I need to replace a battery combining relay (see photo). This relay combines my house and starting batteries when I turn the ignition key. It is covered with a black platic cover when installed. I have searched for a replacement but haven't found one. Any suggestions?
Looking for a relay to connect battery banks
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Why??
First of all why would you want to do that? It is not really needed or good pratice. That said It looks like a Bosch relay. I have to now the amp rating of the contacts and the voltage rating of the coil. How many contacts? is there a set of normaly open and a set of normaly closed contacts. Look at the bottom of the realy and see if there are contact numbers on it. If it is a Bosch, two of the contacts will be numbered 84 and 85. Fair Winds Cap'n Dave
First of all why would you want to do that? It is not really needed or good pratice. That said It looks like a Bosch relay. I have to now the amp rating of the contacts and the voltage rating of the coil. How many contacts? is there a set of normaly open and a set of normaly closed contacts. Look at the bottom of the realy and see if there are contact numbers on it. If it is a Bosch, two of the contacts will be numbered 84 and 85. Fair Winds Cap'n Dave
Cap'n Dave,
Any idea why Bosch uses those numbers? If I knew the secret code, it would possibly preclude breaking out my multimeter every time I mess with mine.
Any idea why Bosch uses those numbers? If I knew the secret code, it would possibly preclude breaking out my multimeter every time I mess with mine.
The relay looks to be a
bosch automotive style relay. used in horn, fuel pump, fan circuits,etc used on many european cars. It looks to be a little light duty to be used in a combiner circuit. The most you want to put through the 1/4 " spade connectors is 20 amps, and thats probably too high. Spade connections in a marine enviroment is asking for problems. Why not put in a real battery combiner rated for that purpose?
bosch automotive style relay. used in horn, fuel pump, fan circuits,etc used on many european cars. It looks to be a little light duty to be used in a combiner circuit. The most you want to put through the 1/4 " spade connectors is 20 amps, and thats probably too high. Spade connections in a marine enviroment is asking for problems. Why not put in a real battery combiner rated for that purpose?
Try a VSR
Bill, The modern approach is to use a Voltage Sensitive Relay. These come in and connect both battery banks when the voltage reaches 14+ and drop out again when it drops to 13+. This means both banks get charged when engine or shore power is on and they separate when engine or shore is off. They are designed specifically for this use on boats and caravans and there is no need for an ignition connection either.
Bill, The modern approach is to use a Voltage Sensitive Relay. These come in and connect both battery banks when the voltage reaches 14+ and drop out again when it drops to 13+. This means both banks get charged when engine or shore power is on and they separate when engine or shore is off. They are designed specifically for this use on boats and caravans and there is no need for an ignition connection either.
No secret code
On the cover there is usually a schematic for the relay that tells you what the numbers for the contacts are. Like others said the Bosch is rated at 20 amps, and the spade connectors are a no no on a boat. It's your boat. LOL Fair Winds Cap'n Dave
On the cover there is usually a schematic for the relay that tells you what the numbers for the contacts are. Like others said the Bosch is rated at 20 amps, and the spade connectors are a no no on a boat. It's your boat. LOL Fair Winds Cap'n Dave
Here is some info on the Bosch
I told you wrong it is terminal 87 and 87a for the coil. Check this link Fair Winds Cap'n Dave
I told you wrong it is terminal 87 and 87a for the coil. Check this link Fair Winds Cap'n Dave
What you should look at is an..........
automatic combining relay. Donalex described it perfectly. I guess they call it a VSR on his side of the pond. I installed the West Marine version that's made by Blue Seas over the winter. Costs about $80, and I'm very pleased with it's operation. Haven't touched a battery switch since! If you must use both banks to start your engine, you can install a switch that will combine them that way. But this should really only be used if the start battery should fail.
automatic combining relay. Donalex described it perfectly. I guess they call it a VSR on his side of the pond. I installed the West Marine version that's made by Blue Seas over the winter. Costs about $80, and I'm very pleased with it's operation. Haven't touched a battery switch since! If you must use both banks to start your engine, you can install a switch that will combine them that way. But this should really only be used if the start battery should fail.
Thanks for the input
Thanks for the suggestions - I am definitely getting rid of the Bosch relay - I was dealing with it because I wanted to straighten out my electrical circuits - I appreciate the advice.
Thanks for the suggestions - I am definitely getting rid of the Bosch relay - I was dealing with it because I wanted to straighten out my electrical circuits - I appreciate the advice.
relays
Pop the hood on a lot of newer cars and you'll find relays like that rated at up to 100 amps@12vdc I've used them a lot for many projects just because they are cheap and easy to find. ken.
Pop the hood on a lot of newer cars and you'll find relays like that rated at up to 100 amps@12vdc I've used them a lot for many projects just because they are cheap and easy to find. ken.
relay source
you can find 100 amp continuous duty relays at jc whitney.com they shound more than do the trick the most discharged battery will charge first because it has the lowest internal resistance. hope this helps
you can find 100 amp continuous duty relays at jc whitney.com they shound more than do the trick the most discharged battery will charge first because it has the lowest internal resistance. hope this helps
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