Trojan T-105 Charging advice

[Stormshag]

Originally Posted by PaulCrawhorn

Charge profile sitting at a shore powered dock (14.2V - 14.6V) is completely different from off grid solar and genset usage.

If motoring for 8+ hours at a time anyway then use the former settings as the manual specs.

But when you don't have the time / input Ah to get to 100% Full every cycle as per endAmps

> If charging time is limited, contact Trojan Technical Support for assistance

A "bulk transition" and Absorption / CV stage setpoint of 14.8V (or even higher, say 15V in cool conditions) will result in faster charging and healthier batteries.

IMO 14.6V for absorb is bare minimum for a T105 and is not going to lead to as long a life as 14.8V

This needs to be held at least 2-4 hours until endAmps is reached, only then dropping to Float V.

Hi Paul, Thanks for the reply.

Hoping to understand the alternator charging a little better. With regards to my shore charger, it's fairly automatic. It has some minor programmable stuff but mostly I just let it do it's pre-programmed routine. What I don't really understand still is charging off the alternator. It's an older automotive style alternator with an older external regulator which isn't smart in any way, certainly nothing that can be programmed or set. My basic question is "How long and at what rpm's should I be running the engine to re-charge my house battery" My system is very old and very basic. I don't want to risk boiling the battery over and I just don't really know what I'm doing when it comes to charging the bank off the alternator. I've read the manual but it seems like it is geared towards setups that allow me to program the charge source amps/volts.

Thanks for any help.

[Quebramar]

Reading the Trojan manual, you will see the recommended voltage for each charging phase. You will notice they are quite higher than standard ones, so adjusting the standard settings on your charger is recommended. For what relates to the alternator, I am not sure but it would probably not go quite high.

[GILow]

So, for those that feel confident that the batteries will provide the adequate resistance to prevent excess current, yes, this is true for conventional alternators and regulators.

But some are advocating smart regulators and these can jack the charging current up hugely by jacking up the charge voltage. Combine a smart regulator with a bigger alternator and you can exceed the recommended charge rate badly.

So, I say it again, read the manual.

And take care of the keyboard warriors who don’t read the manual.

[GILow]

Originally Posted by Dockhead

Wise men will disagree on this, I and will disagree with this wise man

…

You are too kind. [emoji28]

And, to show I’m not a Victron sales guy in disguise, I am very interested in what you’ve said about the deficiencies in the Victron battery monitor. From your reasoning it seems this is going to be a shortfall of any Coulomb counter?

I’ll look into your recommended system for the new boat, where I’ll have even more solar and more battery capacity as I increase my reliance on electricity for cooking.

I am a little worried about the issues you flagged with the device’s ability to function with solar. I rely almost entirely on solar for power and cruise in areas of great solar generation potential. Whichever system I use needs to take this into consideration.

Some reading in my future.

[Dockhead]

Originally Posted by GILow

You are too kind. [emoji28]

And, to show I’m not a Victron sales guy in disguise, I am very interested in what you’ve said about the deficiencies in the Victron battery monitor. From your reasoning it seems this is going to be a shortfall of any Coulomb counter?

I’ll look into your recommended system for the new boat, where I’ll have even more solar and more battery capacity as I increase my reliance on electricity for cooking.

I am a little worried about the issues you flagged with the device’s ability to function with solar. I rely almost entirely on solar for power and cruise in areas of great solar generation potential. Whichever system I use needs to take this into consideration.

Some reading in my future.

It's really pleasant to argue with you


Beer is on me if we ever find ourselves in the same harbor.


If you are using solar, then you need the new Balmar monitor in my opinion.



My job is a lot easier because I don't have any solar (windage, and in my cruising area, I need to go hundreds of miles upwind on regular basis), and I have a heavy duty low speed almost silent generator which I can fire up at any moment when power is short or the batts are getting low.


Your use case is different, and I think you want the Balmar thing.

[GILow]

Originally Posted by Stormshag

Hi Paul, Thanks for the reply.



Hoping to understand the alternator charging a little better. With regards to my shore charger, it's fairly automatic. It has some minor programmable stuff but mostly I just let it do it's pre-programmed routine. What I don't really understand still is charging off the alternator. It's an older automotive style alternator with an older external regulator which isn't smart in any way, certainly nothing that can be programmed or set. My basic question is "How long and at what rpm's should I be running the engine to re-charge my house battery" My system is very old and very basic. I don't want to risk boiling the battery over and I just don't really know what I'm doing when it comes to charging the bank off the alternator. I've read the manual but it seems like it is geared towards setups that allow me to program the charge source amps/volts.



Thanks for any help.

