Battery master blaster.

[Chossy]

When I'm done you'll need a sticky plaster

I've got me a Van Bits battery master as they are quite clearly a great little unit, however I have a question about the wiring.

I have a fat legacy cable run from an old Split Charge Relay that runs to the van battery, so I thought I'll just get a wee terminal or similar and wire it all up on the leisure battery side. Does anyone see any issues with the tiny wee battery master cable feeding into the much larger cable? I sincerely do not want to run a new cable and my limited knowledge can't really see any issues with it.

Thanks for any help all y'all.

 

[Lenny HB]

No, the Batterymaster only passes a couple of amps.

 

[Chossy]

Just to be clear, the split charge relay no longer exists, it's just the cable that remains.

 

[autorouter]

Those wires are ideal for the job. You could always swap the fuse at the battery end, which will probably be quite large (30A to 50A) for a smaller fuse, say 10A or even 5A, if you are bothered, but it's not actually necessary to do that.

 

[Chossy]

Thanks everyone.

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[LithiumConvert]

Always best to keep the fuses at no more than they need to be for protection of the wiring.

so if the battery master is tapped off 50amp battery circuits, it should have its own 5 amp fuses.

The fuses protect the wiring not the equipment.

 

[eddie]

Always best to keep the fuses at no more than they need to be for protection of the wiring.

so if the battery master is tapped off 50amp battery circuits, it should have its own 5 amp fuses.

The fuses protect the wiring not the equipment.

Battery Master does not require any additional fusing if it is connected to an existing fused electrical circuit as it has its own internal resetting fuses

 

[David and Sally]

I did put 10 a fuses in the BM cables right next to the batteries just in case one of the grounded out.

 

[LithiumConvert]

Battery Master does not require any additional fusing if it is connected to an existing fused electrical circuit as it has its own internal resetting fuses

Don't forget that the fuses are primarily there to protect the cables as well as the equipment.

If you have a thin cable connected to any point of supply, then it needs a low value fuse. The fuse should be rated to the thickness of the cables.

 

[eddie]

Don't forget that the fuses are primarily there to protect the cables as well as the equipment.

If you have a thin cable connected to any point of supply, then it needs a low value fuse. The fuse should be rated to the thickness of the cables.

The Battery Master can be connected incorrectly, shorted out, connected back to front, or deliberately connected positive output to negative, it will simply not work. It will automatically reset when the fault is rectified

The unit is potted, with the three short cables ready to connect directly say to a relay or a Schaudt screw terminal block, both examples would have existing fuses, connecting the Battery Master would require no additional fuses

If it did, I’d include them in the kit that I’ve been selling for twenty odd years since designing it

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[LithiumConvert]

I will stick with my view that every circuit should be fused with a fuse value which takes into account the capability of the wiring to carry currents up to of the value of the fuse.

 

[Chossy]

Hello,
Thanks everyone for all your responses, I received my unit today. Nice solid wee thing. Lovely bit of engineering.

 

[dash300]

Hello,
Thanks everyone for all your responses, I received my unit today. Nice solid wee thing. Lovely bit of engineering.

I have a mere 100w solar panel feeding two hab batteries and despite the greyest wettest winter on record the Battery Master has done its job and kept the starter battery fully topped up, it just simply does what it is supposed to.

 

[treblid]

I will stick with my view that every circuit should be fused with a fuse value which takes into account the capability of the wiring to carry currents up to of the value of the fuse.

Depends on the length of wires and their physical protection.

I am sure the device itself is self protected but I would want to fuse the connecting wires, at the energy source end, of any wires that passed through/by metal work, etc. where the integrity of insulation materials can be compromised.

 

[eddie]

Depends on the length of wires and their physical protection.

I am sure the device itself is self protected but I would want to fuse the connecting wires, at the energy source end, of any wires that passed through/by metal work, etc. where the integrity of insulation materials can be compromised.

What does?

