weird battery performance

[dorff]

I've got a 90 amp hr deep cycle crown battery. its new, i took it out of my new 5th wheel to put in two 6v to get more amp hours. The battery was new as the trailer was a custom order, but i don't recall their state of charge when I took them out and that was 6 weeks ago.

anyway I charge them up a full charge with a Noco 10 amp smart charger and finished voltage after resting is almost 12.7v and spec grav is 12.65.

under a 5 amp load the battery only last about an hour before falling below 11.5v.

but as soon as this light load is removed the voltage within minutes is back to 12.6v and SG is still 12.65.

i thought maybe the battery had suffered some sulfation, but won't the SG be low because of the acid being retained in the sulfation?

when i attempt a re-charge it doesn't take very long because i think the Noco charger is being fooled by the battery's normal voltage indication.

any suggestions??

[Mike90250]

When batteries are "new" they sometimes need either a "Initialization or Commissioning charge" to get the plate material fully active. Or sometimes, the same thing happens after a couple weekends of being used and recharged.
As long as the SG is good after recharge, and you don't let them set Low for more than a day, they should be OK.

[max2k]

I've got a 90 amp hr deep cycle crown battery. its new, i took it out of my new 5th wheel to put in two 6v to get more amp hours. The battery was new as the trailer was a custom order, but i don't recall their state of charge when I took them out and that was 6 weeks ago.

anyway I charge them up a full charge with a Noco 10 amp smart charger and finished voltage after resting is almost 12.7v and spec grav is 12.65.

under a 5 amp load the battery only last about an hour before falling below 11.5v.

but as soon as this light load is removed the voltage within minutes is back to 12.6v and SG is still 12.65.

i thought maybe the battery had suffered some sulfation, but won't the SG be low because of the acid being retained in the sulfation?

when i attempt a re-charge it doesn't take very long because i think the Noco charger is being fooled by the battery's normal voltage indication.

any suggestions??

is SG even between cells? You might get bad cell in that battery.

[dorff]

SG is consistent across all the cells at 1265. i've put a load on it and recharged this battery 6 times or more and its amp hour output doesn't seem to be improving. i keep the 6 amp load on it till it goes down to 11.5v while under load-about an hour, take the load off and the voltage goes right back up to 12.8v, but if i let the battery rest and put the load on it again, it immediately falls to 11.5v, yet the SG remains at 1265. My brand new smart Noco 10 amp charger won't charge it more than 30 minutes because it thinks it's fully charged because of the voltage is over 12.6.

so I put an old dumb 6 amp charger on it for 6-8 hours, inbound amps eventual falls to less than 1amp, cells are gassing, no increase in battery temperature. SG is 1270 volts @ 13.0

should I leave it on the dumb charger even longer?

[max2k]

SG is consistent across all the cells at 1265. i've put a load on it and recharged this battery 6 times or more and its amp hour output doesn't seem to be improving. i keep the 6 amp load on it till it goes down to 11.5v while under load-about an hour, take the load off and the voltage goes right back up to 12.8v, but if i let the battery rest and put the load on it again, it immediately falls to 11.5v, yet the SG remains at 1265. My brand new smart Noco 10 amp charger won't charge it more than 30 minutes because it thinks it's fully charged because of the voltage is over 12.6.

so I put an old dumb 6 amp charger on it for 6-8 hours, inbound amps eventual falls to less than 1amp, cells are gassing, no increase in battery temperature. SG is 1270 volts @ 13.0

should I leave it on the dumb charger even longer?

do you know the history of this battery? If it is new I'm wondering if someone added electrolyte there instead of distilled water to top up level. That would lead to behavior you describe- even cells and not taking charge. I'd remove it from that dumb charger as charging current doesn't seem to do anything useful and it is just breaking water into H2 and O2

[SunEagle]

SG is consistent across all the cells at 1265. i've put a load on it and recharged this battery 6 times or more and its amp hour output doesn't seem to be improving. i keep the 6 amp load on it till it goes down to 11.5v while under load-about an hour, take the load off and the voltage goes right back up to 12.8v, but if i let the battery rest and put the load on it again, it immediately falls to 11.5v, yet the SG remains at 1265. My brand new smart Noco 10 amp charger won't charge it more than 30 minutes because it thinks it's fully charged because of the voltage is over 12.6.

so I put an old dumb 6 amp charger on it for 6-8 hours, inbound amps eventual falls to less than 1amp, cells are gassing, no increase in battery temperature. SG is 1270 volts @ 13.0

should I leave it on the dumb charger even longer?

I am not sure what you are measuring when you say the SG of the battery is 1270 & 1265. Are you leaving out a decimal point and the value is 1.265 for each 2 volt cell?

What type of hydrometer are you using and have you figured in the temperature difference?

[Mike90250]

....SG is 1270 volts @ 13.0 should I leave it on the dumb charger even longer?

