Community Forums

Jim_L · 03-25-2016, 10:09 AM

After an evening of charging (full hookups) my coach batteries are fully charged. After a full day of traveling the following day, I find that when I hook up the 50amp again that the batteries go to bulk charge which is surprising since we had little 110v or 12v usage while on the road. Whereas it doesn't stay on bulk for many hours, it does go through the charging cycle and eventually reaching float. It is surprising since I would have thought that the alternator would have kept the batteries charged while traveling. Has anyone experienced the same or should I be looking at the BIM (or BIRD) to see if it is operating correctly. Any input would be appreciated.

dennis45 · 03-25-2016, 10:17 AM

Is this a New to You coach? Or, is this something that just developed?
Usually a sign of overcharging is excessive off gassing of the batteries. Have you noticed having to add water more often? More than usual corrosion of the battery terminals?
What is the charge rate when the converter goes into float?

twinboat · 03-25-2016, 10:17 AM

A test of the BIM or BIRD.

Start engine, let run for 10 minutes.

Check volts at each battery. Should be the same. 13.5 or so.

If chassis battery voltage is higher then house voltage, BIRD or BIM not working.

GaryKD · 03-25-2016, 12:55 PM

Hi Jim_L,
This can get complicated (more complicated than it needs to be). A BIRD, BIM or CB connects and isolates coach and chassis batteries. Because you have a 14 model year coach, gut feel says you have a BIM or CB. It is important to understand which system you have and how it works. twinboat's post works for a BIRD system. It does not always work for a BIM system as the batteries may be connected or isolated depending on what the BIM senses. I have not researched the CB. Definitions of these acronyms are:

The battery bank is controlled by the coach charging system, which consists of a charge bridge solenoid, a bi-directional isolator relay delay (BIRD), or a battery isolation manager (BIM). When the coach engine is running, the alternator charges the chassis batteries and may assist in charging the house batteries through the BIM, BIRD, or Charge Bridge. When the coach is connected to shore power or when the coach generator is in use (when shore power is unavailable), the converter or inverter/converter combination recharges the house batteries, and with the assistance of a BIM, BIRD, or Charge Bridge, it can also charge the chassis batteries. In addition to the alternator and converter, the coach may also be equipped with solar panels to provide an additional option for charging your house batteries.

The above paragraph is from Newmar's Newgle site.

The Charge Bridge is contained inside the Silverleaf system. If your coach does not have Silverleaf then the BIM is what you have. If your coach has the Silverleaf system, the Silverleaf owner's manual will contain how it works.

The BIM works as follows:
The Battery Isolation Manager (BIM) monitors the Battery Voltage of both the Chassis and Coach Batteries over long periods of time. If it senses a charging voltage, it connects the two battery banks together. If the charging system is drastically overburdened, the batteries will be isolated, however, if the BIM sees a long term charging of both batteries it will allow the batteries to remain connected and allow the charging system to do its job. Once the batteries have reached a Float Charge state for one hour, the BIM will isolate the batteries to prevent overcharging, and will only reconnect the batteries for charging if one of the Battery drops to approximately 80% charge, and the other is being charged. If the batteries are not being charged, BIM isolates the two batteries to prevent an electrical draw in one system from depleting the other battery. The BIM is an improvement over the BIRD because it will isolate the batteries to prevent overcharging.

Jim_L · 03-26-2016, 07:23 AM

GaryKD, great info...thanks. I have the BIM system. When I return to the coach, I believe discharging the coach batteries a little and the starting the engine for a few minutes will provide an opportunity to see if the chassis batteries are receiving a charge. I'll plan to compare the charge rate of the chassis batteries compared to the coach batteries as twin boat suggests.

Has anyone with a similar coach noticed going to bulk charge after a long trip?

GaryKD · 03-26-2016, 07:29 AM

Hi Jim_L,
Please remember this part of my post:
"twinboat's post works for a BIRD system. It does not always work for a BIM system as the batteries may be connected or isolated depending on what the BIM senses."

Don't need to have you going off on a wild goose chase.

HHIDan · 03-26-2016, 07:47 AM

I suppose the battery charger has no way of knowing the state of your batteries after a drive, so it starts the cycle to eventually end up floating. The bulk and absorb don't last for very long so I would see no harm done.
Another device which you may have in a 2014 is a battery monitoring kit (Magnum BMK) where the SOC (state of charge) is constantly monitored and that would affect the operation of your charger.
See:
http://www.magnum-dimensions.com/sit...v-A-ME-BMK.pdf

Jim_L · 03-26-2016, 08:13 AM

GaryKD, agree. Was thinking that by deleting some of the charge and perhaps creating a draw by using a tv, the BIM should recognize the need in the coach batteries and begin a charge which should be identified by checking voltage. Not sure if I would be chasing my tail or not.

Actually wondering if what HHiDan describes occurs on other similar coaches therefore wondering if others observe similar behavior. What he describes makes sense.

We boondock and sense that the batteries may not be fully charged when we stop after seeing "bulk" charging when turning on the generator. Wondering if others have noticed the same.

andyh · 03-26-2016, 08:40 AM

The charge mode when you connect to AC is controlled by the Magnum Inverter/ Charger.
Once the Magnum senses AC power, the charge mode begins. The charge mode depends on the battery voltage.. If the voltage is 12.8 V or less, it begins Bulk charging, if it is higher then it goes to Float. When you shut them engine off, there is no charging ( unless you have solar panels on the house batteries) and the fully charged battery voltage will drop to 12.6-12.8V so the inverter will start in Bulk.
Your system is operating as designed, no need to worry.

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