I attempted to start my 280se 4.5 today after 6 months in winter storage. The battery was nearly dead so car would not start. Is it recommended to replace battery or can I attempt to jump start? What is the best battery for the 4.5? The one that is in there is an Interstate brand.

Also, should I disconnect battery when stored for longer periods of time? Thanks

The clock will drain the battery over time. So yes, disconnect the ground.

As for brands, I've just bought blemishes for my car the last 2 times. $35, the one before the one I'm on now lasted a while even with being 100% drained 2-3 times from sitting a while. As for size, I THINK I had a group 49, but it's been years - other members with a 4.5 can say what is in theirs. The tray is massive & I took advantage of that fact.

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

Just put a charger on the battery to see if it will return to service. You've nothing to lose by trying and the 4.5 doesn't have any complicated electronics that might be fried by a charge. Generally, batteries last a long while without any sort of attention if they are not subjected to any sort of drain. Install a disconnect before next winter, not only to prolong battery life but to protect against short circuits caused by rodents gnawing on wires.

I keep battery tenders on my boats and cars while they are sitting. It keeps the batteries up to full charge. You can find them pretty cheap these days, in the $20 range. You should be able to jump start your car without any problems unless the battery is compleyelt flat.

Thanks guys. I will attempt to jump-start then and get tenders for next season.

However, I also now noticed the battery in there is much smaller than the tray. It is this one Interstate Batteries Results Page - Mega-Tron Plus 48/H6 (730 CCA) Six-Year Performance Warranty

Is there any issue by having a different size battery than what the tray accomodates? I understand the 4.5 usually has a series 49 battery?

If you jump start, the battery will need engine running time to recharge ( like an hour + ) . Connecting the battery to a charger would be a better choice as this will lessen the load on the alternator.

If a battery is deeply discharged, it will be damaged. A newer battery can tolerate this but as the battery ages, it becomes more prone to permanent damage.

How a lead acid battery works in basic terms.

LA batteries are a reversible chemical reaction. Two porous lead plates seperated be a paper ( ish ) sheet are submerged in sulfuric acid. One plate is considered positive and the other negative. When an electrical load is placed across the plates, sulfur migrates in to the plates, this also reduces the acid rating of the liquid. When a battery is recharged, sulfur is forced out of the lead plates and back into the liquid.

When a battery sits in a discharged state too long, a crust of sulfur builds up preventing sulfur from being pushed out of the plates during charging or being absorbed during discharge. This is called sulfation.

In order to make 12 volts ( of electrical pressure ) , there need to be 6 cells with separate acid wells. In order to give enough amperage ( electrical volume ) there needs to be high surface ares of the plates. This is done by interleaving more positive and negative plates in a single cell / acid well.

A battery can fail to provide any voltage due to breaks in the internal connecting structure. It can have reduced voltage if a cells plates touch due to a failed separator. It can have reduced available amperage because lead has fallen off the plates or the are blocked by sulfation.

A load test measures available amps ( how big the gas tank is ) , a voltage test measures state of charge ( how full the gas tank is. )

If a battery has not been charged or discharged in 8 hours +, this chart will tell you how full the battery is. ( Checking voltage while the engine is running isn't a valid test as charging voltage needs to be higher than static voltage to push sulfur out of the lead 13.7 to 14.5 ish is typical .)

12.66 100 % charged
12.42 75% charged
12.18 50% charged
11.94 25 % charged
11.70 0 % charged ( going lower will damage the battery )

I just noticed your last post.

Physical battery size isn't a true measure of how large battery capacity is ( gas tank size ) , surface area of the plates is. Basically, the heavier the battery is, the more capacity it has.

No, but asking an alternator to fully charge a battery in addition to running ignition & potentially lights, radio, the blower etc. is putting a high load on it. I would make sure to charge it first, only jumping in an emergency situation.

Batteries have gotten a LOT better over the 40 years these were made. A 49 in today's standards may be "Overkill" but since it fits, it'll also last a lot longer. Not to mention that it looks better. The group 48 you have now is probably 100 or more CCAs better than a 49 was in 1969-1970 when the battery for these was initially specified. But a 49 has even more.

https://www.menards.com/main/electrical/batteries-battery-chargers/automotive-batteries-chargers-jumpers/exide-reg-l5-49x-global-extreme-automotive-battery/p-1444430136186.htm

This is the current equivalent to what I had in my 4.5. I will say that it didn't like sitting one bit either, and died when it was discharged 100% for 2 months.

