I am currently installing an onboard generator in our 1998 Hunter 376. The factory set it up for a starter battery (group 24) and a house battery (4D). They installed a separate switch for both the starter and the house bank. There is no cross over switch. The alternator on the engine and the 120volt shore power battery charger, charge both banks. I replaced the Group 24 engine starter battery with a group 27 battery. I cannot use the starter battery to power the house devices. This is a safety measure so I can start the engine should all of the house capacity be depleted. I am adding a battery for the exclusive use of starting the generator. With that said, I am think of combining my engine starter battery and my house bank. This would allow almost 50% more amp hours overall to the house. Should we accidentally overuse the combined house/engine starter bank, we would have the generator to charge the system. With space and weight being such a premium, it seems like an appropriate proposition. Does anyone have an opinion on this? Is there anyone who is an expert on this? I think I can handle the modification of the wiring but does anyone have experience on this subject? Any comments will be appreciated. Thanks in advance, Mike D P.S. We have replaced the factory battery charger with a True Charge 20. The current batteries are gel and the battery that I am going to buy for the generator will probably also be a gel type.
- Status
- Not open for further replies.
G
Gord
Combined Batteries VS Emerg. Cross-Connect
I'm not in favour of combining different sized batteries; but would prefer to install an emergency paralell switch between your new Engine Start Battery, and your House Bank, and (perhaps) another between your Engine and (new) Generator Start Batteries. This will leave you in charge of your house power utilization. When the house bank is low - YOU choose to switch over to engine battery power (or not). In any case, your system is probably not ideal. The Truecharge 20 will charge two batteries of the same type (Gel ?), but differing sizes (4D House & Gr 27 Eng. Start), but will your engine alternator do the same? Does your Generator have an adequate alternator? I've seen many instances of Generators that don't adequately re-charge their own start battery. It gets a little complicated, so contact me if you wish to discuss these issues in detail. <Gord@Boatpro.zzn.com>
I'm not in favour of combining different sized batteries; but would prefer to install an emergency paralell switch between your new Engine Start Battery, and your House Bank, and (perhaps) another between your Engine and (new) Generator Start Batteries. This will leave you in charge of your house power utilization. When the house bank is low - YOU choose to switch over to engine battery power (or not). In any case, your system is probably not ideal. The Truecharge 20 will charge two batteries of the same type (Gel ?), but differing sizes (4D House & Gr 27 Eng. Start), but will your engine alternator do the same? Does your Generator have an adequate alternator? I've seen many instances of Generators that don't adequately re-charge their own start battery. It gets a little complicated, so contact me if you wish to discuss these issues in detail. <Gord@Boatpro.zzn.com>
J
Jack Tyler
Conceptually - good idea; devi's in details
Mike, you've no doubt already found there are a 100 different opinions on how to set up battery banks. Your basic goal - concentrate all the amp/hrs you can in your house bank while protecting separate engine start capability - is advocated by Nigel Calder, among others. (Suggest you review the electrical section in his Mechanical/Electrical Guide for more info). Besides, how often have you already found yourself in a remote location with your house bank dead? While we all try to plan for this event, it seems fairly rare IME. I would encourage you to reconsider your wiring plans to allow you to start either the generator or engine from the start battery, which will give you even more flexibility. (If the complexity of switches, wires and auto-connecting devices like a Batt Max to do this gets to expensive or confusing, don't overlook carrying and using a simple set of jumper cables when needing more options. Not electrically optimum, but not a bad idea either). But keep in mind that all batteries to be charged should be of the same construction/chemistry. Also, having a house bank of varying size batteries isn't optimum and you might think about moving to identical house bank batteries over time as the existing batteries' performance drops. The real bugaboo in increasing the house bank is how to get a charge back in (vs. what we usually think of, which is how much more we get to take out). With an external regulator and hicap alternator, you'll still need to anticipate longer charging times to get the house bank up to near 80-85% while unplugged and cruising. If you have a conventional internally regulated alternator, a larger bank will inevitably be undercharged frequently (on a sailboat, at least) which can harm the batteries' chemistry. Not a factor when anchoring overnight before returning to the slip & BYC (Big Yellow Cord) but increasingly so if planning multi-day cruises. Every night the batteries will start out with less capacity and, if primarily sailing the following day, fall even further. Good luck on the project. And BTW why a generator? Jack
