Leisure Battery Conundrum (1 Viewer)

Feb 9, 2008
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I would like to improve my understanding of what is going on with my leisure batteries and Sargent system and would appreciate input from informed members.

I have been undertaking a load test on my leisure batteries, 2 x 110 AH. They have been fully charged and left to settle with no incoming source. Voltmeter reading at start of test 12.7

I then put a load of 6 Amps on the batteries and after 1 hour measured again with VM, reading 12.52 V. The Sargent Control panel stated 11.9 V. good.
The reading was the same for the next 2 hourly visits. i.e. 6 Amp draw and VM reading 12.5. (did not check control panel).
On 4th visit (4 hrs on load test) one of my TV's had shut down due to a low voltage warning and my control panel was stating 9.8 V poor. Yet when I measured with my VM directly from the battery terminal I was getting 12.5 V.
I have shut down the system completely now and will see how far the batteries recover tomorrow morning.
Can anyone make sense of this ! I know both the sargent system and my VM are not faulty but clearly there is a conflict.
It's possible my batteries are on there way out, 4 years old and hammered last winter in Morocco but still reading 12.7 when fully charged.
 

jonandshell

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Dec 12, 2010
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It is because Sargent use cable which is way too thin for the load.
As a result you get a massive voltage drop between the battery and PSU. This also adversly affects the efficiency of the split charge system.
Rewiring with a cable which is fit for purpose is the only way.
 

karl c

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Mar 25, 2014
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how have you linked the two batteries up
and where have you fitted the out put to psu

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Feb 24, 2013
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not long enough
I have such little knowledge I really should not be contributing, but your meter readings sound too good to be true, if you are taking 6A out I am amazed they have held 12.5 V for 2 hours

Or have I read it all wrong :)
 

jonandshell

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I have such little knowledge I really should not be contributing, but your meter readings sound too good to be true, if you are taking 6A out I am amazed they have held 12.5 V for 2 hours

Or have I read it all wrong :)

Why not? It's only 12Ah drawn from the battery out of 220 available Ah at 100% DOD.
In fact a draw of 6 amps is about what the batteries should be able to supply for a 20 hr rating.
 

jonandshell

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Of course, not all batteries are what they say on their labels though.......:)

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Feb 24, 2013
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not long enough
Why not? It's only 12Ah drawn from the battery out of 220 available Ah at 100% DOD.
In fact a draw of 6 amps is about what the batteries should be able to supply for a 20 hr rating.

When I plug my 300W inverter in it shows a draw of about 5A when in use, my controller then shows at least a 0.1 V drop every half hour, drawing from 2 x 110A new batteries.

As those that have read of my mishaps will know I completely flattened by cab battery twice in 6 months :D (using wrong socket) hence my surprise that the 12.5 is held for so long
 
Jan 8, 2013
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I don't trust my Burstner Micky Mouse gauge, I only treat it as a gauge (if that makes sense).
Your volt meter will be a truer reading.
My fully charged 2 x 100a Varta battery's will drop from 12.8 to 12.2V after 3 hours of TV use (about 5A)
I think that's perfectly acceptable, we watch TV from 9.00 to 12.00 and then turn it off.
Battery's will fully recharge after 3 hours of travelling
Four year old well used battery's will be getting a bit tired but they should see you OK for another year.
 
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PhilandMena
Feb 9, 2008
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It is because Sargent use cable which is way too thin for the load.
As a result you get a massive voltage drop between the battery and PSU. This also adversly affects the efficiency of the split charge system.
Rewiring with a cable which is fit for purpose is the only way.
I think not! I did the same test 3 years ago with a 6 Amp draw over 4 hours and no warning on the control panel and no TV cut out due to low power.
The wiring is the original wiring and installation from new in 2011. So, I think it must be something other than that. Although I do find your comment interesting and am aware cable thickness is important.

