Battery maintenance equipment

[Manxcat54]

Hi Guys

 

I know I have touched on this matter before, but what would be a reasonable set up to run on my boat to maintain both leisure and starter batteries, I am not going lithium because I don't want the expense. And just one thing, this old boat which I am refurbishing, I sat up in bed again when I realised that whilst stripping out the previous wiring, I have not come across any form of charging system? it just looks as if it relied on the alternator to charge the batteries, but I can't see any sort of protection from over charging? and another thing, I have yet to find a fuse on anything? which sends shivers down my spine, but it's been on the water until 2019 and was built in 1979.

[Paul C]

What kind of charging system were you expecting to find (apart from the alternator)?

 

And also, if you've yet to find any fuses, it doesn't mean it doesn't have fuses, just that you've not found any yet. Worth being 100% sure of that before you go altering anything. After all, they are a BSS requirement and if its been active 1979-2019 it must have had one at some stage. And isolators, etc.

[Manxcat54]

Believe me there are NO fuses but it does have a battery isolator

[Jen-in-Wellies]

8 minutes ago, Manxcat54 said:

Believe me there are NO fuses but it does have a battery isolator

Nothing about what can be found in a boat's wiring system suprises me.

 

38 minutes ago, Manxcat54 said:

it just looks as if it relied on the alternator to charge the batteries, but I can't see any sort of protection from over charging?

That's fine. Lead Acid batteries are self limiting for charging. As they get closer to fully charged, the charge current from the alternator drops to near zero. Alternators are designed to do this job in vehicles and boats.

[Tony Brooks]

41 minutes ago, Manxcat54 said:

it just looks as if it relied on the alternator to charge the batteries, but I can't see any sort of protection from over charging?

 

The alternator's voltage regulator protects the batteries from overcharging, as do modern battery chargers and solar controllers. If you want to maintain the batteries properly then in my view you need a decent voltmeter, ammeter, and a little bit of knowledge.

 

Note: Jen's and Alan's posts rely upon the charging system limiting the charging voltage to around 14.2 to 14.6 volts for a 12V battery.

Edited April 1 by Tony Brooks

[Alan de Enfield]

33 minutes ago, Manxcat54 said:

it just looks as if it relied on the alternator to charge the batteries, but I can't see any sort of protection from over charging?

 

You are very unlikely to overcharge using an alternator.

 

Lead Acid batteries  demand less and less current as they get a higher and higher state of charge, they 'tell' the alternator how much they want and the alternator supplies what it is asked for.

 

Do not think that a 70 amp alternator (or battery charger) will put out a fixed 70 amps continuously.

 

During an average charge period you will average something like 30% of the rated output of the alternator charger :

NOT ACTUAL FIGURES - Just for example

1st half hour = 70 amps output

2nd half hour = 45 amps output

2nd-3rd hours = 30 amps output

4th-6th hours = 10 amps output

6th+ hours  = 2 - 5 amps

 

 

[Tracy D'arth]

You say "A" battery isolator.   Is that just one in the combined negative feed?  If so I would recommend doing away with that one and fitting two new decent ones (not the horrid red plastic key ones) in the engine and cabin feeds so that you can isolate either or both.

If you are fitting an inverter you will need a third one for that too.

[dmr]

Cheaper batteries often don't last very long on a boat, so If you intend to keep for a few years then I think we have got to the point were Lithium are now actually cheaper, but you do have to find the money up front.