New Battery Bank, now how to charge them!

[paboater76]

Thank god it's boating season!!!

Need some help here from the electrical pro's

I upgraded my house bank with 4x 6v trojan t-105's. wired in parallel and series for 450ah @ 12v. This would be battery #1 on my battery selector. connected to my port engine/charger

I also have a G24 1000cca marine starting battery that is battery #2 and connected to my starboard engine/charger

my 3rd battery is a G24 stand alone and is only connected my genset/battery charger.

Here is my problem. I currently have a promariner prosport 20amp 3 bank charger. This charger is not up to the task of charging the Trojans.

Do I either upgrade my current charger to a pronuatic 1240p? or do I get a 2x100w solar panels and a 40amp solar controller to charge the tojans? or both?

Thank you for you input!

[paboater76]

Also, I should add, I need a charger/config that is capable of charging @ 14.8v as a bulk charge per Trojan.

[tomschauer]

I don't have the specs on the prosport, but I don't know why it wouldn't charge the Trojans? It would, of course take longer than a 40 amp, but as long as your charge rate is higher than your draw rate it should not be a problem.
If you upgrade to a 40, make sure you check your existing wire sizes both power to the charge and output to the batteries. You may need to upgrade the wiring and the breaker.
As for the twin panels, that will only give you about 16 amps total at full capacity(very sunny day, very clean and new panels), rather than 20 amps on three banks (720 watts) with the current charger.
(Don't be afraid to check my math, I am a bit rusty)
I personally wouldn't depend on just a solar charging system even if sized for full load.
Also, and I don't know the answer to this, do the cheaper converters that come with these panels have a smart feature to taper the charge when the batteries are full or do they continue to charge at full available output until battery voltage matches charge voltage? If so, your batteries wont last long unless you get a higher priced inverter / charger with smart charging feature. The are usually about $400.00 so if your looking to charge out on the hook OK. If your looking to save money, not going to happen.

[paboater76]

Source of the post I don't have the specs on the prosport, but I don't know why it wouldn't charge the Trojans? It would, of course take longer than a 40 amp, but as long as your charge rate is higher than your draw rate it should not be a problem.
If you upgrade to a 40, make sure you check your existing wire sizes both power to the charge and output to the batteries. You may need to upgrade the wiring and the breaker.
As for the twin panels, that will only give you about 16 amps total at full capacity(very sunny day, very clean and new panels), rather than 20 amps on three banks (720 watts) with the current charger.
(Don't be afraid to check my math, I am a bit rusty)
I personally wouldn't depend on just a solar charging system even if sized for full load.
Also, and I don't know the answer to this, do the cheaper converters that come with these panels have a smart feature to taper the charge when the batteries are full or do they continue to charge at full available output until battery voltage matches charge voltage? If so, your batteries wont last long unless you get a higher priced inverter / charger with smart charging feature. The are usually about $400.00 so if your looking to charge out on the hook OK. If your looking to save money, not going to happen.

Thanks for the reply, from what Trojan tells me, the T105's require a 14.8v bulk charge to reach fully AH rating. my Prosport only goes to 14.6 volts. You're def better at the math than I lol. I do know that a 40 amp charger will charge faster than my 20amp, but it is not about time or money, its about getting the Tojan bank to fully charge to realize the full 450ah rating.

Yes, I would increase the wire size to match the 10ft round trip from the charger to the batteries. 8awg is recc, 6 is what I would run. and the 120 supply is already a 10/3.

The solar would be to charge the Trojan bank while on the hook for sure, while away from shore power to help replenish what I use during the day for night time Fridge, TV's, fans, lights FW pumps etc.

The solar controller I would get is a HQST 40A MPPT Solar Charge Controller ($140) that has multiple stages, bulk, maint, float etc all programmable.

I also have a 6.5genset that could power the battery charger if need be to replenish the Trojans while on hook, but I'm trying not to run the Gen.

[bud37]

You have quite a battery bank there....one bank at 450 a/h....so for the sake of argument ,some math,, if you pulled it down to 50% you would have to put 225 a/h back....assuming 20amps per bank from your charger it would take a minimum of 225/20=11.25 hours...now there is no way you will get that charge because it will cut the amps back.....so that said you still have 2 more cranking.
I guess what I am saying is I believe you are in need of a much larger charger....maybe a 1250 minimum,and if you are going to be changing out the wiring go as big as you can.....this way your genset will need to run a lower number of hours to get the bank back.
I have the same as you and have a 50 amp, and if I was going to rewire I would go much larger.What say you?

[g36]

I also use t105 batteries last set 9 yrs old they had lost some capacity could have left them but found a good deal on new ones and I ended up putting them in my golf car because they still had life left. You pretty much won't get anywhere with solar for charging unless you have no load on them. I would also only realize you will be only in bulk or absorption mode while on genset for this I have a 75 amp charger just for the house bank while on the hook. I let my xantrex 3 bank charger take care of the rest while at the dock. I would look into the largest charger to use while genset is on to limit the amount of run time but don't expect to fully charge the batteries this way because the last stages of battery charging takes hours. So let that be done at the dock.get a good battery monitor such as a victron what i use or similiar don't use more than 1/2 your battery bank capacity no deep discharges and you will have your trojan for a long time.

[Viper]

I agree that you should be going with a larger charger, you'll appreciate the faster charge time off your generator if you spend any real time on the hook. The solar panels you mentioned will delay discharge a bit but they'll likely not replace what your fridge uses while it's running for example depending on the unit you have.

[tomschauer]

PA boater, I really wouldn't worry much about the 14.6 vs 14.8 volts. 2/10 ths is nothing to worry about. I am sure you could reach 99.9999 percent full charge with the 14.6.
Also keep in mind these ratings also have an acceptable margin of error. The ratings given for both the batteries and the charger are at optimum conditions, in a controlled environment, temperature, humidity input voltage, battery charge state, etc. You will never see these conditions on board your boat.

[paboater76]

Thank you all for the replies, I'm way over thinking this (as I normally do with all projects lol) I do believe I need a larger charger, simply for the charging time from 20amp to 50. Leaning towards the 12/50p pronautic. Now here is where I get lost. if this is 50amp charger, do I need a 50amp AC breaker in my panel??

I get that I need min 8awg from my charger to my trojans (I will run 6awg) distance is like 5-6 ft one way. But what size wire from my AC panel to the charger?? the distance is again, like 6ft. My boat has 2x 30amp panels. my current charger is on a 15amp breaker..

The charger says this in the catalog.
Amperage at 100 < 10.0

Does that mean it can draw greater than 10 amp? would this charger be ok on a 15amp AC breaker?

Thanks and sorry for the dumb questions.

[paboater76]

I still have not abandoned the solar idea. but it would be in addition to a good battery charger. When we are on the hook, we are generally not on the boat but floating in the water, standing in the sand.. I really want as full of a bank for when night time comes and we are using lights, pumps TV's Fridge etc.

Would the 200w of solar do anything to help put back what little I use during the day? or is it just not worth it?