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

Testing for Dead Cells:

Put on Safety Glasses and Nitrile gloves

Disconnect all Battery Leads.

Remove battery cell caps.

Take out y'all's old trusty multi-meter.

With the MM on Volts D.C. place the Negative (Common)probe
on the Battery's (-) Negative terminal,Whilst placing the Positive Probe
into each Cell's (Sulfuric Acid) Liquid Reactive bath. One at a Time.

This works best with a battery that's been on a LOW overnight Trickle charge.

Since we're working with a 12 Volt unit each of the (6) Six cells will have
about 2.1 volts (Or so).
We're looking for the cell that's unable to accept a charge ,which prevents
the battery from fully charging.The BAD cell (s) will measure substantially
less than the required 2.1 volts.

__________________
'84 300SD sold
124.128

I just pull the caps while it's on a trickle charge. Any cell that doesn't bubble is dead.

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

Thank you all for very helpful advice.

Per your advice I have not attempted to jump-start to save alternator. I have it on a trickle charger now to re-charge, and will leave it on as a battery tender next winter. The battery is 5 1/2 years old so it may be time to replace soon but hopefully I can get a couple of more seasons out of it.


Thanks again!

+1 on charging first.

Although The alternator does charge the battery, it is a battery maintainer vs being a battery charger. If your battery is over 5 years old it's on borrowed time. It's the beginning of the driving season, buy a new one to avoid a no start situation.

I'm fortunate enough to be in charge of maintenance for a rather substantial number of German automobiles. These vehicle are stored under cover in ambient temperature conditions year round without any supplemental battery chargers or "conditioners." The average battery life I am experiencing is close to ten (10) years with an all time best of seventeen (17) years from a Sears 36 that simply kept going and going. Contrary to internet learning, I attribute these batteries' longevity to two factors: 1) Each vehicle has a battery cut-off switch which eliminates all parasitic drain from the battery when the car is not in use; and 2) No battery conditioner is or has ever been employed. With regard to the latter point, it is my most definite belief that the use of a conditioner actually shortens battery life by constantly changing and adjusting the natural ratios that exist within a wet cell battery. It is far better to allow a battery to achieve its natural equilibrium than to continually force it toward unnaturally high charge levels.

With regard to the questions posed by the OP relative to his 280 SE 4.5 (there's one of those in my realm of responsibility as well), those who suggest bringing the battery up to snuff with a charger prior to use are correct in that it will lessen the amount of work to be performed by the alternator. If a battery is a little "soft" and just misses starting the engine, there would be no harm in employing a jump starter and allowing the alternator to continue the work. If, however, a battery is way down on its power, the safest action is to use a standard charger overnight so as to return everything to normal. and not stress the alternator and its 40+ year old wiring with tasks that may be too strenuous. So far as battery size, although a 49 may properly fit the tray and appear proper under the hood. I see no reason to try and track down one of these or to pay the premium prices commanded by them. The 280 SE is not an overly large consumer of electricity and the 4.5 engine does not require that much to start. I have found a Group 24 battery to be sufficient for that application..

In the 80's when there were some cars with generators running around, generator cars seemed to have longer battery life than alternator cars. In the 80's higher power alts were appearing and I'm thinking that the lower amperage capacity of most gens saved the battery by giving it s softer / longer charge rate.

A battery tender should be slightly higher voltage than 12.70 V, this should be enough to counter self discharge and any small car loads. Any higher voltage and you are cooking the battery full time.

I don't put anything on my low use cars, 1980 Chevy pickup ( with a 292 st 6 ) , 1984 Bronco 2 sit for months at a time and the Bronco all summer. Batteries in these are 14+ years old though the Bronco battery just failed to hold a charge.

My SL has a decent sized drain so I need to recharge it every month or so. I put it on a 2 AMP / 13.0 V charger to top it off.

I would agree with this for your conditions, but there was a scenario where I was damn glad I had that 49.
When it's -10 degrees Farenheit outside, and your engine doesn't want to start and cranks and cranks and cranks, before finally catching, after 5 minutes of trying, and the battery is able to sustain that level, it's one of those "Confidence" things, as in "I have confidence this will allow the car to always start"
...And to use Drygas when it calls for really low temps the next time

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k