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PhilandMena
Feb 9, 2008
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I don't trust my Burstner Micky Mouse gauge, I only treat it as a gauge (if that makes sense).
Your volt meter will be a truer reading.
My fully charged 2 x 100a Varta battery's will drop from 12.8 to 12.2V after 3 hours of TV use (about 5A)
I think that's perfectly acceptable, we watch TV from 9.00 to 12.00 and then turn it off.
Battery's will fully recharge after 3 hours of travelling
Four year old well used battery's will be getting a bit tired but they should see you OK for another year.
By my reckoning, I should get at least 12 hrs of safe usage if a 6 Amp draw is taken from 220 AH battery bank. I will see how well the batteries have recovered in the morning and take it from there.
 

irnbru

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Jun 27, 2013
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I would like to learn too.
So he starts off at 12.7
1hr and 6amps later drops to 12.52
2hr and another 6amp=12.5
3hr and another 6 amp =12.5
4hr and another 6 amp and its srill at 12.5
So why did it drop almost 2 for the first 6 amps and hardly anything for the next 18 ?
A wokshop at the fixit meet or such would be great on this topic.
 

funflair

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Dec 11, 2013
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I would like to learn too.
So he starts off at 12.7
1hr and 6amps later drops to 12.52
2hr and another 6amp=12.5
3hr and another 6 amp =12.5
4hr and another 6 amp and its srill at 12.5
So why did it drop almost 2 for the first 6 amps and hardly anything for the next 18 ?
A wokshop at the fixit meet or such would be great on this topic.

Hi @irnbru I dont think that would be typical, I would expect to see something a bit more linear, I would be pleased to teach you what I know But the trouble is I dont know much;) will be good to meet you at fix it as we have not crossed paths before.

Martin

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funflair

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Dec 11, 2013
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When I plug my 300W inverter in it shows a draw of about 5A when in use, my controller then shows at least a 0.1 V drop every half hour, drawing from 2 x 110A new batteries.

As those that have read of my mishaps will know I completely flattened by cab battery twice in 6 months :D (using wrong socket) hence my surprise that the 12.5 is held for so long

Hi @DavidG58 at 5 amps you are only running about 50 watts from your inverter at 240 volts, If you plug your hairdryer in it will draw a lot more (or go up in smoke):LOL:
 

andy63

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Jan 19, 2014
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So why did it drop almost 2 for the first 6 amps and hardly anything for the next 18 ?
Any battery will show a drop in voltage as soon as a load is applied..as the current draw continues the batteries ability to hold its voltage is a measure of its condition and how good the battery is and a gradual drop in voltage would be normal..

Can anyone make sense of this ! I know both the sargent system and my VM are not faulty but clearly there is a conflict.
I thought Jon's assessment was resonable. . If vm and Sargent are not faulty as you indicate then the Sargent is not seeing the true battery voltage .
I posted a week or so ago about connecting solar to a van with a Sargent control... 2 X 110ah leisure batteries connected to the Sargent panel individually through longish ie 2.5 m runs wire which I thought looked rather thin. They met at the panel but the batteries were not paralled at source...
Looking forward to your findings cause I can't think of what else it could be.
Ta Andy.
 
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PhilandMena
Feb 9, 2008
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OK! Firstly, apologies all round, as I have not given you the full picture (unintentional I assure you). My aim was to put as big a draw on the batteries as I reasonable could so in addition to all my internal lights, external Hab door light and two TV's being on the go, I also switched on my Inverter (300W) and attached a mini battery charger loaded with 4 AA batteries.
The control panel indicated a draw of 6.2 A and now in hind sight I'm sure it was not registering the draw taken by the Inverter as this is wired directly to the leisure batteries and the Sargent system would not know of it's existence.(I believe?)
The battery charger has an output of 1.8 A and for each AA battery .45 A so by my maths a total draw of 3.6 A. The inverter itself would have a draw of 0.95 A making a total of 4.5A to be added to the 6.2 A draw indicated on the control panel.
So, by my reckoning I have taken a total of 25 A out of each battery over 4 hours which the batteries should cope with easily.
When I checked my batteries again this morning, after resting for some 13 hours they had fully recovered and were reading 12 .69 on the VM. This indicates to me that the batteries are still A-O-K.
I just want to understand why the Sargent system indicated 9.8 V after 4 hours of draw and shut down one of my TV's.
I'll have a chat with Sargent next week and see what they say.
Any Idea's what has happened ?

