Interesting discovery while topping off water in house batteries

[Neal]

Hmmm, the magnum only controls the inverter which connects to house batteries. I'm not sure how it's related to chassis battery charging. However, is it really bad to also equalize the chassis batteries? May be a good thing in disguise. What may be "cooking" your chassis batteries is a known issue which is the solar panel for the chassis batteries has no controller and some have noted the overcharge conditions it causes. @redbaron I think was the first to raise this issue. I tend to equalize at night when demands are lower in the CG and on my rig, not in the heat of the day.

 

[Rich W.]

The little (10w?) chassis battery solar panel is long gone. Over-charging my chassis batteries has never occurred before and only happened when I initiated the hoise battery equalizing. It may not be a bad thing, but it‘s unnecessary and seems like it has to stress the batteries. Why the inverter/charger is “equalizing” both is a mystery to me to, but it can’t happen with the chassis batteries off, so until I figure it out or determine that is ok that’s going to be my approach.

 

[Joe Hogan]

In many new RVs they have a Bi-Directional Relay that allows current to charge the chassis battery from the house battery charging circuit. Hence the term Bi in the name

“
00-00362-100

Intellitec’s Bi-Directional Isolator Relay Delay (BIRD) offers a new approach to charging batteries in an RV application. Unlike prior systems that only allowed charging the RV battery from the engine’s alternator, the Bi-Directional Isolator Relay Delay charges both batteries when either one is being charged. When the coach is being driven, both batteries will be charged from the engine’s alternator. When the coach is plugged into shore power, both batteries will be charged from the converter. If neither battery is being charged, the batteries are fully isolated. The controller also senses heavy loads on either battery to prevent the wrong battery from being inadvertently discharged.”

 

[Rich W.]

In many new RVs they have a Bi-Directional Relay that allows current to charge the chassis battery from the house battery charging circuit. Jensen the term Bi in the name

“
00-00362-100

Intellitec’s Bi-Directional Isolator Relay Delay (BIRD) offers a new approach to charging batteries in an RV application. Unlike prior systems that only allowed charging the RV battery from the engine’s alternator, the Bi-Directional Isolator Relay Delay charges both batteries when either one is being charged. When the coach is being driven, both batteries will be charged from the engine’s alternator. When the coach is plugged into shore power, both batteries will be charged from the converter. If neither battery is being charged, the batteries are fully isolated. The controller also senses heavy loads on either battery to prevent the wrong battery from being inadvertently discharged.”

Yes I believe this to be the case. When charging, all batteries get power. When using the house batteries with shore power not connected, the chassis batteries are isolated. So to prevent 15.5v from over charging my chassis batts while equalizing the house bank, I turned off the chassis batts. The things you learn here…... The chassis batts are at 12.6v at rest - 100%; condition of the house bank remains to be seen. Guess I’ll know in a couple hours.

 

[Neal]

Not convinced but still ears wide open. We have to dissimilar battery banks, completely different batteries in each area, who and how is the charge current being controlled to ensure it's appropriate for the type and size of the battery bank?

 

[Rich W.]

Well two 12’s in parallel for the chassis, or three groups of two 6s in series for house, they’re still both 12v battery banks of LA batteries and it would seem the same bulk, absorb, and float voltages would apply, with amperage determining how long it takes to charge each bank. How that magic happens to me is a bit of a mystery beyond my assumption that it’s all regulated by various electronic adjuncts - BIM, BIRD, relays, ….etc. Right? I guess I should be more up to speed on this but as long as its all working, I have other things to concentrate on.

 

[Kevin D Pem]

Well two 12’s in parallel for the chassis, or three groups of two 6s in series for house, they’re still both 12v battery banks of LA batteries and it would seem the same bulk, absorb, and float voltages would apply, with amperage determining how long it takes to charge each bank. How that magic happens to me is a bit of a mystery beyond my assumption that it’s all regulated by various electronic adjuncts - BIM, BIRD, relays, ….etc. Right? I guess I should be more up to speed on this but as long as its all working, I have other things to concentrate on.

So your saying that ahr is programmed for the two banks separately?

 

[Kevin D Pem]

So your saying that ahr is programmed for the two banks separately?

Or are you saying it is a time thing and capacity is not an issue?

 

[Rich W.]

Or are you saying it is a time thing and capacity is not an issue?

not sure I understand the question(s), but I am surmising that the chassis batteries hit their eq charge of 15.5 first (rather quickly actually) because there are just two of them and they are fairly new - less than a year old. At that point I shut them off (started worrying about them), and let the house bank “equalize”. That took several more hours. Once everything was at rest both sets showed 100%, so life is good.

so….charging/equalizing is/was a time thing, and capacity is good (100%) so not an issue? I’m a little slow sometimes, so if I still don’t get it, just let me know.

 

[Joe Hogan]

Here is some useful data on Equalizing. (as I quietly mumble thank god for LiFePo)

RV Tech Library - Equalizing Batteries

BU-404: What is Equalizing Charge?

BU meta description needed...

batteryuniversity.com