I have 2 batteries and a battery selector(1,2,all,off). Iam wondering if I could do a group 24 starting battery on 1 selector and a group 27 deep cycle on number 2?
2 BATTERY HOOK UP STARTING AND DEEP CYCLE
- Thread starter dickauge
- Start date
Yes.
To improve the system a bit more, make certain the alternator output goes to the house battery and the batteries are connected with an Automatic Charging Relay. While you're improving things, separate the house and start batteries by using a Dual Circuit Plus switch (e-Series Dual Circuit Plus™ Battery Switch - Blue Sea Systems) That will eliminate the problem of forgetting to change the battery switch.
To improve the system a bit more, make certain the alternator output goes to the house battery and the batteries are connected with an Automatic Charging Relay. While you're improving things, separate the house and start batteries by using a Dual Circuit Plus switch (e-Series Dual Circuit Plus™ Battery Switch - Blue Sea Systems) That will eliminate the problem of forgetting to change the battery switch.
And it will create MORE problems, like this one:
AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
https://forums.sailboatowners.com/index.php?threads/darn-agm-batteries.133773/
That switch is simply not a good choice for sailboats. It's fine for powerboats. Read the full link.
Careful with that veteran Pearson 28-1's battery selector switch. While most newer battery switches have a built-in protection, yours may not. You should never switch through OFF if the engine is running. If your switch isn't built to allow you to go through OFF safely, if the engine is running, you could fry the diode(s) on your alternator.
Another option, beyond the ACR is to use a battery Combiner. Defender sells them, as do others (or you can go directly to the manufacturer, Yandina https://www.yandina.com/combInfo.htm)
What type of battery charger do you have on your Pearson? Is it a "smart charger", and set for lead-acid batteries, and do you have two outputs on it, etc.
What is our practice for "topping" and keeping the batteries topped-up with shore power? Do you check the water level in the batteries often?
Another option, beyond the ACR is to use a battery Combiner. Defender sells them, as do others (or you can go directly to the manufacturer, Yandina https://www.yandina.com/combInfo.htm)
What type of battery charger do you have on your Pearson? Is it a "smart charger", and set for lead-acid batteries, and do you have two outputs on it, etc.
What is our practice for "topping" and keeping the batteries topped-up with shore power? Do you check the water level in the batteries often?
Using the Dual Circuit Plus switch with out adding additional switches for each battery can create different problems, not necessarily more problems.
The most common issue with 1-2-both switches (assuming you have "make before break" switches) is leaving the switch on both and draining both batteries thus not being able to start the engine to recharge the batteries.
With a single dual circuit switch a problem that can occur is having one bank go bad and not being able to use the other bank in its place, for example if the start battery dies, it is not possible to switch to the house bank to start the engine without disconnecting the start battery by either turning a switch or physically disconnecting the start battery.
The goal for the wiring system should be to offer both the ability to completely isolate a good battery from a bad battery and to offer redundancy. The 1-2-both switch does that at the potential cost of draining both batteries simultaneously. The Dual Circuit Plus switch makes it easy to isolate the batteries, at the cost of redundancy. The redundancy cost can be mitigated by adding separate on/off switches on each battery. If a battery is dead, turn its switch off and put the DC Plus switch on Combine and all systems, including the starter, will run off the remaining bank.
Take a good look at wiring schematic that Maine Sail posted on the link Stu referenced.
The DCP switch has the same potential of draining both batteries simultaneously as the 1/2/B has... There are a heck of a lot of the DCP switches installed, without an ACR, and folks still need to use the "BOTH" or "PARALLEL" position to charge both banks.
Dickauge:
What is your protocol for charging your batteries under way; and, at the dock. What's your general practice of use, etc.
It's not at all unusual to have two batteries and a 1-BOTH-2-OFF selector switch. What is a bit unusual is to have two different batteries for the two banks without some other provisions. IT CAN WORK -- but it would be best to understand how you use the boat, etc.
If the "Engine Start" battery (as you describe it) is just back-up, that's different than that's the one that you plan on switch to when you start the engine. Then, how you use the boat (your loads from equipment, cruising patterns, shore charging, etc. becomes more critical. If you had two of the same batteries (WHICH YOU DON'T), then the OLD practice that we used decades ago went something like:
What is your protocol for charging your batteries under way; and, at the dock. What's your general practice of use, etc.
It's not at all unusual to have two batteries and a 1-BOTH-2-OFF selector switch. What is a bit unusual is to have two different batteries for the two banks without some other provisions. IT CAN WORK -- but it would be best to understand how you use the boat, etc.
