RE: [vintagvw] Battery isolation relay -- number
Bert, Don't know for sure what/where/how you bought what you did, but according to the net it is a glow plug relay. http://www.ebay.com/itm/Diesel-Glow-Plug-Relay-BOSCH-0-332-002-156-/170647516431 example schematic here. http://www.fordmuscle.com/archives/2003/02/electricfan/index.php This might not be what you want. You might want to take a look at this and use something similar from a real vw? http://www.thesamba.com/vw/forum/viewtopic.php?t=297050 Cheers, dave On Fri, 15 Mar 2013, Bert Knupp wrote: Dave (and all), The new Bosch Batterietrennrelais is Nr. 0 332 002 156. It has a schematic printed on top -- but that doesn't tell me exactly what I need. Bert -Original Message- From: vintagvw@googlegroups.com [mailto:vintagvw@googlegroups.com] On Behalf Of Dave C. Bolen Sent: Friday, March 15, 2013 10:34 AM To: Vintage VW Air-Cooled Discussion Group Subject: Re: [vintagvw] Battery isolation relay Bert, Part number for the new Bosch part please? Also, Let's think through your description of how this really works. From you explanation of the original relay wiring that has only 4 terminals, I am not sure that it works the way you think it does. On the original: 51 is the feed providing charging power to either of the two batteries(or could it only be both at the same time!) 61 is ground when the generator is off(I am pretty sure) and provides a small positive comparison voltage when the car is charging(red light on or off comparison to the battery charging state). I am going to guess that when the charging system was off that you could pull the equipment battery all the way down and it would charge up after you restarted...andthat was about it. On the other hand...I have never owned one ofthese of a bus with the dual battery and don't know how it worked in a late model bus. My bet is that both batteries got the same charging current after the engine was started, but the equipment battery would give it's all and then that would be that till you restarted the car. Do you have a type2 manual with the same relay described in it? Seems kinda weird that VW(or Bosch) would use different devices to do the same thing for VW. Send the part number! Bet I can find a reference diagram. Cheers, dave On Fri, 15 Mar 2013, Bert Knupp wrote: Volks, I need some help. Various VW models over the years have used dual-battery systems: campers, sound trucks, fire engines, and police cars to name a few. The two batteries are connected via an isolation relay (in German it’s a “Batterie-Trennrelais”). The idea is to permit both batteries to charge from the generator or alternator, but to “uncouple” the #2 equipment battery when the voltage drops below 11 volts, making sure that the #1 or starting battery doesn’t get pulled down by the equipment. For example, in the police cars, it allowed the car to sit working an accident with the blue light, flashers and radio running but the engine off. If the available voltage dropped below 11 volts, the starting battery would disconnect so the car could start when done. So I’m recreating the Copbug’s two-battery system. I’ve mounted the #2 battery under the left rear seat and found a 75-amp Bosch isolation relay on-line. The problem: the four terminals on the new Bosch relay don’t match the four terminals on the VW factory bulletin for police-car wiring. I’m usually pretty good at logicking-through circuits, but I’m stumped here. The factory bulletin shows an isolation relay with four terminals: 51, 61, 86 and 87. 61 comes from the 61 terminal on the voltage regulator. Skinny wire. 51 comes from the B+ terminal on the voltage regulator. Fat wire. 86 goes out to the #1 (starting) battery (+). Fat wire. 87 goes out to the #2 (equipment) battery (+). Fat wire. The new isolation relay comes with four terminals also: 85-, 86+, 30 and 87. The 30-to-87 circuit seems to be the switch that opens and closes. The 85-to-85 circuit seems to be the coil activation. The 87 and 51 terminals are high-amp screw terminals. The 85 and 86 terminals are low-amp Faston slip-on tabs. But I can’t figure what’s what. Can anybody help me? How do I hook up the new relay to do the job? I’ve written to Bosch, but I won’t hold my breath. The last time I asked them for help, the reply came 5 months later – and they said they didn’t have information on the old equipment. Aargh! Bert Knupp in Music City USA -- Visit the VintagVW archives at http://mail-archive.com/vintagvw@googlegroups.com --- -- Visit the VintagVW archives at http://mail-archive.com/vintagvw@googlegroups.com --- You received this message because you are subscribed to the Google Groups VintagVW - Air Cooled Volkswagen Discussion List group. To unsubscribe from this group and stop receiving emails from it, send an email to vintagvw+unsubscr...@googlegroups.com. To post to this group, send email to vintagvw@googlegroups.com. Visit
Re: [vintagvw] Battery isolation relay
