Bob F

Stay with me on this one, cus it leads to a way of determining whether you should recharge the battery or buy a new one. This is the penultimate question on batteries. BF

The most common way of testing the health of a battery cell is to measure the specific gravity of the electrolyte using a hydrometer. What is the approx specific gravity of a healthy battery cell? 1.000 1.190 1.225 1.270 1.835

Two thirds of you voted to install the negative last. One third voted to install the positive last. The safest method is to install the negative last. If you installed the negative first, there is a risk of shorting the positive lead, in the same ways as described with removing the battery. So, the rules is - REMOVE THE NEGATIVE FIRST WHEN REMOVING. INSTALL THE NEGATIVE LAST WHEN INSTALLING.

Oh Charlie, you just stole my next question. Yes, the gas given off is Hydrogen, which is why it is very important to ensure the batteries are well vented.

When installing a battery which battery lead should you fit last? Negative last. Positive last. Either one, it doesn't matter. Who cares?

Quite a few opinions on this one, but the safest answer, and one you should definitely apply to removing your car battery, is to remove the negative first. Here's why. The roots are from the cars but bare with me. All circuits need a complete loop of wire from one terminal of the battery through the circuit itself (eg: the lights say) and back to the other battery terminal. So basically two wires are needed for each circuit - a "flow" wire and a "return" wire. In order to save on lots of unnecessary wiring, all cars with metal bodies use the chassis of the car as one of the wires. This is called "grounding" or "earthing" in car electrical parlance and thus saves 50% of the wiring (and associated expense) that would otherwise be needed. (Thus fully fibre-glass boats need lots more wire). Now to the crux..... you will only get a big bang if you connect the two terminals of the battery together. So if you leave the negative lead connected and, whilst disconnecting the red positive lead, your spanner happens to touch the chassis while its other end is around the bolt on the positive, you will have connected the two terminals together through your spanner and it will become a permanent part of your chassis as 300 amps flow through it and weld it to the car! You will also probably let go of it very smartly as its temperature reaches that of the Sun!! Conversely, if you disconnect the negative lead first, thus also disconnecting the chassis from having anything to do with the battery, then your spanner can be round the positive and touch the chassis with no ill effects. There is no need to disconnect the positive terminal of the battery unless of course you are taking the battery out for some reason. If you do undo both, always remember, UNDO THE NEGATIVE FIRST. When you have undone the negative lead, tuck it safely out of the way so that it can't suddenly spring back and touch the negative of the battery again before the work is finished. And do undo the negative everytime you work on the electrics. A minute's extra work is better than a fire. Now some will argue that it doesn't matter which lead you remove first on a boat constructed of GRP or wood because there is no metal chasis which the negative is connected to. This is true, but there are circumstances where you can still short out the battery. For example, say you have a two battery set up with a 1-2-BOTH battery switch, and the battery switch is left in the BOTH position. If you remove the positive lead from battery #1 first and leave it dangling and it accidently touches an earth somewhere (for example the engine block or an earth stud or the earth on either battery), there will be an electrical connection through the battery switch to the live positive terminal of battery #2. And hey pesto - messy pants time!! So, safe practice when removing a battery on a car or a boat is to REMOVE THE NEGATIVE FIRST. Now, what about when you reconnect the battery???

When removing a battery which battery lead should you remove first? Negative first. Positive first. Either one, it doesn't matter. You should never remove the battery leads.

Congratulations to those that answered 12.6 volts, which is the correct answer. 14.4 volts is what you would typically see when the battery is being charged by a battery charger or from the alternator on the boat when the engine is running. 13.2 volts is what you would typically see just after a battery charger has been switched off or removed. A surface charge will still be present on the battery plates. This charge will gradually drop to 12.6v over the next couple of hours, or to speed up the process you can remove the surface charge by connecting a load to the battery (e.g. turning on some lights for 10 mins). 12.6 volts is what you should see on a battery that is fully charged and in good condition. Each of the six battery cells produce 2.1 volts which are connected in series and added to make 12.6 volts. 12.4 volts is a battery that is 75% charged. This is actually what you will see on the majority of batteries on pleasure boats like ours. Because we only typically have the engines on for less than an hour or two, the battery never gets fully recharged, and so rarely gets back to 12.6v. To get to 12.6v the battery needs to be on charge for 12 hrs. 12.0 volts is a battery that is 25% charged. 11.8 volts is a battery that is completely flat (0% charge). Check the electroyte levels in each cell.

