Power use advice please

Sep 22, 2017
208
151
Funster No
50,633
I have two 110 amp hour Elecsol batteries that were fitted (apparently) new in April. I have a 100 watt solar panel fitted.
Last week,I was off hookup for the first time since owning the van and on the first evening, after an hour or so, I got the warning sound from the controller that they were low. The van had been on hookup at home, plus the sun had been beating down on the solar all day so I surmised that both batteries were as charged as they could possibly be. Everything was on gas and the only thing on battery was the lighting and the pump etc. This happened every day for over a week and I ended up using a torch to save power.

Yesterday back at home, I started with a fully charged pair of batteries that had been on hookup and solar for two days.
Unhooked the van and turned on 5 of the 12V- 10w lights and within 10 minutes the batteries had gone from 13.2 volts down to 12.4 Volts, they had initially used -7amps then down to 6.5amps.

A tech guy (not the supplying dealer) had done a Drop test on the batteries in May and said they were fine in general. They had been flattened by the fridge over a seven hour drive which was a surprise to me but he suggested we have a split charge relay fitted as a fridge draws too much power???. We had put the fridge on auto as advised, when starting the trip.

What I would like to know is how long should we be able to run the five 10 watt lights etc on those two leisure batteries off hookup obviously at night, so no solar input and no other power drain other than the pump.

Are these batteries or something else faulty? would they go bad in three months only used on hookup?

This latest problem is part of a large body of stress we have had with the van in the four months we have owned it which will be coming to a head shortly so any thoughts greatly appreciated.
 

tonka

LIFE MEMBER
Jul 2, 2008
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Cannock, Staffs or Benidorm, spain
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My first move sould be to go and buy a multimeter if you dont have one.
You need to check if the solar, EHU and alternator are putting any charge into the batteries.
Simple to test..

In reply to your maths question. As you are not meant to deplete below 50% thats 110amps to use. 110 x 12v = 1320 watts
5 x 10w lights = 50w (that is quite high, LED's will be much lower).

1320 / 50 = 26.4 hours... Approx.. sort of.. maybe.. (y) :D
 
Jul 5, 2013
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Tunbridge Wells
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Sounds like your batteries are probably knackered. Also it sounds like your fridge is not wired correctly. Assuming it is an AES fridge it should automatically be fed from the engine battery and alternator while the engine is running.

What motorhome have you got and what model is the fridge?
 
Feb 17, 2017
155
436
Herefordshire
Funster No
47,371
MH
C Class
Exp
Zero
Even at 10 watts each lamp is using less than 1 amp (0.833) so as said by tonka it would take 26.4 Hours to drop your 220 amp hour worth of batteries to 50%.

Your reading of a 7 amps draw should still last over 15 hours before getting to 50% and that is not including any input from your solar.
 
Sep 3, 2012
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Cheshire
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from my experience if you are running the fridge etc on gas and your batteries are fully charged to 13.2v ,as soon as you switch some 12 v lights on the reading will drop to 12.7v. running for a short while will see a drop , 12.4 v is still ok. if you turn off your electric you will hopefully see the voltage go back to 12.7v. with the solar charge on, the battery will go up beyond 12.7 , I see mine to 14v on a sunny day but after a few mins at night with lights on its 12.7v again. I would look to change any halogen bulbs you have to LEDs-straightforward to do , a direct changeover. if you also run a tv your batteries may show a further drop to 12.2 but should still recover close to 12.7v when the tv is turned off. provided you don't go much lower than 11.8 v you should be ok and the batteries will recharge the next day with solar or a drive.
 

pappajohn

LIFE MEMBER
Aug 26, 2007
36,382
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Dark side of the moon
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Since 2005
13.2v is your charge voltage..... Slightly less than would be expected when you first disconnect your charger.
Your battery should stand unused for an hour or so after being taken off charge to allow this residual voltage to dissipate.... Turning on the lights has the same effect.
12.4v is slightly less than a normal battery reading after a small load has been applied.
Your low voltage alarm is at fault, not your batteries..... Though they are a little low on voltage compared to new batteries.
 

pappajohn

LIFE MEMBER
Aug 26, 2007
36,382
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Dark side of the moon
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What I would like to know is how long should we be able to run the five 10 watt lights etc on those two leisure batteries off hookup obviously at night, so no solar input and no other power drain other than the pump.
Theoretically..... 24 hours to 50% discharge.... 48 hours to "bugger, I need new batteries"
 
OP
S
Sep 22, 2017
208
151
Funster No
50,633
My first move sould be to go and buy a multimeter if you dont have one.
You need to check if the solar, EHU and alternator are putting any charge into the batteries.
Simple to test..

In reply to your maths question. As you are not meant to deplete below 50% thats 110amps to use. 110 x 12v = 1320 watts
5 x 10w lights = 50w (that is quite high, LED's will be much lower).

1320 / 50 = 26.4 hours... Approx.. sort of.. maybe.. (y) :D
Thanks Tonka, that's very helpful, I will get a multimeter an check that out (y)
 
OP
S
Sep 22, 2017
208
151
Funster No
50,633
Sounds like your batteries are probably knackered. Also it sounds like your fridge is not wired correctly. Assuming it is an AES fridge it should automatically be fed from the engine battery and alternator while the engine is running.

What motorhome have you got and what model is the fridge?
Hi Peter, it's a Rapido 9048 and the fridge a dometic with the freezer at the top. This will run on gas while driving I have just discovered.
 
OP
S
Sep 22, 2017
208
151
Funster No
50,633
An important point to make is that Elecsol ceased producing batteries 5 or 6 years ago, so they are a lot older than you think.
I think you have given me the answer right there Peter. When I bought the van in April this year, I asked for an additional leisure battery to be fitted.
The dealer said that they had had to fit 'two new' ones as they needed to be the same!! Presumably then, the existing battery had not been an Elecsol. They then fitted 'two new' 5/6 year old unused, impossible to warrantee, Elecsol batteries, which although passed a drop test (whatever that is), failed at the first real world off grid use within a matter of minutes.
So, as suggested they are knackered and were well past their sell by date when fitted back in April!
There can be no excuse for this, can there!:( Oh dear...



Thank you all so much for your thoughts, I really appreciate every word(y)

So, what Batteries would you recommend I get to replace these things. We don't use a telly or hairdryers etc, just lighting and pump etc.

I have just ordered full LED replacement lighting as advised.
 
OP
S
Sep 22, 2017
208
151
Funster No
50,633
Did another test today
On hookup and solar and fully charged, then at 3.45pm this afternoon, I disconnected the hookup but still on solar. At 8.15 pm switched on five 10 watt bulbs intending to leave them on all night. Went out to check on things at 11.00 pm and the whole electric system had shut down, so must have dropped beneath the minimum safety level and shut down.

So, from a pair of supposed to be new,110 amp hour batteries showing a charge of 13.1 volts after being off hookup for 4 1/2 hours so as to settle down, they are flattened in 2 3/4 hours by 50 watts of lighting!.

So definitely knackered! (n)
 
Feb 17, 2017
155
436
Herefordshire
Funster No
47,371
MH
C Class
Exp
Zero
I definitely think you may have 2 EX batteries there, even if they kicked out at 50% depletion after 2 3/4 hours that would be a constant drain in the region of 40 Amps (480 Watts)assuming a 100% start position on good batteries
 
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