GEL or AGM battery
 

Hi, my battery is tired after 5 years of continuous use in temperatures between -35 to +40 and is having troubles starting my 2005 E53 3 litters diesel engine.

so which one do you recommend?

From what I can gather on this AGM battery so far is that it's not far superior in cold temp but it has very small self-discharge curve (around 1-3 percent of capacity per month). That;s why BMW switch to this on newer models since those tend to have more electronics (i.e comfort access, that can drain battery while sitting in garage if the FOB is within 30ft in many cases).

The problem for older X5 would be charging (or over charging in this case) of AGM battery possibly shorthening the life of it. That's why on newer BMW there is inteligent charging algorithm that register the batt mfg date and the car adjust the charging current overtime (being more toward the end of batt life).

That is correct,except that when you switch from AGM to normal battery (or vice versa) the car wont understand that by itself.You have to use a diagnostic software and register the new battery-type and capacity.

I am reading on the net that GEL battery are suffering more from that than AGM :confused:

It maybe, AGM and gel is similar technology (instead of using the liquid sulfuric acid as electrolite it uses gel, while AGM added glass insulation to reduce self-discharge between cells further). Maybe also the glass insulation may be able to absord the gas forming while charging/over charging.

Again assuming you have E53 (not E70) X5, the car alternator/regulator provide up to C/4 (C being the full capacity ~ 80Amp) while GEL/AGM never like anything more than C/8 or C/10 of charge current. Newer BMW like E60/E90 with IBIS circuitry will limit the current by looking at the date stamp of the batt and gradually adjust the charge current over the life of the batt (hence the registration upon replacement to reset this algorithm is required or customer will be back for new AGM batt in 3-4 years due to over-charging).

I am not sure you'll see the benefit of GEL/AGM under severe weather though, does the batt mfg claims that? I never look into bad weather situation since my car always garage and Seattle weather is not that bad.

my car is a 2005 E53, so I should go for a simple battery then and change the batteries more often for the savings I will made right?

thank you for your explanations

AGM should be fine in an E53, repaced my battery with BMW AGM six years ago and its still going strong. This battery was originally speced for 7 series before IBS technology so all is well.

Bosch Silverline should do you and now comes with a 5 year warranty.

can you suggest a national retailer (I see you are from the UK - I am in Edinburgh).

also maybe you know what model from Silverline family suits 05 reg diesel E53 best?

many thanks!

I would highly recommend using an odyssey pc1700. The cranking power at all temps is much more powerful and they have been extremely reliable for me.