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How to combine batteries with this setup
I was thinking about adding a battery combiner to my boat's electrical
system, but I may have to rethink this. Present System ------------------ Bank 1 - Starting battery Bank 2 - House - 2x6V Trojans (225AH) Shore power charger - 2 bank Truecharge 10 charger connected direct to batteries with fused leads Alternator - 55Amp on Yanmar 2QM15. Presently, my alternator charges back via the starter motor cable. It leads to the common terminal of the "red" 1-2-All switch. The batteries are connected to the other two terminals in the usual way. So, I can chose to charge either battery or both. House load also connects to common terminal but also has it's own breaker switch. 1. Using Combiner ---------------------- I have looked at using the New Zealand made BEP VSR (Voltage Sensitive Relay) as the combiner. But, in reading their website, they warn against using such devices if the alternator and batteries are not matched. They say that for the combiner to work, the alternator must be larger (80-90A) or the batteries smaller (100-130AH). Otherwise, the unit will oscillate and not work properly. http://www.bepmarine.com/showproduct.cfm?productid=12 http://www.bepmarine.com/products/inst-710-100a-vsr(web).pdf Another supplier - Sure Power talks of same problem but says that time delay avoids chattering - But they don't provide details - Perhaps if alternator is connected to house battery, it may work better? http://www.surepower.com/separator.html West Marine do not mention this problem in my older catalogue. 2. Echo-Charge ------------------- Another possibility is to use a Xantrex Echo-Charge. http://www.xantrex.com/web/id/103/p/.../5/product.asp Seems alternator is connected to House bank. Then when voltage reaches 13v this unit actuates and then charges starting battery. No mention of cycling with undersize alternator. When unit kicks in, wouldn't voltage likely drop? 3. Diode isolator -------------------- Would work, but voltage drop would likely reduce battery capacity and life. 4. Manual switching ------------------------- That's what we do now! We have zap-Stop to protect alternator. But, it is easy to forget to switch the batteries. 5. New Alternator --------------------- Installing a larger alternator (say 120A) would be an option, but with single belt and a real HP output of less than 10HP at normal rpm, this could diminish engine output and perhaps put loads on engine that 'it's not designed for. (The 55A is the optional alt. - normal is 35A!). Seems overkill just to allow easier switching, but this would allow quicker recharging of house batteries. 6. Portable Generator -------------------------- This has passed my mind - Use a portable Honda to charge the house batteries. But at 10A, this would require a long run! Ideas, comments or condolences welcomed :) GM |
How to combine batteries with this setup
My current boat has two Optima starting bats plus a house bank with 4
6v Trojan T105's. Charging is with Xantrex 100 Amp, and a high output alternator plus solar panels. The factory setup was a large 3 bank combiner. I had to modify it when I added the high output alternator because the alternator output had to feed the house bank, not a starter battery, or else the regulator sensing gets very confused (which can lead to a meltdown!). Although the system works, I never like the "all or nothing" aspect of the combiner, and occasionally it would cycle on and off for no apparent reason. Finally I got an EchoCharge for about $100 and use that to charge the starting bats, which are still on the combiner. I've found no downside (so far) to this setup. The starting batteries get an appropriate trickle charge whenever a charge source is available, and everything is disconnected otherwise. The starting batteries virtually never present a large load, so there is no noticeable "kick in" of the EchoCharge. I don't like the diode isolator solution, because of the voltage drop which means you have to raise the voltage in the regulator to compensate. And it seems you're just converting some of your juice to heat. As for adding a "120 Amp alternator," your battery bank will not accept that much power. Even with a smart regulator, it would only accept about 50 Amps. On the other hand, your 55 Amp Yanmar (actually probably Hitachi) alternator probably only puts out about 25-30 Amps, because it has a simple built in regulator. The new alternator would want a smart regulator, so this is adding up to a serious upgrade - if you want thoughtful advice on this you'll have to tell us want you plan to power with this! The Honda generator is not a bad way to go, I've been on the verge of getting one for a few years. The output is much higher than 10 Amps, because you can feed the AC output into your battery charger. Several threads here discuss the efficiency losses. My problem is that I'm not likely to equal the 100 Amps my alternator puts out, but if I had a smaller system, this would be an attractive alternative. Most of my sisterships (PDQ 36) have outboards rather than diesels, and many use a Honda 2000 for charging. GBM wrote: I was thinking about adding a battery combiner to my boat's electrical system, but I may have to rethink this. Present System ------------------ Bank 1 - Starting battery Bank 2 - House - 2x6V Trojans (225AH) Shore power charger - 2 bank Truecharge 10 charger connected direct to batteries with fused leads Alternator - 55Amp on Yanmar 2QM15. Presently, my alternator charges back via the starter motor cable. It leads to the common terminal of the "red" 1-2-All switch. The batteries are connected to the other two terminals in the usual way. So, I can chose to charge either battery or both. House load also connects to common terminal but also has it's own breaker switch. 