Battery charge controller

[langdav]

Has anyone fitted a CBE battery charge manager BCM 12. I have a 2015 plate Chausson with a solar panel.

Both batteries charge when on hook up but only the leisure is charged from the solar panel.

Will fitting the charge manager have any negative effect on charging on hook up ? Thanks

[aandncaravan]

langdav - 2017-01-24 10:09 PM

 

Has anyone fitted a CBE battery charge manager BCM 12. I have a 2015 plate Chausson with a solar panel.

Both batteries charge when on hook up but only the leisure is charged from the solar panel.

Will fitting the charge manager have any negative effect on charging on hook up ? Thanks

 

 

 

Yes they can have a negative effect on modern units as they short circuit the functionality of a modern power controller/charger. They can steal charge for the Starter battery when you might want every milliamp to go to the habitation battery.

 

The existing Main charger/Power unit, when you engage 230v mains, may only begin charging of the Starter battery once the Habitation battery reaches a certain threshold or when a timer expires, such as after 4 hours.

 

If you fit one of these Battery Master style devices, like the CBE BCM, it will start stealing power from the habitation battery as soon as any charging of the habitation battery takes place. Regardless of where the charge is coming from, or the habitation battery state, which may be fully dis-charged.

 

 

This CBE unit is similar in concept to the other 'battery power theft' devices, like the more common Battery Master, and has the same flaws.

 

While the technical document talks about them triggering at 'the battery' voltage, they are actually triggered by the voltage at the battery, which can make them work quite differently to the description with erratic and uncontrolled operation.

 

For example, if you measure a 12.4v habitation battery with digital meter you will see 12.4v. If you then start charging that battery, the meter will go straight up to the charging voltage of, say, 14.4v.

No matter how hard you try, you will no longer be able to see the batteries 'true' 12.4v.

 

This is what happens to the Battery Masters, CBE BCM, etc they suddenly detect the battery is now at 14.4v and trigger to begin charge of the Starter battery. Even though you might want all your precious Winter Solar amps to go to the Habitation battery, the 'battery power theft' devices will start taking all they need for the Starter battery.

 

You lose control over when they trigger. Worse still so does the CBE Charger/controller

 

So while the technical specs might state, they will only trigger once the habitation battery is at full charge, they don't. They trigger when the voltage 'at the battery' is above 13v or whatever their particular threshold is.

Some trigger on a voltage difference of 0.75v rather than a set voltage. So for example when the Starter battery drops 0.75 below the habitation, it starts charging the Starter battery.

But why would you want to let the Starter battery drop as low as 12.1v, into the damage zone, before you start charging it up??

 

 

Another issue is the units themselves use precious power. The Vanbitz Battery Master for example, is monitoring the voltage of both Habitation and Starter batteries all the time. In other words drawing power from both ALL the time. It is only small amounts, but over a 6 week period in storage it can add up to run down batteries

 

When the Solar panel might only be putting milliamps into the batteries in December, to waste any at all doesn't make sense.

 

The most efficient option for you, that also keeps the functionality as the Motorhome manufacturer intended, is to replace the Solar regulator with a Dual battery version. That will intelligently charge BOTH the Habitation and Starter battery directly. No second tier of unreliability, complexity or uncontrolled behaviour.

This is also now the cheapest option. 8 years ago when Dual battery Solar Regulators were both rare and £100's, the 'battery power theft' devices were pretty much the only way of charging the Starter battery.

As with most things, times change and they are now the least efficient option. Some of these Battery Masters style units cost close on £80, whereas a Dual battery Solar regulator can be as little as £25.

The majority of older style single battery Solar regulators are also likely to be less efficient than a 2017 Dual battery version, so you will gain in improvements all round.

Remember the new solar charger, for maximum efficiency, should be within 3 feet of the batteries/power unit.

 

As to have I fitted any? No, but I have removed a lot.

;-)

 

 

[langdav]

Thanks Allan

Very detailed reply you confirmed what I was concerned about. Will go down the dual regulator route when I can get one wired up.

[chas]

I have solar panel set up with a CBE fitted and on reading this when on EHU will simple remove the fuse feed to the starter battery which comes from the CBE unit, if the habitation battery needs priority. 8-)

[aandncaravan]

chas - 2017-01-26 9:52 AM

 

I have solar panel set up with a CBE fitted and on reading this when on EHU will simple remove the fuse feed to the starter battery which comes from the CBE unit, if the habitation battery needs priority. 8-)

 

 

Chas, That will get around it short circuiting the CBE main control units functionality, but how will you stop the 'power theft device' stealing Solar charge from the habitation battery for the Starter battery when you don't want it to?

