AGM batteries?

sometimes truck makers install water heater only, it heats enging but coolant flows throught the heater core

 

I had been using 4 AGM Group 31 Batteries, w/1200 CCA. (During the winter mos. i'll use a multi grade 5wt Synthetic Motor Oil. I believe the lower grade motor oil has a big impact on cold starts during subzero temps.) They start my truck cold @-20 degrees Fahrenheit. the bunk heater is an espar unit. Typically, i'll run my bunk heater 10-12 hours per day. Alternator is 160 amps. with very few electronics on board my truck. (inverter is used to recharge laptop while truck is running down the road.) In the past, my trucks Volt meter will begin showing low voltage. Additionally, the espar unit will shut off prematurely due to low voltage. After Upgrading to the Maxwell Ultra Capacitor (which replaces one AGM battery), my truck no longer has low voltage issues & the espar unit will run continuously without turning off due to low voltage.

 

im using the Espar D2, (i have a freightliner Columbia Condo), Originally, i had concerns since this is the smallest unit by Espar, but the Thermo King Dealer/installer stated they tested it out on a truck @ -10 degrees fahrenheit & it kept the truck warm. I run primarily between Michigan & New England. Last year, during the polar vortex w/-20 degrees in Ohio, truck was turned off & i was impressed by the Espar D2 units performance. (ESM + 3 AGM Group 31 batteries)

 

ESM for $950 including free ground shipping:

http://www.rvcams.com/merchant2/mer...oduct_Code=ESM123000-31&Category_Code=Trucker

 

i would hold off on the battery exchange, i would think they should work just fine, i would take the wait & see approach; Installing an ESM has more costs, Rewiring the starting system. Only the ESM can be wired to the engine starter. Freightliner had originally wired the Alternator to the starter using a 6 gauge cable on my system....whereas the alternator had to be rewired directly to the 3 AGM batteries. If, your truck has some age, at this time, you may want to upgrade your positive/ground wires running this system. Wires are described by either one of two terms: Gauge or AWG (their numbers describing thickness will have opposite meanings, heavy wire will become thin wire). Originally, freightliner installed an alternator wire that was a 6 gauge. When i rewired i used a 2 gauge. Kenworth dealer did the work & they recommended the heavier gauge cable. Other costs, when i was pricing the bunk heater Espar is being sold by Thermo King Dealers, i found a $400 price variance. My total cost for the purchase of espar and installation was a flat $1,200.

 

Contrary to what people have posted bunk heaters like Espar and others use a lot of juice. The Espar will also shut off when voltage falls below a certain threshold. Draining those batteries and charging them can only last for so long. As time goes on instead of running for 6 hours it will fall to 5 then 4 then useless. My experience has been about 10 months and they have nothing left.

The Espar will use anywhere from .67 to 2.8 amps.