Sargent PX300 charger power draw query

[Moped]

Slightly puzzled as leisure battery was showing 100% charge on the display panel before midnight with the Sargent charger drawing 1.6amp and Sargent charger still drawing 1.1amp this morning with the fridge drawing 0.9amp. Minimal 12v usage just phone charging.

Normally charger has powered down by now.

As we are on 6amp hook up on a French aire and use certain electrical items that use up our 6amp buffer I normally keep an eye on what the charger is consuming and on this occasion it seems to be consuming power over and beyond my normal expectations so I have been managing consumption by turning the charger off as and when.

Just wondering if dodgy French voltage might have anything to do with this or possibly a battery issue although battery a recent replacement.

 

[merl]

I don't know which fridge you've got but 0.9A is OK for a 3 way fridge consumption but at 230V mains.
When you say "Sargent charger still drawing 1.1amp this morning" I take it you're talking about the 12V side current? If so this will be about right if you're charging a phone from the van 12V with a standard 2A plug in cigarette charger.
1.1A draw on the 12V side will result in much less current draw on the 230V side. Technically divide by 19ish (230 divided by 12) but there are losses so it'll probably be closer to divide by 15, either way it's so low it's not worth considering in your 5A allowance.

 

[wildebus]

I don't know which fridge you've got but 0.9A is OK for a 3 way fridge consumption but at 230V mains.
When you say "Sargent charger still drawing 1.1amp this morning" I take it you're talking about the 12V side current? If so this will be about right if you're charging a phone from the van 12V with a standard 2A plug in cigarette charger.
1.1A draw on the 12V side will result in much less current draw on the 230V side. Technically divide by 19ish (230 divided by 12) but there are losses so it'll probably be closer to divide by 15, either way it's so low it's not worth considering in your 5A allowance.

This is the problem when quoting how many amps is being drawn... means nothing without being accompanied by the voltage.

I don't know what Sargent display the OP has and is looking at, but I believe most (all?) Sargent control panel displays, when they show a current draw, will tell you how much the habitation (12V) electrics is demanding - so maybe 1.2A at 12V say. And that will be the draw regardless of if there is hookup or not.

The 0.9A from the fridge ... is the fridge running on AC? Or Is it a 12V DC fridge? (I suspect it is a three-way running on AC as that is spot on consumption with their inefficiency, but I won't assume).
If it is AC, then the power is not via the charger in any way, it is direct from the EHU via the Sargent Consumer Unit section and doesn't touch the charger in any way.
If it is DC, then that 0.9A is about 10W and something like a 0.05A extra demand on the EHU. Just noise when looking at a charger drawing 1.1A (so over 250W - if an AC battery charger is DRAWING a current, it must be a current at a nominal 240V AC.


When quoting numbers it is very important to keep them in context otherwise they don't mean a lot.


ADDENDUM:

.... Normally charger has powered down by now....

The other thing to remember with Sargent units and almost certainly every Motorhome setup ....
The Battery Charger is also essentially a provider of 12V DC when it is on. You have a Motorhome and you have 12V lights, a 12V Water Pump, Phone Charger via a 12V Connection, a TV plus Aeriel booster, both running off 12V, etc, etc. It does not matter if you are on EHU or not, those run off 12V, not off AC.
If you are off-grid, you are pulling battery power to service that load.
If you are plugged into EHU but you switch the battery charger off, you may think you are plugged in to power, but as far as all those 12V loads are concerned, you are STILL off-grid and drawing power battery - you are not supplying them from the AC hookup.
To run 12V circuits without draining the battery, you need the battery charger ON. If it 'powers down' then you are using the battery for the 12V habitation electrics (I am ignoring any presence of a Solar Charger btw in the writing above, before anyone jumps in and says 'what about solar'. If AC charger is off, the load/charge on the battery is whatever the difference is between the hab load and the solar harvesting).

