Charging Trojan T-105

[Oceansailor]

Just installed my new Trojan T-105. 8 x 225Ah Total 900 Ah

Trojan the recommended 14.82V for bulk charge.

I programmed my 100A charger to 14.95 bulk voltage. I have a 0.12 V loss between charger and batteries. The charger does not have voltage sense.

The maximum Voltage I have seen on the charger is 14.81 V That is 14.67 on the batteries.

So my question is. Why does not the voltage go up higher? The charger is programmed to put out 14.95?

[sailorboy1]

How long have you waited? They wouldn’t get to the upper voltage till acceptance gets low.

Btw - I had to lower my voltage back down to 14.8 or the whole boat would start smelling like acid.

[Oceansailor]

Well I did a full charge cycle until float. But I think I figures out the answer myself. As it is quite hot I guess it is the temp. compensation that regulates down the voltage. Yes the do gas. But have sealed boxes that are ventilated outside the boat.

[Sailmonkey]

Originally Posted by Oceansailor

Well I did a full charge cycle until float. But I think I figures out the answer myself. As it is quite hot I guess it is the temp. compensation that regulates down the voltage. Yes the do gas. But have sealed boxes that are ventilated outside the boat.

Just because your charger trips to float (time based) does not mean your batteries are fully charged. Power cycle the charger andeasure the current going into the batteries. I’ll bet it’s more than a few amps.

[Oceansailor]

I do agree about that Sailmonkey. Most chargers have much to short absorbtion time. I have 8 hours programmed. I think the std. was 4 hours. Even with 8 hours it pays off to restart the charger in case the batteries have been heavily discharged.

[rgleason]

Does your alternator have an external regulator? Which one?
Do you have battery and alternator temperature sensors?

Where are your + and - sense wires connected? -The alternator?
Perhaps they should be at the battery, on the shunt and the + terminal of your house bank, due to voltage drop?

[Oceansailor]

Originally Posted by rgleason

Does your alternator have an external regulator? Which one?

Do you have battery and alternator temperature sensors?

Where are your + and - sense wires connected? -The alternator?


Perhaps they should be at the battery, on the shunt and the + terminal of your house bank, due to voltage drop?

Have the older MC-612 with temp sens both for alternator and batteries. Only measuring voltage drop over the + wire. Might consider running a negative sense wire as well if needed.

[noelex 77]

Originally Posted by Oceansailor

So my question is. Why does not the voltage go up higher? The charger is programmed to put out 14.95?

The most likely explanation is the battery charger has adjusted the 14.95v you have set for temperature, hence it is only charging to the 14.81v you experiencing.

[Maine Sail]

Originally Posted by Oceansailor

Trojan the recommended 14.82V for bulk charge.

I programmed my 100A charger to 14.95 bulk voltage. I have a 0.12 V loss between charger and batteries. The charger does not have voltage sense.

I would urge you to not do this as a solution to voltage drop. Once the batteries come up to voltage and current drops, and they eventually will, you'll have minimal to no voltage drop and voltage at the battery end will now be more than you want.

To minimize voltage drop you want to increase wire gauge and ensure all terminations are as well made as can be. The alternative is to buy a charger or inverter charger that offers dedicated volt sensing.

Originally Posted by Oceansailor

The maximum Voltage I have seen on the charger is 14.81 V That is 14.67 on the batteries.

The most likely explanation is one of two things;

1- Your still in bulk with voltage still on the rise
2- The charger is cutting back voltage based on temp

Originally Posted by Oceansailor

So my question is. Why does not the voltage go up higher? The charger is programmed to put out 14.95?

Does it have a temp sensor? Is it still in bulk?

900Ah is a very large bank for a 100A charger. Even if it could run continuously, at full bore, and many dial back output when they get hot, you're still only charging that bank at just .11C or so.

If the bank was at 50% SOC you're looking at replacing about 540Ah's before you're full, so your bulk duration will be many, many, many hours.

[Oceansailor]

Originally Posted by Maine Sail

I would urge you to not do this as a solution to voltage drop. Once the batteries come up to voltage and current drops, and they eventually will, you'll have minimal to no voltage drop and voltage at the battery end will now be more than you want.

To minimize voltage drop you want to increase wire gauge and ensure all terminations are as well made as can be. The alternative is to buy a charger or inverter charger that offers dedicated volt sensing.

I have about 18 feet between charger and battery bank. Lot’s of copper. I do not think I can do much better than what it is. (0.12)
New charger would be ideal. But I do not think the “problem” is that significant.

I will monitor the voltage in the end of the charge cycle.
So far I have had no problem.



The most likely explanation is one of two things;

1- Your still in bulk with voltage still on the rise
2- The charger is cutting back voltage based on temp
Yep that is what happening. I actually have slightly higher voltage in the beginning before the batteries heats up.



Does it have a temp sensor? Is it still in bulk? Yes

900Ah is a very large bank for a 100A charger. Even if it could run continuously, at full bore, and many dial back output when they get hot, you're still only charging that bank at just .11C or so.

It is. I have another 100A charger. Have not yet been running them in parallel. But that is the intention.

If the bank was at 50% SOC you're looking at replacing about 540Ah's before you're full, so your bulk duration will be many, many, many hours.

Agree. It is never a perfect world.