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post #1 of 17 (permalink) Old 03-03-2009, 12:24 PM Thread Starter
TR5
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Sargent Charger unit

My MH is fitted with the sargent power supply unit PSU 2005 and the EC200 control panel.
My concern is the charging voltage being insufficient, and wonder if other more technical buddies think the same.

From their spec:
Mains Input 230 Volts AC +/- 10%
Frequency 50 Hz
Output Voltage 13.5 Volts nominal
Output Current 12 Amps nominal
For optimum performance and safety it is essential that only a proprietary brand LEISURE battery is
used with a typical capacity of 75 to 120 Ah.


Now my understanding is that a 12v battery (or batteries) require around 14.4 to 14.8 volts, both to fully charge and to keep then is good condition (undercharging causing sulphating of the plates,etc.)
Also, most MH users nowadays fit additonal power - I have 2 x 110ah batteries, but the "typical capacity" quoted is 75 - 120ah.

Having previously been in touch with Sargents, they say the battery gets the required 14.4 volts when the MH is being driven, via the split charge relay, and this is enough to keep the batteries in top condition.
However, the MH is not on the road every day, sometimes not for a few weeks, so is this damaging or reducing the life of the batteries? They remain on EHU on charge when at home!

Also, can you couple another charger, like a Ctek unit, and leave it in parallel with the Sargent unit, to use to give a bigger boost to the batteries, with or without the Sargent unit on/off?

Has anyone else envisaged this problem, and found a way round?
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post #2 of 17 (permalink) Old 03-03-2009, 02:11 PM
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Michael,

I use a Ctek Charger on my leisure battery when the 'van is parked at home for an extended period. I do this because I believe that the charging regime of the Ctek is better than that of the Sargent. I base this opinion on things that I have read from others who have more knowledge of battery charging than I do, but who may not have been experts. I also think that the cooling fan running constantly for extended periods in the Sargent may lead to earlier fan failure than if it is used less: again only my opinion.

I have a single 130amp leisure battery in my Starblazer and had the same reservations about the '75 to 120 amp' recommended limit for the Sargent, but then the Ctek that I have suggests suitability only for up to 120amp. As far as I can tell, no harm is done to either the chargers or the battery .........

I have read somewhere, maybe here on MHF that it is OK to parallel connect two chargers to a battery as you suggest but I am not an expert and just don't know.

Harvey
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post #3 of 17 (permalink) Old 03-03-2009, 03:37 PM Thread Starter
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Hi Harvey

Thanks for your reply.
My main concern is the low voltage supplied by the Sargent unit.
The lower the voltage the battery becomes, the more sulphated the plates become. A 12v battery needs between 2.4v and 2.5v per cell to strip this sulphation off, and a continual under-charged battery will last a lot less timewise.
It is not necessary for it to be charged at this rate every time, but i am concerned that, when sat on my drivefor several weeks on EHU, with charging at only 13.5v, the batteries are likely to sulphate prematurely.

Michael
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post #4 of 17 (permalink) Old 03-03-2009, 04:09 PM
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I agree Michael especially at this time of year as at low temperatures the charging voltage needs to be much higher.

at 25 deg C 14.4V
at 5 deg C 15.0V (from memory I might be .05V out)

assuming a flooded battery
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post #5 of 17 (permalink) Old 03-03-2009, 06:52 PM
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Quote:
Originally Posted by TR5
Hi Harvey

Thanks for your reply.
My main concern is the low voltage supplied by the Sargent unit.
The lower the voltage the battery becomes, the more sulphated the plates become. A 12v battery needs between 2.4v and 2.5v per cell to strip this sulphation off, and a continual under-charged battery will last a lot less timewise.
It is not necessary for it to be charged at this rate every time, but i am concerned that, when sat on my drivefor several weeks on EHU, with charging at only 13.5v, the batteries are likely to sulphate prematurely.

Michael
Michael,

I wasn't aware of the sulphating problem due to low charge voltage. It may be worth investing in a Ctek or similar. Mine is a XS 3600, about £50. I also have a couple of the similar but *much* cheaper Tronic T4X from Lidl. You may need something larger / more powerful for your twin 110amps though. Ctek do bigger ones but more money of course.

Edit for:---- I have read somewhere; a motorhome magazine or 'Club' magazine I think, which suggests that some electronic equipment in motorhomes may not like the voltage as high as 14 plus volts, which is why installed chargers are usually lower voltages than this .......

