Time to replace the coach batteries - Again

icarus

Well-known member
I ordered the Victron 700 this morning. I will install it on Tuesday. I am heading on another trip Wednesday morning.

Thanks again


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Make sure you get them FULLY charged before you configure the Victron. (Read up on Bulk/absorb/float charge on them FAQs, make sure they are in float before you config.

Icarus
 

kylecm

Member
I agree with previous posts. Going to AGM batteries will just make your problem more expensive.
You need to find out why they are not lasting and educate yourself on battery maintenance. A good $100, 220 AH, wet cell deep Cycle battery should last for at least five to six years with simple maintenance. The link below will give you some good bedtime reading on the subject.

https://rvingwithmarkpolk.com/2016/09/21/polks-top-10-rv-battery-tips/

Letting them run dry is one sure way to ruin them. I use an old Ketchup Bottle and a piece of clear tubing to add water to mine. I have a photo of mine but this site is not very conducive to adding photos.
Anyway, it's pretty simple, just take an old plastic Ketchup Bottle (the one that stands upside down). Drill out the hole in the lid to 1/4" and insert a 1/4" clear plastic tube so it reaches the bottom of the bottle and extends 18-20". Fill with Distilled Water, squeeze the bottle to add water to each cell.
Thanks for the link. I definitely need to do some more studying.

Chuck
 

kylecm

Member
My guess is that you have two things going on. First, the phantom loads on the battery while parked will kill a battery pretty quickly. A positive battery disconnect is a good idea. Even a cheap battery isolator relay can draw as much as .5 amps (or more) 24/7, a big cumulative draw.

I also suggest that you are probably parking your vehicle with the batteries not fully charged, which as suggested in the battery FAQs is a recipe for quick failure.

Icarus

PS Counter intuitvely, hot climates are harder on batteries than cold ones! In the cold, a battery’s capacity will diminish but it’s total live will be extended all things remaining equal. Hot temps, are hard on batteries in a number of ways. The fact that you are using water may not be because you are charging them enough (or too much) but simply may be do to hot cell temps leading to evaporation.
Icarus,

Thanks. I will add the following to my before it goes back to the storage facility.

1.) Monitor Battery charge on the Victron to fully charged (ordered on Saturday)
2.) Disconnect via coach main disconnect
3.) Disconnect battery via battery isolator (ordered it yesterday)
4.) Make sure the battery water levels are correct

I have been reading the FAQ and will have to figure out the proper way to charge the batteries. I am looking into a solar panel.

Again, I appreciate all the assistance. I am heading to my local auto shop to have my current batteries checked to see if they are actually bad.

Chuck
 

kylecm

Member
Follow up:

Took the RV to my local auto shop to have the batteries tested. The results of the test show both batteries needed to by replaced.

Next Steps:

1.) Replace batteries with the same Interstate SRM-27 ($125 each)
2.) Install Victron BMV-700
3.) Install Battery cut off switch
4.) Implement a maintenance check for the batteries

I am going to take a reading of the RV this morning after the new batteries are installed. I am going to shut off the coach disconnect and check it again in the morning (see if there is anything draining it). I will take another reading tomorrow morning and then Wednesday morning to compare.

Thanks for all the advice.

Chuck
 

kylecm

Member
Chuck, my coach batteries have been disconnected since 9/25/2017, just went out and checked them, voltage was 12.68 and 12.73 They are 2 year old Costco Interstate's.

When I don't use my coach for more than a month I disconnect both house and chassis batteries.

You should get a inexpensive clamp on amp meter such as
https://www.amazon.com/dp/B01C0IYLMM/ref=asc_df_B01C0IYLMM5359565/?tag=hyprod-20&creative=395033&creativeASIN=B01C0IYLMM&linkCode=df0&hvadid=216539147262&hvpos=1o2&hvnetw=g&hvrand=13260432446392043852&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9030261&hvtargid=pla-374110770394

to see and isolate what might be drawing down the batteries

and a battery hydrometer, either you have a bad cell(s) in one or both batteries, or your inverter is killing them. Could this be related to you floating neutral problem you had earlier?

Here are 2 handy charts I use

View attachment 93813

View attachment 93814
Steve,

Good hearing from you. How's Arizona???

I don't think the neutral open would cause the drain since it is on the 120v side. But I can't be sure.

Chuck
 

stevehar

2015 Thor Siesta 24SR
Steve,

Good hearing from you. How's Arizona???

I don't think the neutral open would cause the drain since it is on the 120v side. But I can't be sure.

Chuck
Hi Chuck Arizon is very warm,above avg temps all year good for bike riding though

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kylecm

Member
Good morning

I replaced the coach batteries with Interstate SRM-27. My coach has two. I am assuming that they since they are wired in parallel it should double the AH

I installed the Victron DMV-700. During the initial setup the default AH was 200. I have read all of the FAQs kinda understand the AH but cannot figure out what I should set the DMV-700 too. I cannot find an AH for the SRM-27. However the RC is 160 and I found a formula of AH=RC x 0.6. So my AH is 96? Since they are in parallel I guess the setting should be 192 AH.?.?

Charging. I read all the information on bulk, absorption, and float. If my RV charges while rolling down the road off of the alternator of the sprinter then I am assuming since it is charging at 13.7vdc then it is charging at float.

Sooo. How often is it necessary to go through all 3 phases of charging a battery? How would I physically do this?

I have not gotten the disconnect yet but as soon as I do I will add it to the battery

If anyone is interested in the DMV-700. Really cool device. Installation was not bad. Thor doesn’t give you much room in the battery box to reroute cables. Also the box is not sealed (probably because of batteries) so I had to modify a PVC box from HomeDeport to mount the shunt. But it looks clean so I am happy.

Well the RV is packed and I am on the road for the next week. Thanks for all the tips.

Chuck


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