Should the solenoid get so very hot?

[peterbringloe]

My engine starting battery and service batteries are combined automatically when the engine is started by means of a voltage sensitive relay and a solenoid. When the engine is not running the solenoid switch separates the two battery banks. After running the engine recently, after it was stopped (some while after) the solenoid started switching on and off randomly. Assuming either the relay or the solenoid was faulty I removed the solenoid which was very hot. Having failed to find a replacement (I'm in Antigua) I tested the solenoid and it seemed to work perfectly so I refitted it. All seems back to normal now with no repetition of the random switching and batteroies are combined when engine is running. But the solenoid gets very very hot. Having had no reason to touch it before I weonbder whether this is normal or whether it is faulty. I shall get a replacement when I come back to tghe UK and a new relay anyway. But is it normal for a solenoid switch to get so hot?

 

[VicS]

It'll get warm certainly but it would worry me if it got really hot.

Are you sure it is a device which is intended to be energised for prolonged periods or is it a system cobbled together with unsuitable components.

A VSR that would handle the current directly without an additional relay/solenoid would be one way to go.

OR a Lucas split charging relay which uses the warning light circuit to sense when the engine is running and then link the two batteries automatically is another way.

Perhaps Halcyon will be passing this way to give an expert opinion.

 

[Playtime]

My engine starting battery and service batteries are combined automatically when the engine is started by means of a voltage sensitive relay and a solenoid. When the engine is not running the solenoid switch separates the two battery banks. After running the engine recently, after it was stopped (some while after) the solenoid started switching on and off randomly. Assuming either the relay or the solenoid was faulty I removed the solenoid which was very hot. Having failed to find a replacement (I'm in Antigua) I tested the solenoid and it seemed to work perfectly so I refitted it. All seems back to normal now with no repetition of the random switching and batteroies are combined when engine is running. But the solenoid gets very very hot. Having had no reason to touch it before I weonbder whether this is normal or whether it is faulty. I shall get a replacement when I come back to tghe UK and a new relay anyway. But is it normal for a solenoid switch to get so hot?

I don't understand why you have a VSR and a (separate?) solenoid?

Regarding the solenoid switching in and out, this often happens when starting to charge. The relay operates and the batteries combine when the voltage reaches 13.8V but the second battery immediately pulls the voltage down below the VSR drop out level (12.8V?) and the batteries are separated. At which point the voltage increases above 13.8V again and the cycle repeats until such time as the charging voltage remains above 13.8V.

I guess the same could happen in reverse when charging stops. Was there a significant load on the second battery that was pulling the voltage down below the VSR release point (which would also account for the solenoid getting hot)? This would cause the relay to drop out and the batteries to separate. If the voltage on the first (sensed) battery was then above 13.8V the cycle would repeat.

Not a very clear explanation but I hope you get the idea?

 

[Malish]

have you checked all the wiring connections & crimps? A poor connection might be the culprit

 

[halcyon]

A VSR that would handle the current directly without an additional relay/solenoid would be one way to go.


Perhaps Halcyon will be passing this way to give an expert opinion.

A VSR will not work, it needs the engine running to generate a voltage high enough to pull in the solenoid, so cannot link batteries for starting. Unless the solenoid is operated via the ignition switch, which does away then with the need for a VSR.

He could have a power lock-out relay, opposite to a VSR, operates at low voltage, so pulls in solenoid if the engine battery is low.

What is / was common was a VSR for charge, and a link solenoid for engine starting from service battery, this would be operated from button at the helm. I have seen burnt out link solenoids due to faulty switches, or wiring faults holding in the solenoid, which are normally only an intermittant rated coil.

More detail is required, or photo of units, do draw more conclusions.


Brian

 

[VicS]

A VSR will not work, it needs the engine running to generate a voltage high enough to pull in the solenoid

Ah you have interpreted things differently.
I assumed the OP meant that the two batteries are linked for charging once the engine is running. (Using a VSR but also a relay/solenoid in addition.) You, I think, have taken his description to mean that they are linked for starting.

Clarification obviously required.

 

[peterbringloe]

some clarification

Thanks to all for taking the trouble to reply. The system was installed by marine electricians at Brighton Marina in 2002 and has worked well. I think it is regarded as a simple and effective method - Nigel Calder says he likes it in his book. There is a button close to the engine panel which if pressed operates the solenoid to combine the batteries should the engine starting battery be not up to it. I have never need to use it but it works. I have voltmetres that show that the system combines the batteries when the engine is running (Calder calls it paralleling). One thing that someone said may be relevant - The service bank was in need of charge and while the engine was running I had an invertor charging two laptops. So certainly some load. Ammeter showing about 40 amps going in, voltmetres showing engine battery 13.9 and saervice bank 13,7 - obviousaly gradually increases and amps drop. Solenoid extremely hot though. But as Isaid - could have always been this way.