Maybe it is time an *expert* had a say here

Harvey
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post #6 of 17 (permalink) Old 03-03-2009, 10:46 PM
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Hi Michael, Harvey, on the PSU2005 the nominal system voltage is 13.5 but it rises to charge the batteries at 13.8v On this unit we do use the alternator charging voltage to periodically lift the voltage supplied to the battery, as with the majority of charging systems it is not healthy to have voltages greater than 13.8v on batteries for long periods (on standard lead acid (flooded) types)
There needs to be some recommendation on the suitability of the charger to look after a certain size of battery, this is the main reason for the recommendation upto 120a/h, the main reason for this is due to the time taken to replenish a battery within a reasonable time frame.

We also need to make sure that the system voltage ie the voltage that appliances, lights and other accessories are subjected to meet the manufacturers instructions. This figure does vary, and the majority of equipment being put into the market now can tolerate higher voltages but there are some that cannot, so therefore when an electrical system is being designed all of these have to be investigated and approved.

As to connecting two chargers to the same battery/ies i would not recommend this as they will fight each other. When the units are monitoring the battery voltage it will be "fooled" by the other chargers voltage being present. I am not saying that it will not charge the battery/ies but it will not charge them as intended.

We started (3 years ago) changing all of the battery charging facilities within our power supply units and stand alone chargers, to multistage charging regimes to ensure the best possible maintance of the battery/ies, and these are been placed in new products. Some of these use off line charging (by the use of multiple converters within a single unit) whilst others complete charging whilst also providing the system voltage.

In the research into the exact charging profiles for each battery manufacturer (as no doubt some people will have discovered) the manufacturers recommendations all vary??? so it becomes a very difficult to get a profile that suits all of the differing types/manufacturers but we took data from 10 different manufacturers and used this to build the ones we use.

I hope the above explains some of the points raised.

Best regards

Ian Sargent
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post #7 of 17 (permalink) Old 03-03-2009, 11:37 PM
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Quote:
Originally Posted by Sargent
Hi Michael, Harvey, on the PSU2005 the nominal system voltage is 13.5 but it rises to charge the batteries at 13.8v (snipped )

I hope the above explains some of the points raised.

Best regards

Ian Sargent
Thank you very much for that Ian. I understand from that, hopefully correctly, that the new Sargent units that you have develoved since 2006 are multistage chargers but that the PSU2005 that Michael has and possibly the PSU 2007 that I have ( installed in a 2006 Autocruise ), are not multistage chargers.

Would you be able to confirm, or otherwise, the suitability of both of these for constant charging over an extended period when the 'vans are layed up; maybe for several weeks, or would I/we, really be better off using a multi-stage charger such as the CTEK that I currently use for the purpose?


Thanks.

Harvey
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post #8 of 17 (permalink) Old 04-03-2009, 08:31 AM
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Morning Harvey, you are correct that the 2005 and 2007 are both constant voltage, current limited charging systems and all new units are multistage.

I would confirm the suitability of the 13.8v for the float charging voltage for long periods, this is the recommended float voltage and both ours and CTEK use this figure.
If you wanted to exercise the battery from time to time then you could turn off the PSU charger and couple up the CTEK but you need to discharge the battery somewhat first, to give the unit something to do (if you understand me)

Regards

Ian Sargent
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post #9 of 17 (permalink) Old 04-03-2009, 09:03 AM
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Quote:
Originally Posted by Sargent
Morning Harvey, you are correct that the 2005 and 2007 are both constant voltage, current limited charging systems and all new units are multistage.

I would confirm the suitability of the 13.8v for the float charging voltage for long periods, this is the recommended float voltage and both ours and CTEK use this figure.
If you wanted to exercise the battery from time to time then you could turn off the PSU charger and couple up the CTEK but you need to discharge the battery somewhat first, to give the unit something to do (if you understand me)

Regards

Ian Sargent
Excellent, thanks again Ian ............... and posted before I have even eaten breakfast.

Harvey
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post #10 of 17 (permalink) Old 04-03-2009, 09:15 AM
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I wish I understood this thread.

I have an input box with the following on it.

S.M.E. Components
Model SMECB-240-12
input 100-120Vac 4A 50/60Hz
200-240Vac 2A 50/60Hz

Output 13,8Vdc 18A. max

Is it possible to change it out for another unit, that would allow me to connect a solar panel, or is there a better way to do things?

hope this isn't off topic
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