Every once in awhile, a question comes up that I actually feel qualified to chime in on. I am an electrical control system engineer with 25 years in power plants, and relay logic is a second language to me Check your wiring descriptions again- the description for the 'new' relay doesn't match the terminals you said it had Where did you get the information that this relay was a drop-out on low voltage? If you are translating, you should double-check. The information I can find only deals with the standard VW setup that disconnects the aux battery when the alternator is not providing charging current. Does the 11 volts refer to the alternator output? That would make more sense, but after looking at the codes and wiring description you gave, there is still some confusion. I pulled out one of my generic 30 amp replacement relays, and it has 85 86 for the coil, 30 for the common of the relay contacts, 87 for the normally open terminal (not connected to common when the coil is not energized) and 87a for the normally closed relay contact (connected to common when the coil is not energized). The DIN codes for these are: 30, input from + battery terminal, direct 85, Output, actuator (end of winding to ground or negative) 86, Start of winding 87, Input 87a, 1st output (break side) In the Westy 2-battery wiring, 86 goes to the 61 (alternator light) terminal; 30 comes from the B+ or hot of the main battery; 87 goes to the aux battery; and 85 is grounded. This disconnects the aux from the main battery when the engine is off, connects them to charge the aux when the engine is running. 87a is not connected. I looked up the code numbers on your relays in the list of standard DIN designators. VW has used these designators forever, every one I have worked on uses the same codes and most modern Japanese and American cars do too: Original DIN Codes: 51, DC voltage at rectifier 61, Alternator charge-indicator lamp 86, Start of winding 87, Input 86 should be the coil- are you sure this one is connected to the main battery positive? This seems like it would always be energized There is no 85 terminal- presumably it grounds through the mounting tab (or other screw) to the body. Alternatively, it could be that the 61 terminal is the other end of the coil- the alternator/generator light terminal is ground when the engine is not running, which would energize the relay when the engine is off. Possibly, this would connect all loads to the aux when the engine is shut down, but I don't get how the charging takes place... without the rest of the circuit, I can't be sure. If the wiring is as you say, I'd have to say that this may be a 'special' relay, usually called a voltage sensitive relay, that has a fixed drop-out voltage of 11 volts and a pickup voltage near the charging voltage, so would disconnect the aux when the system voltage dropped to 11 volts and reconnect it when the system voltage was about 12.8-13 volts. It would not be replaceable by a 'standard' disconnect relay. I have never seen this arrangement on a VW, though. New DIN designators: 30, input from + battery terminal, direct 85, Output, actuator (end of winding to ground or negative) 86, Start of winding 87, Input The new relay uses codes that tell you what the relay does, it is presumably generic for the relay. The 85 86 terminals are the coil. One (85) needs to be grounded, the other needs to go to the charge indicator light (old 61). 87 should connect to 30 when the relay energized- 87 would be the aux battery, 30 the alternator output (or main battery positive terminal, which are electrically the same. (this is where your description is confusing- looks like you have more than 4 terminals?? Is the one you called 51 actually the 30 terminal?) This arrangement is then just like the late bus, with the aux disconnecting from the main battery when the engine is off. This arrangement works very well and would be a good alternative. Power all the auxiliary loads from the aux, and they will be supplied by the alternator when the engine is running, but won't pull down the main battery when the car is off. Hope this helps- if you can find out any more, let us know and we can try to refine this. Glen Hadley On 3/15/2013 10:11, Bert Knupp wrote: Battery isolation relay Volks, I need some help. Various VW models over the years have used dual-battery systems: campers, sound trucks, fire engines,andpolice cars to name a few.The two batteries are connected via an isolation relay (in German it's a Batterie-Trennrelais). The idea is to permit both batteries to charge from the generator or alternator, but to uncouple the #2 equipment battery when the voltage drops below 11 volts, making sure that the #1 or starting battery doesn't get pulled down by the equipment. For example, in the police cars, it allowed the car to sit working an accident with the blue light,
Re: [vintagvw] Battery isolation relay
