My new motorhome'ssystem is this:Blue Sky 3000i solar controller. 2 - 115 watt pv panels.Parallax 8355 converter with 3 stage charging and TempAssure sensor.2 Lifeline AGM 6v batteries. Being a newbie to both solar and AGM I was wondering if this system will keep my AGM batteries topped off properly?I've heard that AGM batteries require a higher voltage to maintain a state of charge and don't want to damage them. I'll most likely leave it parked in the sun and unplugged when I'm home between trips.

You can look up the charge specs. Parked at home, yes they will stay charged. When camping, that depends on your usage.

Charging voltage varies depending on temperature. See your battery manual at page 19. I don’t recommend going by what you’ve heard. https://lifelinebatteries.com/wp-content/uploads/2015/12/6-0101F-Lifeline-Technical-Manual-Final-5-06-19.pdf

Good solar charge controllers come with a temperature “probe” to be placed near the batteries.

2oldman wrote:You can look up the charge specs. Parked at home, yes they will stay charged. When camping, that depends on your usage.I'm having a tough time finding the specs on the 3 stage Parallax charger.I installed a Progressive Dynamics converter on my previous motorhome and they very clearly spelled out the specs for each stage.

I had one of those a few years ago. It is a 4455TC IIRC. Specs on their site. You must install the TC module to get stages. Otherwise it is single stage at 13.x. The TC wire to the battery has the sensor on the ring terminal that goes on the neg battery post IIRC.I got 60 amps from the "55 amper" using #4 AWG wire to the batts. With #8 it only did the 55. It worked as well as the Iota a guy on here had when we did a "shoot-out" contest.It did more like 14.2v rather than the usual 14.4, but it still got the job done.

Battery charge questions | Good Sam Community

wa8yxm
Explorer III
Jun 13, 2021
Not sure about the Parallax 8355 so I googled it. 3-stage so yes it **Should**

But will it.. Parallex is not Progressive Dynamics.
pianotuna
Nomad III
Jun 13, 2021
When the motorhome is in storage the solar is quite adequate to recharge the batteries to full and keep them there.
BFL13
Explorer II
Jun 13, 2021
Didn't see the specs on the Parallax site, but Randy still has info here:

https://www.bestconverter.com/Parallax-Paramode-with-TempAssure_c_104.html

Check the links to the manual and voltage curves eg.
SHRED
Explorer
Jun 13, 2021
2oldman wrote:
SHRED wrote:
I'm having a tough time finding the specs on the 3 stage Parallax charger.
I thought you meant the batteries.

These are the batteries:

https://lifelinebatteries.com/products/marine-batteries/gpl-4ct/
Lwiddis
Explorer II
Jun 13, 2021
230 solar watts is a bit skimpy but depending on where you camp it might work. My 300 watts fills the batteries most of the time. I’ll put a fourth panel on the back of the roof one day or another.
2oldman
Explorer II
Jun 13, 2021
SHRED wrote:
I'm having a tough time finding the specs on the 3 stage Parallax charger.
I thought you meant the batteries.
SHRED
Explorer
Jun 13, 2021
KD4UPL wrote:
You need to look up the proper charge voltages for absorb and float for your batteries. You then need to make sure your Blue sky and your Parallax are programmed for those voltages.
Will it keep your batteries charged? It depends on if you use more or less than the amount of power the solar panel produces.

I should have been clearer with my post.

I meant when the motorhome is in storage.
SHRED
Explorer
Jun 13, 2021
time2roll wrote:
Parallax seems to operate at the low end on voltage. What voltage is your solar absorption set to? How long in absorption?

I'm not sure on any of those. I'll look into the Blue Sky specs.
KD4UPL
Explorer
Jun 13, 2021
You need to look up the proper charge voltages for absorb and float for your batteries. You then need to make sure your Blue sky and your Parallax are programmed for those voltages.
Will it keep your batteries charged? It depends on if you use more or less than the amount of power the solar panel produces.
time2roll
Nomad
Jun 13, 2021
Parallax seems to operate at the low end on voltage. What voltage is your solar absorption set to? How long in absorption?