Electrical Advice re: Espar voltage drop

Hi all, hoping to find some smart minds on here who can advise me what to do next:

We have an Espar diesel heater we installed earlier this year. It was previously working great. We did disconnect and then reconnect the heater recently because of a buildout we were doing, but didn’t change the length of the wiring. At that same time we installed a Victron Battery Monitor.

Just returned from a trip, and our Espar heater kept turning off. It said ‘low voltage drop’

Since we now have a battery monitor, I have been keeping an eye on the voltage of battery. In full sun (300W of panels) it is around 13V. When the engine is running (we have an ACR relay), it is around 13.6V. However, out of full sun, or during the nighttime, it says anywhere from 10.6 to 11.5 V. I think this is why the heater is going through an auto shutoff.

We have a 265Ah lead acid AGM battery that is just over one year old. To my knowledge it has never been drained to empty.

What should we do to troubleshoot next? Could this be a dying battery, and if so, isn’t that awfully soon? I’m not too savvy with electrical things, how do I check the intrinsic charge of battery? Does it matter what time of day I check?

Thanks in advance for any advice you have. We have a newborn and spent one really cold night in the van that I’m hoping not to repeat!

Re: Electrical Advice re: voltage drop

Sounds like a bad battery. Try putting a full manual charge on it and and have it load tested by a repair shop. If It is not holding over 12 volts for at least 15 seconds under carbon pile load. Battery is No Beuno.

That Espar Heater draws very little current.

Re: Electrical Advice re: voltage drop

I'm sure the battery is being chronically undercharged. If it is not hitting at least 14.4 V during the day and staying there for hours that it is being undercharged. I suggest putting the battery on a quality shore power charger for 24 hours, ensuring that it gets to at least this voltage for 12 hours straight. Then perform a standard capacity test. The odds are that your battery is toast. 10.6 V is essentially completely empty and this battery has likely been abused quite a bit at this point.

Most inexpensive solar chargers are woefully inadequate for deep cycling battery applications. And even quality ones will need adjusted to prevent going to float too soon. If you have the space I would suggest switching to a set of GC2 batteries available from Sam's Club or elsewhere under the Duracell brand. While you will need to add water occasionally they are dramatically more durable have a longer life and charge quicker higher voltages.

Re: Electrical Advice re: voltage drop

First. I agree that you likely have a battery (system) issue.

As to your title and comment about wire length.

Given even the most minimal wire gauge selection, for an Espar heater wire length within a van conversion will not be a problem. It is possible for voltage drop to be a problem if there are poor connections eg. - loose connectors, corroded grounds, but wire length of itself isn't a real concern.

As mentioned already, concentrate on improving your battery system. Unfortunately with some of the voltages you mentioned you may need to replace the battery sooner than you anticipated. Low voltages = too much discharge = reduced battery service life.

vic

rainwoman30 said:

Hi all, hoping to find some smart minds on here who can advise me what to do next:

We have an Espar diesel heater we installed earlier this year. It was previously working great. We did disconnect and then reconnect the heater recently because of a buildout we were doing, but didn’t change the length of the wiring. At that same time we installed a Victron Battery Monitor.

Just returned from a trip, and our Espar heater kept turning off. It said ‘low voltage drop’

Since we now have a battery monitor, I have been keeping an eye on the voltage of battery. In full sun (300W of panels) it is around 13V. When the engine is running (we have an ACR relay), it is around 13.6V. However, out of full sun, or during the nighttime, it says anywhere from 10.6 to 11.5 V. I think this is why the heater is going through an auto shutoff.

We have a 265Ah lead acid AGM battery that is just over one year old. To my knowledge it has never been drained to empty.

What should we do to troubleshoot next? Could this be a dying battery, and if so, isn’t that awfully soon? I’m not too savvy with electrical things, how do I check the intrinsic charge of battery? Does it matter what time of day I check?

Thanks in advance for any advice you have. We have a newborn and spent one really cold night in the van that I’m hoping not to repeat!

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Hi, I can imagine how terrible it must have been for you and your child.

Your analysis of the relationship between battery voltage and espar heater cut out is correct. The voltage swing of a nominal 12 volt battery can vary considerably, depending on the temperature, charge conditions, loads, etc.

Somewhat less obvious, but important:
- The colder the battery temperature, the "resting" voltage is lower (not being charged)
- The colder it is, the "charging voltage" needs to increase - sometimes to levels of 15 volts on a really cold day.

- The charge voltage of the starter battery over the useful temperature range of the "starter battery" is different. (because many times they are a slightly different type (for example flooded vs AGM)
- The two batteries are often at different temperatures, so the charge voltage for each is different.

- Regardless of how large of wire is used to connect the two batteries together, the house battery will always
In spite of the well intentioned advice of many, an ACR type connection between the starter battery and house battery will not properly charge your system.

You didn't mention the brands of your house battery, solar charge controller, etc, but those can also be factors. If you can add those in, it can be helpful.

One potential improvement is to use a battery to battery charger to more correctly charge the house battery while you drive. Companies such as ctek and sterling build them exactly for this purpose. This will automatically and more correctly charge the battery to the correct voltage and charge profile. It will "help", but not completely resolve the issue.

You already have an electrical system, but if you were starting from scratch, what we do in our "drop in electrical systems" is make them internally 24 volts - similar to a semi truck or boat. (some of our systems are internally 48 volts for larger power demands) For "12 volt" outlets, we use a 24 - 13 volt DC-DC converter so that the voltage never drops below 13 volts, regardless of the voltage swings of the battery pack.

If you don't have an inverter already, it might make sense to consider switching to 24 volts prior to buying one.

