- My model of MX-5 is: __
- I’m based near: __
- I’m looking for technical help or recommendations on: __Hi,
I recently found my battery flat , probably left the door slightly open. So I thought jump start all should be well,
of course those more technical will realise the error of my ways , so I removed the battery and charged on an intelligent charger luckily all well and started.
My point is why don’t the batteries have a sticker saying don’t jump start , as even the Handbook in the car gives instructions on how to jump start !
It was only looking at a website thinking I needed a new one did I see the instructions not to jump start.
A new one on me, looking forward to being educated by those with more knowledge.
2 Likes
Intresting could we have a link please ? Never heard this advice before, though it is well known if not done properly jump starting can fry electrics and therefore is best done sparingly.
1 Like
It’s in the details of the Panasonic Battery on MX5 parts website
2 Likes
You can jumpstart the Panasonic battery, but, depending how flat the battery is, the alternator might struggle to charge it. So jumpstart, get home, take out the battery and put it on a trickle charge. The issue isn’t the battery but the charging system, which was designed I suppose because of the characteristics of the AGM battery.
Websites are sometimes incorrect.
3 Likes
If a battery is really flat and quite aged, it may not even get you home after a jump start. My former housemate had a car with a very old battery, which died one chilly morning. We jump started it and he drove to work. He then needed another jump start at the end of the work day. After 3 miles, the engine cut out and would not restart. He was on the M4 J16 roundabout at the time and had to push it to safety with everyone honking at him. Luckily he had a passenger to help. He got a new battery then.
1 Like
Hi Kentishman
From NB 2.5 1.8 Icon Owner [2005] owned as second owner since 2007
By Coincidence my girl has just had a Full Service & Battery Check [dropped her off yesterday and picked her up this morning]
I literally had the conversation with my mechanic a few hours ago re her Battery !
I add to this my experience of her Battery Fails since owning her from March 2007
BOTTOM LINE
‘Your Battery has Failed’ because It’s Not Been Charged Enough’…Duh!
For me it was because I haven’t/didn’t/couldn’t drive her enough during the years the battery failed [and wasn’t able to link her up to trickle charge etc]
It’s the NB Battery [I call it a baby battery in comparison to previous cars I’ve owned over 40 plus years]…it is what it is
Yep…so with the NB Battery you just need to either drive more or put it on a charge
As for ‘jump start’ …never got to do this on Bullit …hang on a minute
Had Home Start for Her and a Very Nice Man from the AA recommended a ‘Solar Panel’ which I use when the sun is out to keep the battery charged
I strongly suspect he did a ‘jump start’
Hope My Experiences assists your decision making
2 Likes
I forgot to mention the battery is only 3 years old and had done a long drive recently on a 12 car road rally.,
2 Likes
So lights and fan on all night and maybe a map reading light, no reason why you shouldn’t, but wonder if the alternator is charging properly, is the belt loose perhaps ? I always found my '02 NBFL alternator a bit marginal in similar, but not competitive, situatuions until I correctly tensioned the alternator belt when I replaced it.
1 Like
Our NBFL battery failed on jump start. Was advised to only jump start using boot reciever lock machanism on the negative, as a better ground than the battery itself? But our battery was so low it couldn’t start the car anyway, once the panasonic / original battery had lost charge it was non recoverable. New battery and sorted. Kept topped up on a trickle charger since then no probs…
2 Likes
Hi again
Totally concur with Art & Blue Ben latest posts 
‘Probably left the door slightly open’.
Have vague memory of poster Terry M1 saying he’d not shut his boot correctly on The Precious (?) so when Bullit had to go into Dry Dock for 3 months whilst in a queue for specialist welding and undersealing after MOT fail in 2022 I became paranoid about the battery failing [the garage I rent for her has no electric supply] so used to run the engine for 20 minutes whilst she was stationery [not ideal] every so often and the battery appeared to have survived the ordeal as my non specialist mechanics said battery OK just drive her more
But have had occasion on two previous NB batteries that did not survive lack of driving and as the AA Home Start Chap said of mine…it’s probably gone too far…I can get you started but you need a new battery [and I did]
Yet my current mechanics say ‘There is no point getting a new battery because if you don’t drive her enough you’ll be in the same position in six month time’
AA man also said ‘What have you got working on the car off the battery overnight…that will drain it’ so he recommended the Solar Panel
The org I rent the garage from refused to let me do the Solar Panel on their roof so I can only stick mine on the dash in e.g. Tesco car park to draw in all the wonderful sunshine we’ve been having …cough …splutter [that’s me not Bullit 
]
Hope this info helps in your dilemma
2 Likes
Just popped out to the 96 MX5, which has been parked up for 6 weeks. I make a habit of taking the earth lead off when its parked up. Yuasa battery, fired right up, with no chugging.
I have been a fan of Panasonics in the past, but lock down destroyed what was a fairly new battery, and the car’s usage isn’t increasing much more. I’m sure getting the fuel injectors sent off and refurbed has made a huge difference on cold starts though.
The reason you jump start to an earthing point, and not the battery itself, is mainly to avoid the risk of explosion, since rapid-charging a battery tends to vent hydrogen. Otherwise, when the car has started and you remove the negative lead, there could be gas hanging around the electrode. It’s a fairly small risk.
AGM batteries are used on the NA and NB so any leaked acid doesn’t ruin whatever you are carrying in the boot (AGM batteries can’t leak). Mazda went for a normal battery on the NC, where it lives in the usual place under the bonnet.
1 Like