1. Using Combiner ---------------------- I have looked at using the New Zealand made BEP VSR (Voltage Sensitive Relay) as the combiner. But, in reading their website, they warn against using such devices if the alternator and batteries are not matched. They say that for the combiner to work, the alternator must be larger (80-90A) or the batteries smaller (100-130AH). Otherwise, the unit will oscillate and not work properly. http://www.bepmarine.com/showproduct.cfm?productid=12 http://www.bepmarine.com/products/inst-710-100a-vsr(web).pdf Another supplier - Sure Power talks of same problem but says that time delay avoids chattering - But they don't provide details - Perhaps if alternator is connected to house battery, it may work better? http://www.surepower.com/separator.html West Marine do not mention this problem in my older catalogue. 2. Echo-Charge ------------------- Another possibility is to use a Xantrex Echo-Charge. http://www.xantrex.com/web/id/103/p/.../5/product.asp Seems alternator is connected to House bank. Then when voltage reaches 13v this unit actuates and then charges starting battery. No mention of cycling with undersize alternator. When unit kicks in, wouldn't voltage likely drop? 3. Diode isolator -------------------- Would work, but voltage drop would likely reduce battery capacity and life. 4. Manual switching ------------------------- That's what we do now! We have zap-Stop to protect alternator. But, it is easy to forget to switch the batteries. 5. New Alternator --------------------- Installing a larger alternator (say 120A) would be an option, but with single belt and a real HP output of less than 10HP at normal rpm, this could diminish engine output and perhaps put loads on engine that 'it's not designed for. (The 55A is the optional alt. - normal is 35A!). Seems overkill just to allow easier switching, but this would allow quicker recharging of house batteries. 6. Portable Generator -------------------------- This has passed my mind - Use a portable Honda to charge the house batteries. But at 10A, this would require a long run! Ideas, comments or condolences welcomed :) GM |
How to combine batteries with this setup
"Jeff" wrote in message ... Finally I got an EchoCharge for about $100 The starting batteries get an appropriate trickle charge whenever a charge source is available, and everything is disconnected otherwise. The starting batteries virtually never present a large load, so there is no noticeable "kick in" of the EchoCharge. So perhaps this would work in my case? If my house bank gets up to 13v before this kicks in, and starting battery is at 12v or less, hopefully with my small alternator, voltage does not drop below 13v causing cycling? I don't like the diode isolator solution, because of the voltage drop which means you have to raise the voltage in the regulator to compensate. And it seems you're just converting some of your juice to heat. Yes, this is least attractive good option. As for adding a "120 Amp alternator," your battery bank will not accept that much power. Even with a smart regulator, it would only accept about 50 Amps. On the other hand, your 55 Amp Yanmar (actually probably Hitachi) alternator probably only puts out about 25-30 Amps, because it has a simple built in regulator. The new alternator would want a smart regulator, so this is adding up to a serious upgrade - if you want thoughtful advice on this you'll have to tell us want you plan to power with this! Presently, the boat (32 foot sail) would be used for short cruises - maybe up to a week long. It will have new refrigeration that will draw 4 amps when running and hopefully no more than 40AH per day. Other loads are lights, radios, instruments, Autohelm (seldom used), windlass (not presently connected). I expect I will have to run engine for a couple of hours per day or get back to shore power. The Honda generator is not a bad way to go, I've been on the verge of getting one for a few years. The output is much higher than 10 Amps, because you can feed the AC output into your battery charger. I would like to get one too. I could probably sell the idea to the "management" as a safety item for home power back up next time we have an ice-storm or other unforeseen power outage. On the boat, our engine does not have a heat exchanger, and I have considered this as a way of producing hot water - Run the generator for a while - charge the batteries and heat the hot water. A bit of an expensive solution, but a nice-to-have! Thanks for the input GM GBM wrote: I was thinking about adding a battery combiner to my boat's electrical system, but I may have to rethink this. Present System ------------------ Bank 1 - Starting battery Bank 2 - House - 2x6V Trojans (225AH) Shore power charger - 2 bank Truecharge 10 charger connected direct to batteries with fused leads Alternator - 55Amp on Yanmar 2QM15. Presently, my alternator charges back via the starter motor cable. It leads to the common terminal of the "red" 1-2-All switch. The batteries are connected to the other two terminals in the usual way. So, I can chose to charge either battery or both. House load also connects to common terminal but also has it's own breaker switch. 