With the batteries connected in parallel, they cannot have different voltages (axiomatic- they are connected by a very low resistance wire, and current will flow as needed to keep them at the same voltage). The relay can't be triggered by a difference between the batteries. This description makes me think very strongly that it is a voltage sensitive relay, dropping out at about 10 volts, which could not be replaced by a 'standard' relay like the one you have. Glen Hadley On 3/15/2013 14:37, Bert Knupp wrote: Battery isolation relay As described in the factory's shop bulletin, the relay is /actually/ supposed to open the circuit only when the potential between battery #1 and ground drops below 10.0 volts, but keep them connected in parallel so long as both battery #1 and battery #2 hold 10 volts or better. In other words, the relay is triggered by having a (pos+) feed to both coil terminals, one from each battery. If one battery begins to run down, it creates a difference in potential (voltage) between the two batteries, opening the relay so #2 gets cut loose in order to stop it from running down #1. -- Visit the VintagVW archives at http://mail-archive.com/vintagvw@googlegroups.com --- You received this message because you are subscribed to the Google Groups VintagVW - Air Cooled Volkswagen Discussion List group. To unsubscribe from this group and stop receiving emails from it, send an email to vintagvw+unsubscr...@googlegroups.com. To post to this group, send email to vintagvw@googlegroups.com. Visit this group at http://groups.google.com/group/vintagvw?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
[vintagvw] Battery isolation relay
Volks, I need some help. Various VW models over the years have used dual-battery systems: campers, sound trucks, fire engines, and police cars to name a few. The two batteries are connected via an isolation relay (in German it's a Batterie-Trennrelais). The idea is to permit both batteries to charge from the generator or alternator, but to uncouple the #2 equipment battery when the voltage drops below 11 volts, making sure that the #1 or starting battery doesn't get pulled down by the equipment. For example, in the police cars, it allowed the car to sit working an accident with the blue light, flashers and radio running but the engine off. If the available voltage dropped below 11 volts, the starting battery would disconnect so the car could start when done. So I'm recreating the Copbug's two-battery system. I've mounted the #2 battery under the left rear seat and found a 75-amp Bosch isolation relay on-line. The problem: the four terminals on the new Bosch relay don't match the four terminals on the VW factory bulletin for police-car wiring. I'm usually pretty good at logicking-through circuits, but I'm stumped here. The factory bulletin shows an isolation relay with four terminals: 51, 61, 86 and 87. 61 comes from the 61 terminal on the voltage regulator. Skinny wire. 51 comes from the B+ terminal on the voltage regulator. Fat wire. 86 goes out to the #1 (starting) battery (+). Fat wire. 87 goes out to the #2 (equipment) battery (+). Fat wire. The new isolation relay comes with four terminals also: 85-, 86+, 30 and 87. The 30-to-87 circuit seems to be the switch that opens and closes. The 85-to-85 circuit seems to be the coil activation. The 87 and 51 terminals are high-amp screw terminals. The 85 and 86 terminals are low-amp Faston slip-on tabs. But I can't figure what's what. Can anybody help me? How do I hook up the new relay to do the job? I've written to Bosch, but I won't hold my breath. The last time I asked them for help, the reply came 5 months later - and they said they didn't have information on the old equipment. Aargh! Bert Knupp in Music City USA -- Visit the VintagVW archives at http://mail-archive.com/vintagvw@googlegroups.com --- You received this message because you are subscribed to the Google Groups VintagVW - Air Cooled Volkswagen Discussion List group. To unsubscribe from this group and stop receiving emails from it, send an email to vintagvw+unsubscr...@googlegroups.com. To post to this group, send email to vintagvw@googlegroups.com. Visit this group at http://groups.google.com/group/vintagvw?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
RE: [vintagvw] Battery isolation relay
Bert, Carefully reading through your description I think it should be wired like this: New Relay Regulator 86+ B+ terminal 85- 61 New Relay battery 51 #1 (starting) 87 #2 (equipment) Operation would be as follows: if the coil is activated, the generator/alternator is running. Due to that, both + terminals of the batteries are connected to the charging circuit. If the coil is not activated, the + terminals are separated, resulting in two separate electrical circuits in the car. Note though that I have no access to hardware here, all the above is based on your description and reasoning. HTH, Peter. :-) From: vintagvw@googlegroups.com [mailto:vintagvw@googlegroups.com] On Behalf Of Bert Knupp Sent: Friday, March 15, 2013 4:11 PM To: Vintage VW