A couple of points…

You really need to find out more about the shore charger’s settings. It is unlikely to be overcharging the batteries, but as mentioned above, the Trojans have a slightly higher charge voltage than many batteries so there’s a good chance the shore charger is under charging.

Regarding the alternator, you can learn a lot by watching the system voltage while the engine is running. Attach a good quality multimeter to the batteries themselves (not the house electrical system which can have very different readings) and watch what happens over time. The topic is a little big to address here, but in summary you want to see the voltage climb steadily to something close to the battery absorption voltage (14.75V @20C) and hold there without going higher. The absorption phase itself takes around two hours so it’s unlikely you’ll complete that phase from motoring. And most conventional alternators will not reach absorption voltage anyway. In practice what I think you’ll see if the voltage steadily climb then plateau at something sustainable by the alternator, 14.4V is common for modern alternators designed for calcium batteries, closer to 14.2 for older alternators. To know how long to run the engine you really need to see current flow into the batteries. With the Trojans the current starts to fall off around 80% full, so you’d watch for that turning point while motoring. You might be able to spot the 80% full point by noting a brisk increase in voltage.

Charging the last 20% from the engine will take hours and really isn’t worth doing from the engine. This is where some extra solar is worthwhile, even in low solar environments.

[GILow]

Originally Posted by Stormshag

Thanks so much for the thoughtful reply! I really appreciate it. So further to what you discussed, is my understanding of the manual correct that if I am to apply the alternator to charge the batteries, that the amperage should be around 13% of the C20 figure? My bank is a 225AH so I'm assuming that means .13*225= 29.25 Amps. I think my amp is a 30 or 36 amp model. I don't know lots about the alternator, does this mean it puts out 30 amps generally or does it fluctuate based on the rpm's of the engine?



I'll definitely check out the victron products you mentioned. As I just replaced the batteries I'd like to keep them in as good condition as possible and wnat to make sure my charging regimen is as by the book as it can be.

See my response above, regarding the alternator charge strategy, but specific to your question here…

First, yes, your charging maths is spot on. (I can say this with some authority, I’m a high school maths teacher.)

In practice your alternator (if it does not have a smart regulator) SHOULD deliver no more than the batteries can handle at any rpm. The batteries will self regulate their charge rate no matter how big the alternator is and how fast the engine is running. (I say should because there’s always a slim chance the alternator has a faulty regulator.)

The real problem is more likely to be that you will get a lot less output from alternator than it’s rated capacity. This is because of factors such as engine revs, alternator temperature, wiring resistance and battery state of charge.

Smart regulators overcome a lot of these challenges by using remote sensing, field energisation and other tricks.

With deference to Dockhead’s point about the Victron battery monitor I’ll say a “good quality” battery monitor is a wise investment, as are an ammeter and voltmeter that measure the battery bank itself. I’m old school and use remote shunt ammeters everywhere but I live aboard at anchor so thinking about electrons take up way too much of my daily routine.

Finally, I would make some voltage measurements at the battery sooner rather than later. You’ve just bought these batteries so it would be good to know all is as it should be. For instance, is the voltage profile from the shore charger as expected? Has the alternator been modified in some way (An old trick to improve alternator charging was to incorporate a diode in the voltage sense circuit to jack up the charge voltage. I’ve seen these setups on older boats with older alternators.)

[JimsCAL]

To try to answer your question about charging from your basic alternator, here's a couple of comments. The amp rating is the maximum you should expect, and that will taper off significantly as the battery charges and the alternator and battery heat up. It will take a very long time to get your batteries up to 100% charge without a multi-stage external regulator like a Balmar. Some solar is one way to get your batteries up to full without running the engine for hours.
.

[Stu Jackson]

Originally Posted by Stormshag

Hi All,

I dont have a lot of electrical knowledge and seeking advice/knowledge on the use and charging of my house bank.

Current Setup

House Bank: 2 T105 batteries in series. 12v @ 225AH
Primary loads: cabin lights, anchor light, 12v norcold fridge, planar diesel heater with water circulation pump and computer fans at distribution points, cell phone charger, laptop charger.
Alternator: I believe its just a simple 30A auto style on my perkins 4108
Shore Charger: ProMariner 1220i rated at 20A



..............................


I'm trying to figure out the right balance of daily battery use versus alternator charging time so I can gauge how long I can stay away from the dock before needing to hook up the shore power charger again. I also have small solar setup that I'm planning to hook back up, but here in the PNW sun is not that abundant usually.

Thanks for your help!

