BEP VSR wiring

[Heckler]

Some proper engineers have measured this sort of thing with actual engineering instruments.
It's a surge current which will flow for a fraction of a second, which a Nasa monitor is not going to see.
TBH, anyone who thinks their start battery is 70 amps is not really qualified to comment.

This is the one I have just fitted, a 70 amp hr one https://www.carrefour.es/bateria-de...2/p;jsessionid=l17VPib9HgrhUz6KK8PnMK7X.sf2_7
But of course there is always one isnt there?
Why do you do things like that? Does it make you feel good?
It would appear that every one else knows what I mean.
Stu
PS are you a "proper" engineer? a source for your statement would be good.

 

[Heckler]

I agree.

The biggest danger i see with the "fixed" relay is in the event of a battery failure, where a house battery dies and drags all the other batteries down with it. The VSR would disconnect the engine battery when the house bank dragged it down to the relay cut out voltage.

My starter battery cratered the other week as detailed elswhere, surface charge showed on a digital meter as 12.7v but as soon as a load was put on it dropped to 10.55v iirc.
The house bank followed a week or so later with one of them starting to seriously steam. The heat sensors from the Sterling devices failed to shut the "chargers" down, it was only the smell which we noticed which brought it to our attention.
Stu

 

[PaulRainbow]

My starter battery cratered the other week as detailed elswhere, surface charge showed on a digital meter as 12.7v but as soon as a load was put on it dropped to 10.55v iirc.
The house bank followed a week or so later with one of them starting to seriously steam. The heat sensors from the Sterling devices failed to shut the "chargers" down, it was only the smell which we noticed which brought it to our attention.
Stu

When my house batteries went tits up they set the Co alarms off. The solar controller was trying to charge them and with a dead cell in each battery they boiled nicely.

 

[Heckler]

When my house batteries went tits up they set the Co alarms off. The solar controller was trying to charge them and with a dead cell in each battery they boiled nicely.

Of course, the solar! I have mine swivelling on the hand rail like folde able wings, when they are vertical they still give off some charge. Interesting to try and work out what is controlling what, with the Sterling alternator booster sensing the solar surface charge? or the true state of the batteries?
My 110 amp hr (mustnt forget the hr eh! ) that was really bad, took over 24 hrs to cool down before I dared move it. Serious stuff although I isolated all sources of charge and discharge remote from the bank compartment before managing to disconnect the battery straps. I limped back to Gib, over 30 hrs of motoring, no wind, with the bank compartment open to help keep the remaining house batteries coolish. The start battery, I disconnected because It was fully charged and I didnt want to risk this new one, only about ten days old, being overcharged because the knackered house bank could have been "demanding" charge that could have damaged it.
The house bank was warm but not dangerously so and we got back ok.
Stu

 

[BabaYaga]

That's the whole point. If the house battery fails and won't hold its charge it can measure next to 0v, it will drain the battery with the engine running. I see such things on a regular basis, the fact that you have never personally experienced them does not change that.

There are many things that happen that i have not personally experienced, but i like to consider the likelihood that they may happen and take measures to prevent them occurring and minimise the effect they will have should they occur, within reason.

I'm not claiming it cannot happen, please see my post #73, just surprised that it is such a common event as you seem to indicate.
However, if the system voltage was dragged to near 0V while the engine was running and the alternator putting out charging current, I must assume that the voltage at the alternator D+ terminal would also be near 0V? I which case the dumb relay would be open, isolating the engine battery.
(In fact I guess the relay would open already when the voltage at D+ had fell to 10V or so).
BTW, was the alternator uneffected by charging at a system voltage near 0V?

 

[pvb]

What do you have in mind here Pete ? There a few options.

As you say, there are various options. I use a Quick ECS163 (http://www.quicknauticalequipment.com/?lng=en&cs1=01&ms1=2&ms2=3&ms3=67&ms4=151) which has 3 outputs. Works fine. Other options include offerings from Sterling (https://sterling-power.com/products/volt-drop-alternator-splitting-system-pro-split-r), Victron (https://www.victronenergy.com/battery-isolators-and-combiners/argo-fet-battery-isolators) and others.

 

[PaulRainbow]

I'm not claiming it cannot happen, please see my post #73, just surprised that it is such a common event as you seem to indicate.
However, if the system voltage was dragged to near 0V while the engine was running and the alternator putting out charging current, I must assume that the voltage at the alternator D+ terminal would also be near 0V? I which case the dumb relay would be open, isolating the engine battery.
(In fact I guess the relay would open already when the voltage at D+ had fell to 10V or so).
BTW, was the alternator uneffected by charging at a system voltage near 0V?

With no charging the battery can read 0v. Start the engine and the system will see the alternator output voltage. If you were underway and the house battery failed in such a way you would be unaware, the house systems would be running off of the engine battery/alternator. If the engine battery is discharging you'll be unaware of that too.

When my house battery failed underway i had a split charge diode. I was unaware the battery had failed because everything was being powered by the alternator. When i stopped for fuel and switched the engine off all of the house circuits went dead, the battery was totally flat. The diode protected the engine battery. After an overnight charge the battery was still lifeless. Had they have been in parallel whilst underway i think the engine battery may have been flattened too, although i can't be 100%.

I wouldn't say it was common, but my job exposes me to more failures than most people would see and i see some strange and extreme failures.

 

[pvb]

With no charging the battery can read 0v. Start the engine and the system will see the alternator output voltage. If you were underway and the house battery failed in such a way you would be unaware, the house systems would be running off of the engine battery/alternator. If the engine battery is discharging you'll be unaware of that too.

When my house battery failed underway i had a split charge diode. I was unaware the battery had failed because everything was being powered by the alternator. When i stopped for fuel and switched the engine off all of the house circuits went dead, the battery was totally flat. The diode protected the engine battery. After an overnight charge the battery was still lifeless. Had they have been in parallel whilst underway i think the engine battery may have been flattened too, although i can't be 100%.

I wouldn't say it was common, but my job exposes me to more failures than most people would see and i see some strange and extreme failures.

I've experienced a similar situation, when one of six parallelled house batteries developed a shorted cell and dragged the whole 660Ah bank down.

 

[PaulRainbow]

As you say, there are various options. I use a Quick ECS163 (http://www.quicknauticalequipment.com/?lng=en&cs1=01&ms1=2&ms2=3&ms3=67&ms4=151) which has 3 outputs. Works fine. Other options include offerings from Sterling (https://sterling-power.com/products/volt-drop-alternator-splitting-system-pro-split-r), Victron (https://www.victronenergy.com/battery-isolators-and-combiners/argo-fet-battery-isolators) and others.

I think in some installations, particularly those without solar power, there is a good case for the Quick or Victron spliter. More money, but i like the look of the Sterling Pro Split.

With solar charging, and the desire to keep the engine battery topped up (albeit a questionable need in many cases) another solution would be needed. I'm not sure what beats a VSR in these cases.

 

[pvb]

With solar charging, and the desire to keep the engine battery topped up (albeit a questionable need in many cases) another solution would be needed.

Very questionable. Apart from a catastrophic battery failure (unlikely) what's going to cause an isolated start battery to lose charge within a few weeks or so?

 

[lw395]

Very questionable. Apart from a catastrophic battery failure (unlikely) what's going to cause an isolated start battery to lose charge within a few weeks or so?

Possibly a duff house battery will prevent it ever getting charged above the cut out voltage of the VSR.
With solar charging it may get over charged.