Adding a third battery

[L and W]

I have purchased a new 800 Amp cranking sealed battery to replace an older 600A one. The old one is still capable of starting the Westerbeke 2 cylinder, but only if it is kept charged - it drains rather rapidly. My question is: would it do me any good at all to wire the new 800A battery in series to the old 600A battery, thus keeping the old battery? Is there any advantage? Is it unsafe to do so?Thanks!

 

[Ed Schenck]

Not series, not even parallel.

Wiring in series would give you 24 volts to the starter and to the panel. Do NOT do that.Wiring in parallel will give you 12 volts but will cause the new battery to drain into the old battery. You should throw away the old one or, if you have the space, store it as a backup.

 

[Gary Wyngarden]

Ed's Right

Don't do either. If the battery is as depleted as you say, just get rid of it.Gary WyngardenS/V Shibumi H335

 

[L and W]

Thanks, Ed and Gary

Thanks, Ed and Gary. I'll disconnect the older battery and return it for the core charge. I don't trust it enough as an emergency spare...