 

[halcyon]

I think it is regarded as a simple and effective method - Nigel Calder says he likes it in his book. There is a button close to the engine panel which if pressed operates the solenoid to combine the batteries should the engine starting battery be not up to it.


Solenoid extremely hot though. But as Isaid - could have always been this way.

Okay you have a standard system, introduced in the mid 80's, and it works, as you have found.

So which pat is getting hot ? the VSR or the link solenoid.

The VSR may get a little hot from the coil and contact load. If it getting very hot it could be a sign of a problem developing.

The link solenoid, only being used for engine start should be cold, unless you have had problems starting the engine and used th link.
If this is hot, with no use, you have problem as the solenoid is almost certainly engaged. In which case the coil will burn out, and the engine battery can be drained by the boats service load.

Brian

 

[Playtime]

Thanks to all for taking the trouble to reply. The system was installed by marine electricians at Brighton Marina in 2002 and has worked well. I think it is regarded as a simple and effective method - Nigel Calder says he likes it in his book. There is a button close to the engine panel which if pressed operates the solenoid to combine the batteries should the engine starting battery be not up to it. I have never need to use it but it works. I have voltmetres that show that the system combines the batteries when the engine is running (Calder calls it paralleling). One thing that someone said may be relevant - The service bank was in need of charge and while the engine was running I had an invertor charging two laptops. So certainly some load. Ammeter showing about 40 amps going in, voltmetres showing engine battery 13.9 and saervice bank 13,7 - obviousaly gradually increases and amps drop. Solenoid extremely hot though. But as Isaid - could have always been this way.

The above helps a bit but I am still confused by the original post (OP).

If I understand correctly, the solenoid is manually operated to combine (parallel) the batteries but is only used if extra charge from the service battery is required to aid starting (e.g. in an emergency if the engine battery is discharged).

The VSR, on the other hand, is automatic and operates to parallel the batteries when the engine is running and the charging voltage exceeds 13.8V (or thereabouts).

So, I do not understand why the solenoid was getting hot after the engine had shut down. Had you inadvertently left it switched in (i.e. button pressed)? If that is the case, then it will certainly get hot as it is only meant to be used for a short period i.e. emergency engine start (as I understand it).

If the solenoid had not been operated manually, then there may be a problem with the button or associated wiring that is turning the solenoid on. If this is an intermittent fault, it may also account for the solenoid clicking in and out.

Can you clarify your OP if the above is not correct and we will have another go at remote diagnosis.

 

[peterbringloe]

Some more clarification

and thanks again for your help. Yes - button is for use only when engine starting battery needs help - never needed to use it. with engine running batteries are combined - relay a little warm but solenoid very hot. The random switching that caused me to take a look was not long after a longish engine run - so solenoid was still hot

Connections seem OK - terminals connected to solenoid very tightly with nuts and washers. No idea what caused the random switching (which since refitting has never reoccured) - when I removed the solenoid everything was very tight..

My service batteries are not in great shape. They are 5 X 120 AHour wet batteries and do not seem to hold charge very well any more. Engine starting battery is new.

 

[Playtime]

and thanks again for your help. Yes - button is for use only when engine starting battery needs help - never needed to use it. with engine running batteries are combined - relay a little warm but solenoid very hot. The random switching that caused me to take a look was not long after a longish engine run - so solenoid was still hot

Connections seem OK - terminals connected to solenoid very tightly with nuts and washers. No idea what caused the random switching (which since refitting has never reoccured) - when I removed the solenoid everything was very tight..

My service batteries are not in great shape. They are 5 X 120 AHour wet batteries and do not seem to hold charge very well any more. Engine starting battery is new.

Have you checked the 'button' and associated wiring that operates the solenoid - not the big wires connecting the solenoid to the batteries but the thinner wires that operate the solenoid? If the solenoid is hot it means that it must have been in operation for some time. If you didn't manually 'press the button' then there must be a fault in the wiring or the switch.

My money is on an intermittent fault in that area that caused the solenoid to operate and remain on so it got hot and then to operate intermittently after the engine was switched off to cause the clicking in and out.

Since you removed/replaced the solenoid, the fault appears to have gone away. However, this does not mean it won't re-appear so it would be worth checking the switch and wire again, I think.

If the fault is not in that area then I have run out of ideas, I'm afraid.

 

[VicS]

It sounds to me as though the system is wired so that the VSR operates the combining solenoid rather than interconnecting the batteries itself.

Maybe the VSR is not itself suitable to handle the charging current so it has to use an intermediate relay or solenoid

Maybe it has been wired incorrectly

Maybe someone has tampered with the original wiring.