It's recommended that the unit is connected to an existing supply, IE split charge relay or the supply to a CBE for example

Designed for this there is absolutely no requirement for additional fuses as the existing wires are already fused

If your daft or stupid enough to extend the wire and run, to all intents and purposes a new wire alongside existing conveters cabling, cabling that is quite correctly fused, then yes, it would be a good idea to add a fuse to your unnecessary and pointless Battery Master wire extention

Or, follow the instructions and don't waste your time!

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[treblid]

If your daft or stupid enough to extend the wire and run, to all intents and purposes a new wire alongside existing conveters cabling

I think that comment is rather unfair. You are assuming a utopian physical layout your Battery Master short wires will reach. In practice getting to the simplest connection scenario is not always possible so extending one of wires is required.

Designed for this there is absolutely no requirement for additional fuses as the existing wires are already fused

The cables you refer to are fused typically at 30 - 50A so I am sure the Battery Master wires will vaporise and fuse in the event of a short circuit.

 

[eddie]

I think that comment is rather unfair. You are assuming a utopian physical layout your Battery Master short wires will reach. In practice getting to the simplest connection scenario is not always possible so extending one of wires is required.

99.9% of my customers motorhomes have a form of DC - DC charging which is why we have the Battery Master manufactured with about 150mm of wire

The cables you refer to are fused typically at 30 - 50A so I am sure the Battery Master wires will vaporise and fuse in the event of a short circuit.

No again your wrong, as I explained earlier, put the positive output to negative and the Battery Master will shut down, correct the fault and it will start to work again

I spec'd it to be idiot proof

 

[treblid]

99.9% of my customers motorhomes have a form of DC - DC charging which is why we have the Battery Master manufactured with about 150mm of wire

I must be the 0.1% then.......

Our Burstner has a Schaudt B2B. The input obviously comes from the engine battery. The output goes to the input on the EBL that would normally go to a engine battery. This is exactly how Schaudt also recommend it is connected.

The result of this is the normal charging relay (legacy of older non-B2B configurations) inside the EBL is open circuit when the engine stops. Therefore the leisure battery voltage is NOT on the B2B output when stationary - so simply wiring a Battery Master across the B2B charger would not work.

To make a neat job, I had to extend the BM input wire to reach the EBL leisure battery connection. I added a 5A fuse at the EBL leisure battery connection end to protect the longer wire incase of a short to chassis. I see this as good practice. I am sure the BM is protected but it will not stop the energy from the leisure battery with just a 50A fuse if that wire is shorted to chassis. So I am NOT wrong!

 

[eddie]

I must be the 0.1% then.......

Our Burstner has a Schaudt B2B. The input obviously comes from the engine battery. The output goes to the input on the EBL that would normally go to a engine battery. This is exactly how Schaudt also recommend it is connected.

The result of this is the normal charging relay (legacy of older non-B2B configurations) inside the EBL is open circuit when the engine stops. Therefore the leisure battery voltage is NOT on the B2B output when stationary - so simply wiring a Battery Master across the B2B charger would not work.

To make a neat job, I had to extend the BM output wire to reach the EBL leisure battery connection. I added a 5A fuse at the EBL leisure battery connection end to protect the longer wire incase of a short to chassis. I see this as good practice. I am sure the BM is protected but it will not stop the energy from the leisure battery with just a 50A fuse if that wire is shorted to chassis. So I am NOT wrong.

If you want to add wires to a product you should take steps to ensure your happy with your work and it’s safe.

Having recognised a problem, designed a solution, hand manufactured the products for the first few years (in the evenings once the workshop was sorted) personally installed literally thousands of Battery Masters into motorhomes, sold tens of thousands of them to the trade, motorhome converters, solar installers and the public I assure you that fitted from the packet there is no need for additional fusing. As for fitting? if we needed longer fused wires it would be a simple matter to instruct our manufacturers to do so

But we don’t

I only labour the point as someone posts saying the Battery Master should be fused and I get dozens of messages and photos from worried users asking for verification

If you ‘add bits’ to it, as I said that’s up to you to make sure it’s safe and your happy.

