Lucas alternator question for add a battery switch

[Steeevo]

Got it all set up and it works great. The only thing now is that one of the batteries has had it. The acr kicks in after a minute and the alternator is putting out 14.3v into both batteries which is perfect.

when i switch the engine off the batteries run the gps for about 5 minutes then the gps flashes battery low and the acr disconnects the starting battery and the house battery has about 11v left.

looks like i need a new house battery. They are both conventional car starting 12v Yuasa 75ah cca680 batteries so i suspect not great for running gps/radio/lights.

would i be better changing the house battery to a deep cycle battery and keeping the starter battery or replacing both with deep cycle batteries?

 

[VicS]

An ordinary starter battery is the most appropriate type for the engine start battery .... That's what they are designed for.

A leisure battery would be a marginally better choice for house battery. A deep cycle battery even better , but expensive

A deep cycle battery would not be such a good choice though for emergency engine starting

FWIW Ive had very good experiences with Yuasa batteries in a couple of cars ... Over 12 years life

 

[PaulRainbow]

Got it all set up and it works great. The only thing now is that one of the batteries has had it. The acr kicks in after a minute and the alternator is putting out 14.3v into both batteries which is perfect.

when i switch the engine off the batteries run the gps for about 5 minutes then the gps flashes battery low and the acr disconnects the starting battery and the house battery has about 11v left.

looks like i need a new house battery. They are both conventional car starting 12v Yuasa 75ah cca680 batteries so i suspect not great for running gps/radio/lights.

would i be better changing the house battery to a deep cycle battery and keeping the starter battery or replacing both with deep cycle batteries?

Keep the good engine battery for the engine, fit a leisure battery for the domestics. A leisure battery is basically a starter battery with some extra plate support, so will fine for emergency starting of the engine. A deep cycle battery offers no real advantages with your setup.

 

[Steeevo]

So i could replace it with a agm leisure battery because when the engine kicks in it combines the leisure battery and charges them together and then when the engine stops it discharges them together until the voltage reaches 12.7 then it isolates the starter battery

 

[PaulRainbow]

So i could replace it with a agm leisure battery because when the engine kicks in it combines the leisure battery and charges them together and then when the engine stops it discharges them together until the voltage reaches 12.7 then it isolates the starter battery

Yes, you can fit a sealed lead acid leisure battery, an AGM leisure battery or even an AGM starter battery.

 

[Steeevo]

Interesting because everything i have read has said not to mix batteries old/new/ah so thats why i thought i couldnt add a new leisure agm to my current old conventional car starting battery which charges both at the same time

 

[PaulRainbow]

Interesting because everything i have read has said not to mix batteries old/new/ah so thats why i thought i couldnt add a new leisure agm to my current old conventional car starting battery which charges both at the same time

Batteries wired in parallel as a single bank. All batteries should be of the same chemistry. It is often said that we shouldn't mix different age batteries in a bank, but it isn't going to cause any serious issues. If one battery in a bank of 2 or 3 failed it would be common to replace all three, as the others might be close to failing too. But, if you had 2 batteries that were 2 years old and you wanted to add a 3rd, you most likely would not want to replace the two good batteries, sure, the 2 older batteries might fail a little sooner than the new one and you'd possibly throw that away with a year or two of life left in it, but that's surely better than dumping a pair of 2 year old batteries. If you had a bank of large Victron AGM deep cycle batteries, costing £500 each and one failed at 2 years old (just out of warranty) i doubt that many people would dump the remaining good batteries.

What you propose is different to the above, your engine and domestic batteries are not in a single bank and charging them with a VSR does not make them exactly so. There is nothing wrong with having batteries of different chemistries as long as your charging systems are suitable for both chemistries. The charging regimes from SLA and AGM batteries are close enough that they will both be happy being charged from most alternators and mains chargers. As for the ah of each battery, that's not relevant. My engine battery is perhaps 100ah, but my domestic bank is 390ah.

If you stick to your lead acid engine battery and fit a SLA leisure battery, AGM starter battery or AGM leisure battery for your domestic circuits you will, as i said earlier, be perfectly OK.

 

[Steeevo]

Thanks. I went with a yuasa EFB 100ah leisure battery