 

[merl]

This is the problem when quoting how many amps is being drawn... means nothing without being accompanied by the voltage.

I don't know what Sargent display the OP has and is looking at, but I believe most (all?) Sargent control panel displays, when they show a current draw, will tell you how much the habitation (12V) electrics is demanding - so say 1.2A at 12V say. And that will be the draw regardless of if there is hookup or not.

The 0.9A from the fridge ... is the fridge running on AC? Or Is it a 12V DC fridge? (I suspect it is a three-way running on AC as that is spot on consumption with their inefficiency, but I won't assume).
If it is AC, then the power is not via the charger in any way, it is direct from the EHU via the Sargent Consumer Unit section and doesn't touch the charger in any way.
If it is DC, then that 0.9A is about 10W and something like a 0.05A extra demand on the EHU. Just noise when looking at a charger drawing 1.1A (so over 250W - if an AC battery charger is DRAWING a current, it must be a current at a nominal 240V AC.


When quoting numbers it is very important to keep them in context otherwise they don't mean a lot.

Exactly
What puzzles me (as well as a lot of other things!) is the fridge current at 0.9 A.
Assuming that's the 230V side (as we both have) and would be correct but not sure how the OP is able to monitor the mains current? Could it be a 12V compressor fridge and the current that he's measuring is during an off period? I have little experience re compressor fridges so you'd know better than me about that but nearly an amp standby current seems high to me.
Will be interesting for sure when he comes back

 

[wildebus]

Exactly
What puzzles me (as well as a lot of other things!) is the fridge current at 0.9 A.
Assuming that's the 230V side (as we both have) and would be correct but not sure how the OP is able to monitor the mains current? Could it be a 12V compressor fridge and the current that he's measuring is during an off period? I have little experience re compressor fridges so you'd know better than me about that but nearly an amp standby current seems high to me.
Will be interesting for sure when he comes back

A 12V compressor fridge in the ON cycle is around the 4A mark (@12V) - around 50W more or less. The OFF cycle can be regarded as ZERO amps (some of the fancier ones may have a tiny draw for their LED displays & lights and bit of electronics, but again noise).
what CAN be a 0.9A draw on a 12V compressor fridge is the interior light when you open the door if it is not an LED one If I was seeing a 0.9A@12V draw on a fridge, I would check the light is going off when the door is closed

Now here IS an assumption .... Sargent units generally have a 20A Habitation Circuit. A 12V Compressor Fridge I don't know if it would be wired via a Sargent PDU as the compressor in-rush surge would be greater than 20A for sure and so is likely to be wired direct to the battery and if that was the case, the current drawn would a) not register on the Sargent display panel and b) may not form part of any internal Sargent State of Charge calculations - depending how/where they are working out the SOC to provide a "100% Charge on the display panel" - so the battery could be more discharged than the info suggests?

I am going to the NEC motorhome show and as you might expect, will be looking at interest to see how the newer technology - Lithium Batteries, Compressor Fridges, Induction Hobs, etc -are married to the 'traditional' electrics you tend to see fitted to British Motorhomes, as well as European brands for that matter.

 

[merl]

A 12V compressor fridge in the ON cycle is around the 4A mark (@12V) - around 50W more or less. The OFF cycle can be regarded as ZERO amps (some of the fancier ones may have a tiny draw for their LED displays & lights and bit of electronics, but again noise).
what CAN be a 0.9A draw on a 12V compressor fridge is the interior light when you open the door if it is not an LED one If I was seeing a 0.9A@12V draw on a fridge, I would check the light is going off when the door is closed

WOW, incandescent light bulb staying on when door closed! What a diagnostic brain you have mate! You really should get involved in electronics more, that's the sort of 5hit that happens all the time and baffles my brain until......you find the fault and you get that massive eureka moment! I guess you've had it too? Surely cant be just me?

 

[jacquigem]

This is the problem when quoting how many amps is being drawn... means nothing without being accompanied by the voltage.