If the "Engine Start" battery (as you describe it) is just back-up, that's different than that's the one that you plan on switch to when you start the engine. Then, how you use the boat (your loads from equipment, cruising patterns, shore charging, etc. becomes more critical. If you had two of the same batteries (WHICH YOU DON'T), then the OLD practice that we used decades ago went something like:
On "even numbered days", use battery bank 1; and on "odd numbered days" use battery bank 2. That was based on having the batteries charged by a regulator that could charge two banks independently or a combiner (of sorts).
You left your batteries on 1 or 2 -- and you avoided BOTH. If you didn't have dual charging capability, you could charge on "BOTH", but only leave the switch on one- or the other.
There are work arounds -- but it depends on YOU, how much attention YOU pay to what your doing, and HOW YOU USE THE boat and its systems.
You left your batteries on 1 or 2 -- and you avoided BOTH. If you didn't have dual charging capability, you could charge on "BOTH", but only leave the switch on one- or the other.
There are work arounds -- but it depends on YOU, how much attention YOU pay to what your doing, and HOW YOU USE THE boat and its systems.
This what I ve done for the past four years without problems even though we spend a lot of time at anchor with ac refrigeration. Both are group 24, number one is start, number 2 is house. Always leave selector to number two. Shore power charger independently charges both, solar only charges house, engine charges what the slector is set to which always the house. When the house battery goes my intention is to replace it with goup 27 as two golf cart batteries may not fit.
Trying to find a way to have more cranking power on 1 battery and a deep cycle on the other one. But, did not know if the two batteries needed to be identical
If the batteries are placed in parallel, they will work better if matched by brand, size, date of manufacture. If they will be used independently, one for house, one for start, then they don't need to be matched. In your application, they should work so long as they are not routinely placed in parallel.
Lots of us have very mismatched battery banks, I have 4 6v golf cart batteries wired in series/parallel for the house battery and group 24 starting bank. The house bank has 460 ah, the start battery about 70 ah. They are always isolated from each other except for the ACR when charging.
The mechanisms for dealing with them when not-in-parallel become for procedural, i.e. different protocols, additional separations of charging circuits and controllers, etc.
My suggestion was aimed at trying to help Dick[A]uge keep it as simple as possible with what he's got. If you want to simple manage so that you don't make a mistake, putting two identical battery banks on Bank 1 and Bank 2 (adequate capacity Group 27 Deep Cycle batteries will clearly start his engine, if charged, in most conditions outside of "Minnesota in the winter" :^)))). Then he can focus on making sure he leaves one-bank in a position he can always get home.
IF Dickauge wants to go from a very simple system there are a LOT of things he can do to step-by-step get more sophisticated. I think that in order for him to decide which steps and how fart to go, we should better understand his boat, how he sails it, how involved he wants to be in managing his systems, and (finally) what his tolerance for spending money is. :^)))).
My suggestion was aimed at trying to help Dick[A]uge keep it as simple as possible with what he's got. If you want to simple manage so that you don't make a mistake, putting two identical battery banks on Bank 1 and Bank 2 (adequate capacity Group 27 Deep Cycle batteries will clearly start his engine, if charged, in most conditions outside of "Minnesota in the winter" :^)))). Then he can focus on making sure he leaves one-bank in a position he can always get home.
IF Dickauge wants to go from a very simple system there are a LOT of things he can do to step-by-step get more sophisticated. I think that in order for him to decide which steps and how fart to go, we should better understand his boat, how he sails it, how involved he wants to be in managing his systems, and (finally) what his tolerance for spending money is. :^)))).
Even though deep cycle batteries aren't built to have large cranking capacity they should still have plenty to start a small diesel.
I'd ditch the start battery and get another deep cycle. wire them just like you suggest to the three way switch and then leave the switch in both all the time except when you are going to be on the battery for a long period of time and want to be able to start the motor after AND no shore power will be available. that is to say anchoring over night or long sails with more than usual power drains like a long night sail. In those cases switch off one battery so you can be sure you can get the motor started.
The deep cycle will start the engine just fine. Consider that the admiral runs the hair dryer off the house bank and it draws 1000 watts for 10 minutes or more. 1000 watts = 120 amps @ 12 volts. would you EVER crank your starter for 10 minutes straight even if it only draws 50-75 amps?
The deep cycle will start the engine just fine. Consider that the admiral runs the hair dryer off the house bank and it draws 1000 watts for 10 minutes or more. 1000 watts = 120 amps @ 12 volts. would you EVER crank your starter for 10 minutes straight even if it only draws 50-75 amps?