Thought i'd bring this conversation over from the yahoo site...
Mike installed a battery tender and has a nice write up about it. and it spurred questions in my mind...
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Hi Mike,
I remember seeing someone's write up about some dip switches on the standard charger, and how to vary the output voltage my changing the dip switch positions. These switches are internal to the charger. I don't think they had any technical info on the charger, just the simple brochure that has been posted in the files. I believe they just experimented with changing switch positions and monitored output voltage. My memory is that they were boosting output since they had switched to AGM batteries, so they would have a quicker recharge.
Does anyone know what controls the charge voltage to the van batteries during driving?
I assume its the voltage regulator on the alternator,
but does it vary between the two battery systems, van and camper?
They would likely have different states of discharge.
How does it decide which to serve or optimize?
Thanks
David
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David:
I don't know the charge recipe of the onboard charger for charging the camper gel cells, and I didn't touch that part of the circuit on my camper. Mine has the original gel cells and they still seem to be performing well. The documentation someone put on the files section did show 10A charge current and 13.8V and mentioned temperature compensation which is why there is a thermisor on the battery.
I don't know how optimal the onboard charger is for AGM camper batteries. I understand the max. charge voltage for gel cells is lower than that of the AGMs. So if the onboard charger is set up for gel cells, it may not be able to get a 100% charge on AGMs, but I don't think it should hurt anything.
You are right about the alternator - when you start the vehicle and the isolation relay closes, the camper batteries get charged at a much higher rate than when plugged into AC. Driving is probably when the camper batteries really get topped off when you head out on a camping trip. So I wouldn't worry too much about the onboard camper battery charger.
The battery tender I installed is only for the van battery. Its maximum charge current is 5A. and it is optimized for non-gel type lead acid batteries.
Regards,
Mike
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On Thursday, September 11, 2014 11:25 AM, "512westy@... [sprinter_westfalia]" <sprinter_westfalia@yahoogroups.com> wrote:
I have questions concerning the battery charging.
I understand that the original equipment is designed to supply a constant low level charge (10amps)
Design intent being to provide slow charge to the original Exide Gel Batteries as they are very sensitive to over charging.
If one changes to AGM, as many of us have done, I understand the recharge time could be greatly reduced with a smart battery charger, with a 3 stage charging system, (high, med, float).
I believe the high output alternator can supply lots of amps,
what is the high output of the Battery Tender?
With the system described, are you letting the original charger continue to charge the camper batteries?
Would it be more efficient for us who have the AGM's to install a new modern multi-stage battery charger?
Very nice write up!!
Thanks
David
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File : /Battery_Tender_Installation.pdf
Uploaded by : jmfife <jmfife@...>
Description : Instructions for installing a battery tender to charge the van starter battery simultaneously with the camper batteries when plugged into AC or when the gen set is running.
You can access this file at the URL:
https://groups.yahoo.com/neo/groups/sprinter_westfalia/files/Battery_Tender_Installation.pdf
To learn more about file sharing for your group, please visit:
https://help.yahoo.com/kb/index?page=content&y=PROD_GRPS&locale=en_US&id=SLN15398
Regards,
jmfife