battery charging

If you connect the charger and then turn it on, there shouldn't be any power spikes that will potentially cause damage. Rus.

It's preferable to disconnect neg terminal, then there is no risk of anything shorting between pos terminal, and any part of bodywork, engine etc. Shouldn't need to disconnect any terminal, just to charge battery.

Hooroo...

Usually shouldn't need to, but on trying to charge the golf MK1 had to disconnect the negative and positive last night to see the charger charging.
In the past I disconnect both out of habit, and take the fill plugs out too for a heavy charge so the hydrogen doesn't build up too much. Usually check water levels before charging any way. Have seen a few bubbles on charging a low battery.

This is an interesting site for battery info.

Battery Info

A smart regulator acts much as a three-stage battery charger. It is fitted in place of the existing regulator and charges the vehicle battery/s as heavily as is safe and very close to 100%. They are commonly used on boats but are less know in Oz with RVs. I have had one on my OKA for the past eight years - works superbly and will charge the house batteries at up to 100 amps!

Give Outback Marine (Qld) a ring if interested.

Another solution is a very ingenious NZ device just recently developed that boosts the charge voltage and applies it as a variable width pulse at up to 15 volts.

It seems perfect for 4WD and camper trailer use not least because it does not interfere at all with the vehicle's electrics.

I shall be having one for evaluation shortly and will advise what I find on my own website. Will also post a brief report on this site.
Collyn Rivers

Bugger it and all the techno fobes out there, I've got all the electronic ECU and crap, I also have a stack of accessories, I just whack the bugger (8 amp charger) on and let er' rip. Never had a problem.

Thanks everyone for your replies. ;-)

John

Austravel
Apologies for delay in responding - had total computer crash that required equally total computer rebuild.

The 70% limitation is a generalisation but battery makers agree that the most common charging limit with standard alternators and regulators is 70% give or take a few per cent.

The limitation is inherent in constant voltage charging because as the battery voltage rises towards trhe charging voltage, the current tapers off. By 70% the charge rate has dropped to a trickle. Charging will continue but at a progressively decreasing rate. This limitation is deliberate to prevent overcharging in vehicles such as country sales reps cars that are driven vast distances each day.

(Given several days at a constant 14.4 volts however a starter battery will approach 90% or so charge - but this rarely if ever happens in real life, not least because most voltage regs are now set up at 14.2 volts).

In practice conventional lead acid batteries only fully charge (even from three-stage chargers) if they are allowed to run up to about 15.0 volts and then drop back to about 14.4 volts for a few hours to absorb the charge - and onmly then drop to floating.

With your charger, is it a true three-stage charger, or is it one of those constant voltage units that switches directly to float? If it is, then it is sensing the charge across the plates of the deep cycle batteries. This does not reflect the true state of charge.

Do also bear in that a corollary of the above is that instantaneous voltage readings of deep cycle batteries are almost meaningless unless that battery has rested for at least two full days off-load (it is this affect that causes some battery chargers to switch to float prematurely). Any deep cycle battery taken off-charge will show a much higher voltage than reality for many hours - until the internal chemical interactions have ceased and the charge is homogenous.
Collyn Rivers