AGM Batteries Versus Deep Cycle Marine Batteries
 

I am sure this topic has been around the block a couple of times but I'm new to the forum and a new owner of a 2007 Miles ZX40S. The car only has 30 miles on it but it has sat for the better part of 3 years and the batteries are shot. At $395 plus shipping per battery from Miles in California, I would be looking at $2400 plus shipping. I'm looking at alternative batteries to use and the Marine batteries at Wal-mart are 125ah and will fit in the box. Other than less driving time, which I'm not concerned about, what do you all think? Thanks in advance.

talk to a renewable energy installer or a golf cart shop, they are going to cost a little more but they are going to be able to get you much better batteries.

AGM batteries won't spit acid and don't need refilling -- they are cleaner and need less maintenance.

AGM batteries are also very sensitive to over charging and most people just buy new ones instead of figuring out how to maintain them.
either way, figure out what battery your car takes then start calling around to see what other people offer.

Miles rear battery box loves to rust out if you use floodies for any period of time and don't completely coat the inside of the box (just so you know)

As someone who works on Miles vehicles, I would strongly, strongly, recommend you do not use any battery that could vent gas in normal operation. The battery boxes are sealed from the outside and the only place for the gas to dissipate is the passenger compartment.

Best case scenario: your car always smells like you left an egg salad sandwich on the dash for a few hot days.

(almost) Worst case scenario: the gasses eat away at the car. It happens.

Worst case scenario: the gasses are flammable...

I hear that Powersonic makes a battery similar to the Lin-Tian stock battery. Also, try trickle charging your battery. Ours sat for a year and were completely dead. I nursed them back and they lasted 7 months before the #1 battery boiled off.

~Jimbo

That's what I needed to know. I finally found a replacement battery that's only $300 a piece and free shipping so I ordered them. Thanks for the input.

My new e-HDI engine has an AGM battery for the Start&Stop feature. I'm looking for info on how to charge it to keep it healthy.

I have been using a CTEK Multi XS 3600 charger on the previous lead-acid. As those batteries like to be charged "low & slow", I used the "Motorcycle" charging mode on the charger - 0.8A @ 14.4V, instead of the "Car" mode of 3.8A @ 14.4V. Apparently AGM batteries need a higher voltage, and this charger has such an option. It's called "Cold" mode - 3.8A @ 14.7V. The instructions state that this charger is for any kind of lead-acid battery, including AGM, but does not mention whether any specific mode is better for AGM.

What do you think? Is 3.8A @ 14.7V better for my new AGM battery than 0.8A @ 14.4V?

It should help keep the cells better balanced than a lower voltage, in theory.

Not sure if AGM need the voltage to drop off(down to 13.8) after 80% SoC is reached, but I would assume so.

If you want any kind of lead acid to last a while, try and avoid letting the SoC drop much below 50%. You can get ~1000 charge cycles that way, rather than 2-300 if you drop it down to 20%. I'd also avoid pulling more than ~1C out of the battery for more than a few seconds at a time.

Back to your regularly scheduled programming...

Only other thing I will add: no electrolyte to boil after charge so FLA chargers have to be stopped at that point.

I'm not a fan of agm.