1. Using Combiner ---------------------- I have looked at using the New Zealand made BEP VSR (Voltage Sensitive Relay) as the combiner. But, in reading their website, they warn against using such devices if the alternator and batteries are not matched. They say that for the combiner to work, the alternator must be larger (80-90A) or the batteries smaller (100-130AH). Otherwise, the unit will oscillate and not work properly. http://www.bepmarine.com/showproduct.cfm?productid=12 http://www.bepmarine.com/products/inst-710-100a-vsr(web).pdf Another supplier - Sure Power talks of same problem but says that time delay avoids chattering - But they don't provide details - Perhaps if alternator is connected to house battery, it may work better? http://www.surepower.com/separator.html West Marine do not mention this problem in my older catalogue. 2. Echo-Charge ------------------- Another possibility is to use a Xantrex Echo-Charge. http://www.xantrex.com/web/id/103/p/.../5/product.asp Seems alternator is connected to House bank. Then when voltage reaches 13v this unit actuates and then charges starting battery. No mention of cycling with undersize alternator. When unit kicks in, wouldn't voltage likely drop? 3. Diode isolator -------------------- Would work, but voltage drop would likely reduce battery capacity and life. 4. Manual switching ------------------------- That's what we do now! We have zap-Stop to protect alternator. But, it is easy to forget to switch the batteries. 5. New Alternator --------------------- Installing a larger alternator (say 120A) would be an option, but with single belt and a real HP output of less than 10HP at normal rpm, this could diminish engine output and perhaps put loads on engine that 'it's not designed for. (The 55A is the optional alt. - normal is 35A!). Seems overkill just to allow easier switching, but this would allow quicker recharging of house batteries. 6. Portable Generator -------------------------- This has passed my mind - Use a portable Honda to charge the house batteries. But at 10A, this would require a long run! Ideas, comments or condolences welcomed :) GM |
How to combine batteries with this setup
We made the West Marine battery combiner for them for 13 years but now
are using Defender as our primary retailer - you will find Defender's prices are much better than WM had. I don't know what is wrong with other combiners but we've not had any of the problems you describe with over 26,000 sold and all on UNCONDITIONAL warranty. If there were a problem we surely would have heard something by now. You can download the owner's manual from http://www.yandina.com/acrobats/C150Data.pdf and you will find a number of suggested schematics. You can contact Defender at http://www.defender.com/product.jsp?path=-1|328|51495|606044&id=605590 I will be happy to answer any questions you have. Regards, Andina Marie Foster, |
How to combine batteries with this setup
GBM wrote:
"Jeff" wrote in message ... Finally I got an EchoCharge for about $100 .... So perhaps this would work in my case? If my house bank gets up to 13v before this kicks in, and starting battery is at 12v or less, hopefully with my small alternator, voltage does not drop below 13v causing cycling? The actual use for starting is about 60 amps times a few seconds, so the starting battery is never discharged more than a few percent (unless its been off a charger for a few weeks or more). While is may use a significant portion of the alternator output for a few minutes, it will quickly settle into a trickle charge mode. ... if you want thoughtful advice on this you'll have to tell us want you plan to power with this! Presently, the boat (32 foot sail) would be used for short cruises - maybe up to a week long. It will have new refrigeration that will draw 4 amps when running and hopefully no more than 40AH per day. Other loads are lights, radios, instruments, Autohelm (seldom used), windlass (not presently connected). I expect I will have to run engine for a couple of hours per day or get back to shore power. Our previous boat was similar to yours (2 6v batteries) and we had an older Danfoss system. The load was about 50-65 AH per day, which took about 1.5 hours to recharge. Even though we had a high output alternator, the smaller bank limited the charge rate. The cheapest thing we could have done, though not always the easiest thing on a small boat, would be