Article: Pete. R Photos: Pete. R
Problems associated with batteries in parallel:-
a. If one battery dies the additional strain that it places on the good battery will quickly kill the good battery. Now instead of having one battery to replace you have two.
b. If you are running batteries in parallel and one died I would replace both at the same time. The second one (old one) is very close to being on it's way out also and will have a negative effect (reduce the life of) on the new one you just put in.
c. If for some reason the battery goes flat, both batteries go flat. Not good if you're out bush alone.
Advantages of batteries in parallel:-
a. The combined power of the two batteries makes starting easier. This however can be overcome by installing an N70Z battery with 750+CCA (Cold Cranking Amps) as pictured below.
b. ........................................nope, can't think of any others.
Did you notice I couldn't come up with a remedy to the problems caused by batteries in parallel yet I could for advantages.
Battery Voltage Checks
With the engine off remove the negative terminal from the battery you suspect is the problem or both batteries if you want to look at them both. Measure the voltage across the batteries terminals. It should be on or just over 12 volts. If the batteries voltage is less than 12 volts (and you've not left anything electrical on) then there's a good chance one of the batteries is dead. But which one?? Only a hydrometer or a Battery Load Tester will tell you that. A hydrometer will cost less than $10 from an auto shop (I got mine from Super Cheap for $5), a Battery Load Tester will set you back many hundreds of dollars, your choice.
Electrolyte Level Check
Remove the plugs on the top of the battery one at a time. The electrolyte should be just touching the bottom of the plastic where the plug screws in.
If it's not top up with distilled water and not tap water. Tap water has minerals and chemicals that will speed up the degradation of the battery and reduce it's effectiveness.
The hydrometer is a good way of checking the quality of the electrolyte in the battery. The electrolyte is a sulphuric acid and distilled water solution which is supposed to be a specific acidity if the battery is healthy. A fully charged cell should be about 1.265SG at 25 degrees C. The hydrometers these days make it easy as they have a Red (cell dead), White or amber (cell not charged properly) and Green (green is good) section. Each cell of the battery has to be checked as they are not all linked. It only takes one cell to kill a battery.
Charging System Check
To check if the alternator is putting out the correct voltage ensure all terminals on the batteries are on and tight. Start the engine and measure the voltage across either one of the batteries. It should be between 14 and 14.5 volts. Again if your batteries are connected in parallel you only have to measure the voltage across one battery as it will be exactly the same on the other. If you have a duel battery system then I recommend checking the voltage on both batteries to make sure the duel battery controller is functioning correctly and allowing the second battery to charge.
Battery Terminal Maintenance
If you have a white fluffy build up on the terminals of your batteries the quickest and most effective way of cleaning it is with a solution of tap water and bi-carb soda (you can get this from the supermarket, it's used to bake cakes). Before you proceed, make absolutely sure your battery caps are on tight. Into a litre of water add 2 table spoons of bi-carb soda. Pour the solution onto the battery terminals. If you have some build up elsewhere pour the solution on there also. It will fizz. Now use 2 litres of water to rinse the solution from the truck. Grab some Vaseline (no, not for that!) and smear it over the battery terminals. This will prevent future build up of the white fluffy stuff.
Maintenance Free Batteries
Unless it's a gel cell battery there is no such thing. All batteries with a liquid electrolyte solution need maintenance. Some one in the 80's heeded the call of the many who didn't know better for a maintenance free battery, so they produced a battery that didn't have the caps on the top and called it maintenance free. That's it, that's all they did and the gullible believed it. If you have a so called maintenance free battery ripe the big sticker off the top, lift the plastic strip and see the lie for yourself. Then go get real battery that you can nurture, look after and maintain. My suggested battery is an N70Z with at least 700+CCA (the one at the top of this page not the one above, that's my second battery I'll replace when Super Cheap have their next 25% off everything sale).