OEM battery question

[creativepart]

Ed, I do see an alternator issue with LiPo batteries. Not too much charging but too much draw on the alternator. Less charging resitance in the battery potentially damaging the alternator. The dc to dc charger protects the alternator NOT the battery.

But at this point I'm not with you on the FLA or AGM batteries. Ford uses AGM batteries in the vast majority or all of it's models and has done so for no doubt 8 to 10 years. I've had Fords and Lincolns since 2006 and every one had an AGM battery from the factory.

It's an interesting theory. I don't doubt that installing some dc to dc charge is not a problem and not hurting anything. But at this point, until I see some other corroboration I can only presume it's totally unnecessary.

Winnebago may not be be ball on about every possible problem, but I think this is a fairly basic engineering design issue that when working on the Ford Transit chassis integration that they would not have missed.

One more thing. An overcharged battery doesn't just off gas... it swells and bulges. And this is not an issue.

[AJMike]

Originally Posted by CoastalEd

3) Mike, it is apparent to me that you are not up to speed on battery technology and charging.

Well, that is certainly true. It is an issue I have never paid much attention to. As with other things in an RV it is this forum and the posts that raised the question and has become the reason for learning about these issues.

Originally Posted by CoastalEd

In my opinion, the 'regulation' in the Ford Smart Charge alternator system was designed to work with the Ford AGM battery under the driver's seat. The addition of a substantially larger capacity house battery system is screwing up the Smart Alternator system to where it never sees reaching a full charge so that it can drop down to float level (~13.5)

If the house batteries are AGMs then they have the same voltage as the coach AGM and I don't see why the alternator would never see a full charge and drop back to float value.

If the house batteries are Lithium, then I would think that wiring a DC-DC charger to a manual switch would completely fix the problem. If the switch is off, then the house batteries are no longer even in the system and all that the alternator sees is the coach battery. If the switch is on, then the alternator will not see a full charge, but if it is only left on for a minimal amount of time then switching it off would, I would think, solve the problem. If this is not so, why is it not so? I am not trying to be argumentative. I just don't understand.

Originally Posted by CoastalEd

Please, Mike, take a look here for some trusted and reliable battery information. I would suggest you pay particular attention to the paragraphs directly below Table 2 .
https://batteryuniversity.com/learn/...d_acid_battery

I did, and noticed the following information:

Once fully charged through saturation, the battery should not dwell at the topping voltage for more than 48 hours and must be reduced to the float voltage level. This is especially critical for sealed systems because they are less tolerant to overcharge than the flooded type. Charging beyond the specified limits turns redundant energy into heat and the battery begins to gas.

This refers to a 48 hour window but no one is running the engine for that long so I guess I am missing why this is a concern. If the issue is the house batteries, then stopping allows the switch over to the solar system which will apply the proper voltage, bulk or float, as appropriate. If the issue is the coach battery then I would think that the voltage would drop back down when the engine is off.

What am I missing here?

[CoastalEd]

Originally Posted by AJMike

Well, that is certainly true. It is an issue I have never paid much attention to. As with other things in an RV it is this forum and the posts that raised the question and has become the reason for learning about these issues.



If the house batteries are AGMs then they have the same voltage as the coach AGM and I don't see why the alternator would never see a full charge and drop back to float value.

If the house batteries are Lithium, then I would think that wiring a DC-DC charger to a manual switch would completely fix the problem. If the switch is off, then the house batteries are no longer even in the system and all that the alternator sees is the coach battery. If the switch is on, then the alternator will not see a full charge, but if it is only left on for a minimal amount of time then switching it off would, I would think, solve the problem. If this is not so, why is it not so? I am not trying to be argumentative. I just don't understand.



I did, and noticed the following information:

Once fully charged through saturation, the battery should not dwell at the topping voltage for more than 48 hours and must be reduced to the float voltage level. This is especially critical for sealed systems because they are less tolerant to overcharge than the flooded type. Charging beyond the specified limits turns redundant energy into heat and the battery begins to gas.

This refers to a 48 hour window but no one is running the engine for that long so I guess I am missing why this is a concern. If the issue is the house batteries, then stopping allows the switch over to the solar system which will apply the proper voltage, bulk or float, as appropriate. If the issue is the coach battery then I would think that the voltage would drop back down when the engine is off.

What am I missing here?

What you are missing, or as I see it misinterpreting, is that 48 hour comment. That is applied to the occasional overcharge condition of an AGM battery. Regular almost daily overcharge of many hours is not doing much damage each day or week, but over a few years of constantly overheating and off-gassing small amounts does add up. As I previously mentioned, you cannot replace lost electrolyte once it is gone from an AGM battery .... in my opinion, you may lose an extra year or two that you might have gotten out of a properly maintained AGM battery. They should last several years with proper treatment. LET ME BE CLEAR ON THIS - I am not advocating that you are doing drastic damage to batteries with the Ford alternator overcharging on long trips. I am advocating a small but measurable loss of lifetime you would have gotten out of the batteries ... and this applies to the Ford chassis AGM battery, too.


Also, I have not addressed any Lithium battery issue at all because I have not worked with them in my career enough to offer what I consider expert opinion. Most of what you have mentioned seems accurate .... yes, a DC-DC converter is almost a necessity to charge the Lithium battery from the alternator. ... given that Lithium batteries can absorb a much more rapid charge current, I think that this may be true.... but the DC-DC converter also protects the Lithium batteries. Their charging requirements are much different than the charge requirements of SLA batteries and as such, they require a charger that has a charging program taylored to Lithium..... most RV battery chargers are not, and vehicle alternators certainly are not, also.


One last comment - you mentioned a switch to disable alternator charging. I did mention this many posts ago. It is what I and several other Fuse owners have done....and it is a very easy and successful project. One simple SPST switch installed on the removable panel in the doorstep area of a Winnebago Fuse 23A.... it disables the large Solenoid relay behind that panel thus preventing the alternator from charging house batteries.