Air-Cooled Discussion Group Subject: [vintagvw] Battery isolation relay Volks, I need some help. Various VW models over the years have used dual-battery systems: campers, sound trucks, fire engines, and police cars to name a few. The two batteries are connected via an isolation relay (in German it's a Batterie-Trennrelais). The idea is to permit both batteries to charge from the generator or alternator, but to uncouple the #2 equipment battery when the voltage drops below 11 volts, making sure that the #1 or starting battery doesn't get pulled down by the equipment. For example, in the police cars, it allowed the car to sit working an accident with the blue light, flashers and radio running but the engine off. If the available voltage dropped below 11 volts, the starting battery would disconnect so the car could start when done. So I'm recreating the Copbug's two-battery system. I've mounted the #2 battery under the left rear seat and found a 75-amp Bosch isolation relay on-line. The problem: the four terminals on the new Bosch relay don't match the four terminals on the VW factory bulletin for police-car wiring. I'm usually pretty good at logicking-through circuits, but I'm stumped here. The factory bulletin shows an isolation relay with four terminals: 51, 61, 86 and 87. 61 comes from the 61 terminal on the voltage regulator. Skinny wire. 51 comes from the B+ terminal on the voltage regulator. Fat wire. 86 goes out to the #1 (starting) battery (+). Fat wire. 87 goes out to the #2 (equipment) battery (+). Fat wire. The new isolation relay comes with four terminals also: 85-, 86+, 30 and 87. The 30-to-87 circuit seems to be the switch that opens and closes. The 85-to-85 circuit seems to be the coil activation. The 87 and 51 terminals are high-amp screw terminals. The 85 and 86 terminals are low-amp Faston slip-on tabs. But I can't figure what's what. Can anybody help me? How do I hook up the new relay to do the job? I've written to Bosch, but I won't hold my breath. The last time I asked them for help, the reply came 5 months later - and they said they didn't have information on the old equipment. Aargh! Bert Knupp in Music City USA -- Visit the VintagVW archives at http://mail-archive.com/vintagvw@googlegroups.com --- You received this message because you are subscribed to the Google Groups VintagVW - Air Cooled Volkswagen Discussion List group. To unsubscribe from this group and stop receiving emails from it, send an email to vintagvw+unsubscr...@googlegroups.commailto:vintagvw+unsubscr...@googlegroups.com. To post to this group, send email to vintagvw@googlegroups.commailto:vintagvw@googlegroups.com. Visit this group at http://groups.google.com/group/vintagvw?hl=en. For more options, visit https://groups.google.com/groups/opt_out. -- The information contained in this communication and any attachments is confidential and may be privileged, and is for the sole use of the intended recipient(s). Any unauthorized review, use, disclosure or distribution is prohibited. Unless explicitly stated otherwise in the body of this communication or the attachment thereto (if any), the information is provided on an AS-IS basis without any express or implied warranties or liabilities. To the extent you are relying on this information, you are doing so at your own risk. If you are not the intended recipient, please notify the sender immediately by replying to this message and destroy all copies of this message and any attachments. ASML is neither liable for the proper and complete transmission of the information contained in this communication, nor for any delay in its receipt. -- Visit the VintagVW archives at http://mail-archive.com/vintagvw@googlegroups.com --- You received this message because you are subscribed to the Google Groups VintagVW - Air Cooled Volkswagen Discussion List group. To unsubscribe from this group and stop receiving emails from it, send an email to vintagvw+unsubscr...@googlegroups.com. To post to this group, send email to vintagvw@googlegroups.com
Re: [vintagvw] Battery isolation relay
Bert, Part number for the new Bosch part please? Also, Let's think through your description of how this really works. From you explanation of the original relay wiring that has only 4 terminals, I am not sure that it works the way you think it does. On the original: 51 is the feed providing charging power to either of the two batteries(or could it only be both at the same time!) 61 is ground when the generator is off(I am pretty sure) and provides a small positive comparison voltage when the car is charging(red light on or off comparison to the battery charging state). I am going to guess that when the charging system was off that you could pull the equipment battery all the way down and it would charge up after you restarted...andthat was about it. On the other hand...I have never owned one ofthese of a bus with the dual battery and don't know how it worked in a late model bus. My bet is that both