The "right balance" is the right approach.
You are, essentially, asking basic boat electrical system questions that most of us have learned over the years.
These are good questions, that with a bit of research, you can learn.
Many of us "show our age" by mentioning that we "learned the hard way," not with bruised knuckles, although sometimes those, too, but before the internet.
So we had to rely on, gasp!, books.
Nigel Calder's Boatowners Manual for Mechanical and Electrical Systems, and Charlie Wing's Boat Electrical Systems are excellent resources. Amazon is a good source.
Other internet sources are "Maine Sail" and his website:
his website has a load of information that is helpful to all skippers.
http://www.pbase.com/mainecruising/boat_projects
and his newer one
https://marinehowto.com/
I have spent years assembling this information:
Electrical Systems 101 http://c34.org/bbs/index.php/topic,5977.0.html


*************
*************


As far as your systems and loads based on what you wrote:
You are WOEFULLY undersized in your battery bank capacity. Do an Energy Budget and you will soon find that your meager 225ah bank only has a useful capacity of half of that and that your energy budget will most likely exceed 100ah per day, giving you only one night out on the hook.


Given the references provided, I'll let you take it from there.


All the best.

[GILow]

Originally Posted by Stu Jackson

…


As far as your systems and loads based on what you wrote:
You are WOEFULLY undersized in your battery bank capacity. Do an Energy Budget and you will soon find that your meager 225ah bank only has a useful capacity of half of that and that your energy budget will most likely exceed 100ah per day, giving you only one night out on the hook.

..

Stu, I agree the battery bank is small, but I’m not sure I’d assume it is woefully undersized. The only item that concerned me on the list was the Norcold fridge and, depending on the model and climate, that may only require 20 - 30 amp hours per day.

But everything else, particularly the mainesail references I agree with fully.

[GILow]

Originally Posted by Dockhead

It's really pleasant to argue with you


Beer is on me if we ever find ourselves in the same harbor.


If you are using solar, then you need the new Balmar monitor in my opinion.



My job is a lot easier because I don't have any solar (windage, and in my cruising area, I need to go hundreds of miles upwind on regular basis), and I have a heavy duty low speed almost silent generator which I can fire up at any moment when power is short or the batts are getting low.


Your use case is different, and I think you want the Balmar thing.

Beer plan is locked and loaded.

Off to learn about that Balmar. [emoji106]

[sesmith]

I do think it's reasonable to just monitor voltage on a simple marine system that has enough charging for every day needs, though you get a much better picture and insurance with a dedicated monitor.

Contrary to a previous post, I've been quite happy with my Victron Smart Shunt that I use on my off-grid cabin. It is not a simple coulomb counter. It looks at the charge voltage and once that is reached, looks at the tail current over time to determine when the charge hits 100%. Then it resets to 100% and counts down from there. Since all the parameters are input during setup, any setup parameters that are wrong will throw it off. Victron has a video worth watching if you are planning on using the shunt on a solar system. There are some settings that need to be tweaked for solar that aren't obvious from the manual, if I remember right.

[sesmith]

Just to add to my post above (as some of my memory returns). If you follow the standard setup, and the shunt is expecting a steady charging source all is fine. However, if the charging source is solar at least one issue can show up. As the battery bank becomes close to being charged the shunt is watching tail current for a set period of time. Now, if a cloud bank rolls over, the shunt will wrongly decide the bank is at 100%. I do remember making some adjustments to thre tail current settings and possibly the charge voltage setting for this (probably had to enable expert mode to set them). There may be some other tweaks as well but they covered it in the video.

[rslifkin]

I haven't had issues with the Victron battery monitor showing full prematurely with solar. I set the target for a sync to 100% at a tail current of 0.5% and a voltage just a little below float voltage (I think it's set to 13.3 volts). Time required is 10 minutes.

If the solar output drops below the 0.5% threshold (about 2.1 amps in my setup) and the batteries aren't very close to full, the voltage will fall below the threshold in less than 10 minutes. With my setup dropping to float at 4 amps (just under 1%) at absorb voltage, I find the meter usually syncs to 100% about 20 - 30 minutes after the charger or solar has dropped to float. Estimated SOC prior to the 100% sync is typically at least 99%.

[sesmith]

Here are the notes I made from their video and how set mine up. Note that this is on a 24 V system so any voltage settings would be half my value for a 12 v system

Set charged voltage .4V (on 24 V system) below absorption voltage of charger (for solar charging), set efficiency to 80-85% if use is at top end (if never goes less than 80% state of charge, set it to 75-80%), peukert const. 1.29 (fla duracell gc2), check tail current when charger goes to float....wait 10 min and check charging current. That is the float current...tail current is slightly higher than this, set delay to 3-5 min, set tail current to 5-6% for solar charging