to add more battery storage. If you have a good place to stash 2 more 6v bats, you could double capacity for under $200. This would mean you could go 2-3 days without running the engine, greatly increasing the chance you recharge in the normal course of using the boat. This is a frustrating issue, because the urge is to find a "proper" solution, but that costs money. I would love to find a "half decent" alternator/regulator that was under $500, or an amp-hour meter for $50. The only thing that seems cheap are the batteries! I would like to get one too. I could probably sell the idea to the "management" as a safety item for home power back up next time we have an ice-storm or other unforeseen power outage. On the boat, our engine does not have a heat exchanger, and I have considered this as a way of producing hot water - Run the generator for a while - charge the batteries and heat the hot water. A bit of an expensive solution, but a nice-to-have! For this I do have a solution: the black bag. My old boat even had a propane hot water heater, but we preferred the black bag, especially for summer vacations. This was even a way to conserve water and get exercise, since I would row into the town dock to fill up one or two black bags. |
How to combine batteries with this setup
"Jeff" wrote This is a frustrating issue, because the urge is to find a "proper" solution, but that costs money. I would love to find a "half decent" alternator/regulator that was under $500, or an amp-hour meter for $50. The only thing that seems cheap are the batteries! In researching this, I came across what seems a reasonable solution made by Blue Seas. It consists of their Batterylink and their Dual Circuit battery switch http://www.bluesea.com/Article_detai..._ID=137&id=273 Cost seems to be reasonable. Does this seem like a reasonable way to go? GBM |
How to combine batteries with this setup
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How to combine batteries with this setup
GBM wrote:
"Jeff" wrote This is a frustrating issue, because the urge is to find a "proper" solution, but that costs money. I would love to find a "half decent" alternator/regulator that was under $500, or an amp-hour meter for $50. The only thing that seems cheap are the batteries! In researching this, I came across what seems a reasonable solution made by Blue Seas. It consists of their Batterylink and their Dual Circuit battery switch http://www.bluesea.com/Article_detai..._ID=137&id=273 Cost seems to be reasonable. Does this seem like a reasonable way to go? GBM It looks like a battery combiner. Its more expensive then some, but with adjustable set points it is probably a reasonable value. My personal preference is for an EchoCharge, which is only a few dollars more. In fact, I was willing to buy one even though I already had a combiner similar to the ACR. My issue is that I frequently discharge my house bank and then spend an hour or more charging at fairly high voltage. A combiner would be overcharging the starting batteries during these times. The EchoCharge allows the starting batteries to trickle charge, while the house bank getting 90 Amps. |
How to combine batteries with this setup
"Jeff" wrote My personal preference is for an EchoCharge, which is only a few dollars more. In fact, I was willing to buy one even though I already had a combiner similar to the ACR. My issue is that I frequently discharge my house bank and then spend an hour or more charging at fairly high voltage. A combiner would be overcharging the starting batteries during these times. The EchoCharge allows the starting batteries to trickle charge, while the house bank getting 90 Amps. Jeff, If the combiner is set to close the contact at say 13.5v, my concern is that with House at low level, this might not happen before I want to turn the engine off, so the starting battery gets no charge at all! This would presumably be true for Echo-Charge too. Regarding the Echo-Charge vs ACR. In the case of the combiner, once the contact closes, the alternator "sees" both batteries. Wouldn't the current flow distribute itself where needed? I have read that the current to the starting battery should be limited by the wire gauge used. I think I read that oversizing the connections can cause problems such as too high a current flow through the combiner. In the case of the Echo-Charge, how does it "control" the current flow? Is it just a resistor? GBM |
How to combine batteries with this setup
GBM wrote:
"Jeff" wrote My personal preference is for an EchoCharge, which is only a few dollars more. In fact, I was willing to buy one even though I already had a combiner similar to the ACR. My issue is that I frequently discharge my house bank and then spend an hour or more charging at fairly high voltage. A combiner would be overcharging the starting batteries during these times. The EchoCharge allows the starting batteries to trickle charge, while the house bank getting 90 Amps. Jeff, If the combiner is set to close the contact at say 13.5v, my concern is that with House at low level, this might not happen before I want to turn the engine off, so the starting battery gets no charge at all! This would presumably be true for Echo-Charge too. I don't follow. Unless you have a real dead battery, which can screw up all the readings, the alternator will put out 14+ Volts right from the beginning. The contacts will close and both will be charged. The starting battery should never be less than 90% so it should get close to fully charged while you're warming up the engine. There are cases (hopefully rare) when you'll have to do some charging just to get the house bank up to a reasonable state, but you don't want to combine a dead house bank with the starting bank anyways. A trickier issue might be charging from a weak source, such as a solar panel. Regarding the Echo-Charge vs ACR. In the case of the combiner, once the contact closes, the alternator "sees" both batteries. Wouldn't the current flow distribute itself where needed? The current will "distribute itself" but there will be one voltage, and that may be too high. In my case I use AGM starting batteries which can be killed by overcharging. But you do raise a question: if the regulator is instructing the alternator based on its perception of the battery state, how does it tell the difference between the house bank and the starter bank? You must make sure that everything is sensing at the correct point. For instance, I had to disconnect the alternator from the starter and starting battery since the primary recipient of the juice was to be the house bank. These issues convinced me that the EchoCharge was the way to go: the output of the alternator went to the house bank, so the regulator's sense was driven by that. The EchoCharge acts as a second regulator, doing the proper thing for the starting bank. The only bad scenario is a dead starting bank and a full house bank - this requires some special jumpering, either a switch (as I had in my previous boat) or a jumper wire (which I have provision for in my current boat). I have read that the current to the starting battery should be limited by the wire gauge used. Dangerous thinking there - small wires limit current with a voltage drop. The reduced voltage may prevent the battery from overcharging but the wires will be heating up! Also, it means that what the regulator thinks is a trickle charge will be no charge at all at the end of the voltage drop. I think I read that oversizing the connections can cause problems such as too high a current flow through the combiner. In the case of the Echo-Charge, how does it "control" the current flow? Is it just a resistor? I don't know the internals, but I'm sure its not a resistive load - that would generate heat, which it doesn't do. There are lots of ways to do it with modern components. If you buy a 15 Amp battery charger how does it control the flow when the socket you plug into can deliver 200 amps? It certainly isn't by wire size! Perhaps someone with a deeper understanding of electronics will correct me, but I've never heard that "oversized" wires cause a problem by passing too much current. On the contrary, the voltage drop can really mess up any attempt to regulate the charge voltage. |
How to combine batteries with this setup
"Jeff" wrote in
I have read that the current to the starting battery should be limited by the wire gauge used. Dangerous thinking there - small wires limit current with a voltage drop. The reduced voltage may prevent the battery from overcharging but the wires will be heating up! Also, it means that what the regulator thinks is a trickle charge will be no charge at all at the end of the voltage drop. I think I read that oversizing the connections can cause problems such as too high a current flow through the combiner. In the case of the Echo-Charge, how does it "control" the current flow? Is it just a resistor? Perhaps someone with a deeper understanding of electronics will correct me, but I've never heard that "oversized" wires cause a problem by passing too much current. On the contrary, the voltage drop can really mess up any attempt to regulate the charge voltage. Jeff - I read about this in this link: http://www.yandina.com/acrobats/C150Data.pdf that was posted here by Andina Marie Foster. This is what is says: 3. Connect one high current terminal to the positive terminal of each battery bank. Secure the ring terminals tightly under the flat washer and lock washer supplied on each Combiner 150 power terminal. A 7/16" socket wrench will be required to access these connections in the insulated cavities. No other cables should be on these terminals at the combiner end. IMPORTANT:- Use only 6 gauge cable. Use a minimum of 6 feet of wire total between the positive battery terminals to connect the combiner. DO NOT use a heavier gauge (lower gauge #) wire. Do not coil excess wire which can confine heating or create magnetic fields and upset your compass. The insignificant resistance in these leads will result in no voltage loss at end of charge but it is enough to protect the Combiner 150 from excessive currents which can flow when the batteries are first connected in parallel. And also from Yandina site: Q Is the 6 gauge wire recommended for the 150 amp combiner heavy enough? A