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Sean44 Samba Member
Joined: September 30, 2015 Posts: 2 Location: Vancouver, BC
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Posted: Thu Jun 30, 2016 5:59 pm Post subject: New deep cycle battery won't fully charge - Solar & Alternator |
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'71 bus. There's an 80w solar panel on the roof - Bought the bus like this. It's connects to a deep cycle battery in the engine compartment. The old battery didn't hold a charge so I got a new battery, hooked it up. Problem I seem to be having is that I can't get the battery to fully charge. Should it have come fully charged? When I drive the level monitor shows that its fully charged, then when I park at night and start using the battery (the fridge/stereo) the monitor quickly shows 50% then it slowly goes down from there. It's a 80amp hour battery. Does it make sense that running the small fridge all night (and the stereo for a few hours before sleep) will drain the battery by morning?
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telford dorr Samba Member
Joined: March 11, 2009 Posts: 3551 Location: San Diego (Encinitas)
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Posted: Thu Jun 30, 2016 6:37 pm Post subject: Re: New deep cycle battery won't fully charge - Solar & Alternator |
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Batteries generally don' come fully charged as they sit on the shelf until you buy it.
You need to measure the voltage across the battery terminals with a decent voltmeter. Typically, a smart charge controller will charge the battery until it reaches around 14.4 volts, then switches to a maintenance charge of around 13.8 volts. If it's below that level, then the battery isn't being fully charged. If the voltage is at this level but falls under load, then the battery is suspect. _________________ '71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST) |
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BayCreamPuff Samba Member
Joined: August 10, 2015 Posts: 769 Location: Oakland, CA
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Posted: Thu Jun 30, 2016 7:32 pm Post subject: Re: New deep cycle battery won't fully charge - Solar & Alternator |
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1. Get out your voltmeter and check the voltage of the battery with the the car off. Is it below 12.6V? If it's below 12.6V you should hook it up to an external battery charger (ideally with the battery disconnected and outside the bus). Or you can take it to your FLAPS and get them to charge it for you.
2. Battery fully charged? Start up the bus and make sure it's getting charged from the alternator. Should be somewhere between 13.4V - 14.4V with the alternator spinning.
As for running the fridge overnight. The Westy manual recommends only using the auxiliary battery to keep the fridge cool for 4 hours. Is your fridge 12V DC or is it plugged into a DC/AC inverter? _________________ Cream Puff
'79 CA Stock FI Deluxe Campmobile
Earl Grey
'87 GoWesty 2.2 Westfalia
Marsha Mellow
'00 Eurovan VR6 Full Camper |
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72camper Samba Member
Joined: January 25, 2015 Posts: 256
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Posted: Fri Jul 01, 2016 12:10 am Post subject: Re: New deep cycle battery won't fully charge - Solar & Alternator |
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I've been able to run my fridge for a couple of full days without any other charging except for the solar panel during daytime. My panel is quite bigger than 80 watts, too. I don't know how/if that makes a difference. |
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mikedjames Samba Member
Joined: July 02, 2012 Posts: 2736 Location: Hamble, Hampshire, UK
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Posted: Fri Jul 01, 2016 1:39 pm Post subject: Re: New deep cycle battery won't fully charge - Solar & Alternator |
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What kind of fridge ?
Some types of fridges draw 7 amps and will flatten a battery overnight.
Other cheap thermoelectric coolers draw 4 amps and will flatten the same battery in a day.
The best compressor fridges will draw more like 1 amp average.
Your stereo may be pulling more power than the fridge.
In which case any leisure battery that fits in the bus may not have enough capacity to last the night.
But I would say that you may be suffering from overcharging when the sun is shining damaging the battery with 5 to 6 amps of current if you do not have a solar regulator that dumps power or controls the charge.
And then at night suffering from a combination of
1. drawing a lot of power
2. having the battery monitor not connected directly to the battery but instead some distance from the battery on the wires carrying current, so the voltage it sees is less than the actual battery voltage.
That would show up by the voltage immediately jumping back up if you turned off the stereo and the fridge.
It is not a good idea to regularly let lead acid batteries deep discharge. _________________ Ancient vehicles and vessels
1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.
1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy |
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Tcash Samba Member
Joined: July 20, 2011 Posts: 12844 Location: San Jose, California, USA
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