Originally Posted by thomanddebbie
camaraderie, As a follow up to your suggestions. Completed a number of your suggestions and then I decided to charge the two batteries (in tandem) overnight with a typical 6 amp charger. That does not work as I found out from EBCO. For any newbee novice like me, "you can only charge one battery at a time with typical automotive battery charger." Again lesson learned....better to be at home messing up then stranded in the dessert boon-docking. However to my good check list .....one of the new batteries purchased in March 2016 was bad and they replaced and we seem to be up and ready to roll this weekend. Thank you to all who responded.
Glad to be of help. Good point on home chargers...also since they are single stage chargers...it is definitely a no no to leave batteries on them more than a night without checking state of charge and temperature.
There is NO problem using a home charger on 2 batteries if it is big enough but 6 amps ain't.
Don't know what group size you have but from small to large in 12V RV systems we typically see group 24, 27 and 31 which have 75 95 and 110 amp hours respectively (on average) .... a battery may be discharged to HALF of its amp hours before you start to damage it....so for each battery you have somewhere between 40 and 55 amps to put back in after discharge. A 6 amp charger will can put back in 6amphours in an hour when the battery is half full....much less as it nears full.
So using the 40 amp put back goal on the small battery...that means nearly 7 hours at FULL output to get to full battery ....but really translates into 14 hours or so due to the increased resistance when it gets up into the 80>90+% full range. So if you have two small batteries...that's 28 hours to get to full charge!
Thats a roundabout way of saying that ideally a charger should put out 20-25% of the RATED AMP HOURS of the battery bank for shortest charging times. So a 200 amp hour bank needs a 40-50 amp charger etc.
More amps can't be accepted by the battery but won't hurt...and less amps mean a longer wait. At a minimum 10% of capacity should be used.
This is why you had problems with 2 batteries and 6 amps!
Most of the current forest river class C & A models are coming with a 55amp 3 stage charger by comparison.
I'm glad you found the bad battery..it would have ruined your good one in short order.
If you plan on boondocking...think seriously about investing in a true battery monitor. If you stay plugged in at home and away...just a multimeter will be fine... with a $50 clamp on AC/DC one very handy.
All best & see ya out there!