Interesting article on batteries in parallel

[Chris]

Now I know someone will probably have an equally credible opposing view, but this chap seems to know what he's talking about. The whole site is an interesting read actually.

If you have batteries in parallel it says that they do NOT all get treated the same. They may ACT the same, but that's different and not his argument. Maybe this is why typically only one of the two batteries in Cruiser fails.

I have twin batteries in my new trailer and for one, I shall be wiring them up as he suggests.

www.smartgauge.co.uk/batt_con.html

 

[Towpack]

No 2 'identical' batteries will be truly identical due to production tolerances plus, on the 24v start LC's, the offside battery will take more stick than the NS as it's also providing 12v for the starter relay, intake air heater, lights etc in addition to the draw from the 24v starter itself. The air heater alone pulls well over 40amps. I'd wager these are bigger factors in unequal battery life. When I had my old batts tested prior to renewing them both, the OS was down considerably compared to the NS. Coincidence? No reason not to connect the batts as the article suggests though if the theory's sound. JMO

 

[Crispin]

What he says is correct. Method 3 would be the best. I think though that doing this would have the same affect as magnetizing your fuel particles. The difference between 1 and 2/3 would/might be seen in real life if the connections between the batteries were loose, corroded etc. If you're using proper cable, the type that does not glow when you turn the winch on, then it'll make little difference.

Still, no harm in doing it

 

[StarCruiser]

The article is 100% right, methods 3 and 4 give the same result. Method 4 is simply connecting two pairs on opposite corners, then connecting from them on opposite corners. The effect will be to give the batteries the best connection possible which cannot be a bad thing.

Nice find Chris.

 

[Chris]

I was researching AC ground connections on trailers and this came up about narrow boats. The key here is that it's not about battery performance as I said originally. The losses aren't IN the batteries. If you have poor cabling and connections than obviously it gets even worse. The batteries are all equal, but as I said, don't get treated equally.

 

[StarCruiser]

The trailer frame should be earthed on the mains side Chris. Look up BS 7909. You would need to make sure there was no problem with the inverter if you intend earthing the negative of the batteries to the chassis. There should be no problem but worth a check with the manufacturer or their paperwork. The other thing to check is whether or not the neutral is earthed on the output of the inverter. If not, your RCD will never trip. A connection needs to be made pre RCD to Earth one side of the inverter to make it neutral if it has not already been done. Like I say, this needs checking with the manufacturer.

 

[Chris]

Thanks Rich
I know ...