I don't know what Sargent display the OP has and is looking at, but I believe most (all?) Sargent control panel displays, when they show a current draw, will tell you how much the habitation (12V) electrics is demanding - so maybe 1.2A at 12V say. And that will be the draw regardless of if there is hookup or not.

The 0.9A from the fridge ... is the fridge running on AC? Or Is it a 12V DC fridge? (I suspect it is a three-way running on AC as that is spot on consumption with their inefficiency, but I won't assume).
If it is AC, then the power is not via the charger in any way, it is direct from the EHU via the Sargent Consumer Unit section and doesn't touch the charger in any way.
If it is DC, then that 0.9A is about 10W and something like a 0.05A extra demand on the EHU. Just noise when looking at a charger drawing 1.1A (so over 250W - if an AC battery charger is DRAWING a current, it must be a current at a nominal 240V AC.


When quoting numbers it is very important to keep them in context otherwise they don't mean a lot.


ADDENDUM:

The other thing to remember with Sargent units and almost certainly every Motorhome setup ....
The Battery Charger is also essentially a provider of 12V DC when it is on. You have a Motorhome and you have 12V lights, a 12V Water Pump, Phone Charger via a 12V Connection, a TV plus Aeriel booster, both running off 12V, etc, etc. It does not matter if you are on EHU or not, those run off 12V, not off AC.
If you are off-grid, you are pulling battery power to service that load.
If you are plugged into EHU but you switch the battery charger off, you may think you are plugged in to power, but as far as all those 12V loads are concerned, you are STILL off-grid and drawing power battery - you are not supplying them from the AC hookup.
To run 12V circuits without draining the battery, you need the battery charger ON. If it 'powers down' then you are using the battery for the 12V habitation electrics (I am ignoring any presence of a Solar Charger btw in the writing above, before anyone jumps in and says 'what about solar'. If AC charger is off, the load/charge on the battery is whatever the difference is between the hab load and the solar harvesting).

Interesting , so we are not currently travelling . So van parked next to house on hook up and not being used.
I have been switching charger off when sargent tells me batteries are good so as not to "cook" them . Have been finding vehicle battery which was new in April drops to 12.4 volts so I switch charger back on. This is revolving every few days or so. Am I doing the right thing ?
I have solar and victron controller as well as original sargent control for my 2010 Autotrail Mohawk. Leisure batteries seem fine.

 

[merl]

Any decent battery charger should float charge your battery at the correct stand by voltage so you should never be able to cook a battery by leaving it connected to a decent charger. (David will be along in a min and tell us whether the Sargent 2010 era floats correctly so give him a few mins to finish his lunch!) There is a slight cost involved obviously because you're leaving a charger running 24/7 but that should work out better than taking your battery off charge and letting the battery fall back to less than 100% because when you do you'll introduce sulphation of the plates and shorten the battery's life.
All of the above is assuming you've got what most folks have WRT batteries ie standard lead acid and not lithium or lead carbon. Lead carbon are more tolerant of being left standing in a PSC (partial state of charge) and Lithium shouldn't really be left in float at all.
12.4V is much lower than I'd personally let my batteries sit at and I have lead carbons, 12.4V indicates around 60% capacity, much too low for lead acid storage, they'll be knackered in no time.
Check the accuracy of the Sargent panel readout by measuring the voltage AT THE BATTERY with a multi meter if you can.

 

[wildebus]

Interesting , so we are not currently travelling . So van parked next to house on hook up and not being used.
I have been switching charger off when sargent tells me batteries are good so as not to "cook" them . Have been finding vehicle battery which was new in April drops to 12.4 volts so I switch charger back on. This is revolving every few days or so. Am I doing the right thing ?
I have solar and victron controller as well as original sargent control for my 2010 Autotrail Mohawk. Leisure batteries seem fine.