batteries got the same charging current after the engine was started, but the equipment battery would give it's all and then that would be that till you restarted the car. Do you have a type2 manual with the same relay described in it? Seems kinda weird that VW(or Bosch) would use different devices to do the same thing for VW. Send the part number! Bet I can find a reference diagram. Cheers, dave On Fri, 15 Mar 2013, Bert Knupp wrote: Volks, I need some help. Various VW models over the years have used dual-battery systems: campers, sound trucks, fire engines, and police cars to name a few. The two batteries are connected via an isolation relay (in German it’s a “Batterie-Trennrelais”). The idea is to permit both batteries to charge from the generator or alternator, but to “uncouple” the #2 equipment battery when the voltage drops below 11 volts, making sure that the #1 or starting battery doesn’t get pulled down by the equipment. For example, in the police cars, it allowed the car to sit working an accident with the blue light, flashers and radio running but the engine off. If the available voltage dropped below 11 volts, the starting battery would disconnect so the car could start when done. So I’m recreating the Copbug’s two-battery system. I’ve mounted the #2 battery under the left rear seat and found a 75-amp Bosch isolation relay on-line. The problem: the four terminals on the new Bosch relay don’t match the four terminals on the VW factory bulletin for police-car wiring. I’m usually pretty good at logicking-through circuits, but I’m stumped here. The factory bulletin shows an isolation relay with four terminals: 51, 61, 86 and 87. 61 comes from the 61 terminal on the voltage regulator. Skinny wire. 51 comes from the B+ terminal on the voltage regulator. Fat wire. 86 goes out to the #1 (starting) battery (+). Fat wire. 87 goes out to the #2 (equipment) battery (+). Fat wire. The new isolation relay comes with four terminals also: 85-, 86+, 30 and 87. The 30-to-87 circuit seems to be the switch that opens and closes. The 85-to-85 circuit seems to be the coil activation. The 87 and 51 terminals are high-amp screw terminals. The 85 and 86 terminals are low-amp Faston slip-on tabs. But I can’t figure what’s what. Can anybody help me? How do I hook up the new relay to do the job? I’ve written to Bosch, but I won’t hold my breath. The last time I asked them for help, the reply came 5 months later – and they said they didn’t have information on the old equipment. Aargh! Bert Knupp in Music City USA -- Visit the VintagVW archives at http://mail-archive.com/vintagvw@googlegroups.com --- You received this message because you are subscribed to the Google Groups VintagVW - Air Cooled Volkswagen Discussion List group. To unsubscribe from this group and stop receiving emails from it, send an email to vintagvw+unsubscr...@googlegroups.com. To post to this group, send email to vintagvw@googlegroups.com. Visit this group at http://groups.google.com/group/vintagvw?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
Re: [vintagvw] Battery isolation relay -- number
30 -- Aux Battery + 87 -- Starting battery + 85 (or 86) --- GROUND 86 (or 85) --- Attach to the blue wire that goes to the generator warning lamp from the voltage regulator. The blue wire goes from ground to 12+V when the generator spins up and starts charging. It can be used for all kinds of neat relay stuff like this charging circuit or a fuel cutoff solenoid or anything else you don't want running while the motor isn't actually spinning. Dave is correct, all this does is allow the aux battery to be charged when the generator is putting out voltage. When the car is off the aux battery is completely separate from the starting battery. You will need to run new wiring from the aux battery to all of the devices you want to run from it so that they are no longer connected to the main fuse box at all. When the car is off only those devices connected to the aux battery will operate and they will only drain the aux battery. When the key is ON or in ACC position but not running devices attached to the main fuse box that require key on to operate will run from the starting battery and aux devices will run from the aux battery. With the car running and the generator warning light OFF (generator doing it's job) the batteries will be connected together. Both will be charging and the generator will provide power to both main and aux circuits. With your high draw circuits attached to the aux make sure you size the wires accordingly to take advantage of the 75 amp rating on the relay to allow the generator to power the circuits AND charge the battery if you have devices running. I'd use at least a #8, possibly a #6 for (30) and (87). For most people who shut down the high draw circuits while driving the 75amp relay is overkill. A $4 30/40 amp relay from the nearest FLAPS wired with #10 is plenty. Diagram from GermanSupply on thesamba.com http://www.thesamba.com/vw/forum/viewtopic.php?t=297050 G2 On Fri, 15 Mar 2013 11:50:05 -0500 Bert Knupp bert.kn...