Battery Charging Problem ***UPDATE***

[whizbang]

While dry camping in freezing weather, the charging system died for the dual type 24 house batteries (2002 Winnebago Mini).

It appears to be a solenoid system. It failed two years ago and the RV shop ran a new replacement wire "to tell it to charge".

I am going to fix it myself this time. (I am a ham radio operator and licensed general contractor, Tinkering are us). However, I have zero expertise in automotive charging systems.

My inclination too, is to remove the solenoid system and run a battery isolator instead. I had an isolator in my F350 twenty years ago and it worked great.

Comments or suggestions? I have no clue where to start, other than doing lots of homework...

[LOG]

pianotuna wrote:
Log,

Your needs are met by your system. Mine are different, so of course, my recommendation to others is different than yours.

My intent was not to upset you. I'm sorry if our verbal exchange did so.

I am not upset. But I do question if you are intellectually dishonest.

You recommend a DC to DC battery charger. But you do not use one.

You question how I can determine battery state of charge without a hydrometer. But your system cannot be tested with one.

ETc, Etc, Etc.

You give your motorhome as an example of a system that does not fully charge the house bank. But you do not use a DC to Dc charger.

Go figure?

[pianotuna]

Log,

Your needs are met by your system. Mine are different, so of course, my recommendation to others is different than yours.

My intent was not to upset you. I'm sorry if our verbal exchange did so.

[pianotuna]

Brett,

If you have an external adjustable regulator, you would not need a dc to DC voltage boosting device.

But since they are under $20 bucks, and are easier to add than the external regulator, I would go that route.

[wolfe10]

LOG wrote:

wolfe10 wrote:
OK, how about a TIME OUT.

If you want/think you need smart charging from your alternator, you will need an alternator with external regulator.

Then buy a smart regulator-- we have had one to control the sailboat's 120 amp alternator for a decade.

NEXT.

Thank you.

Now please address the need for a DC to Dc battery charger in a Class C Motorhome. The reason for this discussion.

A response from a recognized expert is more than welcomed.

This is my last post in this thread.

If you have a regulator that controls alternator output, why would you need a DC-DC converter?

[LOG]

wolfe10 wrote:
OK, how about a TIME OUT.

If you want/think you need smart charging from your alternator, you will need an alternator with external regulator.

Then buy a smart regulator-- we have had one to control the sailboat's 120 amp alternator for a decade.

NEXT.

Thank you.

Now please address the need for a DC to Dc battery charger in a Class C Motorhome. The reason for this discussion.

A response from a recognized expert is more than welcomed.

This is my last post in this thread.

[wolfe10]

OK, how about a TIME OUT.

If you want/think you need smart charging from your alternator, you will need an alternator with external regulator.

Then buy a smart regulator-- we have had one to control the sailboat's 120 amp alternator for a decade.

NEXT.

[LOG]

pianotuna wrote:

LOG wrote:


You have really gone beyond the need for a DC to DC battery charger.

Log,

Most of the charging is done via solar.

When I am on shore power, I use a Magnum inverter charger with temperature compensation. The remote for the Magnum allows me to adjust charging voltages to meet my needs.

Any charging I get while traveling is incidental. It would not be adequate to my needs.

If I intended to fully charge while driving, I would get a dc to DC device. They are far cheaper than an isolation device. Then I could easily meet Trojan's suggestion of 14.8 volts to fully charge one of their lead acid jars.

Somehow I get the impression that your Magnum charger and your system is OK and you have fully charged batteries, but my charger and my way of determining full charge is inadequate or wrong.

Why is that?

[pianotuna]

Log,

I covered that earlier in the thread. When demand from the bank reaches 0.5 amps per 100 amp-hours of capacity, many AGM batteries are full. It my case that works out to approximately 2.9 amps.

I recently stopped being full time. So the solar system (blue sky MPPT controller with temperature compensation) will show 0.0 amps of charging after a week or so.

My choice of device would probably be a "smart gauge", which is the only charging system I'm aware of that adapts to the real capacity of the battery bank.