By the way, from memory I’m pretty certain you still have an engine 12VDC for the fridge at the EBL so you could have plugged your Batter Master in there without extending the wires Lenny HB would know, he’s the Schaudt Guru on here

 

[peterc10]

I spec'd it to be idiot proof

The problem with that Eddie is that the world is breeding better idiots.

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[Lenny HB]

By the way, from memory I’m pretty certain you still have an engine 12VDC for the fridge at the EBL so you could have plugged your Batter Master in there without extending the wires @Lenny HB would know, he’s the Schaudt Guru on here

Not read all the thread, the normall arrangement with the EBL the fridge side is fed from a 20 amp fuse by the starter battery to the fridge relay inside the EBL.
The relay is switched by the D+ plus so when the engine is running the fridge is connected to the starter battery. With the relay off engine not running the fridge us connected to the hab battery. Not all manufacturers wire them so the fridge connects to the hab battery, Hymer do.

 

[The Wino]

If the cable is a legacy cable and not powering anything else I think it certainly is a good idea to add a low power fuse at the battery end to protect the cable. If anyone then shorts it by mistake the fuse will blow well before anything gets hot. I can see no disadvantage in fitting a fuse whether the battery master needs one to protect it is neither here nor there .

 

[David and Sally]

If you want to add wires to a product you should take steps to ensure your happy with your work and it’s safe.

Having recognised a problem, designed a solution, hand manufactured the products for the first few years (in the evenings once the workshop was sorted) personally installed literally thousands of Battery Masters into motorhomes, sold tens of thousands of them to the trade, motorhome converters, solar installers and the public I assure you that fitted from the packet there is no need for additional fusing. As for fitting? if we needed longer fused wires it would be a simple matter to instruct our manufacturers to do so

But we don’t

I only labour the point as someone posts saying the Battery Master should be fused and I get dozens of messages and photos from worried users asking for verification

If you ‘add bits’ to it, as I said that’s up to you to make sure it’s safe and your happy.

By the way, from memory I’m pretty certain you still have an engine 12VDC for the fridge at the EBL so you could have plugged your Batter Master in there without extending the wires Lenny HB would know, he’s the Schaudt Guru on here

I bought and fitted one to our Burstner. But, I could not get to the back of the charger block without lot of messing with the wiring to get enough wiggle room. Not wishing to risk any subsequent electrical failures I fitted it into the LB locker and ran a decent sized cable to the starter battery with 10a fuses at both battery terminals.

 

[treblid]

the normal arrangement with the EBL the fridge side is fed from a 20 amp fuse by the starter battery

After studying the EBL circuit diagram, I did look at the fridge connections as an option to pick up the feed.
Our van has a compressor fridge that appears to be connected to the leisure battery. None of the EBL fridge connections are populated so there was no engine battery input to the fridge relay I could use.

 

[autorouter]

After studying the EBL circuit diagram, I did look at the fridge connections as an option to pick up the feed.
Our van has a compressor fridge that appears to be connected to the leisure battery. None of the EBL fridge connections are populated so there was no engine battery input to the fridge relay I could use.

I don't know which EBL model you have, but most have a 5-way connector, which has a 20A fused positive from the starter battery, a starter battery negative, a D+ signal input from the alternator, and a pos/neg pair of sensor wires from the leisure battery. It's usually next to the 4-way connector that goes to the fridge. Even if you wire the fridge completely bypassing the EBL, all those 5 wires are used for other purposes. The 20A starter battery wire is used as a voltage sensor wire for the display panel, for example.

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[eddie]

If the cable is a legacy cable and not powering anything else I think it certainly is a good idea to add a low power fuse at the battery end to protect the cable. If anyone then shorts it by mistake the fuse will blow well before anything gets hot. I can see no disadvantage in fitting a fuse whether the battery master needs one to protect it is neither here nor there .