I would guess a 2010 Autotrail Mohawk will have either a Sargent EC325 or a Sargent EC328. (and to add a slight confusion, if the EC325 was ever returned to Sargent for a repair, it is likely they upgraded it to a EC328 and that may or may not be noted on the case. I don't know if they did).
Check the big number on the Silver Sargent box - located in the top locker behind the Drivers I would think in your Motorhome? Let us know what it is.

The EC325 has a basic "power supply" charger. I have found it is a 13.8V Supply. It won't go higher, so won't charge the battery fully. It won't go any lower, so is at the top end of a float voltage.
The EC328 has according to the Sargent specs a much better Battery Charger and IIRC is a 3-stage charger much more like a smart charger.

IF you are seeing the vehicle battery dropping when the charger is off, then that suggests you have the control panel set so the hab electrics are running off the Vehicle Battery and not the Starter Battery, as the Sargent charger will only charge whatever battery is selected (when you have the EC325/EC328 and many/most other Sargent models).
(I think we have had a conversation about the Sargent control panel and how the battery selection works?)

Are you doing the right thing? If you are using the Sargent Charger, and especially if you have an EC325 then you are doing absolutely the right thing by powering it on periodically. I would maybe have it switched off much more than on though. The battery will charge much faster than it will discharge parked up.
Personally speaking, I would get an external better smart charger to charge the batteries. It will charge them correctly to the right levels. It will also be more efficient and only charge when the battery needs it - if you have solar and the charge from the solar controller is more than the battery loads, that will look after the battery and the mains charger will still there plugged in but doing nothing, so even though you ARE plugged in, you are still getting free solar polar instead of using expensive grid power. I often leave my motorhome plugged in for weeks and during the day the grid power is maybe 2-3W but the solar is 100W or whatever.

However/But (always a but ) - If you add an external Charger, that will work on the Leisure Battery and it doesn't matter what battery is selected on the control panel, it charges the Leisure Battery regardless. You really want to be selecting the Leisure Battery anyway on the Control Panel by default. And then to charge the Vehicle Battery periodically, switch to Vehicle and turn the Sargent charger back on; or get a little battery maintainer such as a Vanbitz Battery Master or the much superior Ablemail AMT12 which will send a small charge current to the vehicle battery whenever the Leisure battery is being charged by solar or by mains.

 

[merl]

Puzzled by the advice to turn a Sargent 325 off periodically David? If the Sargent 325 doesn't actually charge the battery fully then it's going to suffer sulphation to some extent but turning it off will make things worse?
Anyway it's a proper 3 stage jobbie PX300, sez so in the title.

 

[wildebus]

Puzzled by the advice to turn a Sargent 325 off periodically David? If the Sargent 325 doesn't actually charge the battery fully then it's going to suffer sulphation to some extent but turning it off will make things worse?
Anyway it's a proper 3 stage jobbie PX300, sez so in the title.

I don't think it is a good idea to keep a constant 13.8V on the battery.
I don't think it is a good idea either to use a charger that does that to start with.

 

[wildebus]

Puzzled by the advice to turn a Sargent 325 off periodically David? If the Sargent 325 doesn't actually charge the battery fully then it's going to suffer sulphation to some extent but turning it off will make things worse?
Anyway it's a proper 3 stage jobbie PX300, sez so in the title.

Bear in mind my last post was in response to Jacquies post, and not the OP. The OP may have a PX300, but a 2010 Mohawk is pretty unlikely to.

