up 25 AHs overnight (5 amps x 0.5 x 10). The number of AHs in your house battery or batteries will determine the state of charge (SOC) in the morning. You do not want to run your house battery completely down! So the more AHs you have the better your SOC will be with any given load. If you only have lights, and they are LED, then your power requirements will be a LOT less!
By me, a Victron Battery Monitor, or comparable battery monitor, is a very worthwhile investment if you really want to know what is going on with your power usage and you have any appreciable load. In my case, since I have solar panels, it also tells me how many AHs I have restored to my house batteries as well as how many I have used, and gives me SOC at any given moment. I really am loving my Victron!
We anchor out almost all the time, and even at a dock now, like Barry, we don't use shore power, so knowing what the state of our batteries is pretty important to us.
As far as batteries go, let your cruising style and budget determine what you get. You definitely want deep cycle batteries for the house. There are two ratings on batteries (forget about "cold cranking amps," that is an automobile thing). What you really want to know is amp hours (AH). If your battery or batteries are rated in reserve capacity (RC), divide by 2.4 to get a rough and apparently conservative converstion to AH. You want to know how much of your battery's AHs your boat's load will use up when the engine is not running. Our house batteries are two NAPA Premium Deep Cycle RV/Marine batteries, with an estimated 133 AHs. When we need new batteries we will probably get AGM batteries with considerably more AHs. We have a freezer and spend a lot of time on the hook. The freezer, lights and a little fan for our Airhead typically uses 20 AHs overnight.
You need to consider your own particular power needs. Say you have a fridge, with a 5 amp rating and a 50% duty cycle. It runs for 10 hours before your recharge. It is going to use up 25 AHs overnight (5 amps x 0.5 x 10). The number of AHs in your house battery or batteries will determine the state of charge (SOC) in the morning. You do not want to run your house battery completely down! So the more AHs you have the better your SOC will be with any given load. If you only have lights, and they are LED, then your power requirements will be a LOT less!
By me, a Victron Battery Monitor, or comparable battery monitor, is a very worthwhile investment if you really want to know what is going on with your power usage and you have any appreciable load. In my case, since I have solar panels, it also tells me how many AHs I have restored to my house batteries as well as how many I have used, and gives me SOC at any given moment. I really am loving my Victron!
We anchor out almost all the time, and even at a dock now, like Barry, we don't use shore power, so knowing what the state of our batteries is pretty important to us.
I'm going to have to disagree a little with Rob--I find that charging the batteries with an VSR that charging both batteries at the same time from the same source is fine. (However it may be slightly better using an identical set of batteries which do both--like the AGM's.). If you charged them separately with the outboard then at some point during the day you have to remember to switch over batteries with the 1/2/all switch--and not disconnect the charging lead to avoid damage to the diodes. If you have two charging circuits off the motor, that solves problems.
The danger might be over charging the starting battery, however, the outboard's charging circuits are not sophisticated as the 3 or 4 starge chargers. Certainly you should have a two bank charger if you have two batteries.
Just to clarify how a VSR (also called ACR) works: Although there may be some voltage differences this is a general scheme. When the battery voltage is 12.8 or less, the batteries are isolated from each other. When the starting battery is up to 13.5 volts (this does not mean that the starting battery is fully charged) and has begun to charge, then the relay closes, and the two batteries are combined, and charging as if they are one battery. (Some, but not all, if the charging voltage goes too high, it also opens the relay). As you shut off the motor, when the battery voltage drops below 12.8+/-, the batteries are disconnected, and remain isolated until charging occurs again.
Even a deep cycle battery's life will be shortened if it is run down. I use the 50% discharge as a good compromise--or open battery voltage of 12.2 volts as the limit of how much I discharge a battery. Digital volt meters are available on the internet for as little as $6 now days, and are a great investment to avoid battery damage.
The danger might be over charging the starting battery, however, the outboard's charging circuits are not sophisticated as the 3 or 4 starge chargers. Certainly you should have a two bank charger if you have two batteries.
Just to clarify how a VSR (also called ACR) works: Although there may be some voltage differences this is a general scheme. When the battery voltage is 12.8 or less, the batteries are isolated from each other. When the starting battery is up to 13.5 volts (this does not mean that the starting battery is fully charged) and has begun to charge, then the relay closes, and the two batteries are combined, and charging as if they are one battery. (Some, but not all, if the charging voltage goes too high, it also opens the relay). As you shut off the motor, when the battery voltage drops below 12.8+/-, the batteries are disconnected, and remain isolated until charging occurs again.
