Battery Charging Problem ***UPDATE***

[whizbang]

While dry camping in freezing weather, the charging system died for the dual type 24 house batteries (2002 Winnebago Mini).

It appears to be a solenoid system. It failed two years ago and the RV shop ran a new replacement wire "to tell it to charge".

I am going to fix it myself this time. (I am a ham radio operator and licensed general contractor, Tinkering are us). However, I have zero expertise in automotive charging systems.

My inclination too, is to remove the solenoid system and run a battery isolator instead. I had an isolator in my F350 twenty years ago and it worked great.

Comments or suggestions? I have no clue where to start, other than doing lots of homework...

[theoldwizard1]

whizbang wrote:
It is a Ford E350 chassis.

It may or may not have a smart charging system. Ford phased it in over a period of years.

[theoldwizard1]

pianotuna wrote:
That is why a DC to DC voltage boosting device works better. You will still need a solenoid so that the starter battery is isolated from the house batteries when the engine is not running.

I have NEVER seen a DC-DC charger that will allow the house battery bank to send power back to the chassis battery without some kind of "bypass" being applied.

(FYI - A DC-DC charger actually first converts the incoming DC voltage to AC, runs it into a transformer (or some kind of inductor). The resultant AC is then converted back into DC. Current can not flow "backward" because DC current can not flow through a transformer/inductor.)

[theoldwizard1]

bobndot wrote:

theoldwizard1 wrote:
If you want to charge your house batteries while driving, you need a DC-DC battery charger.

This technology is all new to me. I didn't realize that I could add a DC to DC charger to the BIM (Battery Isolation Manager). I thought the BIM was doing that job.

Your BIM is a fairly simple device. It allow the vehicle charging system to send whatever voltage is available from the alternator/chassis battery to the house batteries when there is "adequate" voltage available (ie. the engine is running). It does not allow the house bank to send voltage to the starting battery unless you press the "emergency start switch".

With modern "smart" charging systems ADEQUATE IS NOT SUFFICIENT ! You will NEVER restore a proper, full charge to a house bank without a DC-DC battery charger.

A DC-DC charger takes the voltage available from the vehicle system (somewhere between about 11.5V and about 15V) and raises or lowers that voltage to the appropriate amount for the "stat of charge" of the house bank.

[whizbang]

It is a Ford E350 chassis.

Winnebago WF324V.

[pianotuna]

The EMC on the engine will "see" the starter battery voltage. It will drop the voltage down fairly quickly.

That is why a DC to DC voltage boosting device works better. You will still need a solenoid so that the starter battery is isolated from the house batteries when the engine is not running.

Starter battery-->solenoid-->dc to DC device-->house batteries.

Do not set the dc to DC unit output higher than 15.3 volts output.

[bobndot]

theoldwizard1 wrote:
If you want to charge your house batteries while driving, you need a DC-DC battery charger.

This technology is all new to me. I didn't realize that I could add a DC to DC charger to the BIM. I thought the BIM was doing that job.

Am I understanding things correctly ? What I have in my Smart system is a BIM, which is what I replaced because my coach batteries were not charging at all. It was a Precision Circuits Battery Isolation Manager 200amps.
I do have an emergency start switch on the drivers seat, when I hit that switch, I hear the solenoid click on, raising my coach battery volts. As soon as I release that switch, the volts drop back down to whatever it was .
This tells me the solenoid is working ok, or could it not be ?

While I'm driving, the coach batteries will accept a charge from the alternator when voltage drops low enough or if I'm driving with the furnace on, creating a draw on the coach batts.

By adding a DC to DC charger to the system I have will be a benefit because it will always put the coach batts in a charge mode to fully charge them. Using the BIM alone will only offer a part time charge and not fully charge the coach only to 80% .

#1- Am I understanding how this BIM system works and how adding the DC/DC will help ?

#2- Could I have NOT replaced the bad BIM and bypassed it to charge both battery banks to old way ? Or would I have damaged the system ?

[time2roll]

whizbang wrote:
While dry camping in freezing weather, the charging system died for the dual type 24 house batteries (2002 Winnebago Mini)..

May also want to review your converter model for better (faster) charging while the generator runs. Cold batteries like to get all the voltage they can get.

[pianotuna]

whizbang,

If you really wish to get a full charge on the house batteries, then add a DC to DC voltage boost device.

https://www.ebay.ca/itm/DC-DC-Converter-10-15-20A-150-250-300-400-1200W-Step-up-Boost-Step-down-Buc-... or similar.

If you wish to only maintain the house batteries then an Amp-L-Start wired from Engine to House will work if there is a manual switch to prevent the House from killing the starter batteries.

http://www.lslproducts.net/ALS_Overview_Page.html

If you wish to maintain the starter battery then use a Trik-L-Start.

If you wish to fix the OEM solenoid, replace it with a new one rated for 200 amps continuous.

Personally I'd go for the voltage boost device.

[theoldwizard1]

whizbang wrote:
This is a 2002 RV.

The existing system used to charge the house batteries. Until it failed, there was no problem. Driving down the highway keep us charged up.

Now, no charge with the engine running.

What chassis ? Ford stated installing smart charging on some vehicles before 2002.

Humor me. Check the voltage at the starting battery in the manner I recommended.

[theoldwizard1]

bobndot wrote:
I actually like the old way, it seems more simple without these sensitive digital electronic parts to breakdown. KISS is what I prefer and probably what I should have done, but I had to satisfy my curiosity.

The whole purpose for smart charging is to improve fuel economy AND IT DOES ! Not by much, but some.

Charging is controlled by algorithms (programs/strategies) inside the engine control computer. Some of these algorithms look at battery temperature or other special sensors. All of them are based on an assumption of the the size of the starting battery and the amount of energy used by the starter motor plus other information.

The voltage regulator inside of the alternator does the "heavy work" of controlling power to the field coil which is what controls the output voltage of the alternator.

Connecting your house batteries to a smart charging system will NOT TOP OFF YOUR HOUSE BATTERIES, but it will prevent them from going dead if you have DC loads turned on in back.

If you want to charge your house batteries while driving, you need a DC-DC battery charger.

[whizbang]

Gosh. It sounds like it will be easy enough to fix.

It occurs to me I have no idea where my fuse panel is....

I guess I have been lucky up til now.

[time2roll]

I would get an automatic relay (BIRD)

Example here - shop around

[bobndot]

This is a 2002 RV.

If I had read that in the first place I could saved myself the typing . :S :B


Well then, if you ever buy a new rv, just remember what we said 🙂

Drew got it right .

[DrewE]

The solenoid is a kind of battery isolator. The system is quite simple conceptually: there's a relay (the solenoid) that connects a wire between the two batteries when the engine is running. Often this is done simply by powering the solenoid from a run circuit on the vehicle, similar to other accessories like the windshield wipers. If you can find the solenoid (which is occasionally a bit hidden), it shouldnt' be too hard of a task to sort out where the fault is: whether the solenoid itself is bad, or a connection to it, or a wire or fuse or something similar.

[whizbang]

This is a 2002 RV.

The existing system used to charge the house batteries. Until it failed, there was no problem. Driving down the highway keep us charged up.

Now, no charge with the engine running.