Brand new 12V battery discharging

[Nickel]

I didn't know the bug affected MK1's as well.

What I was carrying was an SLA booster pack, intended for cranking ICE's. It was simply to hand and free. I agree it has more oomph than needed for an EV, but I'm not aware of EV "starters" being available.

 

[Lovemyev]

A high powered booster pack maybe seen as a sledge hammer, to crack a nut .
But rescue services will only be carrying a single unit for boosting all cars, so it will be fine !.

 

[Fluffykins]

lead acid needs to be charged to a higher voltage than normal when it's cold.

Minus 28mV per degree C IIRC.

 

[Coulomb]

Minus 28mV per degree C IIRC.

It seems to be -3mV/°C per cell, so -18mV/°C for a 12V battery (6 cells in series). So about half a volt higher at -3°C.

 

[Tim Green]

unfortunately we don't have much 25C normal round here!

 

[pollenface]

I would imagine it would also make some wind noise and create a bit of drag, even if mounted so that it with only hits the end.

Yes it does create a negligible amount of wind noise and drag.

I guess it's probably also different from country to country, if I did this in the Scandinavian country I live in, I would certainly have people looking funny at me

Maybe others would do the same (pic from google)

 

[hmadsen]

Yes it does create a negligible amount of wind noise and drag.

Maybe others would do the same (pic from google)

Yeah i would definitely be considered a nutter if i drove around with that on top of my car all the time here (No offence)

But then again....Living in Scandinavia, most of they year we dont have a lot of sun, so would hardly be worth it for us.

Shame you can not put a bit of the energy you collect into the HV battery, with solar panels like that i bet your LV battery will be fully charged pretty quickly and any extra energy from the solar panels would go to waste.

Might not give more than a few miles a day, but every little bit counts (And would maybe offset the loss of energy, due to the drag produced by these )

 

[pollenface]

Shame you can not put a bit of the energy you collect into the HV battery, with solar panels like that i bet your LV battery will be fully charged pretty quickly and any extra energy from the solar panels would go to waste.

I think if you charge the 12V battery, you lessen the draw needed from the HV battery.

 

[hmadsen]

I think if you charge the 12v battery, you lessen the draw needed from the HV battery

I agree, but only to the point that you will "gain" whatever the car "consumes" from the 12V battery.

Lets imagine the car draws 200 watts from the 12V battery, this will of course mean that when you drive you could potentially save 200 Watts (LV Watts) but the solar panels might potentially make 800 watts.

So while driving there is a lost potential of 600 watts but when the car is stationary it's even 800 watts.

Please also remember that it does not take 200 watts from the HV battery, to charge the LV battery with 200 watts.

 

[pollenface]

I agree, but only to the point that you will "gain" whatever the car "consumes" from the 12V battery.

Lets imagine the car draws 200 watts from the 12V battery, this will of course mean that when you drive you could potentially save 200 Watts (LV Watts) but the solar panels might potentially make 800 watts.

So while driving there is a lost potential of 600 watts but when the car is stationary it's even 800 watts.

Please also remember that it does not take 200 watts from the HV battery, to charge the LV battery with 200 watts.

I get what you're saying but realistically you're not putting 800W of PV on your EV. I have a single 190W house panel on my ICE vehicle, it measures 80x160cm and that's big enough. It's summer at the moment in Australia and the highest number I've seen in the last 30 days is 142W

 

[JohnV6]

10.4V indicates it was a dud. I had an agm battery fail on my Morgan at 2.5 years old. The AA told me it is common. The warranty is usually 2 years but I have had then typically last 9 years

As said here get a Ctek battery conditioner not just a charger.

 

[CallMeDave]

Update:
Got a new battery from Farmer and now the car works normally.
New battery behaves exactly as expected and holds its charge. No parasitic drain from car.
Relief all around. It was going to be a 3 month wait for a diagnostic appointment.

I charged the suspect Halfords battery for >24 hours at room temperature and the highest reading I got from it was 11.70V. A day later (still at room temp, completely disconnected) this was 10.78V.
I've had to phone and message Halfords several times now to get a refund. They told me they would arrange pickup of the defective battery within 72 hours. That was 2 weeks ago. Apparently it is impossible for a mere mortal to contact the relevant department directly and I have to wait for them to contact me.
Awful product, awful service.

I see there has been a lively chat since I last checked in!
Thanks for all the suggestions.
I already have a booster and a charger that I keep in my boot at all times.
The mini solar panel for inside the car is a consideration for the future if we see loss in between weekly uses.

 

[Coulomb]

I charged the suspect Halfords battery for >24 hours at room temperature and the highest reading I got from it was 11.70V. A day later (still at room temp, completely disconnected) this was 10.78V.

It sounds to me that one of the cells collapsed to near-zero volts. Lead acid cells don't come back from that.

 

[hmadsen]

It sounds to me that one of the cells collapsed to near-zero volts. Lead acid cells don't come back from that.

Exactly the same thought here.

And it did not go open circuit, so it was probably the dud cell that did the parasitic drain.

 

[pollenface]

As said here get a Ctek battery conditioner not just a charger.

Also consider the Victron equivalent, similar price but with Bluetooth connectivity to adjust charging parameters