Even a deep cycle battery's life will be shortened if it is run down. I use the 50% discharge as a good compromise--or open battery voltage of 12.2 volts as the limit of how much I discharge a battery. Digital volt meters are available on the internet for as little as $6 now days, and are a great investment to avoid battery damage.
This may or may not help much. I don't have any of the fancy electronic switches or AGM batteries. Not that it would not be nice, but in the interest of keeping things really simple, I have 2 outboards, (40 Yami's, carbed and no electronic monitoring), and I have 2 batteries, fairly big - Group 29's that are Deep cycle and a 1-2-Both-Off switch. I typically run with the switch in the "Both" position, and m y last set of batteries lasted 6 years. I run a fairly large draw for electronics, and at night I use a CPAP machine about 7-8 hours. My SOC is usually at 12.8 or 12.9 when I stop for the night. CPAP for 8 hours will take it down to 12. 5. No lights at night, or fridge, or anchor watch monitor. Each engine charges it's own battery, and it is rare that I do not have them running together. Pretty simple, not much to remember, and so far has been very reliable.
The batteries are one each in the Lazarettes. My mechanic says he is good with a shoehorn and some slippery stuff.
Harvey
SleepyC :moon
The batteries are one each in the Lazarettes. My mechanic says he is good with a shoehorn and some slippery stuff.
Harvey
SleepyC :moon
Pat Anderson
New member
Harvey,
Maybe things work for you like that, sounds like they do, but I would not run at night with the switch in the "Both" position. One dead battery, the boat starts on the other one. Two dead batteries, no she go! My voltage at 100% SOC is 12.5 - 12.6 (after it settles in after charging). 80% SOC takes it down to about 12.2 volts. Just my $0.02 worth as general advice for everyone considering managing their batteries.
Pat
Maybe things work for you like that, sounds like they do, but I would not run at night with the switch in the "Both" position. One dead battery, the boat starts on the other one. Two dead batteries, no she go! My voltage at 100% SOC is 12.5 - 12.6 (after it settles in after charging). 80% SOC takes it down to about 12.2 volts. Just my $0.02 worth as general advice for everyone considering managing their batteries.
Pat
I took it to mean that Harvey "runs" -- as in moves along with the engine running - on the "both" position. This seems normal as then you are charging both batteries so that when you stop they are both as topped up as possible. Then you would switch to one battery while not underway, with the other reserved for starting.Pat Anderson":3kfces3y said:
One thing to mention (probably not a concern in reality if you have 24/27 or similar) but it's good to look at your ability to re-charge too. In other words, if you only have the engine alternator(s) for charging (this is how my boat is now), and that's giving you around 20 amps, then you probably don't want 300 amp hours of house battery, because you'd have to run for a loooooong time to ever charge it back up, even from 50%. When I was outfitting my boat, I read that around 5 times the alternator's output in house bank was a good baseline (of course if you typically do run for 14 hours between stops, then that's different).
I ended up with a cruising style system (smaller dedicated start battery/larger house battery, but I kept the house battery to one Group 31 (115 amp hours) until such time as I have additional means of re-charging (now just have engine alternator).
Anyway, just wanted to mention the concept of battery size vs. re-charging capability.
Other than I have Honda 40's instead of Yamahas & the batteries are AGM my set up is very similar to Harvey's. None of the fancy monitoring stuff just the simple 1,2 or all Perko switch. Time running both motors together has declined every year as I more & more prefer displacement speed cruising, though when run together I have found out the hard way the charge coils don't like the Perko, all, switch setting. If the motor rpm's are not kept very closely matched, which can be difficult to do in some sea places & conditions the differences in what's happening between the two motors electric grid (which I don't understand, but Les of EQ told me occurs) causes the burning out of the charge coil. This has happened to us twice once coming back through Venn Passage to Prince Rupert in 2004 & the other just as we entered Lisianski Strait coming in off the open Gulf of Alaska in 2007. So, to us the batteries are both house & start. Which battery I select for the house depends on their charge state monitored by a cheep 12v plug in, & can vary a lot, especially when running long periods at displacement speed, where the single Honda 40 only puts out 10 amps. Due to this low alternator output on cruises we carry a Honda 2000 generator set up to be easily run for charging or any other purpose whenever needed. I don't worry about switching on the go with the make before break switch.