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andy63

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Jan 19, 2014
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I just want to understand why the Sargent system indicated 9.8 V after 4 hours of draw and shut down one of my TV's.
I'll have a chat with Sargent next week and see what they say.
Any Idea's what has happened

Can you open the Sargent control panel up and measure the battery voltage at the point the battery wires enter the Sargent ,with the volt meter? See what you get there..
Ta andy
 
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PhilandMena
Feb 9, 2008
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Can you open the Sargent control panel up and measure the battery voltage at the point the battery wires enter the Sargent ,with the volt meter? See what you get there..
Ta andy
I had the control panel off two years ago when I fitted a Solar Panel and fortunately there was already a Sargent regulator installed from new so making the connection was simple. The only problem I would have with your suggestion is knowing which wires were coming from the battery ? However, it's an option and I'll bank it in case no other explanation makes sense. Thanks.
 

Emmenay

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I have the same problem with the Sargent control panel, or should I say the inadequate wiring to and from it.
My panel reads 12.2 volts with the TV on but my v/Meter reads 12.5.
I have made my own panel now with digital v/meters wired directly from the leisure batteries and the cab battery. No more confusion :D

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andy63

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Jan 19, 2014
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I had the control panel off two years ago when I fitted a Solar Panel and fortunately there was already a Sargent regulator installed from new so making the connection was simple. The only problem I would have with your suggestion is knowing which wires were coming from the battery ? However, it's an option and I'll bank it in
case no other explanation makes sense. Thanks.

Hi your Sargent is a later one than the one I'm on about as mine didn't have the built in solar regulator...
The Sargent harness from the batteries was colour coded (orange/white. And brown /blue ) from memory... It was easy enough to pick them up inside the panel...
Just thought if you could do that it would answer the question about the voltage the Sargent was seeing.
Hope you solve it.
Ta Andy.
 
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PhilandMena
Feb 9, 2008
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I have the same problem with the Sargent control panel, or should I say the inadequate wiring to and from it.
My panel reads 12.2 volts with the TV on but my v/Meter reads 12.5.
I have made my own panel now with digital v/meters wired directly from the leisure batteries and the cab battery. No more confusion :D
I find your comment interesting. Does that mean when your TV is on, the panel is indicating a true voltage state at the point of measurement because of the wiring (? and if so, this could indicate why the system shut down the TV when there was still plenty of juice in the batteries) and, if fitting an alternative measuring point would this prevent the system shutting down ?.
 
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PhilandMena
Feb 9, 2008
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Corby, Northants
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Since 2007
Hi @irnbru I dont think that would be typical, I would expect to see something a bit more linear, I would be pleased to teach you what I know But the trouble is I dont know much;) will be good to meet you at fix it as we have not crossed paths before.

Martin
Hi Martin, I think the reason it stayed at 12.5V over 3 hours (drop below 12.5 was on hour 4) is simply because the battery bank was sufficient and at 12.5 V there was plenty in reserve. The initial load taking the voltage down to 12.5 and it stay's here until x amount of hours pass or x amount of Amps have been used up.......perhaps.

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Emmenay

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Dec 11, 2011
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I find your comment interesting. Does that mean when your TV is on, the panel is indicating a true voltage state at the point of measurement because of the wiring (? and if so, this could indicate why the system shut down the TV when there was still plenty of juice in the batteries) and, if fitting an alternative measuring point would this prevent the system shutting down ?.

I think I know what you're asking, yes, the panel is reading true at the point of measurement so it is actually accurate. The wiring is letting the side down before it gets there or anywhere else.
I haven't had the issue with the tv switching off because of it but it would if the voltage went low enough,as a precaution I think I will use the inadequate feed wire to the tv socket as a trigger wire for a relay and use heavier wire staight from the leisure battery, but still allowing it to switch off when the panel is switched off.
The home made panel does not prevent the switch off but the relay would. It is very easy to build your own voltage meters straight from the batteries with a few bits from ebay and maplins.(y)
 

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