 

[jacquigem]

Any decent battery charger should float charge your battery at the correct stand by voltage so you should never be able to cook a battery by leaving it connected to a decent charger. (David will be along in a min and tell us whether the Sargent 2010 era floats correctly so give him a few mins to finish his lunch!) There is a slight cost involved obviously because you're leaving a charger running 24/7 but that should work out better than taking your battery off charge and letting the battery fall back to less than 100% because when you do you'll introduce sulphation of the plates and shorten the battery's life.
All of the above is assuming you've got what most folks have WRT batteries ie standard lead acid and not lithium or lead carbon. Lead carbon are more tolerant of being left standing in a PSC (partial state of charge) and Lithium shouldn't really be left in float at all.
12.4V is much lower than I'd personally let my batteries sit at and I have lead carbons, 12.4V indicates around 60% capacity, much too low for lead acid storage, they'll be knackered in no time.
Check the accuracy of the Sargent panel readout by measuring the voltage AT THE BATTERY with a multi meter if you can.

Thanks ,they are standard lead acid so looks like better to leave charger on .Will have to get voltage checked. Van does start well so maybe I am getting a false reading on my

 

[jacquigem]

Van currently going through Spanish I T V so will answer your questions when I get it back . Thanks for your input , and apologies to original poster as I appear to ha e hijacked this thread . Cap Diem I'm afraid.

 

[jacquigem]

I would guess a 2010 Autotrail Mohawk will have either a Sargent EC325 or a Sargent EC328. (and to add a slight confusion, if the EC325 was ever returned to Sargent for a repair, it is likely they upgraded it to a EC328 and that may or may not be noted on the case. I don't know if they did).
Check the big number on the Silver Sargent box - located in the top locker behind the Drivers I would think in your Motorhome? Let us know what it is.

The EC325 has a basic "power supply" charger. I have found it is a 13.8V Supply. It won't go higher, so won't charge the battery fully. It won't go any lower, so is at the top end of a float voltage.
The EC328 has according to the Sargent specs a much better Battery Charger and IIRC is a 3-stage charger much more like a smart charger.

IF you are seeing the vehicle battery dropping when the charger is off, then that suggests you have the control panel set so the hab electrics are running off the Vehicle Battery and not the Starter Battery, as the Sargent charger will only charge whatever battery is selected (when you have the EC325/EC328 and many/most other Sargent models).
(I think we have had a conversation about the Sargent control panel and how the battery selection works?)

Are you doing the right thing? If you are using the Sargent Charger, and especially if you have an EC325 then you are doing absolutely the right thing by powering it on periodically. I would maybe have it switched off much more than on though. The battery will charge much faster than it will discharge parked up.
Personally speaking, I would get an external better smart charger to charge the batteries. It will charge them correctly to the right levels. It will also be more efficient and only charge when the battery needs it - if you have solar and the charge from the solar controller is more than the battery loads, that will look after the battery and the mains charger will still there plugged in but doing nothing, so even though you ARE plugged in, you are still getting free solar polar instead of using expensive grid power. I often leave my motorhome plugged in for weeks and during the day the grid power is maybe 2-3W but the solar is 100W or whatever.

However/But (always a but ) - If you add an external Charger, that will work on the Leisure Battery and it doesn't matter what battery is selected on the control panel, it charges the Leisure Battery regardless. You really want to be selecting the Leisure Battery anyway on the Control Panel by default. And then to charge the Vehicle Battery periodically, switch to Vehicle and turn the Sargent charger back on; or get a little battery maintainer such as a Vanbitz Battery Master or the much superior Ablemail AMT12 which will send a small charge current to the vehicle battery whenever the Leisure battery is being charged by solar or by mains.

It's a sargent EC 500 . Yes we did discuss battery selection and I now make sure Sargent is set to leisure when we are using van. , but switching to vehicle when on charge and not using hab.Also showing victron controller fitted recently and seems to sort out our Leisure batteries but I am not sure if it helps engine battery.
I also have a cheap Chinese small solar panel which feeds into cigarette lighter but don't use sin e read so.ewhere only works when ignition on ?
Thanks for your continued help.

 

[merl]

Bear in mind my last post was in response to Jacquies post, and not the OP. The OP may have a PX300, but a 2010 Mohawk is pretty unlikely to.

Yep, senior moment (again)!

