Battery monitors again (sorry)

[alan006]

I'm thinking of getting a battery monitor because I had a failure on my recharging circuit and I only found out when my domestic batteries failed me. I have a system of voltage sensitive relays so my engine batteries are charged first and then the domestic batteries get topped up.
My point is that I'm not really bothered by the amount of current I'm drawing but I want to know if the voltage is dropping (when the engine is running) because then I can do something about it.
My question is how useful is it to know what current you are drawing or really is checking the battery voltage good enough? If knowing the voltage is good enough then an accurate voltmeter will be a lot cheaper.

 

[rogerdog]

to just check charging - why not a simple ammeter ?

 

[alan006]

Well Roger, the alternator was working and charging up the engine batteries but the Voltage Sensitive relays didn't work so the domestic batteries were not getting any charge.
I should think that normally VSR's are reliable but since they have let me down once I don't want to be caught again.

 

[rogerdog]

should have been clearer - ammeter on each bank would give very clear indication and should be able to be picked up cheaper than battery monitor (thats just a fancy ammeter in effect)

 

[Talbot]

simple voltmeter will definitely tell you that the batteries are being charged, but not by how much. It should also tell you when the batteries are getting a float charge, or a full charge, which is also a sign of the state of the battery.

 

[alan006]

Thanks for your suggestions everyone. I was going to keep it simple and just use voltmeters but then sod's law would say that I would regret not doing the full job. I hadn't thought of Talbot's point that the charge rate will give me usefull info on the battery state.

 

[markdj]

If using an ammeter, far better to use one that incorporates a shunt as opposed to the amps going right through the ammeter. Sterling and BEP Marine both do very good monitors, the Sterling one supporting multiple amps reading.

 

[William_H]

Your VSR may or may not have a LED indicating that it is connecting. ie that the engine battery voltage has risen and the domestic is getting a charge. You can usually rely on the relay of the VSR functioning OK.
I think you should go back to the way you were before the failure I think you were probably very unlucky. ie it won't happen again.

However An amp meter in the VSR charge line would be usefull. As suggested use a shunt type. It saves taking heavy wires to the instrument panel. But use fuses in the small wires to the shunt.

good luck olewill