It's going to be 56 here today. (Miata AGM battery content)

I haven't driven the Miata since Thanksgiving. Figured i'd drive it today since it's going to be ridiculously nice out today.

HAH.

So after cranking the car for almost 2 minutes (it never starts quickly because... well.... because.) it finally starts just as the battery starts to fail.

Runs for 10 seconds.

Then stalls. Because the start up and idle control is not good.

Not enough juice to start it again.

So my questions:

1) Any special procedure to jumping an AGM battery? Or am i being paranoid and there's no difference?

2) If i replace the battery with something stronger in an effort to combat the drain from the ridiculously long cranking times this thing always has, is the "tune" on the Hydra unit safe? As in... saved to a ROM that will remain even if it loses all power for an hour or two?

3) Fix the cause of the cranking issue.

Just saying....

Jump starting is as usual. Just be sure you connect properly. Fixing the slow start and stalling problem will eliminate most of the battery problems.

aussiesmg wrote: 3) Fix the cause of the cranking issue. Just saying....

That's getting into another discussion involving Hydra-equipped cars and the utter lack of anyone local with the willingness/knowledge to tune one.

Appointment made for March, but i'm sure it'll get bumped a time or 7 again.

iceracer wrote: Jump starting is as usual. Just be sure you connect properly. Fixing the slow start and stalling problem will eliminate most of the battery problems.

Cool, thanks. :)

Alternatively, anyone have recommendations on batteries for a Miata?

As for taking the car out on the road...have the local road already had salt applied to them this year?
If the answer is yes, then i would not take out the car, no matter how strong the temptation.

When you see, "never driven in snow" what I really want to know is, "never been subjected to road salt." For my car, even in the spring when the weather changes, I resist taking out mine until it has rained a couple of times heavily to wash all that damn salt away from the road.

If taking you car out today will get that damn white residue all over your car then do not do it.
I know many think, well I will just wash it before I put it back away. The problem here is the underbody. Everything gets that damn white residue and then things go to hell.

jrw1621 wrote: As for taking the car out on the road...have the local road already had salt applied to them this year? If the answer is yes, then i would not take out the car, no matter how strong the temptation. When you see, "never driven in snow" what I really want to know is, "never been subjected to road salt." For my car, even in the spring when the weather changes, I resist taking out mine until it has rained a couple of times heavily to wash all that damn salt away from the road. If taking you car out today will get that damn white residue all over your car then do not do it. I know many think, well I will just wash it before I put it back away. The problem here is the underbody. Everything gets that damn white residue and then things go to hell.

Point taken.

They salted the roads a week or so ago, use that liquid stuff though. Doesn't seem to get all over the cars i'm actually driving, luckily.

That liquid brine is much worse on the car than the granulated stuff

92CelicaHalfTrac wrote: Alternatively, anyone have recommendations on batteries for a Miata?

I had to buy one for my NA and got one from Batteries Plus. Seems to work OK, but like all Miata batteries it's not cheap.

The PO had battery drainage problems on my Miata as well, most likely thanks to the stupid alarm on the car so he wedged in a regular car battery that vented into the trunk. Oops.

Part of the problem is the fact that the car sat for a couple of months. That pulls down the battery. If it's going to sit that long, install a cutoff or spend $10 on a float charger.

Charging an AGM battery is different than a normal battery, but jumping is the same. The Hydra's tune will be fine.

Keith wrote: Part of the problem is the fact that the car sat for a couple of months. That pulls down the battery. If it's going to sit that long, install a cutoff or spend $10 on a float charger. Charging an AGM battery is different than a normal battery, but jumping is the same. The Hydra's tune will be fine.

Thanks Keith.

That link says "not for use on AGM batteries," though. Do i ignore that warning?

Remove battery from car before putting on a float charger?

I have that particular charger. I ended up buying a battery tender - if you want the HF one you can have it for the cost of the postage.

I normally leave the battery hooked up in the car or bike and just hook up the float charger. Works OK so far.