Keep charging it till the SG stops rising Check every hour (6A charger should not cook it)

[dorff]

using an E-Z Red SP101 Battery Hydrometer, temperature compensating per the cover.

someone off line suggested trying a much smaller load and see if watts extracted are the same as the 6 amp load. He thinks the battery is fully charged per the voltage and SG readings, but there is some sort of a high internal resistance issue (defect) between the inside and the outside battery terminals that is quickly bringing the battery's ability to delivery 6 amps even though its still fully charged. got me, could be a WAG.

[SunEagle]

using an E-Z Red SP101 Battery Hydrometer, temperature compensating per the cover.

someone off line suggested trying a much smaller load and see if watts extracted are the same as the 6 amp load. He thinks the battery is fully charged per the voltage and SG readings, but there is some sort of a high internal resistance issue (defect) between the inside and the outside battery terminals that is quickly bringing the battery's ability to delivery 6 amps even though its still fully charged. got me, could be a WAG.

That sounds about what I am thinking. Something in the circuit is pulling down the battery voltage very quickly even though the load is small and the battery recovers back up to a high voltage once the load is disconnected.

Let us know if a different load gives you the same result.

[Sunking]

E-Z Red SP101 Battery Hydrometer, temperature compensating per the cover.

Never used this hydrometer before, so cannot really comment on it. All I can say is not something I would use or recommend.

someone off line suggested trying a much smaller load and see if watts extracted are the same as the 6 amp load. He thinks the battery is fully charged per the voltage and SG readings, but there is some sort of a high internal resistance issue (defect) between the inside and the outside battery terminals that is quickly bringing the battery's ability to delivery 6 amps even though its still fully charged. got me, could be a WAG.

That is a WAG, but is exactly the problem. There is high resistance somewhere, either in your connection, or the batteries have sulfated. The symtoms you describe fit that of a sulfated tired battery. Sitting 6-months without a charge can do that.

Note the proper charge voltage for you battery is 15 volts. Read the manual. Bulk/Absorb = 2.5 vpc or 15 volts on a 12 volt battery. All battery manufactures have upped charge voltages. Get with the program.

You need to preform an EQ Charge and see if the battery can be saved or not. EQ voltage = 15.9 volts. You apply the EQ charge until SG quits rising over a period of 60 minutes. Allow the battery to rest 12 hours, then do a discharge test.

For the discharge test apply whatever load you can be it 6, 10, or 20 amps. C/10 would be great. Use a timer and discharge the battery until it reads 10.5 volts. Terminate the discharge and record time in HOURS. Take note if these are say 200 AH batteries, and you discharge at say 6 amps is hopefully going to be a very long day because 6 amps on a 200 AH battery is C/33 or 33 hours. So if you discharge at C/10, realistically is a 9 hour test at most.

Amp Hours = Amps x Hours
Hours = Amp Hours / Amps
Amps = Amp Hours / Hours

Note if you discharge at the C/10 or 10 hour rate, the battery will not test at rated capacity. Batteries are rated at C/20 or the 20 hour discharge rate. Peukert Law will bite you. A 200 AH battery discharge at 20 amps will only test at 170 AH. Give me the battery Model Number and I can be more helpful.

That will tell you the capacity. Don't worry about a full discharge to 10.5 volts. Will not hurt the batteries one little bit Once completed recharge at 15 volts until current stops. If I had to guess, you have never fully charge the battery yet. It needs an Initialization charge which is basically a EQ charge. If you have been charging to less than 15 volts, it is a good bet they are not charged up. SK knows wtf he is talking about. Read the manual.

Final note. Make sure you have good connections on proper sized wire. There is a chance that is your whole problem. CHARGE @ 15 VOLTS.

[dorff]

if the batteries have sulfated, wouldn't the SG be low since so much acid is being held in the sulfate on the plates.

i can program my Xantrex inverter/charger to charge at any voltage up to 17, so I'll try 15.9v as you suggested and see what happens.

thanks

[Sunking]

OK when you EQ just monitor the battery. Some things you need to look for and do before you EQ

Before you EQ, check water levels, add if needed. Then do a full charge at 15 volts until current stops. Then let it rest (cool off) and then EQ.

1. Fast boiling water. If it boils so much it starts to spew. reduce the charge rate (amps, not voltage).
2. Temperature. Stay below 120 degree. Should not be a problem.
3. Monitor SG. Take measurements of all cells every 15 minutes.
4. Stop when SG stops rising for 60 minutes. It should be up around 1.275 +/- .005 spread among all cells. Example no lower than 1,272, and no greater than 1,277.

WHAT IS THE MODEL NUMBER????

[dorff]

xantrex inverter/charger is a freedom hfs 2055 model #807-2055

batteries are Crown 27DP600 SM27600 90 Ah marine dual propose

[dorff]

if i do the full charge with the dumb charger it does get a little over 15v, but I've never let is run till amperage goes to zero.

the xantrex I can set both bulk/absorption & float modes to 15v, but i think it will stop charging once it thinks voltage is high enough.

so I guess I'll use the dumb charger and just wait until amperage going into the battery gets close to zero.

[Sunking]

batteries are Crown 27DP600 SM27600 90 Ah marine dual propose

Oh Crap hold the buss. I though you had Rolls. My bad.

Charge @ 14.5
EQ @ 15.5

Everything else remains the same.