 

[Moped]

Hi guys. We are now off grid for 2 days before our next AC hook up. Will check things out then with fresh AC supply. Basically I am used to seeing AC power draw on the Sargent display panel of under 1amp when the hooked up with the 3 way Dometic fridge running on AC and the charger trickling when battery 100% with no 12v in use so what was observed was odd hence the query.

 

[merl]

Although all of Europe including the UK is supposed to have the same 230v supply voltage in reality this is not the case. The voltage in France and Europe is typically lower than in the UK.often around 10% lower. When powering some items like chargers this will result in a higher draw current from the mains. It's also possible that the mains wiring on the site you visited was let's say sub optimal and with many campers using the mains supply for heating and cooking at the same time this resulted in a further drop in supply voltage which caused your battery charger to draw even more mains current than usual. Either way I doubt nothing to worry about.

 

[wildebus]

Any decent battery charger should float charge your battery at the correct stand by voltage so you should never be able to cook a battery by leaving it connected to a decent charger. (David will be along in a min and tell us whether the Sargent 2010 era floats correctly so give him a few mins to finish his lunch!) There is a slight cost involved obviously because you're leaving a charger running 24/7 but that should work out better than taking your battery off charge and letting the battery fall back to less than 100% because when you do you'll introduce sulphation of the plates and shorten the battery's life.
All of the above is assuming you've got what most folks have WRT batteries ie standard lead acid and not lithium or lead carbon. Lead carbon are more tolerant of being left standing in a PSC (partial state of charge) and Lithium shouldn't really be left in float at all.
12.4V is much lower than I'd personally let my batteries sit at and I have lead carbons, 12.4V indicates around 60% capacity, much too low for lead acid storage, they'll be knackered in no time.
Check the accuracy of the Sargent panel readout by measuring the voltage AT THE BATTERY with a multi meter if you can.

This is quite a good indication of a setup which maintains the battery but also takes advantage of the 'free' power from the solar....


Screenshot 2023-10-05 at 11-43-44 Monty - VRM Portal by David, on Flickr
Plugged into EHU, but the charger is on float and is drawing nothing as all the power requirements are being met by the Solar.

However .... what you could do to make it even more efficient if you have solar and EHU is have the EHU on a time clock so it only comes on later in the day for a period of time. This would let the solar work harder when it is available. If you have both EHU and Solar you would have a situation where the EHU will start working to keep the battery topped up as soon as it is dusk and maintain that until the solar wakes up, and you would never get the full capablity of the solar during the day (hence why in the screeshot above, all the solar is doing to providing just what is needed as the battery is full.

If you are looking at the cost of the electricity when the charger is active though in the example above, you could be looking at maybe 15 pence a day if you have a compressor fridge? (if you have an Absorption fridge running on AC when laid up, that is more like £1.50 a day just to run the fridge!)


(I could actually set the charger to 'storage' instead of float, which could be better for some - maybe most - setups in a situation where the motorhome is laid up unused, but in my particular config, the storage mode was not suitable)

 

[Moped]

Although all of Europe including the UK is supposed to have the same 230v supply voltage in reality this is not the case. The voltage in France and Europe is typically lower than in the UK.often around 10% lower. When powering some items like chargers this will result in a higher draw current from the mains. It's also possible that the mains wiring on the site you visited was let's say sub optimal and with many campers using the mains supply for heating and cooking at the same time this resulted in a further drop in supply voltage which caused your battery charger to draw even more mains current than usual. Either way I doubt nothing to worry about.

We were using the 6amp hook up on a relatively rural coastal Camping-Car Park aire when I noticed the charger draw seemed high for a fully charged battery.

Then on an aire off grid for 2 days with battery and solar working fine.

We are now on a site with decent 10amp hook in a major resort and the trickle charge draw is now only 0.5amp and slowly dropping which is a more normal level so I guess the voltage drop described above was the root cause of the higher draw rate with the fully charged battery.