Battery Master not working? (1 Viewer)

Apr 29, 2009
1,193
725
West Sussex
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Burstner Nexxo T740
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since 2008
Motorhome has been parked up since 20th Oct with the Alarm on. Went to start it this morning and the battery was flat. I plugged into EHU for a couple or three hours and it starts ok.
I have a battery master fiitted which I thought would utilise the 2 x Leisure Batteries to start the Engine if the Engine Battery couldnt, but this didnt appear to happen - even with the Leisure Batteries showing 14 volts on hook up the Engine wouldnt start until I left if on hook up for a while. The leisure battery voltmeter didnt flicker when I tried to start the engine.
Any ideas how I can check/test or am I mistaken as to what the Battery Master does?
 

pappajohn

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Aug 26, 2007
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leisure battery cannot be used to start the engine.....it doesnt have the required wiring size or suitable relay.

battery master is to link the hab and starter batteries for charging purposes only....ie: relatively low current, not the 400 or so amps needed for starting.

many American RVs have the ability to do this, but the hab and starter batteries are connected with starter motor sized cables and a 400amp relay

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Mr Colpot
Apr 29, 2009
1,193
725
West Sussex
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Burstner Nexxo T740
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since 2008
Thanks for the replies - posted before I read the instructions - we have a solar panel but I guess we havent had the sun for the last 3 weeks and now the alarm is working properly and flashing the leds front/back/inside 24/7 maybe the drain is significant.
Will keep on EHU although we usually use it most weekends it was just I was hospitalised and recuperating so pride and joy didnt get the usual attention.
 

Techno

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The battery master was designed for vehicles that DO NOT have solar panels'
It works by transfering charge from the liesure batteries to the engine battery whenever the engine battery falls to more than half a volt or so below that of the liesures.
Eddie designed it in response to alarms flattening the engine battery.
Having said that it is also suitable for vans that do have solar although the better device in this case is a CBE CSB2 often sourced for around ÂŁ25
If your engine battery is not keeping up despite having a good voltage on your leisures then you either have a bad connection on the battery master or the engine battery terminals.

EDIT
Having re read your post
The fact that your batteries show 14 volts on hook up does not mean your batteries are not flat it is simply showing the charger output voltage.
I suspect in this case that they were discharged in their effort to maintain the engine battery.
This cannot happen with the CSB2 as it only sends surplus charge to the engine battery whilst with battery master the leisure batteries are at the mercy of the engine battery
 
Last edited:
Dec 6, 2011
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had battery master on my last van and suffered the fate of all batteries becoming flat as a result of the trickle discharge to alarm etc.

so your battery master must have a wiring issue. or as Techno says perhaps your liesure batts were also flat.

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Techno

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I would make sure there isn't anything else aside from the alarm draining your batteries.
With this you cannot flatten your leisure batteries
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Mr Colpot
Apr 29, 2009
1,193
725
West Sussex
Funster No
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Burstner Nexxo T740
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Thanks again for the advice - I will keep an eye on the batteries over the next few days to see what happens. There is nothing else on (as far as I can see) that would cause a drain on the batteries other than the alarm.
Will also check the wiring.
 

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