# amps v's volts x 2 leisures + solar... and ran out of power!



## wilse (Aug 10, 2007)

Hi folks

Just back from 2 weeks in France & Germany for Christmas.
For all those who haven't been to Germany... go it's great!... anyway.

In August I bought 2 new 100amp elecsols & 135w Kyocera solar panel... all new items.
We have an electrobloc power supply unit.
When set correctly it is 200amp nominal, and the unit reports working ampage of 160amp. Usual voltages report around 12.7-13v when stood with NO EHU.

On the last night the boiler dial flickered a red light... at first I thought it was the gas, but knew it had a near full tank.

A few minutes later the control panel lit up and reported low voltage 8O 
I checked the amps, but that reported 97amps left.

The voltage was 11.5. I turned everything off and went to bed.
I must admit I tried to reset the alarm [to stop it blinking] and somehow when I'd finished it showed 0amps!

We did have the TV on [well the radio on TV] and a fair few lights, heating, fridge and oven. I estimate that our drain was around 7-9amps per hour for 8 hours.

Did a 4.5 hour drive home and the truck was showing 65 amps.
I have left it on hook-up last night, and will be hoping to see it full again.

It's shaken my confidence a bit... as I thought I'd get more than 1 day sat around [granted this was at the end of 12 days with only 1 day of EHU at day 7]
I did manage 2 days at Kayersberg.

Just wanted to make sure I haven't got a defective battery/charger??

Any advice appreciated.

PS my batteries are in a slide-out tray which is under the van and bl00dy freezin!

w


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## DTPCHEMICALS (Jul 24, 2006)

i think the cold weather had a part to play. My mh is on permanent EHU at home. batteries fully charged but it took some starting yeterday.

I do not know how i manage with only one liesure battery. :? 

dave p


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## DABurleigh (May 9, 2005)

"PS my batteries are in a slide-out tray which is under the van and bl00dy freezin! "

And that's the reason 

In my experience if the temperature is low and you have taken ~half the energy out of the batteries, and, crucially, are discharging at highish amps, then the terminal voltage will drop sufficiently that some applications will switch off. 

If you allow the batteries a while to recover with minimal load, you will find they will happily power lower loads for a long while still.

IMHO the best solution to this is a third battery, as the problem is basically one of inadequate plate area at low temperatures with significant discharge (both energy and power)

Dave


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## wilse (Aug 10, 2007)

Thanks for that, but I'm afraid 3 into 2 won't go... physically that is.

Previous truck had 1 80amp battery... and I thought that upgrading to 2 x 100amp was enough.... doh!

I have read up about Peukert's Exponent and have seen how battery discharge is affected.

In the short term I think the answer may be only go away to hot & sunny climbs  

w


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## DABurleigh (May 9, 2005)

There is a trick to consider, which I posted here:
http://www.motorhomefacts.com/ftopicp-699911.html#699911

I've bought a marine 1/2/both battery switch, but am waiting to the warmer weather to fit it. At least you have some measure of current and Ah discharge, so it makes these things FAR easier to manage. It is nigh on impossible with just a voltmeter indicator, as there are too many variables.

Your problem is a smaller variant of the big inverter one you asked about here:
http://www.motorhomefacts.com/ftopicp-683712.html#683712

Dave


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## sallytrafic (Jan 17, 2006)

I once had a colleague size a battery bank for 0 degrees C in certain knowledge that the temperature would drop that far and then for -10 on the off chance that the temperature would drop that far sometimes, the resultant battery bank was huge. 

If your charger has the facility of temperature sensing then its as well to use it with the temperature sensor touching a battery. My charger adds 30mV for every degree drop in temperature so at zero it adds 0.6V making it charge at 15V at the peak of its operation.


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## nicholsong (May 26, 2009)

I bought my 'A' Class with a heated underfloor area to ensure tanks do not freeze, but had not thought about the advantage of helping the battery performance, A BONUS !


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## wilse (Aug 10, 2007)

Yes... funnily enough I have underfloor heating and it's an A class...??
water tank is internal, waste has a heater, all lockers are also heated.

The battery cabinet is great as you can slide it in and out, but it's not good for keeping out the cold... think I will investigate to seal it up is some manner.

w


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## airstream (Jan 7, 2009)

*Elecsol*

Hi wilse,
Note that your batteries are Elecsol - Elecsol rate the battery using C100 not the industry norm of C20 - to compare like with like your 100 a/h are in reality other manufacturers 85/90 amp/hour 
To get a full understanding try http//jgdarden.com/batteryfaq
Regards Ray


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## Losos (Oct 28, 2009)

wilse said:


> In the short term I think the answer may be only go away to hot & sunny climbs


RS Componants publish a useful data sheet which shows that the drop off in solar panel efficiency in winter is dramatic and coupled with the batteries getting cold means it's an uphill struggle no matter what size (Within reason) batteries you have.

It'll cost an arm and a leg but there is always the EFOY option :roll:


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## greentub (Oct 20, 2009)

*NASA BATTERY MONITOR*

Hello All

Firstly forgive my numbtyness in all things Motorhome. We are recently retired sailing yacht cruisers with an Autocruise Augusta on order. That said, and having spent plenty of my spare time sucking up info on this site, it is clear to see that in terms of the systems and equipment a motorhome is just a cruising yacht with wheels. One of the best £90 things I fitted to the yacht was a NASA battery monitor. It's a very simple DIY instrument that permanently tells you how much current you are drawing from your battery, how much is left in your battery, how long it will take to recharge etc etc etc. The instrument comes with a 5 mtr cable and a 100 amp shunt. In short, (perhaps a bad phrase for an electrical item) it is the answer to sensibly monitoring your 12v electrical use without the4 need to have a working knowledge of Ohms law. Visit any Marine chandlery website and you can see it for yourself. Hope this is useful.


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## DABurleigh (May 9, 2005)

Indeed. I've always been a battery monitor fan. NASA is probably the best value, though as I had a Victron charger/ inverter/ UPS I matched it with a Victron battery monitor.

Just search MHF for battery monitor if anyone wants any more info.

Dave


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## Chascass (May 10, 2007)

Hi thanks, I will certainly be looking at that, dose it also tell you what charge the battery's are receiving, for example from a solar panel.

Charlie


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## DABurleigh (May 9, 2005)

Yes. The sensor is a shunt mounted AT the leisure battery, so in Brian Hanrahan's terms, counts them all out and counts them all back 

Dave


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