Rapid voltage drop under small loads with new Trajan T-105

[BluJu]

After 5 years of service and signs of declining capacity, I decided to replace our house batteries. We have 4 6V batteries wired in a series/parallel configuration providing 450 Amp-hr of theoretical capacity.

I bought 4 Trojan T-105 2 weeks ago. They were manufactured in March 2018 and were only ~65% charged when I got them (6.19V). After installing them on the boat, I gave each 12 V bank a long reconditioning charge with a CTEK Multi 25000 charger. But they could not seem to handle any load. As en example, an evening I recorded voltage dropping from 12.7 to ~12.2 V after 7 hours under 8 amp of load.

Suspecting an issue with the batteries, I talked to the dealer which agreed to replace them. The new batch was nearly fully charged. I installed them yesterday and am in the process of giving them a good reconditioning charge with the same CTEK charger. The bank that has not been put on charge yet (besides couple hours of engine run) is already showing the same rapid voltage drop syndrome under small load. After 12 hr, the bank on charge had not reached float charge, which is surprising since the batteries were supposedly nearly charged when I got them 2 days ago. Specific gravity measured 1 hr after disconnecting the charger was 1.26 on all cells for one battery and 1.24, 1.25 and 1.26 for the cells of the other battery.

Unless the dealer has badly neglected a whole batch of battery, what could trigger such a rapid voltage drop under even small loads?

Thanks a bunch, this is driving me crazy!!

[sparrowhawk1]

I'm not going to give any advice, I'll just tell you a story. Once upon a time I bought a starter for my van that only lasted one to two weeks. this happened three times. the "dealer" had no problem exchanging them but after the third one I went someplace else and lived happily ever after.

[darylat8750]

It is possible that they need a few cycles to get "broken in". A friend of mine had that type of issue with a set of batteries and the manufacturer said to "hammer 'em for 3 or 4 cycles and they should be better" and they were.

[BluJu]

I talked to Trojan today and they suggested it might take 50 full cycles for the batteries to deliver their full capacity. They said capacity might be as low as 80% of rated capacity upon leaving the factory.

I just found another thread describing the same issue.
http://www.cruisersforum.com/forums/...ad-205478.html

Seems like some consider my observations normal, others not. I will continue with the "breaking in" but any advice as to what may be causing this voltage drop is welcome. I have no indications of unwanted/undetected current draw but I'm wondering if that could be a factor.

[Stu Jackson]

Breaking in New Wet Cell Batteries: "Breaking In" New Wet Cell Batteries

[john61ct]

Yes, AKA "commissioning charging." The first few dozen cycles, go easy on the amps, avoid high current rate discharges and charges.

First step really **fully** charge, as in hold Absorb V to the top spec until amps taper to .005C in your case 2A or below, however long that takes. Let SG go a bit over spec, no harm occasionally.

Then manually follow Trojan's equalizing instructions, ideally on each 6V unit separately, again letting trailing current taper down to .005C or 1A at the higher V.

Next, discharge at .05C or 10A in your case, for about 20 hours. The battery voltage should then be around 5.25,

don't let it drop past that, and start recharging immediately,

at ~.15C for the rest of the break-in period, say two months if regularly cycling, trying to avoid huge draw currents as well.

Note if it takes lots less time than 20 hours for any one 6V unit to get to 5.25V from 100% Full, return it.

Where are you located?

[john61ct]

You should not be allowing any other loads than the ones you control during the commissioning / testing draw-down process, and none at all during the charging side.

[svlamorocha]

Originally Posted by john61ct

Yes, AKA "commissioning charging." The first few dozen cycles, go easy on the amps, avoid high current rate discharges and charges.

First step really **fully** charge, as in hold Absorb V to the top spec until amps taper to .005C in your case 2A or below, however long that takes. Let SG go a bit over spec, no harm occasionally.

Then manually follow Trojan's equalizing instructions, ideally on each 6V unit separately, again letting trailing current taper down to .005C or 1A at the higher V.

Next, discharge at .05C or 10A in your case, for about 20 hours. The battery voltage should then be around 5.25,

don't let it drop past that, and start recharging immediately,

at ~.15C for the rest of the break-in period, say two months if regularly cycling, trying to avoid huge draw currents as well.

Note if it takes lots less time than 20 hours for any one 6V unit to get to 5.25V from 100% Full, return it.

Where are you located?

Great post, but I want to emphasize the importance of making SURE (as when using a multimeter, not any fixed instrument) that the voltage AT THE BATTERIES during absorption phase is equal to spec by the manufacturer. It its very easy to overlook the importance of voltage on the relationship between trailing amps and SOC.

[Maine Sail]

Originally Posted by BluJu

After 5 years of service and signs of declining capacity, I decided to replace our house batteries. We have 4 6V batteries wired in a series/parallel configuration providing 450 Amp-hr of theoretical capacity.

I bought 4 Trojan T-105 2 weeks ago. They were manufactured in March 2018 and were only ~65% charged when I got them (6.19V). After installing them on the boat, I gave each 12 V bank a long reconditioning charge with a CTEK Multi 25000 charger. But they could not seem to handle any load. As en example, an evening I recorded voltage dropping from 12.7 to ~12.2 V after 7 hours under 8 amp of load.