Adding an unnecessary potential fault down the line. I’ll try one more time

Use a split charge relay as an example, just an example So, a supply, and a load, both fused, a negative connection and a D+ connection

When the engine starts, the alternator produces 12 volts on the D+ this causes the relay to close ( think of it as a switch) Now the correctly fused supply (Engine Battery) will charge the correctly fused Load (Leisure Battery)

Everything safe, fused, and electrically sound.

The relay is a switch that remotely and automatically switches ON & OFF

If you connect the three Battery Master wires parasitically the Brown wire connects to the load the Red to the supply and the black to the relay negative

Nothing has changed at this point, absolutely nothing. The Battery Master reads the voltage on both sides of the “switch” (relay) and does nothing, absolutely nothing until the Engine Battery (EB) is circa 3/4 of a volt below the Leisure Battery (LB) then, it allows about an amp to trickle charge the EB from the LB, a trickle charge, along an existing fused charging circuit. It’s doing what the split charge does, at very low amperage.

If the engine battery goes flat, which it will eventually even if due to age, there will come a point when once started, the empty (flat) engine battery, will try to suck the life out of the leisure battery, often blowing the in line fuses fitted at the factory. Not really an issue as you’d probably notice next time you drove as the leisure battery wouldn’t be charging and a quick peek at the fuse board would reveal why!

However, this high demand would also be via the Battery Master, which will automatically shut down, and will automatically re-set once the condition is normalised, the same as if it’s short circuited or any other issue, it’s what is designed to do, fully automatic and idiots proof!

If you have added a superfluous fuse in line between the Battery Master that will blow and will NOT reset, so will render the Battery Master inoperative which you may not know until it’s too late!

You can connect a Battery Master up the wrong way round, in a bucket of water for a week, take it out, connect it correctly and it would be working as soon as it’s correctly connected

 

[LithiumConvert]

Our fridges are safe. The manufacturers say so.

Our charges are safe. The manufacturers say so.

Our B2Bs are safe. The manufacturers say so.

Our radios are safe. The manufacturers say so.

Our heating system are safe. The manufacturers say so.

Our lighting is safe. The manufacturers say so.

But we still fuse each with a fuse value appropriate to the device and the wiring which connects them.

 

[treblid]

I don't know which EBL model you have, but most have a 5-way connector

Thanks autorouter. It's a EBL119 and that connector (block 2) is fully populated. I was confused by the term 'leisure battery sensor' for pins 2 and 5. I was not sure if it was going to an actual sensor or simple were feeds from the leisure battery for monitoring inside the EBL. (The positive is fused at 2A I see from the diagram).
Assuming it is the latter, then could a Battery Master simply be wired across the appropriate pins of block 2? It would however required splicing into 3 wires which I was trying to avoid.

 

[autorouter]

I was confused by the term 'leisure battery sensor' for pins 2 and 5. I was not sure if it was going to an actual sensor or simple were feeds from the leisure battery for monitoring inside the EBL. (The positive is fused at 2A I see from the diagram).
Assuming it is the latter, then could a Battery Master simply be wired across the appropriate pins of block 2? It would however required splicing into 3 wires which I was trying to avoid.

In theory you could do that, but I'd be reluctant to use those leisure battery sensor wires. They are there to allow accurate voltage sensing without any voltage drop. They are thin wires so if used for any supply purpose they will have some voltage drop. And if that 2A fuse blows, the whole EBL shuts down.

The usual way to avoid splicing into wires is to make a short 5-way extension cable, maybe 100mm long, and crimp in extra wires to the pins. That's how Schaudt wires their solar controller, and they supply this as part of the installation kit. That takes care of the starter battery wire. There's many options for the leisure battery wire. There's a pin on the 3-way Solar connector or on the 2-way Auxiliary Charger (Zus. Lader) connector (if you use those, you have to put a fuse in the Solar or 'Zusatz Ladergerat' slot).