40 Amp Relay to 100 Amp Solenoid Conversion Help.

[wallablack]

Good Evening All......
I got a great little charge controller from Jason Markham yonks ago and want to change the 40A Relay to a 100A Continuous Cycle Solenoid/Relay. I have tried to do the rewire in different configurations but none seem to work. It seems such a simple conversion but why am I having so much greif with it. It's not the controller as it has been working perfectly with the 40amp.
Does anyone have any input that could help me with this? What wire goes where? I've confused myself. My source is the + and - from my rectifier of course and my dump load are just resistors as in the diagram but 4 @ 300W which are in one string.
I want to use this for it's reliability not to run 100 Amps.
Terminals 9 & 10 (at the top of the picture go to the relay coil, 9 being positive)go to the two small terminal on the front of the solenoid to operate the coil.
The Diagram of the 40 Relay.

The 100 Amp Solnoid I wish to use.

[sean_ork]

why not leave the smaller relay as is and use it's contacts to control the large relay - perhaps the relay driver on the PCB doesn't have enough power to drop the new relay coil

[OperaHouse]

I would definitely keep the external relay to drive the 100A relay.  These big power relays can easily draw 12A on the coil destroying anything on the board over time.  Make sure the B terminals are not internally connected to the large studs  or the case with an ohm meter.  If you connected the big relay already to the board directly, you may have zapped what looks to be the power transistor.

[tanner0441]

Hi

A question... If it is on a solar set up with no wind turbine why do you want a dump load?  A solar controler simply backs off the charge going into the battery, they are quite happy running without a load on them, my solar set up simply looks at the battery voltage and adjusts the chatge rate accordingly..

Brian.

[equiluxe]

That 100 amp relay looks very like a starter solenoid and the current draw for the coil will be far to high for the board to source you will need to use the small relay to work the large one. I would also check if that relay is continuously rated it may be intended for vehicle winches and the like and therefore intended for intermittent use only.

[Flux]

I agree with the others. The only way is to use the existing relay as a pillot to the solenoid. I suggest you also fit a freewheel diode to ease the load on the pilot relay contacts.

I also suspect the idea is doomed with a starter solenoid as they must surely be short term rated, I really can't imagine the coil surviving continuous use. By the time you go to a proper 100A dc relay the thing will cost more than a decent controller.

To make the best of a bad job, if you can split the dump load into sections I would use the existing relay as a pilot to several similar automotive relays. If you look around there are a few with a claimed rating of 70A but I can't see how the holders or crimp connectors are going to handle that, but using 3 off 40A relays fed from a single pilot should do the job and do it better than a starter solenoid.

Flux

[mab]

If I understand the diagram using the 40a relay, then it is a changeover relay, it uses the 87a contact (I think 'normally closed') to pass current to the battery, until the relay is energised, then the current goes via the 87 contact (normally open) to the dump load.

If I'm right, then you cannot use your 100A as a like for like replacement - it doesn't have a normally closed contact. The only way I can see it working is by connecting the cable going to 30 (common contact) directly to B+ (87a cable) but this would mean when the relay closed you are connecting the dump load to the battery as well as the panel.

I'd stick with the 40A relay and just get a good make.

m

[Flux]

The drawing is not very clear but I think you are right and it is change over.

What for I can't imagine, solar only needs the break contact there is no point in changing over to a dump load.

If there is wind in the system then it should be directly to the battery and the dump will not be effective. If you connect wind through the change over scheme then anything can happen, it is safer to stick to just dump for wind.

Another reason why the solenoid won't work in addition to the intermittent rating and stupid coil current.

Flux

[TheEquineFencer]

Here in the USA, back when I was working on big trucks, 4070A and B models IH trucks had two solenoids in the dash. One was intermittant duty rated the other was continuos. The Cont duty one was around a 100A rated. Check with an IH dealer, he may have one in stock he'd love to get rid of as old as a 4070 model truck is now.

[ghurd]

I could understand the desire for a heater dump load of some sort on a very large solar system.

That said, a decent controller will run faster than a relay can survive for very long.
And 12V wold mean a fairly small system to waste what a suitable 100A relay coil will waste.
Solid state is the way to go... Big Giant $50 mosfets!   
G-