Suspecting an issue with the batteries, I talked to the dealer which agreed to replace them. The new batch was nearly fully charged. I installed them yesterday and am in the process of giving them a good reconditioning charge with the same CTEK charger. The bank that has not been put on charge yet (besides couple hours of engine run) is already showing the same rapid voltage drop syndrome under small load. After 12 hr, the bank on charge had not reached float charge, which is surprising since the batteries were supposedly nearly charged when I got them 2 days ago. Specific gravity measured 1 hr after disconnecting the charger was 1.26 on all cells for one battery and 1.24, 1.25 and 1.26 for the cells of the other battery.

Unless the dealer has badly neglected a whole batch of battery, what could trigger such a rapid voltage drop under even small loads?

Thanks a bunch, this is driving me crazy!!

1- Your CTEK charger is not capable of charging your Trojans as the manufacturer suggests and is likely why your SG readings are what they are. It may be telling you the batteries are "full" but, they're not.

Unless something has recently changed the max absorption voltage for the CTEK is 14.4V and this is just not high enough for deeply cycled Trojans. A target of 14.8V for absorption will result in healthier batteries.

2- Your batteries need to be broken in. The fastest way to do this is deep cycling them and then recharging to 100% SOC after each discharge. Your CTEK is likely not capable of getting your batteries back to 100% SOC...

3- Where are you measuring this voltage and with what equipment. The only voltage reading that matters is one taken directly from the battery terminals with a known accurate volt meter or DVM. Taking this measurement anywhere else in the system, as most boats volt meters do, is simply a poor data to work from.

4- Lead acid batteries can exhibit a voltage drop then a rebound on discharge. This discharge graph below was a Trojan battery during a 20 hour capacity test that delivered 77% SOH based on the factory rating of 130Ah. Notice the initial dip in voltage to the far left and then the rebound. This dip, then rebound, was close to 0.1V. A voltage difference for a lead acid battery of 0.1V can actually be 10% of a lead acid batteries capacity, so going by voltage here can could certainly be a bit misleading.

I've also highlighted when this battery hit about 88% SOC based on the actual Ah's it could deliver. Your battery bank, based on the "as new" rating, was also down about 12% +/-. The voltage under the .05C load on this used battery was 12.26V.

With a 0.018C load, and that voltage, I suspect you have a charger issue, non-broken in batteries and potentially a voltage sensing location or equipment issue. If you get a good quality charger, that can charge them per Trojan's guidance, I suspect you will see your loaded voltage support do much better as they begin to break in.

[john61ct]

Is the mfg date also March on the new set?

[ohgary]

Originally Posted by BluJu

I bought 4 Trojan T-105 2 weeks ago. They were manufactured in March 2018 and were only ~65% charged when I got them (6.19V). After installing them on the boat, I gave each 12 V bank a long reconditioning charge with a CTEK Multi 25000 charger. But they could not seem to handle any load. As en example, an evening I recorded voltage dropping from 12.7 to ~12.2 V after 7 hours under 8 amp of load.

Confused by your note 65% and 6.19v those are 6v batteries. If your talking about 6.19v in your series batteries then you should look at the battery that was not changed. What are the voltages of each battery.

[BluJu]

Originally Posted by john61ct

Is the mfg date also March on the new set?

yes, same batch of batteries

[BluJu]

We're in Halifax right now, but getting ready to leave to Bermuda in the next few days, and Caribbean after that.

[BluJu]

"1- Your CTEK charger is not capable of charging your Trojans as the manufacturer suggests and is likely why your SG readings are what they are. It may be telling you the batteries are "full" but, they're not.

Unless something has recently changed the max absorption voltage for the CTEK is 14.4V and this is just not high enough for deeply cycled Trojans. A target of 14.8V for absorption will result in healthier batteries.

2- Your batteries need to be broken in. The fastest way to do this is deep cycling them and then recharging to 100% SOC after each discharge. Your CTEK is likely not capable of getting your batteries back to 100% SOC...

3- Where are you measuring this voltage and with what equipment. The only voltage reading that matters is one taken directly from the battery terminals with a known accurate volt meter or DVM. Taking this measurement anywhere else in the system, as most boats volt meters do, is simply a poor data to work from.

4- Lead acid batteries can exhibit a voltage drop then a rebound on discharge. This discharge graph below was a Trojan battery during a 20 hour capacity test that delivered 77% SOH based on the factory rating of 130Ah. Notice the initial dip in voltage to the far left and then the rebound. This dip, then rebound, was close to 0.1V. A voltage difference for a lead acid battery of 0.1V can actually be 10% of a lead acid batteries capacity, so going by voltage here can could certainly be a bit misleading.

I've also highlighted when this battery hit about 88% SOC based on the actual Ah's it could deliver. Your battery bank, based on the "as new" rating, was also down about 12% +/-. The voltage under the .05C load on this used battery was 12.26V.

With a 0.018C load, and that voltage, I suspect you have a charger issue, non-broken in batteries and potentially a voltage sensing location or equipment issue. If you get a good quality charger, that can charge them per Trojan's guidance, I suspect you will see your loaded voltage support do much better as they begin to break in."




Thanks for this detailed reply. I measured all voltages at the battery terminals with a conventional digital voltmeter. I realize that the CTEK charger does not deliver the required absorption voltage. I will see about sourcing one that can.

[john61ct]

This thread goes into some detail on optimal care specs for those

http://www.cruisersforum.com/forums/...ml#post2640525