Mike, you've no doubt already found there are a 100 different opinions on how to set up battery banks. Your basic goal - concentrate all the amp/hrs you can in your house bank while protecting separate engine start capability - is advocated by Nigel Calder, among others. (Suggest you review the electrical section in his Mechanical/Electrical Guide for more info). Besides, how often have you already found yourself in a remote location with your house bank dead? While we all try to plan for this event, it seems fairly rare IME. I would encourage you to reconsider your wiring plans to allow you to start either the generator or engine from the start battery, which will give you even more flexibility. (If the complexity of switches, wires and auto-connecting devices like a Batt Max to do this gets to expensive or confusing, don't overlook carrying and using a simple set of jumper cables when needing more options. Not electrically optimum, but not a bad idea either). But keep in mind that all batteries to be charged should be of the same construction/chemistry. Also, having a house bank of varying size batteries isn't optimum and you might think about moving to identical house bank batteries over time as the existing batteries' performance drops. The real bugaboo in increasing the house bank is how to get a charge back in (vs. what we usually think of, which is how much more we get to take out). With an external regulator and hicap alternator, you'll still need to anticipate longer charging times to get the house bank up to near 80-85% while unplugged and cruising. If you have a conventional internally regulated alternator, a larger bank will inevitably be undercharged frequently (on a sailboat, at least) which can harm the batteries' chemistry. Not a factor when anchoring overnight before returning to the slip & BYC (Big Yellow Cord) but increasingly so if planning multi-day cruises. Every night the batteries will start out with less capacity and, if primarily sailing the following day, fall even further. Good luck on the project. And BTW why a generator? Jack
D
Don Alexander
More Capacity
Mike, On my 1996 376 I needed more house capacity. However the locker was too narrow at the base to allow the batteries to be mounted athwartships. Then I realised that there was considerable space above the existing batty so I fitted a false bottom in the locker about 1 3/4" above the original and then was able to put my batteries athwartships. Now I have 4 batteries connected together for the house supply - see archives. Also, although I did not get a circuit of the DC power in my manual, I discovered a 'Battery Combiner' solenoid in the space under and behind the chart table and this connects both engine and start batteries together when the engine starts. It may do so as soon as the ignition switch is turned or when the alternator begins to charge, but I haven't checked this out yet. You may have one of these too. If your aim is to simply start your genny why not use the engine battery? The starting load from a generator will be small and you would not persist if the generator did not start quickly. Incidentally my Yanmar starts first time every time so I have left the engine battery alone - since 1996! Good luck.
Mike, On my 1996 376 I needed more house capacity. However the locker was too narrow at the base to allow the batteries to be mounted athwartships. Then I realised that there was considerable space above the existing batty so I fitted a false bottom in the locker about 1 3/4" above the original and then was able to put my batteries athwartships. Now I have 4 batteries connected together for the house supply - see archives. Also, although I did not get a circuit of the DC power in my manual, I discovered a 'Battery Combiner' solenoid in the space under and behind the chart table and this connects both engine and start batteries together when the engine starts. It may do so as soon as the ignition switch is turned or when the alternator begins to charge, but I haven't checked this out yet. You may have one of these too. If your aim is to simply start your genny why not use the engine battery? The starting load from a generator will be small and you would not persist if the generator did not start quickly. Incidentally my Yanmar starts first time every time so I have left the engine battery alone - since 1996! Good luck.
M
Mike O'Toole
Batteries Seperated
I eliminated the battery combiner on my 376 to have the alternator or charger/inverter directly charge the house batteries. I then installed a Heart Echo Charger to keep the starter battery charged up from the house batteries. The echo charger follows the charging cycle of the alternator or inverter/charger system but is limited to 15 amps max. I have 400 amp hr house system and 100 amp hr starter battery now. Works great.
