Lithium batteries (1 Viewer)

Glyn and Debbie

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May 18, 2011
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Hi this has probably been asked before but here goes, I have a fifth wheel caravan with a lithium leisure battery when towing my pick up truck is draining leisure battery can I fit a smart alternator to cure this thanks in advance
 

Calamaster

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I don't have Lithium Leisure Battery but seems to me there is a wiring issue here. Your Truck should be charging the lithium not draining it.
 
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Glyn and Debbie

Glyn and Debbie

Free Member
May 18, 2011
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465
Manchester
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Since 2008
I agree fifth wheel company want to charge me £1150 to fit a b2b charger instead of trying to find one it what’s causing the drain
 
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TheBig1

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Nov 27, 2011
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many many years! since I was a kid
Fit your own B2B a hell of a lot cheaper than that
 
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Jul 6, 2009
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With the engine on you truck running use a multi meter to check you have at least 13.4 volts at the plug from your truck where it goes into your trailer. That’s the first thing to check.

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Calamaster

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Jun 12, 2019
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Autotrail Cheyenne 6
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I agree fifth wheel company want to charge me £1150 to fit a b2b charger instead of trying to find one it what’s causing the drain
WOW!... Now, I assume that when the Fifth wheeler is parked up and connected to Mains the Lithium Charges fine..?
If so then just disconnect Lithium when 'On Road'.... or £7.99 fix with a simple Toggle Battery rated switch.
Amazon product ASIN B088WM7SHF
Just a suggestion if you feel competent enough to have a go, or find a guy who can cut a cable and wire to the terminals.
 
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Apr 27, 2016
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Hi this has probably been asked before but here goes, I have a fifth wheel caravan with a lithium leisure battery when towing my pick up truck is draining leisure battery can I fit a smart alternator to cure this thanks in advance
You need to check some fundamental things first. Does the alternator charge the starter battery when the engine is running? I know it's supposed to, but maybe the alternator is faulty. When the engine is stopped, the starter battery voltage should be between 12.0V and 12.8V. When the engine is running, the starter battery voltage should rise, to at least 13.0V, and ideally up to about 14.5V. If it doesn't rise then the alternator is faulty. If it's a standard alternator, that is. If it's a smart alternator it might not rise much above 12.5V.

Is the existing alternator a smart alternator or a standard non-smart one? If it's a smart alternator then a B2B is almost certainly necessary to give you a good level of charge in the leisure battery, especially if it's lithium.
 
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Sep 29, 2009
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i would assume the electric braking is not getting sufficient power from the truck and drawing from the leisure battery, or is it the charging profile of the lithium leisure battery different to the vehicle lead acid battery and not charging correctly. It would be interesting to swop a standard leisure battery on while towing to see if the same occurred.
 
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