Yes, in fact this is a MAXIMUM size, using a heavier gauge can damage the combiner. Increasing the length above the minimum recommended can actually prolong the contact life with virtually no reduction in charging efficiency. See the following question for more information. Q I installed a 50 amp combiner on my boat which has a 90 amp alternator. Last year the contacts welded shut so I replaced it but now it has happened again. Should I have used a 150 amp combiner? A No, the 50 amp combiner is probably adequate. Typically only a portion of the current flows through the combiner because the charging source is connected directly to one of the banks. Your problem is most likely that the installer did too good a job and did not follow the installation instructions. The intuition that bigger is better applies to most installations, however it can kill a combiner. The instructions for the 150 amp combiner recommend a minimum wire run from the battery of 3 feet to each combiner terminal and recommend a wire size no heavier than 6 gauge. The leads come already attached with the 50 and 100 amp combiner which must not be shortened. This wire has a negligible resistance to the normal charging current and has zero voltage drop as the batteries reach full charge but it does have enough resistance and inductance to prevent the contacts welding when the batteries being combined are at different voltages and one battery is supplying high power to the other for a few seconds. This kind of thing makes me wonder if I am adding yet another item that might give me trouble! GBM |
How to combine batteries with this setup
GBM wrote:
"Jeff" wrote in I have read that the current to the starting battery should be limited by the wire gauge used. Dangerous thinking there - small wires limit current with a voltage drop. The reduced voltage may prevent the battery from overcharging but the wires will be heating up! Also, it means that what the regulator thinks is a trickle charge will be no charge at all at the end of the voltage drop. I think I read that oversizing the connections can cause problems such as too high a current flow through the combiner. In the case of the Echo-Charge, how does it "control" the current flow? Is it just a resistor? Perhaps someone with a deeper understanding of electronics will correct me, but I've never heard that "oversized" wires cause a problem by passing too much current. On the contrary, the voltage drop can really mess up any attempt to regulate the charge voltage. Jeff - I read about this in this link: http://www.yandina.com/acrobats/C150Data.pdf that was posted here by Andina Marie Foster. This is what is says: 3. Connect one high current terminal to the positive terminal of each battery bank. Secure the ring terminals tightly under the flat washer and lock washer supplied on each Combiner 150 power terminal. A 7/16" socket wrench will be required to access these connections in the insulated cavities. No other cables should be on these terminals at the combiner end. IMPORTANT:- Use only 6 gauge cable. Use a minimum of 6 feet of wire total between the positive battery terminals to connect the combiner. DO NOT use a heavier gauge (lower gauge #) wire. Do not coil excess wire which can confine heating or create magnetic fields and upset your compass. The insignificant resistance in these leads will result in no voltage loss at end of charge but it is enough to protect the Combiner 150 from excessive currents which can flow when the batteries are first connected in parallel. OK. But what's really going on here is that the normal high current path is from the alternator (or large charger) directly to the large house bank. It would be foolish to use 6 gauge for this because when passing 100 Amps the Voltage drop could be 10% (check out the chart in the West Catalog). This can have a HUGE affect on the charging if 14.4 Volts is dropped to 13! (People don't always consider that if the alternator is 12 feet from the battery, the run is 24 feet, and even 1 gauge will have 3% drop, or 0.4 Volts, enough to greatly affect performance.) The wire they are talking about is tapping off that to feed the combiner which feeds the starting battery. For the primary purpose of keeping that battery charged, the current flow is probably under 15 Amps so there is no issue at all with Voltage drops. In the rare case where the charging current is high enough to cause a drop, the situation would resolve itself fairly quickly. Thus, they can use smaller relays with the reduced current. However, if you want to use the house bank for starting the engine (by forcing the combiner) then you're getting back into a high current range where the will be a drop, something you might not want in this situation! Consider that your house bank could be down to 12 Volts, then you find your starting battery is dead. Forcing the combiner seems like the right thing, but the starter load (plus the load of the dead battery) means that the current in the 6 gauge forces a 10% voltage drop, and now you trying to start the engine with under 11 Volts! This is why I have shutoff switches on each battery and can quickly rewire