@comcast.net wrote: Dave (and all), The new Bosch Batterietrennrelais is Nr. 0 332 002 156. It has a schematic printed on top -- but that doesn't tell me exactly what I need. Bert -Original Message- From: vintagvw@googlegroups.com [mailto:vintagvw@googlegroups.com] On Behalf Of Dave C. Bolen Sent: Friday, March 15, 2013 10:34 AM To: Vintage VW Air-Cooled Discussion Group Subject: Re: [vintagvw] Battery isolation relay Bert, Part number for the new Bosch part please? Also, Let's think through your description of how this really works. From you explanation of the original relay wiring that has only 4 terminals, I am not sure that it works the way you think it does. On the original: 51 is the feed providing charging power to either of the two batteries(or could it only be both at the same time!) 61 is ground when the generator is off(I am pretty sure) and provides a small positive comparison voltage when the car is charging(red light on or off comparison to the battery charging state). I am going to guess that when the charging system was off that you could pull the equipment battery all the way down and it would charge up after you restarted...andthat was about it. On the other hand...I have never owned one ofthese of a bus with the dual battery and don't know how it worked in a late model bus. My bet is that both batteries got the same charging current after the engine was started, but the equipment battery would give it's all and then that would be that till you restarted the car. Do you have a type2 manual with the same relay described in it? Seems kinda weird that VW(or Bosch) would use different devices to do the same thing for VW. Send the part number! Bet I can find a reference diagram. Cheers, dave On Fri, 15 Mar 2013, Bert Knupp wrote: Volks, I need some help. Various VW models over the years have used dual-battery systems: campers, sound trucks, fire engines, and police cars to name a few. The two batteries are connected via an isolation relay (in German it’s a “Batterie-Trennrelais”). The idea is to permit both batteries to charge from the generator or alternator, but to “uncouple” the #2 equipment battery when the voltage drops below 11 volts, making sure that the #1 or starting battery doesn’t get pulled down by the equipment. For example, in the police cars, it allowed the car to sit working an accident with the blue light, flashers and radio running but the engine off. If the available voltage dropped below 11 volts, the starting battery would disconnect so the car could start when done. So I’m recreating the Copbug’s two-battery system. I’ve mounted the #2 battery under the left rear seat and found a 75-amp Bosch isolation relay on-line. The problem: the four terminals on the new Bosch relay don’t match the four terminals on the VW factory bulletin for police-car wiring
RE: [vintagvw] Battery isolation relay
Volks, Several of you have sent good suggestions how to wire the isolation relay. In each case, it’s been recommended to have the relay disconnect the two batteries any time the system is not charging, then re-connect them when it is charging (using the K pilot-light lead from the VR to close the relay). As described in the factory’s shop bulletin, the relay is actually supposed to open the circuit only when the potential between battery #1 and ground drops below 10.0 volts, but keep them connected in parallel so long as both battery #1 and battery #2 hold 10 volts or better. In other words, the relay is “triggered” by having a (pos+) feed to both coil terminals, one from each battery. If one battery begins to run down, it creates a difference in potential (voltage) between the two batteries, opening the relay so #2 gets cut loose in order to stop it from running down #1. Otherwise, any plain old SPST continuous-duty relay (like a headlight or foglight relay, as somebody suggested) could be used, intended to open any time the system is not charging. The circuit from GermanSupply does that, I believe. That’ll work, but it’s less elegant. This IS a German system, after all! Eleganz über alles! If anybody can come up with the correct German system diagram, let me know. Bert From: vintagvw@googlegroups.com [mailto:vintagvw@googlegroups.com] On Behalf Of Bert Knupp Sent: Friday, March 15, 2013 10:11 AM To: Vintage VW Air-Cooled Discussion Group Subject: [vintagvw] Battery isolation relay Volks, I need some help. Various VW models over the years have used dual-battery systems: campers, sound trucks, fire engines, and police cars to name a few. The two batteries are connected via an isolation relay (in German it’s a “Batterie-Trennrelais”). The idea is to permit both batteries to charge from the generator or alternator, but to “uncouple” the #2 equipment battery when the voltage drops below 11 volts, making sure that the #1 or starting battery doesn’t get pulled down by the equipment. For example, in the police cars, it allowed the car to sit working an accident with the blue light, flashers and radio running but the engine off. If the available voltage dropped below 11 volts, the starting battery would disconnect so the car could start when done. So I’m recreating the Copbug’s two-battery system. I’ve mounted the #2 battery under the left rear seat and found a 75-amp Bosch isolation relay on-line. The problem: the four terminals on the new Bosch relay don’t match the four terminals on the VW factory bulletin for police-car wiring. I’m usually pretty good at logicking-through circuits, but I’m stumped here. The factory bulletin shows an isolation relay with four terminals: 51, 61, 86 and 87. 