A fully charged battery that has been standing for a few hours will have a voltage of (assume the battery is fully disconnected): 14.4 volts 13.2 volts 12.6 volts 12.4 volts 12.0 volts 11.8 volts

76% answered "six cells connected in series" 24% answered "six cells connected in parallel" The correct answer is "six cells connected in series" Each individual cell produces 2.1 volts. By placing them in series the voltages are added together to produce 12.6 volts. If the cells were connected in parallel the voltage across all the cells would remain at 2.1 volts no matter how many cells you added in parallel. Next question to follow.

Which of the following is true of a 12 volt boat battery? It has six cells connected in series. It has three cells connected in series. It has six cells connected in parallel. It has three cells connected in parallel.

The voting was: 62% answered Sulphuric Acid. 32% answered All of the above. The correct answer in Sulphuric acid. A mixture of 64% Water and 36% Sulfuric Acid make up Battery Electrolyte. The water needs to be de-ionized to prevent contamination of the battery plates. Do not use ordinary tap water to top up your battery. If you have ever noticed holes in your clothes after messing around with a car or boat battery you now know why. It's the acid from the Electroyte that eats away your clothes if you spill any. So, congratulations to those that answered correctly. Next question to follow.

Thanks again, guys. BF

By the way, your votes (answers) will be anonymous, so if you don't know the answer just have a guess. The range of answers will help me decide what the next question will be. And the number of votes will help me decide if it's worth continuing the theme. cheers BF

Battery Basics - Question 1. Battery Electrolyte (the liquid inside a typical car/boat battery) is a mixture of water and what? Lead Peroxide Sulfuric Acid Lead Sulfate All of the above

My misses just wet herself with that one.

Thanks for all your comments and advice. Early days yet, but I won't be sitting around twiddling my thumbs hoping something turns up. I like to stay busy. It's just a shame that they chose the quietest time of year (fishing wise). Yes, working for myself is something I'm strongly considering. Jim, I'll PM my number. cheers BF

Gunna have more fishing time soon. Being laid off. I should be pissed off but I'm not. It's a relief to get out whilst the company still has some money for the redundancy package. But after 20 years with the same company it's going to be very strange doing something different. I've got some ideas of what I'd like to do, but I'm not making any decisions yet. Still got 3 mths notice to serve so I have a bit of time. But if there are any local prospects that you know of for a technical sales, electrician, electronics wiz, techno geek, hands-on labourer, DIY nut, boat builder (one to date!), presenter, teacher, and general all-round good egg...let me know. cheers Bob F

Certainly got some weird voltage readings going on. The 12.6V reading whilst the engine is running does not indicate a bad battery, but it's not a normal reading either (when the engine is running). If there was a bad cell in the battery the voltage would actually be very high (above 14.4v depending on the rating of your charging circuit (i.e. the charging circuit would produce its maximum regulated value usually between 14.5 and 14.9V). A reading a 12.6v is exactly what you would get from a 100% fully charged battery when the engine is off. But you shouldn't see 12.6V when the engine is running. It would normally be higher than 13.4v. A reading of 14.4v or slightly higher just after turning on the engine is normal. The circuit is sensing that the battery has been drawing a lot of current to start the engine and so the alternator produces its maximum output to recharge the battery. On a pleasure fishing boat where we typically do short engine runs of less than a hour, our batteries never get fully recharged (because a battery needs many hours of continuous charge to charge it properly). So, on our fishing boats it's typical to see the voltage readings always being over 13.8v (i.e. the alternator is sending charge to the battery because it is not fully charged yet, or there are other circuits like lights and electronic equipment that are drawing current from the alternator). If you say that the battery, connections and cables have been verfied, then I think you are left with two things to check. 1 - the regulator or 2 - check if there are any fuses in the charging circuit or around the engine and make sure they have not blown. How where the connections checked? Was it just a visual check and a tightning with a spanner? Or did they perform a voltage drop test across all the cables? This is really the only 100% way of ensuring that your cables and connections are fully operational. But I'm not an expert, either. BF

Is that what we can all expect when we are over 50? Get well soon. BF

Adam, I can input the numbers onto an SD card. Drop the book off at my place. BF

I'd just like to point out that Adam caught all the fish apart from one whiting and a dogfish...and all on my mark!!! I'm reconsidering the term "Joint" Venture. BF

It will be through-hull. At the moment its just laying on the floor of the battery bay until we find the optimum location and then bond it in. BF

Lowrance LRA-1500 2KW radome radar for sale. Full working order. 2yrs old. Includes Radar Interface Module (RIM) and cables. New price ~

Thanks for the heads-up chaps. Strange that the recall isn't showing on the official Volvo-Penta web site. The recalls section doesn't show anything for the D3. I'll call Volvo on Monday and see what's going on. cheers BF