What to do with ECM voltage regulator when utilizing external voltage regulator ?
 

Hi Forum. I'm interested in installing some Lithium-iron-phosphate batteries to replace my original lead-acid batteries. Why Lithium you ask, who knows, perhaps because I'm strange...Towards that end, I need different voltage regulation that stock to protect the Lithium-iron-phosphate from overcharging. From other threads I understand that regulation happens in the ECM so is it possible to move regulation to outside the ECM or change the charging regimen that happens inside the ECM ?

Thanks, Sven

What's the difference in voltage regulation???

Let me try asking this question another way. From the wiring diagram of this truck it would seem that the ECM ( pin 7 ) is responsible for field control of alternator. ECM inputs include battery temperature, battery voltage. So what is the best way to disable this closed-loop. For example, removing battery voltage input on ECM means field is maximum and perhaps results in fault codes ? I suppose I could leave battery voltage to ECM connected and have field constantly changing trying to affect desired change, but perhaps this too will result in fault codes. Ideas ?

PWong, depends on cells/battery. In my case <14.5 for charge and 13.6 for float which is functionality available with a third-party voltage regulator.

Sven

Svenne,
You need to get out more. There is no way Li Ion batteries can replace lead acid in your truck. This is especially true in your neck of the woods. Li Ion cannot handle the temperature extremes your truck experiences. Please read more.

Steve-l,

I'll have to assume you are not talking about LFP batteries since you say "Li Ion". The addition of Phosphate changes the temperature characteristics tremendously. LiFePo4 are said to operate between -20C to 70C although one manufacturer I found is advertistising -45C to 85C. I'm going to guess 85C ( 185F ) covers the temp of CTD bay, but perhaps I'm wrong ?

Thanks for link PWong. From the link I've learned that external voltage regulator supposedly works on 3rd gen and this particular case had an strange behaving voltage gauge at instrument panel while external voltage regulator was being used.. Guessing the PCM outputs voltage to voltage gauge at instrument panel, but am unable to find wiring diagram for the gauge.

Sve

Hoping you will use Li-Ion batteries with built in protection from undervoltage/overvoltage charging. Without this smart battery technology very bad things can happen (especially if trying to charge a battery that is below it's minimum voltage threshold for charging).

Thanks MikeyB. All the batteries/cells I'm considering have BMS ( balance/monitoring system ) that ensure each cell is protected and balanced.

Svenne,
You are very wrong. I am talking about LiFePO4 batteries. I am speaking from experience.......very expensive experience. These batteries are no way close to operating in the same temperature range Lead Acid batteries do. LiFePO4 battery charge and discharge ability falls drastically below 10C. Both storage and use at these temperatures and lower will dramatically reduce the life of these batteries. I own a Segway. These LiFePO4 batteries are duel redundant 73 V, with 92 5.2 AH cells in each. They cost $1,000 each and must be exchanged in pairs. Each of these batteries have there own firmware controlled battery managers and built in battery chargers. These are top of the line, high tech batteries. Please educate yourself, read the directions of use. I can personally validate the advice in those directions. I store my Segway in heated temperature controlled space. Even so, using the Segway at 0C and colder will cause the Segway Computer to error off. At 5C, my available range will be reduced by 50%.