Battery charging question. Magnum 2812 inverter

[Navionflyer]

We recently purchased a 2009 Newmar Essex. I'm changing the old lead acid batteries over to Lifeline AGM batteries. I was planning on leaving the chassis batteries as lead acid batteries. I understand that I need to set the inverter to type 1 in order to properly charge the new AGM batteries. However, in doing so will this over charge my lead acid chassis batteries? In other words if you have AGM batteries for the house, do you have to have AGM batteries for the chassis? Thank you in advance. C a r y

[redbaron73]

No, this will not harm your chassis batteries. The BIM will only cross connect once you enter into a float charge, not during the bulk operation.

[Smitty77]

While minor, the AGM1 setting on older MS2812's, does not provide the Float Charge that Lifeline now recommends. So you might as well go ahead and set up a Custom Profile on you MS2812. It was Feb, 2017 Rev E, that slightly increased the Float Value recommended voltage.

https://2cw8eb1vmmgg3g5i7jzt6upo-wpe...al-5-06-19.pdf

And I agree with redbarron73 - the Chassis battery should be fine!

Best to you,
Smitty

[twinboat]

Agree that the chassis battery will be fine but most Bi-directional charging systems combine the 2 battery banks based on voltage only.

They sense 13.4 volts and combine. That can happen in bulk, absorb or float mode of the charger.

The " BIM ", a brand name of a battery combiner, has a routine built in that actually manages the batteries.

The 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 batteries 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 charged for one hour, the

BIM will isolate the batteries to prevent overcharging, and will only reconnect the batteries

for charging if one of the batteries drops to approximately 80% charge, and the other is being

charged. This long term monitoring of the batteries prevents the annoying relay clicking that

exists in simpler isolation modules today. The BIM does not guarantee 100% battery charge,

but prevents harmful battery charge levels.

[lwmcguire]

Originally Posted by twinboat

Agree that the chassis battery will be fine but most Bi-directional charging systems combine the 2 battery banks based on voltage only.

They sense 13.4 volts and combine. That can happen in bulk, absorb or float mode of the charger.

The " BIM ", a brand name of a battery combiner, has a routine built in that actually manages the batteries.

The 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 batteries 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 charged for one hour, the

BIM will isolate the batteries to prevent overcharging, and will only reconnect the batteries

for charging if one of the batteries drops to approximately 80% charge, and the other is being

charged. This long term monitoring of the batteries prevents the annoying relay clicking that

exists in simpler isolation modules today. The BIM does not guarantee 100% battery charge,

but prevents harmful battery charge levels.

Excellent description

[757driver]

Originally Posted by Navionflyer

We recently purchased a 2009 Newmar Essex. I'm changing the old lead acid batteries over to Lifeline AGM batteries. I was planning on leaving the chassis batteries as lead acid batteries. I understand that I need to set the inverter to type 1 in order to properly charge the new AGM batteries. However, in doing so will this over charge my lead acid chassis batteries? In other words if you have AGM batteries for the house, do you have to have AGM batteries for the chassis? Thank you in advance. C a r y

In terms of settings AGM1 profile is not correct for Lifeline AGM batteries, Magnum has not kept up with the times. Use Custom. Change final charge setting from Multi to Float otherwise your batteries will not keep a complete charge. Depending on your battery bank size (anything greater than 400AH) up your charge rate to 90-100%. Your chassis batteries will be fine with the AGM batteries.