 

[Gypsy]

I think 'Playtime' has answered why the solenoid 'chattered' a bit even when the engine was off. As for the solenoid heat here are two possibles:
1) The solenoids commonly used are those designed for short cycle operation such as starter motor currents so they need to have very good contact closure but for only a few seconds at a time. It is probable that the solenoid will get hot if held 'ON' for any length of time such as when kept in parallel whilst the VSR considers the voltage high enough to pass charge current to the house batteries. Of course any one make of solenoid could have different characteristics to another so it may be quite normal for one to heat up after prolonged use in the 'ON' state.
2) The internal contacts of the solenoid may be pitted and offering high resistance. These units are usually sealed so you can't see but the test is to measure the voltage drop across the terminals when the solenoid is engaged and a reasonable current (say 10A+) is passing to the house battery. There should be NO voltage drop, well a DVM might show a few mV but not 100s. If there is any significant voltage it means the contacts are offering high resistance and then heat will be generated. To measure, put the probes across the switching terminals of the solenoid using autorange or starting at 20v then switching down ranges to get a reading - should be VERY low.

 

[peterbringloe]

Thanks again

for all your replies - maybe I should look into getting a better relay and solenoid when I get back to the UK ina week or so.

 

[Playtime]

for all your replies - maybe I should look into getting a better relay and solenoid when I get back to the UK ina week or so.

I suggest before you spend money, possibly unnecessarily, that you work out exactly what is causing the problem.

It would be worth checking VicS's idea that the VSR operates the solenoid as well as checking the solenoid low current wiring as I suggested.

If you do decide to modify the system, I would replace the solenoid with a simple battery switch to parallel the batteries (manually when required) and replace the VSR with a unit that can take the maximum current that can be output by the alternator.

 

[VicS]

I suggest before you spend money, possibly unnecessarily, that you work out exactly what is causing the problem.

I ceratinly go along with that.

Take note of what Halcyon said in post #8. Determine if it should work as he says ... He is the one who knows all about this sort of stuff.

 

[peterbringloe]

Thank you all

very much for all your advice. I do have a wireing diagram that the installer gave me before installing system. If I can figure out how to scan and post it I'll do so when I get home. Thanks once again.

 

[VicS]

It will be interesting to see it.

If you don't have Photobucket or similar account save the scanned image as a jpg and upload it as an attachment.

 

[brianhumber]

Suggestion

Have you asked - Do I actually need this complication, however simple and reliable it may have been to date?

What is wrong with simple hand operated isolating switches to connect engine/service banks together or use one or the other for both if required.

Pros - as basic as you can get, you can use banks in parallel ( which I do not like) or change over to use them seperately

Cons - it is possible to switch off batteries from engine when running and blow charging diodes but on most systems you can muck it up to do this anyway.

Battery Life
I have an on line volt meter on my busbar showing volts described as full/half/discharged etc so I try to never run down to a discharged state on the service even though I always start the engine on the service bank, thus keeping a fully topped up engine battery for emergencies.

I use standard 648 traction batteries ( my engine is 50hp Ford XLD ie the 1.6 Fiesta ) as fitted to vans 4*4s etc , the service one (new June 2003) is just starting to loose its capacity, so the current engine one ( May 2006) will be swopped to the service bank and a new engine 648 fitted. Over the years on swinging moorings and marina berth I seem to get around 7 seven years out of a standard battery starting it off as engine and then swopping to service. I get mine from standard auto factors for best price. In 1997 I paid £70 for a 648 I see today 648 of similar cranking capacity is £89

No need to buy expensive 'special' batteries as long as you do not deep cycle IMHO, standard ones are cheaper and last just as long.



Brian

 

[peterbringloe]

Battery switches

Thanks Brian. When I bought the boat it dad two 1, 2 or Both switches. My previouse boats had the same but I had it changed because all the advice (YM, PBO etc) tended to dismiss these in favour of separate isolators. The necessary human interaction being the main reasons I think - as you point out. The system was rewired by Marinetek in Brighton to their recommended design. When I get home I will speak to Malcolm at MarineteK and show him this thread. Insidentally, the combining system works regardless of whether the isolating switches are on or off. The solenoid may have behaved this way from day one (Getting Hot). I only noticed it after the erratic switching phenomenon.

I note what tou say about batteries. Mine are conventional wet batteries 5 X 120 AH. I leave the boat for up to 8 months out of the water in the Caribbean. The year befor last I allowed them to dry out and altghough I now check the water level regularly and they seem to have recoverred I think I will replace them when I come back in November. I'm never sure what to do as far as leaving them is concerned. Last year I disconnected them completely but they need to be fully charged I think. Or I may leave them connected with one solar panel (50W) keeping them topped up.