Is my Battery Master kaput

[Bart]

My set up consists of 400w of solar which is connected to 3 x 90ah leisure batteries.
Along with that I also have a Battery Master ( cheap version from flea Bay) which is about 2 years old now, I use it to trickle charge my starter battery.
However despite my leisure battery bank being fully charged and being in float mode with a voltage of around 13.4v my starter battery is dropping to just above 12v.
The green light is lit on the battery master ( not sure if this is just a light to show its powered or if it is to show that it is indicating that it is charging the starter battery)
But the starter voltage remains around 12.1v, yet if I put a volt meter on the output from the battery master it is like 13.4v the same as my leisure battery bank.

 

[Camping Gaza]

It would be interesting for you to take a peek inside your battery master and see what electronics you find.

So somewhere from the OUT from the BM to the IN to the cab battery there is a voltage drop ie OUT 13.4 and to the cab 12.1?

Did you install the BM yourself? and where does the OUT from the BM go to?

If you look inside the BM there could be a short to earth from your cab battery, due to a bad diode perhaps? only a guess of course, not being there to take a meter to it.

 

[Boycie]

The same as I installed. I would check the blue wire connection to the Cab battery also the black ground. Check with a meter the output from the BM.
Phil

 

[Steve N Tracy]

The green led shows that the leisure batteries are charged and the CSB2 has switched to charge the cab battery, if you have 13.4 volts showing on the cab battery charge lead it looks like your cab battery could be on its way out.

 

[Robert Clark]

2nd vote for dying cab battery
I’d disconnect it and test the voltage again after a few hours

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[gerry mcg]

Cab Battery = starter battery? or
Cab Battery = leisure (habitation) battery?

 

[Taran_Las]

From the CSB2 user manual.

 

[eddie]

You don’t have a Battery Master, or even a “cheap knock off” as they work differently

The CBE unit simply switches on when the voltage in the leisure battery (s) reaches 13.65 VDC

Battery Master starts to trickle charge as soon as the voltage difference is circa 0.8:VDC

So the CBE unit has to see the leisure batteries fully charged be before the engine battery benefits

Also the CBE unit switches off if the engine battery reaches 12.4 VDC which is counterproductive in my mind, which is why ours doesn’t

So you need to buy the right product from Jim’s shop immediately

THEN you can tell people you have a Battery Master, until the you have a CBE voltage sensed switch

 

[andy63]

Also the CBE unit switches off if the engine battery reaches 12.4 VDC which is counterproductive in my mind, which is why ours doesn’t

Is that supposed to read switches off when the leisure batteries reach 12.5v not engine battery as stated..
Ie to avoid draining the leisure battery at the expense of keeping the start battery topped up..
Andy..

 

[eddie]

Is that supposed to read switches off when the leisure batteries reach 12.5v not engine battery as stated..
Ie to avoid draining the leisure battery at the expense of keeping the start battery topped up..
Andy..

Yes sorry when the leisure battery(s) are 12.5 VDC (Circa 80%) the CBE switches off which seems daft as the engine battery ultimately in my mind is the most important, and far more likely to be damaged by a deep discharge.

Which is why mine doesn't

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[Bart]

It would be interesting for you to take a peek inside your battery master and see what electronics you find.

So somewhere from the OUT from the BM to the IN to the cab battery there is a voltage drop ie OUT 13.4 and to the cab 12.1?

Did you install the BM yourself? and where does the OUT from the BM go to?

If you look inside the BM there could be a short to earth from your cab battery, due to a bad diode perhaps? only a guess of course, not being there to take a meter to it.

Yip installed myself, so I'll recheck wiring

The same as I installed. I would check the blue wire connection to the Cab battery also the black ground. Check with a meter the output from the BM.
Phil

Thanks, as above I'll recheck wiring esp neutral, as when I tested it I just used leisure battery neutral

 

[Boycie]

As eddievanbitz so eloquently points out there is a very subtle difference between a BM & the CBE unit but it has worked well for me for over 3 years and even when the van is in storage it will start every time. I do have solar to keep the hab batteries topped up so the cab battery is also trickle charged. I like to check the state of my batteries but of course they can fail at an inopportune moment normally.

 

[eddie]

Battery Master

 

[Bart]

Battery Master

Bought and installed today, working good yy yy