How will you also get around a Battery Master continually draining down both batteries?

 

If you are installing Solar, fitting a dual battery Solar Regulator that charges both Habitation and starter batteries directly, is the optimum.

Why have an extra level of complexity and unreliability by fitting a second piece of electronics?

 

I know that Battery Master style devices work for many, but the owners are not getting the best from their system at all. When Solar Power in Winter is all about small amounts of power from a weak Sun and a short day, the smallest amount of amps makes a big difference.

A good installer with even a basic understanding of electricity will see they are not the most efficient option.

 

As a result where these devices are fitted, there tends to be other, significant weaknesses with the Solar Installation, such as an inferior regulator fitted up near the roof, not right next to the batteries/Main power controller.

Hence our advice to fit a modern dual battery regulator within a very short distance of the Main Power controller.

 

Such a change, along with ditching a Battery Master, usually results in a 30% increase in Solar gain in typical UK conditions, especially during Winter months.

If the upgrade also includes an MPPT Solar dual regulator, the improvement can be double what the owner saw before.

 

Remember as well that the Battery Master device is not 100% efficient. In passing current from the habitation battery to the starter battery significant amounts of the charge may be lost, they are not 100% efficient.

 

 

 

 

 

[lennyhb]

I fitted one to my van when I changed the Schudt LR1218 regulator for a better MPPT unit which is only single output. Works a treat I agree you get some losses only time it is lightly to be a problem is in deepest winter but nice to know you will always be able to start the van. I have already decided that on the new Hymer due in a few weeks when I fit the system I will fit an isolation switch so if I need max charge to the leisure battery I can switch it out of circuit.

[aandncaravan]

Just fixed an unusual problem, relevant to this thread, with a Sargent EC 325 where the Starter battery kept running down and appeared to be taking the habitation battery with it.

 

We witnessed the Starter battery getting a 4 amp charge and the Habitation battery 'putting out' about as much, but everything on the EC325 checked out as working correctly.

 

We then discovered the issue was the Solar Power installation linked to a Starter battery powering a Car style Alarm (tend to have higher standby current) and a Tracker.

 

The Solar system had a 100w panel, a single Sun Solar regulator and a Sterling 'Battery Master' power theft device to top up the Starter battery.

 

 

What we discovered was that the Battery Master style unit was detecting the Solar power voltage at the habitation battery by 'seeing' 13.9v and then stealing power for the Starter battery.

However because the 'charge' from the Solar Regulator this time of year is very small, less than a 0.2amps in this case, it wasn't doing any real charging to replace the 4amps being stolen for the Starter.

The Solar installation, although clearly 'professional', was poor. More on that later.

 

 

During the Winter months the power from the Solar Panel is expected to be very low, so although the Solar Panel and regulator were poorly installed, they were working as expected.

However, the 'Battery maintainer' was not being very intelligent, stealing more from the Habitation battery than was being put in.

 

 

Exactly as we state above, and have said elsewhere, the Sterling Battery Maintainer (actually the most efficient of it's breed and better than the CBE or Vanbitz unit) was stealing power in an uncontrolled way.

 

When the Solar Panel was isolated from the Regulator, so no Solar 'charge', the Sterling battery maintainer 'switched off' and the power draw from the habitation battery stopped.

However, it's draw from the Starter battery was about 100 milliamps in this idle state and more than we expected. It's 'idle' draw from the Habitation battery was also higher than we expected.

 

 

Resolution:

We decommissioned the Solar regulator originally fitted up near the ceiling about 4 metres from the batteries and wired the Solar Panel directly into the Inbuilt Solar regulator already inside the EC325.

The exact way Sargent and the Motorhome manufacturer state it should be done, enabling the EC325 to control Starter battery charging.

 

It took about 15 minutes to wire the Solar as it should be and at 12:50 we saw 0.6amp, an increase in Solar charge of 50% over the old setup. With the battery maintainer also no longer drawing any power out of the batteries when idle, the overall improvement is probably quite significant.

 

Starter battery was then replaced and all then working correctly.

The old Starter Battery, which still started the engine, was clearly past it's best. Every cell was dry, plates clearly visible, don't know the age but at least 5 years old?

 

 

The EC325/EC328 charger can output up to 18v charge and Sargent say nothing must ever be connected directly to the Habitation battery, we were surprised the old Sun Solar regulator and battery maintainer had survived.