I used to use a solar float charger. Too bad Japanese cars turn off the cig. lighter circuit when the ignition is off :(

BoxheadTim wrote: I have that particular charger. I ended up buying a battery tender - if you want the HF one you can have it for the cost of the postage. I normally leave the battery hooked up in the car or bike and just hook up the float charger. Works OK so far.

Is it safe to use on an AGM?

Leave trunk closed is ok?

ProDarwin wrote: I used to use a solar float charger. Too bad MOST Japanese cars turn off the cig. lighter circuit when the ignition is off :(

Fixed that for you. Had a few AllTrac Camrys that stayed hot.

Disconnect the battery instead of using a float charger. I have a quick disconnect I use when the car is going to sit more than a few days. The AGM battery loses little voltage when sitting unconnected.

I don't have anything here with AGM batteries, but looking at the Battery Tender website you can interpret the words in their users guide that it should be OK to that one with AGM batteries. No idea about the HF one, though.

Leaving the trunk closed might be an issue with getting the wires in but if your battery is hooked up to the vent pipes I don't see any reason why it has to remain open.

Chas_H wrote: Disconnect the battery instead of using a float charger. I have a quick disconnect I use when the car is going to sit more than a few days. The AGM battery loses little voltage when sitting unconnected.

Now you're giving me bad ideas of putting a cut-off switch in the license plate panel.

Well, i've gotta charge it again first i guess. I think i have a small cheapo charger up in my garage somewhere

I've got a "schumacher" one that I've used on AGM batteries for years. I've seen it with different labels elsewhere, I just assumed the HF one was the same. Never looked too closely. AGM batteries do act a bit differently under charge, so it's possible that the electronics simply won't understand what the battery's doing. There certainly are float chargers that are suitable for AGMs. Look on the Sprockets side of the fence.

If you're going to charge that AGM, they prefer a slow rate of charge over a long time. 2A if you can.

Disconnecting the battery will deep-six your radio settings (which is part of what killed your battery in the first place), but the Hydra won't care (unlike a GM PCM). So that's the best choice if possible. I have battery cutoffs on most of my vehicles.

Keith wrote: I've got a "schumacher" one that I've used on AGM batteries for years. I've seen it with different labels elsewhere, I just assumed the HF one was the same. Never looked too closely. AGM batteries do act a bit differently under charge, so it's possible that the electronics simply won't understand what the battery's doing. There certainly are float chargers that are suitable for AGMs. Look on the Sprockets side of the fence. If you're going to charge that AGM, they prefer a slow rate of charge over a long time. 2A if you can. Disconnecting the battery will deep-six your radio settings (which is part of what killed your battery in the first place), but the Hydra won't care (unlike a GM PCM). So that's the best choice if possible. I have battery cutoffs on most of my vehicles.

Cool, thank you Keith.

The radio settings would be a bit annoying (fairly high-end complicated setup), but one of those things that would probably only happen 1-2x a year.

Let's bump this because i'm half-assed thinking about getting this thing on the road sometime this summer. Maybe.

I'm guessing at this point that the battery is 100% toast and it's likely that i'll need a new one.

1) Good guess?
2) I'm pretty much guaranteed to spend $100-$110 for a new Miata battery, aren't i... Seems some people are using Deka EXT9s. Anyone have experience or input on doing this? $50 cheaper, seems to be just as strong if not stronger, lighter, smaller.

Try a long slow charge. AGM batteries like foreplay, not just wham bam here's your charge ma'am It may come back.

There's an Autozone one that people have used. Me, I have an Optima yellowtop in both of mine. I used to have an Odyssey PC680 in the Targa car, that worked well but it doesn't have the reserve capacity of an Optima.

Maybe you should go megasquirt, my Miata starts right up

Thanks Keith, just ordered the Battery Tender JR and we'll see how that goes.

EvanB wrote: Maybe you should go megasquirt, my Miata starts right up

Car was never supposed to be a project at all, if i have to deal with that sort of thing to make it run right, i'll just sell it and turn it into an MR-S AND an RX8.

I'm kindof thinking about doing that anyways, but it's easier to think about selling a car that actually starts.