Jay
Jay
I would agree with Pat and Jay, that it is best to not combine two batteries which are charging from two different engines. If running on one engine, then it does make sense.
The Group 29 battery is not as common as group 24, 27 or 31, but it is an excellent combination battery in the "marine" configuration. (Remebering that the "group" refers to case size)
The Group 29 battery is not as common as group 24, 27 or 31, but it is an excellent combination battery in the "marine" configuration. (Remebering that the "group" refers to case size)
Pat Anderson":1lnlt52l said:
Pat,
You are pretty close to right. I normally leave the switch in the "both" position for over night. After running, my SOC is usually about 12.8+. Then I turn the switch to "off" until I turn it back on for the night. I only run my CPAP at night plus my phone charger. Morning reading is about 12.5.
You are right about the dead battery, she no go, but I do carry a jump start set, in stead of a generator, and in 7 years have not used it once. I took it off the boat when I put the new batteries in this spring. I have had a plane to go to #1 on odd days and #2 on even days. I need to test it to see how far down my over night drain takes it. I figured it was better to have both on and us a little from each than to continuously be taking each battery down to or below the 12.2..
My monitoring device is a cheapo cig plug monitor, so nothing fancy but it gives me VDC and battery state as a bar graph. AND I check the bats every morning, night and engine run and shut down.
Jay, and Bob I have never thought about the different charge from running at different speeds. I don't do that much, usually try to keep pretty close to the same. Even when I cruise at hull speed I still run the twins equal.
Harvey
SleepyC :moon
After my summer cruise, Almost 2 months on Vancouver Island without taking my Jump start kit (a West Marine portable == about 10 pounds) and not having any electrical issue, I have decided to go back to carrying a jump start kit again. I found this one at Costco:
Lithium Jump Starter and Portable Power Bank
Features: High Output Jump Starter
2 USB Ports for Fast Charging of Mobile Devices
8000mAh High Capacity Power Bank
3 Mode Flashlight
Product Specifications:
Product Dimensions: 5.16 x 2.95 x 0.98 inch (131 x 75 x 25 mm)
Product Weight: 1.1 lbs (500g)
Capacity: 8000 mAh
Input: 12V 1A
Output: USB2.0; 5V 2A; 12V for car jump starter
Charging Time: 3 hours
Starting Current: 200A
Peak Current: 350A
Operating Temperature: -4ºF ~ 140ºF (-20ºC ~ 60ºC)
Package Includes:
Jump Start Power Bank
Jumper Cable with Built-In Polarity Protection
12V Car Charger
User’s Manual
Storage/Travel Case
Item #750766
Your Price$59.99
Shipping & Handling: $5.99 *
If it will start 3 or 4 V-8's on a single charge, it should be able to start my to little 3 cylinder Yami's. Pat, I hope this lets you sleep better. Thanks for putting the bug on me.
Harvey
SleepyC :moon
Lithium Jump Starter and Portable Power Bank
Features: High Output Jump Starter
2 USB Ports for Fast Charging of Mobile Devices
8000mAh High Capacity Power Bank
3 Mode Flashlight
Product Specifications:
Product Dimensions: 5.16 x 2.95 x 0.98 inch (131 x 75 x 25 mm)
Product Weight: 1.1 lbs (500g)
Capacity: 8000 mAh
Input: 12V 1A
Output: USB2.0; 5V 2A; 12V for car jump starter
Charging Time: 3 hours
Starting Current: 200A
Peak Current: 350A
Operating Temperature: -4ºF ~ 140ºF (-20ºC ~ 60ºC)
Package Includes:
Jump Start Power Bank
Jumper Cable with Built-In Polarity Protection
12V Car Charger
User’s Manual
Storage/Travel Case
Item #750766
Your Price$59.99
Shipping & Handling: $5.99 *
If it will start 3 or 4 V-8's on a single charge, it should be able to start my to little 3 cylinder Yami's. Pat, I hope this lets you sleep better. Thanks for putting the bug on me.
Harvey
SleepyC :moon