any battery to either starter. And also from Yandina site: Q Is the 6 gauge wire recommended for the 150 amp combiner heavy enough? A Yes, in fact this is a MAXIMUM size, using a heavier gauge can damage the combiner. Increasing the length above the minimum recommended can actually prolong the contact life with virtually no reduction in charging efficiency. See the following question for more information. Q I installed a 50 amp combiner on my boat which has a 90 amp alternator. Last year the contacts welded shut so I replaced it but now it has happened again. Should I have used a 150 amp combiner? A No, the 50 amp combiner is probably adequate. Typically only a portion of the current flows through the combiner because the charging source is connected directly to one of the banks. Your problem is most likely that the installer did too good a job and did not follow the installation instructions. The intuition that bigger is better applies to most installations, however it can kill a combiner. The instructions for the 150 amp combiner recommend a minimum wire run from the battery of 3 feet to each combiner terminal and recommend a wire size no heavier than 6 gauge. The leads come already attached with the 50 and 100 amp combiner which must not be shortened. This wire has a negligible resistance to the normal charging current and has zero voltage drop as the batteries reach full charge but it does have enough resistance and inductance to prevent the contacts welding when the batteries being combined are at different voltages and one battery is supplying high power to the other for a few seconds. This doesn't make me happy. Or perhaps I should say I feel justified in switching to the EchoCharge. It also might explain why I've seen a few combiners fail when the relay are "certified for millions of cycles"! This kind of thing makes me wonder if I am adding yet another item that might give me trouble! GBM |
How to combine batteries with this setup
"Jeff" wrote OK. But what's really going on here is that the normal high current path is from the alternator (or large charger) directly to the large house bank. It would be foolish to use 6 gauge for this because when passing 100 Amps the Voltage drop could be 10% (check out the chart in the West Catalog). The articles were talking about teh actual combiner leads, not the lead from the alternator. But, seeing you brought it up , in my case I will actually use 6 ga. But, I only have a 55A alternator and the return trip run is only about 10ft. But, do see your point. At present, my alternator feed is via the 2 ga starter cable but this will change when I go to the House bank. However, if you want to use the house bank for starting the engine (by forcing the combiner) then you're getting back into a high current range where the will be a drop, something you might not want in this situation! The Blue Seas two circuit switch I referenced earlier has a manual combine position - We would use that as we do now with the old switch in the Both position. This doesn't make me happy. Or perhaps I should say I feel justified in switching to the EchoCharge. It also might explain why I've seen a few combiners fail when the relay are "certified for millions of cycles"! True - It seems like there can be problems, but many boats have combiners and most seem to be happy with them. Thanks for your input - It is useful! GBM |
How to combine batteries with this setup
Batteries are charged with current - ie. amps, not volts. You measure
charge in amp-hours, not volts. So a low battery will drop the charger voltage to the battery voltage. If there is 10% voltage drop in the cable (which it isn't!) then that is because ALL the current the charging source can supply is being absorbed by the battery. As the battery reaches full charge the regulator will reduce the current to stop the voltage getting too high. As the current is reduced, the voltage drop along the protection cables will also drop so finally at end of charge there is no voltage drop in the cable. ALL the current going through the cable is going into the battery! All our combiners include a manual combine. Adjustable threshold settings are not necessary and we eliminated them in 1995 because the potentiometer was a maintenance item. All our combiners include an optional 14.2 volt cut-off that you can use to protect a gel type battery from the high voltages often found on lead acid batteries. The blue seas unit is just a battery combiner copy of ours. We invented the combiner in 1993. We are the cheapest. Ours are the only ones carrying an UNLIMITED warranty. We have sold over 26,000 of them all on unlimited warranty! We get about 20 returns per year of which about 15 have nothing wrong with them. There is an extensive FAQ on battery combiners at http://www.yandina.com/combInfo.htm Regards, Andina Marie Foster, |
How to combine batteries with this setup
wrote in message oups.com... I use something similar to the Bluesea - Smartbank split charge controller - www.smartgauge.co.uk That site has some very interesting technical info - Well worth a read! GBM |
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