The reason that I designed it this way is to deal with exactly the challenge that you are having. 12 volt compressor refrigerators have the same exact issue.

You can consider to run a high quality 10 awg wire from the battery directly to the heater as an option. Of course it needs a fuse, but use a high quality in-line type, don't run it through a fuse block first as those have too much resistance. Make sure that the wire and connections are tin plated and very well crimped. If they were crimped with a $15 home depot crimper that isn't going to reliably work. A marine electrician will have the tools to do this correctly.

Re: Electrical Advice re: voltage drop

Midwestdrifter said:

I'm sure the battery is being chronically undercharged. If it is not hitting at least 14.4 V during the day and staying there for hours that it is being undercharged. I suggest putting the battery on a quality shore power charger for 24 hours, ensuring that it gets to at least this voltage for 12 hours straight. Then perform a standard capacity test. The odds are that your battery is toast. 10.6 V is essentially completely empty and this battery has likely been abused quite a bit at this point.

Most inexpensive solar chargers are woefully inadequate for deep cycling battery applications. And even quality ones will need adjusted to prevent going to float too soon. If you have the space I would suggest switching to a set of GC2 batteries available from Sam's Club or elsewhere under the Duracell brand. While you will need to add water occasionally they are dramatically more durable have a longer life and charge quicker higher voltages.

Click to expand...

Most of what you wrote I agree with. Where we differ is that I would never recommend to someone to install flooded batteries inside of a conversion van, regardless of their potential electrical lifetime benefits. It isn't the small H2 out gassing that concerns me, it is the acid fumes. Is it worth a few $100 to risk the effects of acid fumes on the other electronics in a van, much less the health of a mother and child?

My personal recommendation would be to use a pair of Lifeline size 31XTs and wire them in parallel for 12 volts or series for 24 volts. Obviously I am biased toward the 24 volt configuration. There are 2 or 3 equivalent batteries out there, but few if any better.

Either way, without a substantial change in the method of charging, no battery is going to hold up.

I have personally lived full time in several vehicles with flooded batteries in the cabin. If desired a vent system is not complicated. However, unless you are equalizing (which you can manually control if desired), there is minimal acid odor. The sulfur dioxide is not a silent killer or poison. If its present, you will know it! A solar system is simply not powerful enough to heat the battery sufficiently for high level acid vaporization. I am very conservative on safety issues. I examined this issue in detail, and discovered the risk is minimal. In fact a number of MFGs actually mount the starter battery (flooded) in the passenger compartment of cars/SUVs. I have also been in off grid power rooms during a charge cycle with tons of batteries. Again, not a major air quality issue.

Midwestdrifter said:

I have personally lived full time in several vehicles with flooded batteries in the cabin. If desired a vent system is not complicated. However, unless you are equalizing (which you can manually control if desired), there is minimal acid odor. The sulfur dioxide is not a silent killer or poison. If its present, you will know it! A solar system is simply not powerful enough to heat the battery sufficiently for high level acid vaporization. I am very conservative on safety issues. I examined this issue in detail, and discovered the risk is minimal. In fact a number of MFGs actually mount the starter battery (flooded) in the passenger compartment of cars/SUVs. I have also been in off grid power rooms during a charge cycle with tons of batteries. Again, not a major air quality issue.

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I don't doubt for a moment your expertise and experience. IIRC:
- Both you and your wife are experienced engineers
- You are a champion of building up a van and jerry rigging things to keep it all working in the middle of no where with minimal resources
- I think I remember you being on the side of the road in New Zealand with the guts of the alternator pulled apart to adjust the output voltage to more correctly charge a Lifeline 8D battery?
- I seem to remember that you bypassed a blue sea fuse block at one point due to voltage drop

Now compare this to the current situation:
- A young family - mother with an infant and nominal electrical knowledge
- She isn't going to even imagine the idea of putting a box of acid in the van with her baby that could potentially fume in the heat of a 130 F interior + charging on a summer day.

They could very well be the victims of some bogus renogy kit or similar installation. In the meantime, all they want is to not have their child freeze on a cold night.

It is important that people see these types of installations for what they are - fundamentally incorrect for critical situations. Working "sometimes" just isn't good enough for a family in a van on a cold night.

Thanks all for your input.

We are using AM solar panels, with Victron 40A MPPT charge controller. We only recently hooked up the battery monitor, so I’m not sure what type of charge the battery had over the last year since we installed it. We did successfully use all the electronics (heater, fridge, fan, pop top) in the van for a year.

There was around a month recently where we had the solar disconnected as we were building out cabinets. At that time we weren’t driving the van at all, so the battery wasn’t getting any charge from the alternator. However, we weren’t using any of the electronics either. Maybe the battery slowly lost its charge then...I guess in hindsight we should have at least started up the van occasionally to give it a little bump.

I will take battery to a repair shop and get it tested, and I guess eat the cost for a new one Sounds like from what you are all saying, the battery is the culprit. Lithium battery out of our budget. The one we have now is Interstate. Any advice for a new AGM battery, hopefully around 250Ah?

Hopefully our system will work for us long term. We live in AZ so as long as the solar is hooked up, there is plenty of incoming power.

The battery may or may not be perfect, but without changes you cannot be sure that the heater will work on a cold night.

Batteries aren't like a light switch on/off - good / bad. They degrade but still work to some level.

If you are going to replace it, my suggestion for similar capacity is Lifeline GPL, either 1 each 8D, or 2 each 31XTs. It is a lot easier to lift the 31XTs than an 8D.

Regardless, the charging situation needs to be improved - as in a battery to battery charger, and perhaps replace the wires to the heater with a 10 awg, marine grade cable directly from the battery to the heater.