Relay Troubleshooting

[coal_man]

I’m working on a Rascal electric scooter for my wife’s uncle. I think I’ve found a problem with the relay shown in the photo. With the relay plugged into the scooter, it will not operate. If I remove the relay and install a jumper between terminals 30 and 87, the scooter will operate as it should. If I test the relay on my work bench with my battery charger and put 12V+/- across terminals 85 and 86, the circuit is completed between terminals 30 and 87. I’m only getting around 9.5V+/- between terminals 85 and 86 on the scooter and the relay wont “close” with this voltage. Is there any additional troubleshooting I can do, or is the 9.5V too low to make the relay function normally.

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Thanks in advance,

coal_man

 

[dumper]

can you remove the cap on the relay(many of them are removable)? If so, you will be able to visualize the actual switch contacts, which may make it obvious if its a contact problem. On second thought, if you remove the relay, and jump the contacts and everything is fine, then it sounds like the coil winding in the relay is causing an excess voltage drop 24v to 9.6v. If thats the case, replace the relay. No way to service that.

 

[Sanny81]

Sounds like a coil problem like dumper said. Not enough voltage to activate the relay contacts.

 

[w1im]

The datasheet for your series of relay can be found here:
http://www.mouser.com/ds/2/418/NG_DS_VF4A-X0000-A001_0312-111094.pdf

It says the operate voltage is 14.4V, so it won't necessarily switch until it hits that voltage.

I see 2 possibilities for your issue.

1. The relay coil or diode has a problem which is decreasing their resistance, causing the voltage drop you are seeing. The solution to this is replacing the relay. The datasheet shows a coil resistance of 360 ohms for your relay, so you can try measuring that (not connected to the scooter) but you may need to reverse the leads from your meter as the diode will cause an abnormal reading in 1 direction.

2. There is an issue in the circuit leading up to the relay which is causing the voltage drop and preventing the relay from switching. Look for loose/bad connections, or shorting between conductors.

 

[goneflyin2002]

is it the right relay?
should it have a 12v coil instead of the 24v coil?

 

[James-W]

Is it the right relay?
Should it have a 12v coil instead of the 24v coil?

That was my first thought too.

 

[Rookie2]

I believe the relay is 24 volts because the Rascal is 24 volts . Does the Rascal have two batteries ? then its 24 volts !

switch or control wiring or circuit board problem !

Poor battery connections .

9.5 volts is not correct for either a 12 volt system or a 24 volt system

 

[RPH]

Check the impedance of the contacts. Most likely the have arced and this is causing a large voltage drop. Those relays are fairly cheap, I would just replace. Plenty of online sources.

 

[arsco]

9.5 volts is not going to switch a 24v relay. keep looking figure out what should be supplying voltage to that. key switch,seat switch etc.

 

[w1im]

Check the impedance of the contacts. Most likely the have arced and this is causing a large voltage drop. Those relays are fairly cheap, I would just replace. Plenty of online sources.

The contacts and coils are electrically separate in the relay, so contact issues shouldn't affect the voltage drop seen at the relay coil unless there was a major meltdown inside the relay. If that was the case I would expect to see case damage as well.

 

[coal_man]

Thanks for all the replies.

The Rascal has two 12 volt batteries wired in series to make 24 volts. I'll check the resistance across the coil and see what that reads. Like many have said, I think the problem is the incoming voltage of 9.5 volts into the relay. I'm going to try another relay and continue to trace wiring.

I'll post the results.

Thanks again,

coal_man

 

[LS6 Tommy]

No two ways about it. A 24VDC relay will not operate on 9.5VDC. It's not the relay.
Tommy

 

[myredracer]

Probably can get one at a local electrical wholesaler instead of waiting for one in the mail. They can cross-reference to another brand if needed as it's a common type relay.

 

[James-W]

Probably can get one at a local electrical wholesaler instead of waiting for one in the mail. They can cross-reference to another brand if needed as it's a common type relay.

Since he only has 9 volts going to the relay coil I doubt the relay is defective.

 

[myredracer]

Since he only has 9 volts going to the relay coil I doubt the relay is defective.

Good point. But if that doesn't work, he doesn't have to wait... I wonder if the relay is even original? Would a P&B Mexican relay be in what I would guess is a made in Ch*na scooter? Maybe it's not the right part no. or rating?

 

[racer-john]

If I test the relay on my work bench with my battery charger and put 12V+/- across terminals 85 and 86, the circuit is completed between terminals 30 and 87. I’m only getting around 9.5V+/- between terminals 85 and 86 on the scooter and the relay wont “close” with this voltage. Is there any additional troubleshooting I can do, or is the 9.5V too low to make the relay function normally.

Check the wiring feeding terminals 85 and 86. You should be seeing battery voltage.

 

[Jbullfrog]

Test the Batteries! I have yet to replace a relay on any make of mobility scooter or chair, and I've been working on the for almost 10 years! Check the voltage of the batteries ether together, or by disconnecting them and checking separately. It's a 24v system and charger, which won't charge it if a battery is below 10v.

 

[RPH]

Sorry guys, read it at work and missed the part about coil voltage. There are two current spec's for coils. I eus the current required to pull in the relay and another to hold the relay in. At 9.5 vdc this relay won't come in. Bad connection or as was mentioned bad batteries.
Verify the ground.

 

[James-W]

Test the Batteries! I have yet to replace a relay on any make of mobility scooter or chair, and I've been working on the for almost 10 years! Check the voltage of the batteries ether together, or by disconnecting them and checking separately. It's a 24v system and charger, which won't charge it if a battery is below 10v.

I would suspect the batteries too, but in the opening post he said that when he jumps out the pins on the relay the scooter operate as it should. In other words, the scooter works normally. I would take that to mean the batteries are charged up to their full potential.

 

[bmxr4life87]

What is controlling the trigger circuit for the relay? I would trace the 85 and 86 pin wiring as the relay and load wiring have been tested and function as intended

 

[coal_man]

Thanks for all the replies.

I'm working to trace the wiring from the 85 and 86 terminals to see what I find. The batteries in the scooter are shot, but I'm able to pick up 24 volts from my golf cart for testing purposes.

Thanks bullfrog for confirming that the charger wont kick on if the batteries were low voltage.

My wife's uncle bought the scooter cheap, knowing it wouldn't run. I'm trying to make sure that it is okay other than the batteries. Hopefully it will help him get back out into his garage with new batteries.

I'll post my findings later. Thanks again.

coal_man

 

[coal_man]

Problem solved!!

I worked this morning following the control wires for the relay in question. I eventually got to the motor. There is a micro-switch on the end of the motor that is engaged by the push/ride foot switch. I had the dang thing in push mode all this time. doh! When I put the switch in ride mode, I was good to go.

Thanks again for everyone's input.

coal_man

 

[LS6 Tommy]

Great! So, that was all that was wrong with it? They tossed it for that?

Tommy

 

[Rookie2]

Thanks for the follow up ! A lot don't reply with what they found.

 

[Jbullfrog]

Great! So, that was all that was wrong with it? They tossed it for that?

Tommy

Batteries are $85 each is usually the reason they get parked.

 

[coal_man]

Batteries are $85 each is usually the reason they get parked.

Yeah. They don't have a whole lot invested at this time. I'm assuming these scooters are worth the $85 X 2 cost for new batteries, huh?

coal_man