I wrote briefly in another topic. 5 years old, left in a warm climate for 8 months with terminals disconnected. Upon return found it completely discharged, Voc=11.86. Multimeter "might" read lower than it is, but 8 months is enough for a complete self-discharge anyway. Water was 1/8" below the plates, added water to the mark.Charged until current dropped to 0.5A, which is just about right - don't know the capacity in AH, they never tell this on starter batts, but by the size and weight ~40 AH.Could only raise the charging voltage to 14.4, then it went into absorption stage (setpoint was 14.6, but it didn't want to raise it that high).Tried to equalize at 15.5V, but it wouldn't raise the voltage over 14.7, so equalization is now "new absorption".Wintering in Mexico away from civilization - though with solar power - I wonder what can be done and what to expect.Buy Trik-L-Charge? Not sure that local village store would even know what this is, and it won't let me stray too far from the solar panels and my rig. When not driving, it's losing charge at the rate ~8% A DAY. Can buy a new battery, but if I leave it again for 8 months I might as well buy it next winter. Questions:1) What can be done to restore it a little - prolonged charging, desulfators, snake oil?2) It runs the truck, but how dangerous is to drive with such a battery, can it just fail down on me on the road?3) Will try and find some maintenance option for the next long storage, but what if I leave it again for 8 months - will it degrade so badly that wouldn't accept charge at all?

Desulfate it. This is what I just love about stupid smart chargers. They don't work.The battery is on its last legs. Five years in a warm climate makes it = to an octogenarian. If you drive mostly short distances, you may have left with the battery 70% charged.If the motor never gets shut off then there is little chance the battery will fail to start the car. Otherwise it is a crap-shoot.Being a maintenance charger with you from home. And a gallon of distilled water. Some purified drinking water down here has high TDS.I recommend for 28C a maintenance voltage of `13.4

For long storage you can use a solar panel charger sold at Harbor Freight or Northern Tools it will maintain the battery.Or take the battery out and put it on a bench with a trickle chargerOr use the trickle charger with the battery in the vehicle.Anytime my batteries get beyond 5 years I expect the possibility they will fail.

Hi Almot,There is nothing to loose on this battery. Get a manual charger and "have at it".If you leave--get a diode and connect the starter battery to a 15 watt panel. You might want to almost overfill the battery if you can find a source for "real" distilled water.Next year bring a trik-l-start with you and replace the battery.I'd class the trik-l-start as a "smart diode" that will do about 1/2 volt less than what is presented to the "house" bank.

As long as you are stationary I would use a small jumper to allow the solar to give it a boost for a few weeks. After this period of charging disconnect the battery and see if it holds 12.6+ volts for three days. If it is still failing get a new chassis battery.For long term storage with the old battery just leave it disconnected and bring a new one next season. If you get a new battery now just put that small jumper on while you are away. Either way bring a Trik-L-Start when you return.

Nearly dead starter battery - what to expect?

23 Replies

Almot
Explorer III
Nov 29, 2013
Mex, I wish that option was available :)... These days, you just carry booster cables and hope for mercy of others. And, in these parts - a rope to tow it with another truck. Yes, on the rope, this is how they do it, Mexican way.

Meanwhile, 3 AGM + 1 half-dead starter dropped down to 0.8A Float. Made a typo earlier, sorry - the current to transition to Float was set 3.5A, not 1.5A.
MEXICOWANDERER
Explorer
Nov 27, 2013
Almot
Explorer III
Nov 27, 2013
This is odd. Following the advice by SMK, I hooked up dying flooded starter to solar charger and 245W panel. Yes sir, AGM and flooded in parallel to one charger.

3 AGM before this were floating at 13.6V for 3 days and came down to <1A current.

Dying starter before this (when tried to charge separately) was sitting at permanent ABS stage for 2 days, 14.4V and current gradually dropping to 0.5A, and solar charger hated this battery and was switching back and forth between ABS and bulk mode. Rest overnight Voc (before today's experiment) was 12.45.

Didn't change Bulk-ABS 14.6V setpoint. Didn't change ABS-Float 13.6 V setpoint. Changed Float current setpoint to 1.5A (1+0.5=1.5).

In parallel, 3 good + 1 bad: as if bad one wasn't even there. Started with bulk, raised quickly to 14.6, transitioned to ABS, then dropped quickly to 13.6 Float setpoint, and went into Float. All 4 are peacefully floating now at 13.6. No erratic behavior of the charger (no switching ABS/Float every minute). The only minor difference is that current is now 1.5A, which makes sense as 3 good batts were at 1A and one bad - at 0.5A.

Will see what happens.
westend
Explorer
Nov 27, 2013
What truck do you have? If it's a compact that doesn't need a lot of amps to spin the starter, there are industrial AGM's that may fit your use. An AGM definitely fits your usage, I left one idle over a Minnesota winter, outside, and the SOC was still at 12.4 or so after 6 months. It was probably stored less than 100% SOC, also.
Almot
Explorer III
Nov 26, 2013
Mex, pure led battery with 1% a month discharge - this is even better than AGM starter. Must cost a fortune. Could have bought AGM starter for $200 before driving South. The dirty secret is that I don't plan to keep the truck. A season, maybe two, and then off it goes to some local ranchero/pescadero for a few hundred bucks and a bag of rice ;)... Until then, I need to maintain it on cheap.
time2roll
Nomad
Nov 26, 2013
Almot wrote:
smkettner wrote:
As long as you are stationary I would use a small jumper to allow the solar to give it a boost for a few weeks.

My 3 almost-new house AGMs are floating on solar. This dying starter batt behaved odd when I put it on same solar charger, I wrote about that. Connecting it in parallel to 3 good AGMs while those are floating, confusing solar charger with two different types of batts, of which one doesn't accept charge properly? Sounds scary...

Keep an eye on it. Post the morning start voltage.
Otherwise get a new start battery already.
j-d
Explorer II
Nov 26, 2013
Don't trifle with a failing Chassis Battery. Neighbor just loaned his Class A (on Ford F-53 with V10) to a friend. Friend got to the storage lot and found the battery very low. Kept trying to crank it. I don't know if he even knew the coach (probably) has start assist from the House Batteries, but the Starter Motor and Starter Solenoid both had to be replaced that day. I suspect that permanent magnet starter took a dim view of low cranking voltage and threw in the towel.
MEXICOWANDERER
Explorer
Nov 26, 2013
Then there is the pure lead battery that discharges about 1% per month. This eliminates fiddling with chargers, having them scamper off into the bananas, getting covered with a quarter inch of salt grime and losing 80% of their photo generating capability.
Almot
Explorer III
Nov 26, 2013
MNtundraRet wrote:
I use 2 Coleman 9-watt panels for maintaining my batteries during the winters here in Minnesota. One for the starting battery, and the other for the pair of T-105's. No controllers needed. I have no shore-power.

Mark

Yeah, but the SMALLEST panel on the neighbor's shack is 80-watt :)...
Almot
Explorer III
Nov 26, 2013
smkettner wrote:
As long as you are stationary I would use a small jumper to allow the solar to give it a boost for a few weeks.

My 3 almost-new house AGMs are floating on solar. This dying starter batt behaved odd when I put it on same solar charger, I wrote about that. Connecting it in parallel to 3 good AGMs while those are floating, confusing solar charger with two different types of batts, of which one doesn't accept charge properly? Sounds scary...