- October 9, 2019 at 14:29 #35220JayParticipant
I want to upgrade my batteries and solar panels. I have a Lance 825 one 100 watt solar panel and one battery stock from the factory. What is the best way to upgrade to 2 panels and 2 batteries?
which panels are better Mono-crystalline or polycrystalline?
Is it worth going to lithium battery set up and does the whole system need to be changed?
- October 9, 2019 at 18:33 #35229AnonymousInactive
As far as Mono vs Poly goes, in theory the mono’s are slightly more efficient, but in practice I seriously doubt you’d ever notice a difference, therefore I’d go with the best cost…Solar nowadays can be had on ebay for less than a buck a watt (vs mine at over $5.00 per 10 yrs ago!!)…
Over the last few months I’ve had a chance to gain a fairly decent hands-on working knowledge with a single 100a LiFePo4, running an air conditioner (via inverter) and recharging via 400w solar and a basic PWM controller…
The only downside to Li (besides the initial cost!!) is that they cannot be recharged below 32df (say, when mounted in an outside compartment), yet will continue to provide a discharge down to just below zero df…
The big advantages are, less than half the weight of the equivalent wet-cell,
the voltage remains nearly constant throughout the entire discharge, the harvest-charge recovery rate appears to be at least twice as fast (in my estimation – using just a PWM controller) than with a chemically sluggish wet-cell (great during off-season solar harvesting!), and Li is reported to have about 10 times the available life cycling as does the wet-cell (4-5k cycles vs about 300)…
In my opinion, IF limited to only one battery (due to space limitations) I would definitely go with one Li in order to benefit from more available amp hrs capacity over whats only about 50% ‘usable capacity’ that only one wet-cell will offer…
If you decide on Li, you’ll need to configure your converter-charger and charge controller (if adjustable??…) for a Bulk output at somewhere between 14.4v – 14.6v, and Equalization modes (if present) must be disabled…In many cases (depending on charger specs) Bulk voltages will often fall within this range, while Absorption setting (usually around 13.6v) is not needed but if present will not harm the battery…
If you add another panel (or more) you’ll want to allow for about 10% additional ‘head room’ controller ampacity, and ‘may’ want to upsize the wiring as well to accommodate…As I previously stated, a PWM controller will do fine (due to the uber high receptivity rate of Li), yet a slightly costlier MPPT controller can do even better (gaining roughly 25% or so additional panel efficiency).
- October 14, 2019 at 11:09 #35456
I’m looking into some similar options. I already have 2 100 w panels in place, along with 2 6V Harris AGM batteries, but lately, I have been experiencing some weird things. My solar controller has been giving me some weird battery level readings, and my batteries have been running down very quickly, even though they are only 1 year old. Recently, they went from 30% to 0% in about an hour, while we were away from the camper, with nothing cut on.
I am looking at installing the Vicktron battery monitor, as well as a MPPT controller. Both are bluetooth ready, and hopefully will allow me to monitor my draws and see what might be killing these batteries so quickly.
- October 14, 2019 at 12:25 #35458AnonymousInactive
Hi Chris, AGM’s definitely have their place due to low maintenance and no off-gassing, but one downside is that they (the cells) cannot be equalized to reverse the effects of sulfating overtime, which may also impact longevity…And since they are still considered ‘wet-cells’ voltage will normally sag as the SOC (state of charge) drops off…
As such, this can ‘sometimes’ (particularly when aged and sulfated…) lead to a mild discrepancy between what a shunt based type SOC meter reads versus actual measured voltage as it relates to SOC…The Victron (or equivalent LinkLite or Trimetric) uses a shunt device (installed in the battery negative cable) which once programmed kinda works like a amp counter to arrive at SOC…
Having said that, regardless of which battery type, I believe that a shunt based SOC meter is an invaluable ‘MUST HAVE’ tool to help understand what the actual condition of the battery is…The ‘sometimes’ discrepancy I previously mentioned tends to be virtually non-existent with LiFePo4 lithium due to their near stable voltage characteristics…
- October 14, 2019 at 13:40 #35459
Phil, thanks for the informative response! Since I started experiencing my issues, I keep wading deeper and deeper into this battery situation. I really can’t find anything wrong, so I’m wondering if there could possibly be an issue with my solar controller. I almost never hook up to shore power, so if that controller is doing something weird, maybe that is producing my problem. It shows both the voltage and % of charge, and both have been down very low after only minimal usage. I think I will definitely go with the battery monitor just to be able to see what individual items in the camper are using, and what might be draining the battery so quickly.
I just don’t think under any circumstances that some LED lights, a Fantastic fan, and occasionally the water pump should take my batteries from 100% to under 50% in less than a day.
- October 14, 2019 at 16:40 #35465AnonymousInactive
Chris, you might try using a clamp-on type VA meter to see how much current is leaving the battery…You must make sure that the meter is ‘d.c. capable’ and note the correct pos (+) and neg (-) orientation symbols on the meters clamp…
I would normally suggest to be aware that this time of year solar harvest is reduced, but a 50% loss with only minimal usage sounds a bit unusual…Not sure if this applies, but this can sometimes happen if you have an inverter quietly idling while set to the ‘standby mode’…Or the battery may have lost capacity due to improper charging or too extreme DOD (depth of discharge) – just saying.
FWIW, Here’s a brief primer on d.c. clamp-on VA meter techniques:
- October 15, 2019 at 12:06 #35486
I had a long conversation with the folks at AM Solar about my situation today, and I’ve decided to go with the Victron battery monitor to I can being testing to see what kind of individual loads I am putting on the battery. They suggested if I could accurately measure amp hours used, and compare it to what my batteries are rated for at 100% charge, I could figure out if my batteries might be bad. They are only a year old, so hopefully that’s not the issue, but there seems to be no other good explanation for what is happening.
- October 21, 2019 at 10:22 #35657Joel GambinoParticipant
Search on “handy bob solar”. There is a lot of good info there (in spite of the author’s demeanor).
Look at Bogart Trimetric battery monitor and charge controller.
Here’s a link to a description of my solar installation: https://www.truckcamperadventure.com/forums/topic/my-solar-power-installation/
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