I eliminated the battery combiner on my 376 to have the alternator or charger/inverter directly charge the house batteries. I then installed a Heart Echo Charger to keep the starter battery charged up from the house batteries. The echo charger follows the charging cycle of the alternator or inverter/charger system but is limited to 15 amps max. I have 400 amp hr house system and 100 amp hr starter battery now. Works great.
R
R.W.Landau
A word of caution
If you have a large house bank and it goes dead, I would not switch your switch to both to be able to use your house lights. The problem: Your starting battery will deliver all of it's charge to the depleated house bank thus discharging itself. This would not only depleate the starting battery but possibly overheat the starting battery with the rate of discharge. You can configure an emergency switching arrangement. This switch would cut the house battery out conpletely and only draw the power required from the starting battery. This arrangement also can be used in reverse to start the engine from the house battery without charging the starting battery. I think that the caution on combining batteries has already been mentioned. I agree that Nigel Calder is a good read for this question. r.w.landau
If you have a large house bank and it goes dead, I would not switch your switch to both to be able to use your house lights. The problem: Your starting battery will deliver all of it's charge to the depleated house bank thus discharging itself. This would not only depleate the starting battery but possibly overheat the starting battery with the rate of discharge. You can configure an emergency switching arrangement. This switch would cut the house battery out conpletely and only draw the power required from the starting battery. This arrangement also can be used in reverse to start the engine from the house battery without charging the starting battery. I think that the caution on combining batteries has already been mentioned. I agree that Nigel Calder is a good read for this question. r.w.landau
D
Don Alexander
Combiners - Strange!
Mike, Hunters fitted my combiner specifically to enable the alternator to charge both batteries. I have long pondered the warnings issued by some 'experts' about connecting a well charged battery across one that is in a low state of charge. In my experience, as soon as the smallest charging current flows into a battery, it immediately rises to 13.5 volts or more. As this is above the normal off charge and off load voltage of a fully charged battery there will be little current flowing from the charged battery to the low one. Accordingly I do not see how a combiner can result in a significant loss of charge from the engine battery. Two caveats - one is that if the house battery has a defective or short circuit cell then plenty of current will flow. The other is if left permanently connected the charges will eventually equalise out. In the case of a combiner the only time the batteries are connected together is when they are on charge. I haven't read Calder on this but if he says it will deplete the house battery then I suspect he may not have thought much about the problem. Is this heresy or does anyone know better please?
Mike, Hunters fitted my combiner specifically to enable the alternator to charge both batteries. I have long pondered the warnings issued by some 'experts' about connecting a well charged battery across one that is in a low state of charge. In my experience, as soon as the smallest charging current flows into a battery, it immediately rises to 13.5 volts or more. As this is above the normal off charge and off load voltage of a fully charged battery there will be little current flowing from the charged battery to the low one. Accordingly I do not see how a combiner can result in a significant loss of charge from the engine battery. Two caveats - one is that if the house battery has a defective or short circuit cell then plenty of current will flow. The other is if left permanently connected the charges will eventually equalise out. In the case of a combiner the only time the batteries are connected together is when they are on charge. I haven't read Calder on this but if he says it will deplete the house battery then I suspect he may not have thought much about the problem. Is this heresy or does anyone know better please?
M
Mike O'Toole
Combining Batteries
Don You raise interesting points. I had the same combiner as yours. When I redid my system to add more house battery capacity I also added a high output alternator (100 amp). I wasn't sure what would happen to my startbattery when the combiner paralled it with the much larger house system as the new alternator output is controlled by the charge state of the house system. So I decided to isolate it as much as possible by using this echo charger (one way current flow only). I've had it now for 3 seasons now and the system is working very well.
Don You raise interesting points. I had the same combiner as yours. When I redid my system to add more house battery capacity I also added a high output alternator (100 amp). I wasn't sure what would happen to my startbattery when the combiner paralled it with the much larger house system as the new alternator output is controlled by the charge state of the house system. So I decided to isolate it as much as possible by using this echo charger (one way current flow only). I've had it now for 3 seasons now and the system is working very well.
C
cole
- Status
- Not open for further replies.