thomasaspin makes a very point, I did include this in my earlier post and the battery and alternator are best checked together but more often it's the use of the modern cars that depletes the battery's store, so I'd not rule out the charging system and if you can borrow a tester then test it but to use the car you want a battery in a good state of charge and health (and good electrical connections) and recharging the battery will only help and not hinder (unless you use a booster/very fast charge it and kill it)..

 

365 of 550 is 66% (according to Google) and according to my neighbour's Ring charger manual more than 74% is "Good" , 50%-74% is "check" and less than 50% is "bad".

 

But these are just figures and there are lots of variables, so my advice is.

 

If possible don't borrow a high powered fast charger rather one that goes low and slow for as long as possible, 4 amps or if you know the battery the manufacturer may give a higher suggestion.  Charging overnight isn't always enough it can take longer.  Different chargers can do different things, depends on what you can borrow, let us know.

 

Not vital but preferable, take the battery off the car and charge it somewhere cool - if it's off the car the charger isn't fighting anything that's live/on and you are more able to control the environment it's recharged in and keep an eye on it to see how it's going and how long it takes.

 

Removing the battery or fully disconnecting it also gives you the chance to try a free quick method of clearing some error codes, with the battery disconnect so no power to the car,- [ETA: - carefully bridge/join the positive and negative battery leads post clamps together to complete a circuit ] - turn the ignition on and press and hold the brake pedal down for a few seconds so that if the battery was connected the brake lights would have lit up, then switch the ignition off and remove the key.

 

All being well you may be able to recover the battery but you'll still want to keep an eye on it and possibly recharge it again depending on your car, and its/your electric, use.  Car batteries are one of the most oversold car parts and often can be rescued with a bit of proper care but sometimes they can be flogged too much and you have to bite the bullet and replace them.

 

What is vital - the opportunity to prove an engineer wrong (again), it wont harm (or touch) their ego or mental health but will give great satiation to others, including me, so any details or advice you can give or need on charging the battery just ask. 😁 

Edited 18 February, 20233 yr by nta16
ETA: an important bit I missed out

31 minutes ago, sepulchrave said:

This has been going on for TEN days, you assured us you'd checked the battery and alternator already.

 

What does 365 out of 550 even mean, are you off your meds?

That’s probably some BS number Halfords probably give you for sticking a tester on the battery to convince you to pay there ridiculous prices for parts 

Cold Cranking Amps, measured versus specced.

1 minute ago, thomasaspin said:

That’s probably some BS number Halfords probably give you for sticking a tester on the battery to convince you to pay there ridiculous prices for parts 

In my personal 4 decades long experience that's a bit unfair as you're more likely to get ripped off by a garage, how well the test was done and with what sort of tester is a different matter but I'd personally expect many other places would do no better.  I've nothing against or with Halfords but personally feel from personal experience that to me generally the workers there don't seem as nasty and dishonest as many in the motor trade, the company and it's management might be a different matter, I don't know.

 

We don't know as we've not been told whether the person at Halfords used these figures to get a potentially unnecessary sale or not.  RAC may make unnecessary battery sales based on how my friend was advised.

 

Blah, blah warning.

As my friend was an Architectural Engineer so obviously didn't listen to my advice about batteries, despite my old BL car having to give his much more modern expensive Japanese car a jump start on a previous battery failure, and he bought a new battery at a lower price elsewhere, well Engineers are generally loathe to spent money on parts.  So I very easily recharged the battery and showed he'd wasted his money on a new battery - well that's what friends are for.  😁    

1 hour ago, sepulchrave said:

This has been going on for TEN days, you assured us you'd checked the battery and alternator already.

 

What does 365 out of 550 even mean, are you off your meds?

Please take your childish frustration elsewhere.

1 hour ago, thomasaspin said:

That’s probably some BS number Halfords probably give you for sticking a tester on the battery to convince you to pay there ridiculous prices for parts 

I watched the tester myself, they only recommended recharging it btw. It's a lot more info then the multimeter gave me, more is better than nothing for a free 10 point check.

16 minutes ago, DariusFabiaestate said:

Please take your childish frustration elsewhere.

He means well just sometimes has a peculiar way of showing it.

 

I know he'll want to know how my neighbour's old battery is going, well as you asked, after 20 hours of slow charging a battery that was stated by an electronic device as 90% recharged my old Carcoon maintenance charger gave the green light.  2 hours later and it's 13.31v on my optimistic digital multimeter.  I have to wait for my neighbour's return to se if he's got any 12v off the car stuff we can use to test the resilience of the battery or if it's just display figures. 

47 minutes ago, DariusFabiaestate said:

Please take your childish frustration elsewhere.

 

It's not childish to express frustration that you're ignoring GOOD advice given freely by someone extremely experienced but listening to BAD advice from someone trying to sell you stuff.

 

Goodbye and good luck.

4 hours ago, Breezy_Pete said:

Cold Cranking Amps, measured versus specced.

I make that 4.3kW assuming a nominal 12v.

1 hour ago, KenONeill said:

I make that 4.3kW assuming a nominal 12v.

Doesn't that depend on how the CCA are measured/spec'd/qualified/insert correct word/terminology/description.  Not taking into account . . . aw, just so many things.

 

It's enough if it's all that's needed to complete whatever is required, depending on . . . more variables.

 

Or stock up with more electrickery  now to have a safe margin now and for a reasonable amount of future needs so as not to be back at this point again too quickly.

 

I'll give 10 to 1 on it's not 4.3kW now anyway.  😁  From now on I will think of the dear departed as TenTo, I wonder if Doris can get a message to him, or him to her.  Blah, blah.  😄

 

6 hours ago, nta16 said:

As my friend was an Architectural Engineer so obviously didn't listen to my advice about batteries

He probably switches off when Battery Man goes into yet another monologue on his favored subject.

 

Pun intended.