As I've only had 3 sets of batteries since I started RV'ing, I'm not likely to get more technology.

But in 2009 dc to DC charging devices were an arm and a leg and your first born child as far as cost goes. So I stayed "old school" with low and slow charging.

I love the Solar and it has paid for itself many times over.

[LOG]

pianotuna wrote:
Log,

Voltage may be the least accurate method to check state of charge. I suggest verifying the charge level a few times using a temperature compensated hydrometer. You may be surprised at of "real" state of charge where the battery charger goes into float mode.

How do you determine state of charge with your AGM batteries?

Not by some electronic tester I would suspect?

[pianotuna]

LOG wrote:


You have really gone beyond the need for a DC to DC battery charger.

Log,

Most of the charging is done via solar.

When I am on shore power, I use a Magnum inverter charger with temperature compensation. The remote for the Magnum allows me to adjust charging voltages to meet my needs.

Any charging I get while traveling is incidental. It would not be adequate to my needs.

If I intended to fully charge while driving, I would get a dc to DC device. They are far cheaper than an isolation device. Then I could easily meet Trojan's suggestion of 14.8 volts to fully charge one of their lead acid jars.

[LOG]

pianotuna wrote:
Log,

I'm glad your system works well for your needs.


It takes a great deal of time for a battery bank to become full. At 85% state of charge, the acceptance rate is a mere 15 amps per 100 amp hours of capacity. The closer the battery bank is to full the slower the charging rate.

Sulphated batteries behave by showing they are fully charged by voltage, shortly after being connected to a charger.

Most "smart" chargers fail to drive a battery 100% state of charge. Getting to truly 100% requires "dancing on the needles", especially if voltage is the only parameter being used.

You have really gone beyond the need for a DC to DC battery charger.

[LOG]

pianotuna wrote:
Log,

Voltage may be the least accurate method to check state of charge. I suggest verifying the charge level a few times using a temperature compensated hydrometer. You may be surprised at of "real" state of charge where the battery charger goes into float mode.

By the way, how is that hydrometer working out with your AGM batteries?

[pianotuna]

Log,

I'm glad your system works well for your needs.


It takes a great deal of time for a battery bank to become full. At 85% state of charge, the acceptance rate is a mere 15 amps per 100 amp hours of capacity. The closer the battery bank is to full the slower the charging rate.

Sulphated batteries behave by showing they are fully charged by voltage, shortly after being connected to a charger.

Most "smart" chargers fail to drive a battery 100% state of charge. Getting to truly 100% requires "dancing on the needles", especially if voltage is the only parameter being used.

[LOG]

pianotuna wrote:
Log,

Voltage may be the least accurate method to check state of charge. I suggest verifying the charge level a few times using a temperature compensated hydrometer. You may be surprised at of "real" state of charge where the battery charger goes into float mode.

My battery tester, a state of the art micro-load electronic tester, shows voltage, state of charge, amp hours, cca, marine cca, percent of amp hours, etc.

It is the same one use by auto/rv shops around the US.

I recommend that you research micro-load battery testers.

[LOG]

pianotuna wrote:
Log,

Voltage may be the least accurate method to check state of charge. I suggest verifying the charge level a few times using a temperature compensated hydrometer. You may be surprised at of "real" state of charge where the battery charger goes into float mode.

I believe voltage is close enough for this discussion

The issue here is whether or not a motorhome with a "smart" charging system fully charges the batteries with the engine alternator. And if they require a DC to DC battery charger as advocated by you and THEOLDWIZARD1.

The answer is they obviously don't.

The fact that your highly modified motorhome may require one in no way shows that the average motorhome requires one.

After a day of driving, even if the batteries were slightly lower than fully charged, shore power or generator would almost immediately restore them to fully charge (measured by any method).

This high tech talk you are exposes means nothing to the regular motorhome owner. And, the suggestion that they should add an expensive, unnecessary piece of equipment as a DC to DC battery charger is ill advised.