61 comes from the 61 terminal on the voltage regulator. Skinny wire. 51 comes from the B+ terminal on the voltage regulator. Fat wire. 86 goes out to the #1 (starting) battery (+). Fat wire. 87 goes out to the #2 (equipment) battery (+). Fat wire. The new isolation relay comes with four terminals also: 85-, 86+, 30 and 87. The 30-to-87 circuit seems to be the switch that opens and closes. The 85-to-85 circuit seems to be the coil activation. The 87 and 51 terminals are high-amp screw terminals. The 85 and 86 terminals are low-amp Faston slip-on tabs. But I can’t figure what’s what. Can anybody help me? How do I hook up the new relay to do the job? I’ve written to Bosch, but I won’t hold my breath. The last time I asked them for help, the reply came 5 months later – and they said they didn’t have information on the old equipment. Aargh! Bert Knupp in Music City USA -- Visit the VintagVW archives at http://mail-archive.com/vintagvw@googlegroups.com --- You received this message because you are subscribed to the Google Groups VintagVW - Air Cooled Volkswagen Discussion List group. To unsubscribe from this group and stop receiving emails from it, send an email to vintagvw+unsubscr...@googlegroups.com. To post to this group, send email to vintagvw@googlegroups.com. Visit this group at http://groups.google.com/group/vintagvw?hl=en. For more options, visit https://groups.google.com/groups/opt_out. -- Visit the VintagVW archives at http://mail-archive.com/vintagvw@googlegroups.com --- You received this message because you are subscribed to the Google Groups VintagVW - Air Cooled Volkswagen Discussion List group. To unsubscribe from this group and stop receiving emails from it, send an email to vintagvw+unsubscr...@googlegroups.com. To post to this group, send email to vintagvw@googlegroups.com. Visit this group at http://groups.google.com/group/vintagvw?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
Re: [vintagvw] Battery isolation relay
On Fri, 15 Mar 2013 14:37:01 -0500 Bert Knupp bert.kn...@comcast.net wrote: As described in the factory’s shop bulletin, the relay is actually supposed to open the circuit only when the potential between battery #1 and ground drops below 10.0 volts, but keep them connected in parallel so long as both battery #1 and battery #2 hold 10 volts or better. In other words, the relay is “triggered” by having a (pos+) feed to both coil terminals, one from each battery. If one battery begins to run down, it creates a difference in potential (voltage) between the two batteries, opening the relay so #2 gets cut loose in order to stop it from running down #1. Otherwise, any plain old SPST continuous-duty relay (like a headlight or foglight relay, as somebody suggested) could be used, intended to open any time the system is not charging. The circuit from GermanSupply does that, I believe. That’ll work, but it’s less elegant. This IS a German system, after all! Eleganz über alles! The relay you have *IS* a plain old SPST relay. http://www.texasindustrialelectric.com/relays_0332002156.asp In order to do what you want there will have to be additional circuitry involved. Especially since the drop out voltage on this relay is 1.5 - 4 VDC. Once it's closed it won't open again until voltage drops to essentially completely dead for a car battery. The pick up voltage is 8VDC so if one battery were at a solid 12VDC the other would have to be at 4VDC to *ENERGIZE* the coil and CLOSE the contacts. That's the reverse of what you want. I think I know how to make it work but I need to flesh it out a bit. I'm not sure it will work with *this* relay though. I'll get back to you. Can you put a copy of the service bulletin (translated if it's in German) so we can see it? G2 -- Visit the VintagVW archives at http://mail-archive.com/vintagvw@googlegroups.com --- You received this message because you are subscribed to the Google Groups VintagVW - Air Cooled Volkswagen Discussion List group. To unsubscribe from this group and stop receiving emails from it, send an email to vintagvw+unsubscr...@googlegroups.com. To post to this group, send email to vintagvw@googlegroups.com. Visit this group at http://groups.google.com/group/vintagvw?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
