Car battery

I've bought this nifty little bluetooth FM transmitter and it shows my battery voltage. It's 12.3v at rest and goes up to 13.9v with the engine running, although went to 13.7v. Is that showing a good or bad battery?

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Depending on how accurate that is 12.6V is what it should be at rest, below 12.4V and the battery is on its way out.
 
Rroff said:
Depending on how accurate that is 12.6V is what it should be at rest, below 12.4V and the battery is on its way out.
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Yeah, I was thinking that. I think this battery is past its use by date. Enough is enough, time to get a new one now, one of the ones you mentioned earlier in the thread. Great sound quality from this device by the way, I've just had a good play around with it. And it's got a regular and fast charge usb, but I just tried it and the fast charge is rubbish, it's literally 1 minute faster than regular charging.
 
Unless one of the fast charge protocols is supported properly on both ends fast charge is usually rubbish anyhow.
 
Rroff said:
Unless one of the fast charge protocols is supported properly on both ends fast charge is usually rubbish anyhow.
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Oh I got it wrong. I just checked the fast charge at home, (which is definitely fast charging) and it's exactly the same speed in the transmitter device. So that's good. The non fast charge usb in the transmitter is actually just slightly slower, it was 4 minutes slower just now.
 
Scythe said:
As Rroff said, it should be 12.6V at rest with no electrics, ignition etc on. If your battery is not fully charged, it will read less than 12.6V. Had you charged the battery or given it a good drive?

https://haynes.com/en-gb/tips-tutorials/how-test-car-battery
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Yeah, I was going to get a multimeter or a car charger, and bought neither so far. :p
Car has been flawless, starts every time, been driving it a fair bit. It would seem to be a very old battery though.

Well it was 12.3v with the ignition on, (not engine) and the device on showing me the voltage. So I suppose that could mean it might be 12.6v without those things enabled?
 
If it is anything like the batteries I've experience of if it is holding around 12.3-12.4V without fading out within days it will probably hold up until the first properly cold weather at which point chances are it will die quickly.
 
Rroff, I've finally chosen a battery I'm ordering. This one,
https://www.batterymegastore.co.uk/product/varta-blue-dynamic-d47-car-battery/

And that's exactly the same dimensions as the one you linked in post #26 on page 2.

What happened was that I removed the battery today to measure it properly and measure the tray. Well there's no way I can see a 242mm length battery fitting without it sitting on the lip of the tray. All these online sites specifying compatible batteries for my car are wrong.

Anyway, reinstalled the battery and car wouldn't start, it was down to 7v according to my bluetooth gadget. Cue RAC to the rescue again! :p But it seems I left an interior light on all night which obviously drained already weak cells.

I'm glad though because he said he knows what I need and told me to buy any 005 battery. He said otherwise if the height is too low the clamp won't tighten on it. The one you linked is a 005. Dimensions have to be 230 length x 170 width x 225 height. That's what both the one in your link and mine measures at.

 
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Rroff said:
Cool. Aslong as it fits can't really go wrong - current capabilities are upto spec, etc.
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Yep, best bang for the buck, good spec, qualiity brand and battery megastore with cheapest price of all online shops. Just bought it, says next day delivery but it's bank holiday tomorrow, so might come Saturday but probably Monday. The old battery is 13 years old. Talk about squeezing every last bit out of it, lol.
 
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